WO1996022266A1 - Hydroformylation of a multi-component feed stream - Google Patents

Abstract

A process for the production of C3 to C6 aldehydes by hydroformylating a mixture of (i) C2 to C5 olefins and mixtures thereof, (ii) C2 to C5 alkynes and mixtures thereof and optionally (iii) cumulated dienes in the presence of a solution of a rhodium organophosphorus complex catalyst at a concentration of rhodium in solution of from 1 to 1000 ppm by weight, in particular the olefine is ethylene and the alkyne acetylene and the ratio of phosphorus to rhodium is greater than 30. The aldehydes are useful intermediates in the production of various alcohols, polyols and acids.

Description

HYDROFORMYLATION O F A MULTI-COMPONENT FEED STREAM

FIELD OF THE INVENTION

This invention relates to hydroformylation methods for certain multicomponent syngas feed streams containing hydrogen, carbon monoxide, C₂ to C₅ olefins, and C₂ to C₅ alkynes.

BACKGROUND OF TF1E INVENTION

There is intensive research worldwide aimed at the utilization of natural gas as a petrochemical feed stock The current use of natural gas is mainly restricted to the production of synthesis gas ("syngas", a mixture of carbon monoxide and hydrogen), and heat.

It has been long known, however, that methane can be converted to acetylene containing synthesis gas mixtures using short contact time acetylene burners. Co-producing ethylene or mixing ethylene with these acetylene rich feeds could provide a cheap, natural gas based feed stock. However, use of such co-produced feed streams has presented problems in certain processes.

Hydroformylation of highly purified olefins and syngas mixtures to aldehyde and alcohol products is well known (sec B Cornils "Hydroformylation Oxo Synthesis, Roelen Reaction" in "New Syntheses w ith Carbon Monoxide", Ed J Falbe, Springer Verlag New York, 1 980) When pur e alcohol products are desired, the aldehyde pr oduct s can be hydrυgenated to the corresponding alcohol deriv atives A par culai ly uselul catalyst has been described lor the hydr oformylation of pure light olefin feeds as a homogeneous oil soluble phosphine modified Rh catalyst (see, e g , US Patents 3, 527, 809 3.917, 661. 4, 148,830) w hich operates at low er pressures than other homogeneous catalysts, giv es high normal to iso ratios in the hydroformylation of C₃ and higher olefins, and has been prov en to be very effective with those pure olefin feeds The use of such an oil soluble homogeneous Rh catalyst to hydr oformylate pu rified ethylene feeds to propanal has been also descr ibed by Evans et al (J. Chem. Soc. (A) 1968, 3 1 33), as well as Pruett et al (J erg Chem 1968, 3 4, 327). There is a great need, however, for a stringent purification of the feed stock, because the activity of the catalyst is st rongly inhibited by acetylene and other highly unsaturated hydrocarbons if they are present as impurities in commercial oxo feeds These components must essentially be removed before hydroformylation ( see B Cor nils " Hydroformylation Oxo Synthesis, Roelen Reaction" in "New Syntheses with Carbon Monoxide", Ed J Falbe, Springer Verlag New York, 1980, pp 64 and 73).

Highly purified feeds of syngas (mixtures of CO and H₂) and olefins are currently made in two separate processes. Light olefins are usually made by steam cracking and purified by cryogenic distillation and selective hydrogenation to remove even traces of acetylenes and dienes. The currently used highly purified olefin feeds contain less than 100 ppm and typically less than 10 ppm of these impurities In fact, a large portion of the cost of ethylene currently produced for hydroformylation by steam cracking is associated with its purification. The syngas component can be made from a hydrocarbon, such as methane or a crude distillate, and oxygen in a partial oxidation (POX) reactor run in a mode that produces essentially no dienes or acetylenes. Even though the syngas made in the POX reactor contains only trace amounts of acetylenes and dienes it is also carefully further purified before being blended with the purified olefin feed.

Hydroformylation of pure acetylenes and of pure dienes with Co or Rh catalysts is also known (see: US Patent 5,312,996, 1994, P. W. N. M. Van Leeuwen and C. F Roobeek J Mol Catal 1985, US Patent 4,507,508, 1985, 31, 345, B Fell, H Bahrmann J Mol Catal 1977, 2, 211, B Fell, M Beutler Erdol und Kohle - Erdgas - Petrochem 1976, 29 (4), 149, US Patent 3,947,503, 1976, B Fell, W Boll Chem Zeit 1975, 99(11),452, M Orchm, W Rupihus Catal Rev. 1972, 6(1), 85, B Fell, M Beutler Tetrahedron Letters 1972, No 33.3455, C K Brown and G Wilkinson J Chem Soc (A) 1970, 2753 B Fell W Rupilius Tetrahedron Letters 1969, No 32, 2721, F H Jardine et al Chem and Ind 1965, 560, H Greenfield et al J Org Chem 1957,22, 542,H Adkins and J L R Williams J Org Chem 1952,71,980) The hydroformylation of these highly unsaturated compounds with cobalt catalysts is slow even at high temperatures and pressures ( 145 - 175 ºC, 20 - 30 MPa) Furthermore the reaction often yields side products and results in runaway reactions with sudden temperature and pressure singes The hydroformylation of olefins is severely inhibited by acetylenes since these compounds form very stable adducts with cobalt carbonyl Stoichiometric amounts of acetylenes can effectively transform the cobalt catalyst into these catalytically inactive acetylenic adducts ( 11 Greenfield et al J Org Chem 1957, 22, 542) With conventional Rh catalysts the reported reaction conditions and reaction rates are far from being practical for any commercial use Fell typically used 17-23 MPa pressures using PPh₃/Rh catalyst, yet high conversions required 2 to 5 hour reaction times Wilkinson achieved high conversion in the hydroformylation of hexyne-1 at 48 MPa pressure but only with a reaction tune of 12 hours Van Leeuwen and Roobeek applied conditions of 12 MPa, 95 - 120 ºC and P/Rh ratios o f 10 or below in the hydroformylation ol butadiene but observed low activities (orders of magnitude below that for olefins) In US Patent 3,947,503 a two stage process is described to hydroformylate 1,3-butadiene In the first stage PPh₃/Rh catalyst is used in the presence of alcohols or diols to make the acetals of the unsaturated C₅-aldehyde In the second stage this intermediate is hydroformylated using Co catalysts The process disclosed in US Patent 4,507,508 also claims the conversion of conjugated dienes with organic acid or ester promoted P/Rh catalyst in the presence of alcohols. US Patent 5,312,996 describes a polyphosphite ligand modified Rh catalyst for the conversion of 1,3-butadiene. When using a two stage process for the hydroformylation of 1,3-butadiene with the disclosed catalyst more severe conditions are recommended in the second stage to ensure acceptable conversions This later patent also describes 1,3-butadiene as a strong inhibitor in the conversion of alpha-olefins In the co-conversion of alpha-olefins with 1,3-butadiene oxo aldehyde products of both the alpha-olefins and 1,3-butadiene were produced

As mentioned, acetylenes and dienes act as strong inhibitors/poisons of catalysts in the hydroformylation of alpha-olefins and their removal is required from oxo feeds European Patent Application No 0225143 A2 discloses a method for the production and utilization of acetvlene and ethylene containing syngas mixtures One of the disclosed utilization schemes is to produce propanal by hydroformylation. but acetylene first must be removed from the feed by selective hydrogenation to ethylene over a heterogeneous metal oxide or sulfide catalyst US Patent 4,287,370 also teaches that inhibitors such as 1,3-butadiene must be removed from C₄-olefin feed stocks bv selective hydrogenation prior to hydroformylation using HRh(CO)(PPh₃)₃ as a catalyst German patent, DE 2638798. teaches that the removal of acetylenes and dienes is necessary in order to ensure acceptable catalyst life in the hydroformylation of olefins with a phosphine modified rhodium catalyst In one of the most often cited sources (B Corruls "Hydroformylation Oxo Synthesis Roelcn Reaction" in "New Syntheses with Carbon Monoxide", IX J Falbe. Springer Verlag Neve York, 1980, p 73) acetylenes and dienes are relerred to as "classical catalyst poisons" for the phosphine modified Rh oxo catalysts Acetylenes and dienes are also reported to be strong poisons in the hydroformylation of olefins with cobalt catalysts (V Macho and M Pohevka Rau Roc 1976, 18( 1), 18, US Patent 2,752,395)

Known catalytic processes convening acetylene and ethylene containing syngas mixtures either produce products other than propanal or the conditions used and /or the reaction rates achieved are far from being practical Thus, for example, European Patent Application No 0,233,759 (1987) leaches the conversion of acetylene and ethylene containing syngas (a mixture of acetylene, ethylene CO, and H₂ with a ratio of 633061, respectively) into a mixture of acrylate and propionate esters in the presence of an alcohol using a Rh catalyst When using a PPh₃ modified Rh oxo catalyst to convert the same feed at a P/Rh ratio of 10.6 under otherwise identical conditions, the essentially dead catalyst (turnover frequency of 1.5×10^-4 mol product/mol Rh/sec, and total turnover of 13 in 24 hours) described in European Patent Application No 0,233,759 (1987) produces some propanal and acetone in a molar ratio of 90 to 1 with traces of methyl ethyl ketone and methyl propionate It has been reported by T. Mise et al. (Chem. Lett. 1982, (3), 401) that syngas mixtures containing acetylene and ethylene yield α,β-unsaturated ethyl ketones in the presence of a Rh catalyst, however, no phosphine is present in the catalyst Observed catalyst activities are very low, on the order of 5 turnover/h, or 139×10^-3 mol product/mol Rh/sec even though the concentration of ethylene in the gas feed is high, 41.7 v. % The total turnover reported by Mise is only 30 in 6 hours.

Thus it would be desirable if methods could be found to enable the processing of oxo/hydroformylation feed streams using rhodium based catalysts that contain olefins and alkynes, particularly ethylene and acetylene. The present invention addresses these needs

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 describes a hvdrotreating guard bed to reduce the level of multiunsaturates in a multicomponent syngas using a rhodium complex as a reagent in a scrubber guard bed.

Figure 2 describes a two-stage oxo process for the hydroformvlation of multi-component syngas mixtures

Figure 3 describes an integrated process for aldehyde product separation and alkyne-olelin recovery with alkyne-olelin recycle

SUMMARY OF THE INVENTION

The present invention provides for methods ol using a multicomponent syngas containing mixed unsaturated hydrocarbon feeds having both an olefin (particularly ethylene) and more highly unsaturated hydrocarbons particularly alkynes ( particularly acetylene) cumulated dienes (particularly allene) and mixtures thereof rather than single type feed streams, in hydroformylation reactions carried out in the presence of certain rhodium complexes as catalysts. As a benefit the invention allows for the co-conversion of acetylen and ethylene using rhodium based catalyst technologies and provides new feed stock and processing options, and simplified production schemes lor the synthesis of the corresponding product aldehydes particularly propanal Thus, the present invention provides a process for the production of C₃ to C₆ aldehydes, comprising hydroformylating a mixture containing

- - (a) C₂ to C₅ olefins and mixtures thereof, and

- - (b) (i) C₂ to C₅ alkynes and mixtures thereof or (ii) C₃ to C₅ cumulated dienes and mixtures thereof or (iii) mixtures of (i) and (ii),

with CO, H₂ and a solution of a rhodium complex catalyst produced by complexing Rh and an organophosphorus compound at a concentration of Rh in solution from 1 to 1000 ppm by weight.

The present invention also provides a process for the production of C₃ to C₆ aldehydes, comprising hydroformylating a mixture containing

- - (a) C₂ to C₅ olefins and mixtures thereof, and

- - (b) (i) C₂ to C₅ alkynes and mixtures thereof or (ii) C₃ to C₅ cumulated dienes and mixtures thereof or (iii) mixtures of (i) and (ii),

with CO, H₂ and a solution of a rhodium complex catalyst produced by complexing Rh and an organophosphorus compound wherein the catalyst solution has a P/Rh atom ratio of at least 30.

The present invention also provides a process for the production of C₃ to C₆ aldehydes, comprising hydroformylating a mixture containing

- - (a) C₂ to C₅ olefins and mixtures thereof and

- - (b) (i) C₂ to C₅ alkynes and mixtures thereof or ( ii) C₃ 10 C₅ cumulated dienes and mixtures thereof or (iii ) mixtures of (i ) and ( ii ).

with CO, H₂ and a solution of a rhodium complex catalyst produced bv complexing Rh and an organophosphorus compound wher ein the catalyst solution has a P/Rh at om ratio greater than the value R₁ wherein

wherein R_B is the P/Rh ratio sufficient for a catalyt ically active Rh complex. pKa_TPP is the pKa value for triphenylphosphine, pKa_L is the pKa v alue for the tr ior ganophosphor us compound, R is the gas constant, and AS _B is 35( N- 1 ) cal/mole/°K. wherein N is the number of P-Rh attachments per ligand molecule

Hydroformylation, as described above, produces the cor r esponding C₃ to C₆ aldehydes T ypically, the P/Rh atom ratio R_B for the catalytically active Rh complex is between 1 and 3. Typically, the rhodium complex catalyst is an oil soluble rhodium complex catalyst produced by complexing in solution a low valence Rh and an oil soluble triorganophosphorus compound. Typically, the catalyst solution may be prepared with an oily solvent such as aliphatic or aromatic hydrocarbons, esters, ethers, aldehydes, the condensation side products of the product oxo aldehydes, etc

The present invention also provides for the production of the corresponding derivatives of the aldehydes produced as provided above, including alcohols, acids, aldol dimers, and various hydrogenation and oxidation products produced from the aldol dimers.

We have also found that the presence of acetylene stabilizes the hydroformylation catalyst.

The present invention may suitably comprise, consist or consist essentially of the elements disclosed herein and may be practiced in the absence of any step not specifically disclosed as required.

DETAILED DESCRI PTION OF THE INVENTION

The headings herein are solely for convenience and are not intended to limit the invention in any w ay In addition, solely for convenience the numbering in Figures and throughout the text is as follows process (e.g., reactant and product) streams are numbered in hundreds, and means for carrying out a process or oper ation ( e.g., units or devices) are numbered in lens T he first digit of each identifies the f igur e to w hich it cor responds

The pr esent invent ion pertains to processes that u se mult icomponent synt hesis gas A mul ticomponent synthesis gas ( MCS ) mixture is defined as gas mixtur es containing carbon monoxide, hydrogen, olefins ( with a general formula of C_nH_{2 n} and w it h a functional group of C=C) having fro m 2 to 5 carbon atoms, and a mor e highly unsaturated hydrocarbon such as alkynes ( wit h a gener al formula of C_nH_{2 n- 2} and wit h a f unct ional gr oup of C= C ) having from 2 to 5 car bon atoms or comulated dienes (with a gener al formula of C_n H_{2 n-2} and w ith a functional group of C-C=C) MCS mixtures can opt ionally contain other unsaturated hydrocarbons such as and conjugated dienes (with a general formula of C_nH_{2n- 2} and with a functional gr oup of C=C-C=C) having 3 to 5 carbon atoms, enynes (with a general formula of C_nH_2n-4 and with a functional gr oup of C=C-C=C ) and drynes ( with a general formula of C_nH_2n-6 and a functional gr oup ol C=C-C=C hav ing 1 t o 5 car bon atoms MCS mixtures may also contain inert components, e g , nitrogen, car bon dioxide, functionally men hydrocarbons such as alkanes and aromatic hydrocarbons, and water vapor As used herein the term "olefin" includes alkenes and excludes dienes, dienes, when present, are referred to separately

In the following discussions "monounsaturates" are understood as a subgroup of hydrocarbon MCS components which have one unsaturated functionality that is olefins or alkynes The "C₂ unsaturates" are ethylene or acetylene individually or combined The "multiunsaturates" are a subgroup of hydrocarbon MCS components which have at least two multiple carbon-carbon bonds 1 e dienes, diynes, and enynes as defined herein taken individually or in any combination

The present invention provides methods for converting certain MCS feeds by reassembling its main components, hydrogen and carbon monoxide (i.e., syngas), C₂-C ₅ alkynes, particularly acetylene, and C₂-C₅ olefins, particularly ethylene, by hydroformylation (oxo reaction).

One embodiment of the process of the present invention provides a method for using a multicomponent syngas feed containing at least carbon monoxide, hydrogen and monounsaturated hydrocarbon reactants of olefinic hydrocarbons having from 2 to 5 carbon atoms (i.e. ethylene, propylene, butencs, and pentenes), and alkynes having from 2 to 5 carbon atoms (such as e.g., acetylene and methvl acetylene ) in a rhodium catalyzed low pressure oxo conversion process I hese monounsaturated alkynes and olefins include the individual C₂-C₅ alkyne components and olefin component s as w ell as mixtures of the C₂-C ₅ alkyne components and mixtures of the C₂-C₅ olefin components I n a preferred embodiment the major monounsaturated hv drocarbon r eactants are essentially ethy lene and acetylene I hese reactants ar e fed into the process as components of a multicomponent sy ngas which may also contain depending on its preparation method reactive C ₃ to C₅ monounsatur ates and C ₃ to C₅ multiunsaturates as minor components and functionally inert mater ials in varying quantities such as carbon dioxide water vapor nitrogen and functionally inert hydrocarbons (such as alkanes and aromatics)

Multicomponent syngas containing substantial amounts of inert (and functionally inert ) components may be referred to as dilute multicomponent syngas Dilute multicomponent syngas can embody any multicomponenl syngas feed wherein the reactiv e components (CO, H₂, olefin alkyne) may be present toget her with substant ial amounts of inert component s The use of f eed str ea ms ha v ing subst ant i al diluent lev els is de sirable in t hat t hese f e ed st reams may be available at substantial discount relative to the cost of highly purified components For example, the olefin contained in cat cracker light ends or in steam cracker furnace effluent can be available at substantial discount relative to purified olefins Likewise, acetylene and syngas are less costly if they can be obtained without complete purification Furthermore, partial oxidation (POX) processes can be less costly if air is used as feed instead of oxygen Syngas or multicomponent syngas from such an air-blown POX might be characterized as dilute multicomponent syngas due to the substantial levels of included N₂. In principal, the amount of inert components present in a dilute multicomponent syngas may be any value, even reaching 99% of the feed stream Typically, inert component levels in a dilute multicomponent syngas are between 1 % and 80% of the stream Table 2 (Example 1 ) shows an example of hydroformylation of a dilute multicomponent syngas having 63% of inert components, including N₂, CO₂, CH₄, and C₂H₆

Certain trace components in the multicomponent syngas feed of the overall process referred to herein as "multicomponent process feed" are known to be detrimental in the oxo reaction Some are irreversible catalyst poisons , e.g , sulfur compounds such as H₂S and COS Others cause reversible poisoning or accelerated catalyst deactivation This later group includes components like halides, cyanides, oxygen, and iron carbonvls The concentration of these detrimental components can be ad|usted by a variety of techniques known in the art to provide an acceptable multicomponent syngas feed to the oxo reactor or unit referred to herein as "multicomponent oxo reactor feed"

Multicomponent syngas mixtures are available f rom a variety of different sources A benefit of the present invention is that any mixed acety lene-et hy lene sy ngas mixture can be used as a f eed stock in the processes of t he present inv ent ion

A variety of methods exist to manufactur e mult ic omponent sy nthesis gas mixtures useful in t he process of the present inv ent ion One is 10 blend a stream containing syngas (a mixture of CO and H₂ ) w ith a str eam containing a mixture of acetylene, ethy lene, and optionally other unsatur ated hydr ocar bons Both of t hese streams can be obtained from conventional petrochemical processes T he syngas ( C O and H₂ ) containing stream can be produced bv conventional partial oxidation ( PO X ) Lig ht monounsaturates (C₂-C ₅ ) containing ethylene and acetvlene as major unsaturated hydrocarbon components can be obtained from petrochemical processes such as steam cracking or acetvlene manufacture, or by modification of one of the known pr ocesses used to manuf acture acetylene or syngas T hus acetylene can be f ormed using a ini t ial oxidation pr ocess that applies a burner to react met hane-ox ygen mixtur es. Ac ety lene bur net s led w ith about tw o to one molar ratio of methane and oxygen can directly produce an acetylene rich gas mixture that contains ethylene as well as CO and hydrogen Quenching the reaction with naphtha can further increase the concentration of acetylene and ethylene in the acetylene burner product stream Ethylene or syngas can also be added to acetylene rich mixtures to adjust the molar ratios of the components An advantage of the foregoing is that it allows for the utilization of an abundant feed stock, such as natural gas, and eliminates the need of elaborate and expensive separation and purification of oxo feeds often resulting in significant yield losses and added expense

In order to maintain the partial pressure of acetylene below the safety limit, a part of the acetylene may be scrubbed from MCS feeds before compressing them to the reaction pressure for the oxo reactor Alternatively, acetylene-containing streams can be diluted with other feed components, e.g., ethylene, carbon monoxide, hydrogen or mixtures thereof

Multicomponent syngas streams entering the oxo hydroformylation reactor or reaction zone (multicomponent oxo reactor feeds) in the process of the present invention contain C₂ to C₅ monounsaturates, among which the ethylene to acetylene ratio is in a range from 1 100 to 100: 1 , preferably 1 : 10 to 10.1. Typically, the mixture contains an amount of olefins that is at least 40% of the total unsaturates The amount of CO and H₂ in the multicomponent oxo reactor feed, with respect to the amount of monounsaturates is preferred to be at levels of at least about that required for the stoichiometnc conversion of monounsaturated hydrocarbons in the oxo reaction A stoichiometnc conversion of these species requires that the mole percent of CO be equal to the sum of the mole percents of monounsaturates Similarly, for stoichiometnc conversion, the mole percent of H₂ should be equal to the sum of the mole percents of C ₂ to C ₅ olefins plus tw ice the mole percents of C₂ to C₅ alkynes It is preferred that the CO and H₂ be pr esent in the multicomponent oxo r eactor feed in a range from half to 100 times that required for stoichiometric conv er sion I t is mor e pr ef erred that the concentrations of CO and H₂ be in the r ange from 1 to 1 0 t imes that r equired for a stoichiometric conversion

Subject to these r equir ement s , H₂/CO r atios in the mult icomponent sy nthesis gas entering the oxo reactor (i. e. in the multicomponent oxo reactor feed ) can range fr om 1 1 to 100 1 , preferably 1 : 1 to 50: 1 , more preferably 1: 1 to 10: 1 While the presence of excess volumes of H₂ is pr eferred fr om a chemistry perspectiv e, a large excess of H₂ of greater than 10 is not desirable from a materials handling perspective and can result in unnecessary expense in unit operation A range of composition values, as well as a typical composition for the principle species present in multicomponent syngas mixtures entering the oxo reactor (i.e. in the multicomponent oxo reactor feeds) for the process of the present invention are given in Table

1.

Multicomponent syngas mixtures produced by, e.g., steam cracking or by partial oxidation can contain a variety of molecular species which are detrimental to the hydroformylation process or are known to deactivate oxo catalysts For example, rhodium metal complex hydroformylation catalysts are known to be poisoned by certain sulfur containing molecules (e g., H₂S, and COS) which irreversibly bind to the metal center Such poisons can be removed by use of common chemical and chemical engineering techniques such as the use of guard beds, particularly guard beds containing zinc oxide

The streams used with the present invention mav also contain multiunsaturates having 3 to 5 carbon atoms Their concentrations are typically less than 5 mole% of the total unsaturated hydrocarbon fed to the hydroformylation Catalysts discussed herein as being active tor the hydroformylation of olefins and alkynes will similarly be active for the hydroformylation of olefins and multiunsaturates. Highly unsaturated components such as these multiunsaturates can be inhibitor in the oxo conversion of olefins They may reduce the activity of the oxo catalyst bv associating very strongly with the metal and thus diminishing the activity of the catalyst toward the hvdroformylation of olefins Therefore, the quantities of multiunsaturates are preferably less than 5% of the total unsaturated hydrocarbon fed to the hydroformylation More preferably, multiunsaturates should be present in hydroformylalion feed in amounts less than 1 mole% of total unsaturates Examples 4 and 8 demonstrate the hydroformylation of multicomponeni svngas mixtures that contain olefins and multiunsaturates (specifically allene) An exception to the foregein preferences on multiunsaturate concentrations is the group of non-conjugated, non-cumulated dienes (diolefins), for which there are no restrictions

Generally speaking, the multicomponent oxo reactor feed streams preferably contain monounsaturates Multiunsaturated hydrocarbons containing conjugated and cumulated diene and enyne type unsaturation are considered less desirable. These multiunsaturates may be removed from multicomponent process feeds or their concentrations may be reduced before contact with the hydroformylation catalyst Although multicomponent syngas products generally do not require treatment before their use in the processes of the present invention, feed streams containing multiunsaturates in higher concentration than the above preferred concentrations may be treated, segregated or diluted with streams comprising substantially CO, H₂, monounsaturates, and inerts.

MULTIUNSATURATES REMOVAL

Multicomponent process feeds can be treated if necessary before entering the oxo reactor (i.e, prior to hydroformylation) if the concentration of the above specified multiunsaturated inhibiting components is too high Mild selective hydrogenation, for example, using heterogeneous catalysts (e.g, Pd on alumina, or mixed oxide and sulfide catalysts as described in EP Application 0,225,143,1 can convert these reactive hydrocarbons to olefins and alkanes These conventional heterogeneous hydrotrcating methods, however, have drawbacks For example, in heterogeneous systems high concentrations of unsaturated hydrocarbons (i e olefins, alkynes, and multiunsaturates) with high concentrations of hydrogen present a hazard of a highly exothermic runaway reaction Catalyst selectivity and other plant operation issues provide further incentives to seek alternative solutions

Therefore, another embodiment of the piesent invention provides a selective, liquid phase process to address the problems associated with the application ol the known heterogeneous catalvsis The liquid phase used in the pioccss can be a homogeneous phase or a pumpable, solids-containing sluny Applicants have found that the Rh catalyst used in the hydroformylation process of the present invention is suitable for the selective conversion ol the foregoing multiunsaturated hvdiocarbon components to olefins when the complex is used not as a caialysi but as a stoichiometric reagent in a separate pre-treatment step The preferred reagent is the organophosphorus modified rhodium catalyst of the oxo/hydroformylation reactor described more detail in "Rh OXO CATALYST" below In a preferred embodiment a two step proscess is used to convert excess multiunsaturates in the MCS to olefins and alkanes In the first step ol the process the Multicomponent Syngas is contacted with a solution containing the liganded rhodium complex as a reagent T he str ong preferential binding of multiunsaturates to the rhodium complex serves to extract them from the MCS and into the solution where they are held as bound species on the rhodium This gas/liquid "scrubbing" effectively removes the multiunsaturates from the MCS feed The Rh complex essentially functions as a stoichiometric reagent, binding the multiunsaturated hydrocarbons from MCS during the contacting. In a separate, second step the multiunsaturates are converted to the corresponding olefins and the rhodium complex is regenerated by contacting the complexed multiunsaturates containing solution with a gas of high hydrogen and low carbon monoxide content for an amount of time sufficient to effect the conversion of multiunsaturates

If such multiunsaturates hydrogenation was carried out under .conventional hydroformylation conditions, i .e, at CO partial pressures of 10- 1000 kPa, the conversion of these strongly bound species to olefins would be slow (see Example 4), such that the required rhodium concentrations would be uneconomical However, we have discovered that the conversion of these multiunsaturates can be substantially accelerated under conditions of higher hydrogen, and especially, lower CO partial pressures than conventional rhodium hydroformylation The complexed multiunsaturates-containing Rh solution can be regenerated in a separate reactor, with a hydrogen rich gas, i e , a gas having high hydrogen and low CO concentrations or pure hydrogen During this regeneration, the Rh complex is returned to its multiunsaturate-free form, while the multiunsaturates are hydrogenated to the corresponding olefins and alkanes Thus allene, for example, is hydrogenated during this process first to propylene, while butadienes ar e hydrogenated to buienes I n this r egeneration hydrotreating step some of the olefins formed fr om mult iunsaturates will be further hydrogenated to the corresponding alkanes The hydrogenat ion rate in t he regenerat ion step can be adjusted by adjusting the partial pressures of hydrogen and CO Higher partial pressur es of hydrogen will increase the rate of hydroge nation On the cont rary incre asing partial pr essures of C O will reduce t he hydrogenat ion act ivity of the catalyst T he r at e and selectivity can be convenient ly cont rolled by adjust ing t he par t ial pressur e of CO in t h e hydrotreating reactor

T he benefit of the herein descr ibed process is that the composition of the scrubbing solution used for the stoichiometric removal of multiunsatur ates can essentially be t he same a used for the catalytic oxo step Any level of multiunsaturates removal can be accomplished The multiunsaturated hydrocarbons ( e g allene or vinyl acetvlene) are prefcrent ially remove from the gas phase because they bind st ronger than the monounsaturates, part icular ly olefins Since the str onger binding component s ar e t he str onger i nhibit or s in t he oxo co nversion of monounsaturates, in particular in the oxo conver sion of olefins, the process removes the strongest inhibitors first and produces a purified, multiunsaturate-deficient MCS, which is preferred as oxo/hydroformylation reactor feed. An additional advantage of using the rhodium oxo catalyst solution for the pre-treatment of MCS hydroformylation feed is that it is unnecessary to rigorously control losses of rhodium complex due to entrainment in the MCS gas phase, because the downstream hydroformylation reactor system must have means to effectively capture this Rh complex Furthermore any Rh compound carried over by the MCS stream will not contaminate the catalyst in the oxo reactor since the compositions are essentially the same.

By way of example, Figure 1 shows Absorber 1 1 , in which the multiunsaturates- containing MCS feed ( 101 ) is contacted with a multiunsaturates-depleted solution of the oil soluble rhodium complex ( 105) This absorber is analogous to guard beds of sacrificial catalyst that are sometimes used in heterogeneous catalysis The multiunsaturates-depleted MCS stream ( 102) emerges from the absorber to be sent to hvdroformvlation (shown here as two reactors ( 13 and 14) in series, each with pumparound cooling ( 107 and 109) and reactor effluents ( 108 and 1 10)) Unlike the "guard bed" of heterogeneous catalysis, the multiunsaturates-containing "sacrificial" catalyst of this process is a pumpable liquid phase solution of a Rh complex ( 106) that is recovered at the bottom of the absorber The complexed multiunsaturates-containing solution ( 106) is pumped into a regeneration reactor ( 12) in which it is treated with a hydrogen-containing gas ( 104) I n the regeneration reactor, the multiunsaturates-free rhodium complex is recovered by the hydrogenation of the complexed mult iunsaturates to olefins and alkanes A gaseous pur ge stream ( 103 ) from the regeneration reactor is used to preserve high concentrations of hydrogen The regenerated multiunsaturates-depleted solution of the Rh complex ( 105) is r eturned from the regenerator ( 1 2) to the absorber ( 1 1 ) To the extent that the olefin and alkane products of multiunsatui ates hydrogenation remain dissolved in the catalyst solution, they w ill be transferred back to the MCS stream d uring contact w ith the catalyst solut ion in absorber ( 1 1 )

T he leniperatui e in the absorber ( 1 1 ) is maint ained in the range of 0 to 1 50 °C pr efer ably bet w een 20 to 60 ºC If the temperatur e exceeds these limit s, the Rh complex can decompose unacceptably fast Also, at higher temper atur es there is the possibility of high reactivity and exotherms if the absoiber has locations where both the Rh containing solution and MCS are depleted in inhibitors This would be true, for example, at the lop of a counter-current absorber Lower temperatures are acceptable However, the rate of equilibration between the Rh complex and inhibitors will become limiting at some low temperatures Furthermor e, low temper at ures can entail an ext ra cost of r efriger at ion with no added advantage from a process point of view The pressure in absorber 11 is kept preferably at less than about 5 MPa with a partial pressure of acetylene below the safety limit of 02 MPa In a preferred embodiment the absorber is positioned immediately before the oxo/hydroformylation reactor

The temperature in the regenerator (12) is maintained in the range of 50 to 150 °C, more preferably between 80 to 125 °C The pressure in the regenerator is typically limited by engineering, and economic factors. Higher hydrogen pressures accelerate the regeneration of the multiunsaturates-free Rh complex and the hydrogenation of the scrubbed and complexed multiunsaturates, permitting smaller regeneration vessels and smaller quantities of rhodium complex. Preferably the pressure in the regenerator is maintained in the range of about 01 to 50 MPa, and more preferably in the range of about 1 to 10 MPa The liquid feed to the regenerator leaves the absorber (11) without any treatment The gas feed is a hydrogen containing gas, which can be either essentially pure hydrogen or a gas mixture enriched in hydrogen and deficient in CO Other guard beds designed to remove irreversible poisons of the Rh oxo catalyst such as sulfur compounds, halides, cyanides, iron carbonyls and the like, should also be used to pretreat the MCS feed stream to the multi-unsaturates absorber (11) The hydrogen-rich feed gas to the regenerator (12) should also be essentially free of the foregoing irreversible poisons, and other detrimental compounds to the Rh complex The addition of pure, sulfur free hydrogen is preferred in the gas feed to the regenerator The rate and selectivity of the hydrogenation step toward producing olefins from multiunsaturates and alkynes can be controlled by adjusting the partial pressure of CO The H₂/CO partial-pressure ratio in the regenerator should be 10 or higher, preferably 50 or higher Higher CO partial pressures lead to higher selectivity to olefins but reduced late to multi-unsaturates conversion In certain cases the CO dissolved m the complexed multi-unsaturates-coiuaining solution (106) can pi o vide a sufficient partial pressure of CO in the regenerator (12) If necessary, CO can be co-fed with hydrogen containing gas into the regenerator or gas mixtures deficient in CO and enriched in hydrogen can be used

The absence of CO does not have a destabilizing effect on the Rh complex but does affect the rate and selectivity of the hydrogenation of the unsaturated hydrocarbons present in the regenerator With no CO present all unsaturated hydrocarbons, including olefins, tend to be hydrogenated to alkanes It is therefore desirable to maintain CO concentration in the regenerator at a level sufficient to preferentially hydrogenate the multiunsaturates only to olefins in order to achieve an economic compromise between faster regeneration of the multiunsaturates-free Rh complex (therefore smaller equipment size, and smaller Rh load) and loss of C₂ to C₅ olelin source due to reduced selectivity The separation of the multiunsaturates from the main stream of the multicomponent syngas improves the over all selectivity of the process since the multiunsaturates are tr eated separately so that the bulk of ethylene and acetylene in MCS is not exposed to the hydrogenation conditions appropriate for rapid conversion of multiunsaturates

The flow rate of catalyst solution to the absorber is set to meet the concentration limits given for multiunsaturate of the multicomponent oxo reactor feed, as described previously The flow rate of rhodium should be set at a sufficient level to stoichiometr ically combine with the amount of multiunsaturates to be removed Thus, a treat ratio can be defined as the ratio of the flow rate of rhodium to the absorber (expressed as moles per unit time) to the flow rate of multiunsaturates to be removed (also as moles per unit time) For an ideal absorption system, this treat ratio can be exactly 1 0 for perfect removal of only, the desired multiunsaturates Treat ratios should be between 0 5 and 50 in the current invention, preferably between 1 and 10 Higher treat ratios would be recommended if a significant fraction of the rhodium complex is inactive, or if it is desired to remove and convert some fraction of the alkyne component of the MCS in addition to the multiunsaturates

Conditions (temperature, pressure, residence time, etc ) in the regenerator are set such that conversion rate of multiunsaturates equals the rate at which they are being carried into the regenerator by catalyst solution (which, in turn, equals the rate of mulu-unsaturates removal in the absorber) Example 4 includes selected rates of multiunsaturates conversion that can be used by one skilled in the art of chemical engineering to specify operat ing conditions of the regenerator The scrubbing solution may be essentially the same as t hat of the catalyst solution used in t he oxo reactor step or any soluble ot slur ry phase c ataly st that achiev es t he same effect under the conditions her ein Pr eferably the absorpt ion pr ocess uses the spent catalyst solution from the oxo r eactor as a scrubbing solut ion befor e its final disposal and/or recycling

An advantage of t he use of t he above described tr eatment from the aspect of the process of the present inv ention is t hat the multiunsaturates ar e not conver ted in the oxo reactor ther efor e do not tie up a lar ge amount of activ e cataly st T hey ar e r emov ed f rom the mam f eed str eam and separately conv er ted into olefins The for med olefins ar e then preferably recycled to the multicomponent oxo reactor feed, and hydrofor mylated in the oxo reactor A further advantage of the use of the present absor ption-regener ation pr ocess for multiunsalurates conversion is in the elimination of the hazard of runaway hydrogenation reactions associated with hydr ogenat ion of highly unsatur ated hydrocarbons T his hazard is eliminat ed in t he pr act ice of t he un i on invent ion because the amount of u nsaturat ed spec ies in the r eactor is limited to the amount carried in bound to the r hodium or physically dissolved in the solvent T hus, each Rh site is limited to a very limited turnover before it runs out of unsaturated species to hydrogenate. Under this situation, even a rapid increase in reaction rate can only result in the conversion of a limited amount of unsaturated species and so the resulting heat release is strictly limited.

Rh OXO CATALYST

In the process of the present invention the oxo/hydroformylation catalyst is a rhodium complex catalyst, preferably an oil soluble rhodium complex catalyst The oil soluble catalyst is typically formed by a complexation reaction in solution between a low valence rhodium, an oil soluble organophosphorus compound, preferably a triorganophosphorus compound or a mixture of such compounds, and carbon monoxide Under reaction conditions the Rh central atom may be complexed w ith other species present in the r eaction mixture, such as ethylene, and other olefins (e.g., propylene), acetylene, and other alkynes (e g methyl acetylene), dienes, and other highly unsaturated hydrocarbons (e.g., allene, butadienes, vinyl acetylene, etc. ), and hydrogen, which also can act as ligands.

The preferred triorganophosphorus compounds suitable for the pi eparalion of the Rh complex catalyst for the use in the oxo reactor in the present invention belong to the group of oil soluble tr iarylphosphines, trialkylphosphines alkyl-diarylphosphines. aryldialkylphosphines, trialkylphosphites, tr iarylphosphites, containing at least one phosphorus atom per molecule These should be capable ol complexation w it h Rh by the v irtue of hav ing a lone pan of electr ons on the phosphorus Non- i mmti ng examples ol such of soluble triorganophosphor us compounds lor use in the cata lyst include trial y lphosphines such as triphenylphosphine or tri-p-tolylphosphine, trialkylphosphines, such as triocty Iphosphine or tricyclohexy lphosphine, or alkyl-diarylphosphines. suc h as octv ldiphenylphosphinc or cvclohexykliphenylphosphine, or ary ldialkv lphosphines. si. eh as pheny I droctylphosphine or phenvTdicvclohcxylphosphine, etc T he tnorganophosphoi us compounds that can serve as ligands can also be othei phosphor us containing compounds such as triorganophosphites e g , trialkvlphosphites such as triocivlphosphite, tr iarylphosphites such as in-p-tolylpho sphite I n addition to monodentate phosphor us ligands, bidentat e compounds such o diphos (bis(diphenylphosphino)ethane) can be used An extended list of suitable phosphine hgands is given in Falbe's book at p 55 - 57 Pr efer ably, the oil soluble triorganophosphoi us compound is a trialkylphosphine such as t r icyclohexylphosphi ne and t r ioct y lphosphine or a t r iarylphosphine such as t r ipheny Iphosphine However ot her ligands such as phenyldicyclohexylphosphine, diphenylcyclohcxylphosphine, phenyldiocivlphosphine, tri-p-tolylphosphine, trinaphthylphosphine, phenyl-dinaphthylphosphine, diphenylnaphthylphosphine, tri-(p-methoxyphenyl)phosphine, tri-(p-cyanophenyl)phosphine, tri-(p-nitrophenyl)phosphine, p-N,N-dimethylaminophenyl-(diphenyl)phosphine, and the like can be used if desired Mixtures of triorganophosphorus compounds can also be used

It will be recognized by one skilled in the art that other ligands used with rhodium for hydroformylation can, in turn, be used in the present invention for the hydroformylation of multicomponent syngas, provided the catalyst is used at sufficient ligand/Rh ratio Further examples of ligands for hydroformylation include transition metal bis-phosphite catalysts (as disclosed in US 4,885,401 ), bidentate organophosphorus ligands (as disclosed in US 4,742, 178), and transition metal polyphosphite ligands (as disclosed in US 4,769,498)

It will be further recognized by one skilled in the art that reaction media other than oily ones can be used in the present invention for the hydroformylation of multicomponent syngas Typically, the catalyst is rendered soluble in a reaction medium by using suitable ligands for complexation Thus the hydroformylation of MCS can be performed in aqueous media by using organophosphorus ligands containing at least one substituent on the hydrocarbon radical of the ligand which imparts water solubility to the ligand Such subtituents include, for example, the carboxyhc, amino, and sulfo functional groups Examples of such ligands can be found in US patents 4,24S,S02, 4,808,756, 5,3 12.95 1 , and 5,347,045 which are incorporated herein by reference Hy droformylation of MCS can also be performed in a fluorinatcd hydrocarbon medium providing that the Rh complex is rendered fluorous soluble as described in US patent 5.463,082 w hich is incorpor ated herein by ref erence

Rhodium complexe s prepai ed using the af orementioned ligands may also be used in solution in the multiunsaturates remov ing absor ber/regenerator sy stem described prev iously In fact using the spent catalyst solution from the hydrolormy lat ion reactor before it s final disposal and/of recycle could be advantageous because of the potential say ings in reagent cost in the multiunsaturates removing step

Rhodium complex cataly sts prepared using the aforementioned ligands are known to provide good catalytic activity in the hydrolormylation oi pure olefin feeds but are inhibited/poisoned by alkynes, particular Iy acetylene Applicants, however have unexpectedly found that these ligands can be used in the hydrof ormylation of syngas containin g mixed C ₂ to C₅ olefin and alkyne feed stocks especially acetylene and et hylene provided that the phosphorus and t hodium in t he cataly st ar e pr esent in amount s t hat r ender t he c ataly st catalytically active Preferably, the P/Rh ratio is maintained above a specified minimum value We have found that, for triphenylphosphine (PPh₃), this minimum value should preferably be 30 The preferred ligand concentration can also be expressed in terms of the minimum concentration of the coordinately active phosphorus [P] in the solution or in terms of a minimum [P]/_pco ratio in the reaction, wherein p_co is the partial pressure of carbon monoxide in the gas phase. For PPh₃, [P] should preferably be above 0.01 mol/l, and the [P]/pco ratio should preferably be above 0.1 mmol/l/kPa. The Rh concentration in the reaction mixture should be in the range from about 1×10^-5 to about 1×10^-2 mol/liter This range of Rh concentrations corresponds to a Rh concentration in the range from about 1 to about 1000 ppm (by weight) In a more preferred embodiment the Rh should be present in the range of 50 to 750 ppm, based on the total weight of the solution Within the above ranges, the choice of catalyst concentration can reflect engineering and economic considerations

The hydroformylation of the oxo reactor feed is carried out by contacting the catalyst with the multicomponent syngas in a solution of the catalyst prepared with a solvent or a mixture of solvents Oily solvents that can be used for the preparation of a catalyst solution used in the oxo/hydroformylation step are known in the art, and include aliphatic, and aromatic hydrocarbons (e.g., heptanes, cyclohexane toluene, etc), esters (e.g., dioctyl phthalate), ethers, and polyethcrs (e. g. , tetrahydrofuran, and tetraglyme), aldehydes (e.g., propanal, butanal, etc.), the aldol condensation products of the oxo product aldehydes, the triorganophosphorus lignnd itself (e g , triphenylphosphine), etc

For catalyst compositions outside of the specified ranges, particularly for catalysts with P/Rh ratios below the minimum value for a catalvticallv active hydroformylation catalyst (which for PPh₃ is 30), the catalyst has a significantly reduced activity Preece and Smith (EP 0,233,759). for example, have investigated the hydroformylation of an acetvlene containing multicomponent syngas mixture in the presen/e of PPh₃ modified Rh₆(CO)₁₂ catalyst In spite of the fact that the feed gas contained high concentrations of the reactants (acetylene ethylene, CO, and hydrogen with a ratio of 6330 ol respectively), the catalvst solution contained high concentration of Rh (00108 mold) and PPh₃ (0114 mol/l). and the total pressure was 091 MPa. the catalyst tailed as evidenced by the fact that the total turnover in the presence of acetvlene was only 13 m 24 houis. giving a veiv low turnover frequency of 15x10^-4 mol propanal/mol Rh/sec Under those reported conditions the Rh catalyst has high activity in the hydroformylation of ethvlene alone (C K Brown, and G Wilkinson. Tetrahedron Letters 1969, 22, 1725) Resides the expected propanal. the product mixture also contained 1 1 mole% acetone not observed in hydroformylation pioduct mixtures of ethylene. This effect ol acetylene on the oxo conversion of ethylene is well documented in the literatur e, and is the reason that acetylenes are referred to as "classical catalyst poisons" for the phosphine modified Rh catalysts (sec B Cornils, "Hydroformylation Oxo Synthesis, Roclen Reaction" in New Syntheses with Car bon Monoxide, ed J Falbe, Springer Verlag. New York, 1980, p. 73).

Applicants have found, however, that under proper conditions, particularly at specific, appropriate P/Rh ratios the inhibiting/poisoning effect of alkynes can not only be overcome but in fact the alkyne components themselves can be converted to the corresponding saturated aldehydes. These ratios are typically high. The catalyst used by applicants herein shows enhanced activity, and is not poisoned by C₂-C₅ alkynes such as acetylene but rather co-converts them with olefins to corresponding C₃-C₅ aldehydes, as evidenced by its high turnover frequency with feed streams containing acetylene, ethylene. CO, apd hydrogen Applicants have found that the catalyst system evidences changed activity with varying coordinatively active P concentrations and P/Rh ratios Physical evidence of this change comes from experiments conducted with acetylene and ethylene containing multicomponent syngas feeds at 100 and 1 10 °C, and 0.8 and 2 2 MPa total pressures, respectively, with different PPIr/Rh ratios (see Examples 1 , and 2) When the PPh₃/Rh ratio was 9.3, essentially the same as in the experiment of Preece and Smith, albeit using a different Rh source, the final catalyst solution had a dark brown color but was orange when the PPh₃/Rh ratio was. higher, e g , 300 The brown color of the solution containing the catalyst with a P/Rh ratio of 9 3 evidenced that the catalyst decomposed At 1 10 °C. and 2 2 MPa total pressure the total turnover with a PPh₃/Rh ratio of 9 3 w as only 4.9 in 2 hours, while under milder condit ions of 100 °C, and 0 8 MPa total pressure the total turnover w as 22 1 in 4 s minutes when the PPh₃ /Rh ratio was 300 This later catalyt ic rate is in the range of t he hydroformylation rate of pr opylene under otherwise ident ical conditions T he catalyst with a PPh₃/Rh ratio of 300 thus showed an average turnover fr equency of 0 082 mol propanal/mol Rl\/scc, w hile the catalyst with a PPh₃ /Rh ratio of 9 3 gav e an average t ur nover frequency of 6.8× 10^-4 mol propanal/mol Rh/sec, i e 120 times slower I nitial turnover frequencies as high as 2 mol propanal/mol Rh/sec have been achieved with the process of the present invention in the conver sion of an MCS feed which contained 1 5 5 volume % ethvlene. and 6.5 volume % acetylene using a PPh₃ /Rh catalyst with a PPh₃ /Rh ratio of 660. and above ( see Example 3 )

Thus, one embodiment of the present invention is that, for any organophosphorus compound used to modify rhodium for use in hydroformylation, there exists a catalyst P/Rh ratio sufficiently high to create an active catalyst for the hydrofor mylat ion of multicomponent syngas While catalysts below this P/Rh ratio may pro vide a minimal lev el of tur nover , as evidenced by the turnover f r equency of 6 8× 10^{- 1} mol oxo/m ol R h/sec achiev ed with PPh ₃ at a P/Rh ratio of 9.3, a catalyst with utility would preferably be at P/Rh ratio sufficiently high as to provide activity of at least 10^-2 mol oxo/mol Rh/sec

Other experiments carried out with multicomponent syngas mixtures in the presence of rhodium PPh₃ catalysts with P/Rh ratios of 100 or higher showed high selectivity for propanal of about 995 %, in a wide range of H₂/CO, and acetylene/ethylene ratios and temperatures, even at conversions as high as 99 % The only other product detected was ethane On the other hand it has been reported (T Mise et al Chem Lett 1982, (3), 401) that acetylene and ethylene containing multi-component syngas mixtures yield α,β-unsaturated ethyl ketones in the presence of unmodified Rh catalyst, where the P/Rh ratio is zero

Applicants have found at PPh₃/Rh ratios of at least 30, and preferably above about 100, significant improvements in rate, conversion, and stability ate achieved For example, at PPh₃/Rh ratios above 30, initial rates of at least 0.04 mol/mol Rh/sec and conversions of at least 80% have been achieved with an orange-yellow catalyst color that indicates a stable catalyst At these PPh₃/Rh ratios, the hydroformylation of acetylene and ethylene containing MCS mixtures is facilitated and also may stabilize the catalyst in a form that catalyzes hydroformylation in preference to the formation of other oxygenates, such as ketones and esters

The aforementioned eflect in which the hydroformylation of acetylene and ethylene containing MCS mixtures stabilizes the catalyst, can provide a strong incentive to add alkynes (especially acetylene) to olefins (especially ethylene) for hydroformylation Under conditions suitable for hydroformylation of olefins with alkynes and other multiunsaturates both the ligand and the alkyne have equilibria strongly biased toward binding to the rhodium This greatly reduces the reservoir of rhodium that has insufficient ligation which in lion reduces the rate of rhodium cluster formation, which cluster toim.ilion is the pimcipal pathway of rhodium deactivation Thus, as shown in Example 7 catalyst deactivation can be greatly reduced by the addition of a small amount of alkyne As such one pretcired embodiment of the present invention is a process for hydrolormylating olefins (particularly ethylene) in which a small amount of alkynes (particularly acetylene) and/or multiunsaturates are added sufficient to mitigate catalyst deactivation A preferred alkyne addition level would be from about 10 ppm to about 10% on total unsaturate, more preferably from about 100 ppm to about 5% on total unsaturate The addition of alkynes or multiunsaturates may provide sufficient advantage in terms of reduced deactivation and in terms of the higher seventy conditions (eg temperature olefin conversion etc ) enabled by reduced deactivation, that this embodiment can be used to improve olelin ( particularly ethylene) hydroformylation, wherein the alkynes or multiunsaturates ar e pr esent essentially for the purpose of mitigating deactivation, and wherein aldehyde yield from those alkynes or multiunsaturates may be inconsequential or insignificant

For ligands other than triphenylphosphine, the minimum ligand concentration may be different When the catalyst is used to convert multicomponent syngas mixtures that contain alkynes, an important characteristic of the ligand is its ability to compete against the alkyne for binding with the rhodium. The active rhodium catalyst has a varying amount of bound ligand, but an average over the active states can be defined in terms of a net bound-phosphorus/rhodium ratio, R_B For common hydroformylation catalysts, R_B changes over time in the catalytic cycle, but has an average value of approximately 2 If a ligand has a greater attraction to be bound to Rh, less ligand w ill need to be in solution in order to maintain the Rh in its pr eferr ed (R_B) state.

A measure of the level of attraction of the ligand for the rhodium can be found in the pKa value of the ligand (pKa values for some common ligands are listed in B Cornils, "Hydroformylation Oxo Synthesis, Roelen Reaction" in New Syntheses with Carbon Monoxide, ed ) Falbe, Springer Verlag, New York, I 9S0, p 4S) pKa is the base- 10 logarithm of K_a, which is the equilibrium constant for the acid-base interactions of the ligand A second measure of the level of attraction of the ligand for the rhodium can be drawn from the entropy of interaction when multi-dentate ligands are used T his entropy of interaction, Δ S_B, has a value of about 35 cal/ mole/°K for each added point of attachment (see, for example. Benson, S W T her mochemical Kinetics, Wiley New Yor k 1 976 ) This ent ropy contributes to free-ener gy as -T ΔS, thus prov iding a tree energy contr ibut ion of about - 1 0 to - 15 kcal/mole f ree energy influences equilibria as exp( -ΔG/RT), such that the influence of entropy eflect of multidcntate ligands is included as exp(ΔS_B/R )

Both measur es of strength of binding will attenuate t he concentrat ion of unattached ligand that is r equir ed in solution in or der to maintain an act iv e amount of ligand bound to the r hodium R₁ is defined as the ov erall r atio of phosphor us to r hodiu m f or a hydr ofor my lation cataly st w ith ligand "L", and includes both unat tached ligand and ligand bound to r hodium T he unattached ligand concentration (expressed as a r atio to r hodium concentration) is ( R₁ - R_B) T he following equation defines the effect of binding strength par ameters on the minimum ligand concentration for ligands other than PPh₃

Where R_L is the minimum P/Rh ratio sufficient to provide an active hydroformylation catalyst with this ligand R_TPP is the minimum P/Rh ratio for the ligand PPh₃ (R_TPP=30), R_B is the average ratio of P bound to the rhodium (~2), pKa_TPP is the pKa value for PPh₃, pKa_L is the pKa value for the new ligand ΔS_B is about 35 kcal/mole/°K for each additional point of attachment (beyond the one point of attachment of PPh₃) and R is the gas constant (1.99 cal/molc/°K)

Thus R_L, as calculated using this equation represents the minimum P/Rh ratio sufficient to provide an active hydroformylation catalyst for any ligand "L"

Rhodium can be introduced into the reactor bv methods known in the art either as a preformed catalvst for example, a solution of hydridocarbonyl tris(triphenylphosphino) rhodium (I) [HRh(CO)(PPh₃)₃] or formed in situ If the catalyst is formed in situ, the Rh can be introduced as a precursor such as acetylacetonatodicarbonyl rhodium (I) [Rh(CO)₂(acac)] rhodium oxide [Rh₂O₃] rhodium carbonyls [eg, Rh₄(CO)₁₂ and R_h6(CO)₁₆] tris(acetylacetonato) rhodium (1) [Rh(acac)₃], or triarylphosphine substituted rhodium carbonyls [ [ Rh(CO₂(PAr₃)]₂ wherein Ar is an aryl group]

REACTOR VARIABLES

Typically in the process of the present invention in dioformyIation of multicomponent syngas feeds is conducted at a temperature in the range from 80 to 180°C and preferably in the range from 80 to 155ºC If the temperature exceeds these limits the catalyst may rapidly deactivate l ower temperatures are acceptable however the rate ot reaction may become too slow to be economically practical The reaction is conducted at a total pressure in the reactor in the rang e of le ss than about s MPa (absolute) preferably about 005 to 5 MPi with a partial pressure of carbon monoxide not greater than 50 % of the total pressure The maximum practical pressure can be limited by considerations of production and capital costs and safety The mole percent of carbon monoxide hydrogen C₂-C₅ olefins preferably ethylene, and C₂-C₅ alkynes preferarably acetylene in the multicomponent syngas feed to the oxo reactor at the foregoing pressures should be maintained as follows CO from about 1 to 50 mol%. preferably about 1 to 35 mol%, H₂ from about 1 to 98 mol%, preferably about 10 to 90 mol%, monounsaturates individually and in combination from about 01 to 35 mol%, preferably about I to 35 mol% Gas compositions within the oxo reactor in the process of the present invention are then affected by the mode of operation, feed composition, and conversion

The reaction can be conducted either in a batch mode or on a continuous basis Preferably the reaction is run on a continuous basis In a continuous mode, superficial velocities of from about 15 to about 61 cm/sec (005 to 2 ft/sec), preferably from about 3 to about 30 cm/sec (01 to 1 ft/sec) should be used

Since the catalytic oxo conversion takes place in the liquid phase and the reactants are gaseous compounds, high contact surface between the gas and liquid phases is very desirable in order to avoid mass transfer limitations The high contact surface can be provided by any suitable manner, for example, by stirring in a batch reactor operation In a continuous operation the reactor feed gas can be contacted with the catalyst solution in, for example, a continuous stirred tank reactor in which the gas is introduced and dispersed at the bottom of the vessel Good contact between the catalyst and the gas feed can also be ensured by dispersing the solution of the Rh complex catalyst on a high surface support by methods recognized in the art

In the process of the present invention the hydroformylation of multi-component oxo reactor feeds can be conducted in single-stage reactor or using multiple reactors The reactors may be arranged in any numbers of parallel t rams when operating in a continuous mode the number ol parallel trams is determined by the desired total capacity and the capacity of a single train The present invention can be practiced using one or more stages per train, and each reaction stage can be engineered using any suitable reactor configuration for example, plug How or constant stirred tank reactor (CSIR) contacting are two common reactor configurations the number ot stages and the reactoi types for the stages can be computed using conventional chemical engineering principals given the kinetics and objectives of the reaction system

In batch experiments, there is an indication that the olefin and alkyne components of MCS feeds react in two well defined phases The first phase roughly corresponds to the conversion of the olefins present in the MCS oxo reactor feed In the second phase on the other hand mostly the alkyne content is converted The first phase is essentially the hydroformylation of olefins in the presence of alkynes the second phase on the other hand itself is a two step conversion in which alkynes are first hydrogenated to olefins and then those olefins formed are hydroformylated to the corresponding aldehydes The rate determining step in this second phase of MCS conversion is the hydrogenation of alkynes to olefins Following this unexpected order and complexity of the oxo conversion of mixed olefin-alkyne feeds, conditions for the different phases of the oxo reaction are preferably different. Thus, a preferred embodiment of the present invention is to divide the total hydroformylation into two stages, with each stage operated under conditions advantageous to the chemistry occurring in that stage Thus reaction conditions and catalyst composition in the first reactor should enhance the hydroformylation of olefins in the presence of alkynes Reaction conditions and catalyst composition in the second stage, on the other hand, should facilitate the hydrogenation of alkynes which is the slowest step in their conversion to aldehydes

US Patent 4,593,127 describes a two stage hydroformylation process for the oxo conversion of olefins The patent gives a common engineering solution for an improvement in the overall conversion of the reactant olefins It has to be understood, however, that the purpose and need for a multi-stage and in particular for a two stage oxo conversion in the process of the present invention is different The chemical reactions taking place in the different stages of the oxo process of the present invention are different In the first oxo stage the main reaction is the hydroformylation of olefins in the presence of alkynes In tire second stage, however, the main reaction is the hydroformylation of alkynes which is itself a two stage reaction The first step in the alkyne conversion is the hydrogenation of alkynes to the corresponding olefins which is followed by the hydroformylation of the for med olefins to the corresponding aldehydes The chemical reaction in the two stages of the process disclosed in US Patent 4,593,127 on the other hand is the same hydroformylation ol olefins to aldehydes The need lot the two stages in the process of the present invention therefore does not simply stem from the need for a better overall conversion but from the unexpected nature ol the chemical process, namely, that the stronger binding alky ic components react much slower than the weaker binding olefin components As a result ol this characteristics of the oxo conversion of alkyne-olefin mixtures olefins react first producing the corresponding aldehydes and thus the alkyne reactants will be enriched in the reaction mixture furthermore since the oxo conversion of alkynes to the final saturated aldehyde products requires first the hydrogenation of alkynes to the corresponding olefins and since it is this first step which determines the overall rate of this reaction, conditions in the second reactor static should enhance in fact not only the hydroformylation of olefins but the hydrogenation of alkynes as well The need for the second reactor static therefore stems from the nature of the chemistry and not simply a common engineering solution to improve of the overall conversion of a chemical process

An example of a two-stage, single-train oxo/hydroformylation unit is shown in Figure 2 and described as follows. The hydroformylation reaction is carried out in two continuous stirred tank reactors (21, 23). Each reactor is cooled and stirred using a pump-around cooling loop (202, 207) The hydroformylation feed (201) enters the first reactor The product from the first reactor (203), possible containing some entrained solvent and/or catalyst, may be cooled and separated in a flash drum (22) for intermediate withdrawal of aldehyde product (204) Remaining (unconverted) multicomponent syngas (205) is introduced into the second reactor (23) Additional MCS components, such as hydrogen, can be added (206) to this MCS feed to the second reactor Hydrogen addition, for example, could be .employed to provide the higher H₂/CO ratios that are preferred in the second stage The product from the second reactor (208) is combined with the intermediate product (204) to yield a stream (209) that is introduced to a product separation and catalyst recovery train (combined for simplicity into block 24) This block can use conventional boiling-point based separations (eg distillation) to separate the crude product into an unconverted MCS stream (210), a purified aldehyde stream (211), and a process solvent/catalyst stream (212) the process solvent and catalyst stream (212) is recycled back to the individual reactor stages

Conditions in a two-stage oxo unit embodiment of the process of the present invention are adiusied for the two stages of the conversion of multicomponent syngas feeds as described previously Therefore, in the preferred embodiment reaction conditions in the fust stage of the two-stage oxo unit should be oplimized to facilitate hydroformylation of ethylene in the piesence ol acetylene In the second stage ot the conversion process the overall conversion rate is essentially determined by the rate of hydrogenation of alkynes in the piefened embodiment acetylene Thus, reaction conditions in the second stage of a two-static oxo unit should facilitate hydrogenation of the alkyne reactant, in the preferred embodiment acetvlene Reaction conditions in the first stage should be maintained as follows H₂/CO ratio from about 1.1 to 100.1, preferably 1.1 u> 10.1, the temperature should be from about 80 to 180 °C, preferably in the range of 80 to 155 °C, more preferably liom about 80 to 130 °C the total pressure in the reactor should be from about 005 to 5 MPa preferably from about 0.1 to 25 MPa, with a partial pressure of CO not greater than 50 % of the total pressure, and the partial pressure of acetylene rcactant not greater than 0.2 MPa (safety limit) Reaction conditions in the second stage of a two-stage oxo unit of the process of the present invention should facilitate the hydrogenation of alkynes to olefins by, for example, maintaining higher 112 and lower CO partial pressures than in the first stage Higher temperatures may also be applied in the second stage to increase reaction rates In some cases it may become economically advantageous to use a different ligand in the second stage to improve the heat stability and/or hydrogenation activity of the catalyst. Thus reaction conditions in the second stage should be maintained as follows: H₂/CO ratio from about 1 : 1 to 100:1, preferably from about 2:1 to 50.1; the temperature should be maintained between about 80 to 180 °C, preferably from about 80 to 155 °C; the total pressure should be maintained between about 0.05 to 5 MPa, preferably from about 0.1 to 2.5 MPa, with a partial pressure of CO not greater than 35 % of the total pressure, and the partial pressure of acetylene not greater than 0.2 MPa (safety limit). Superficial velocities of from about 1.5 to about 61 cm/sec (0.05 to 2 ft/sec), preferably from about 3 to about 30 cm/sec (01 to 1 ft/sec) should be used in both reactors in order to entrain the catalyst in the reactor Rhodium complex catalysts within the range of compositions disclosed previously are used The compositions of. the catalyst solutions in each stage of a multistage oxo unit are preferably the same, but can also be different, within the disclosed ranges for the rhodium complex catalyst, if so desired

The overall conversion of the alkyne and olefin content of the multicomponent syngas feed in the oxo unit of the process of present invention can be essentially as high as desired The catalyst life, however, is shortened as the conversion approaches 100% in a single pass if higher catalyst concentrations and/or more severe conditions, i. e. higher temperatures are used to reduce, the necessary residence lime to achieve the desired conversion It is therefore generally desirable to maintain the conversion in a single pass lower than the desired overall conversion and to recycle the reactants after the separation of the product Thus, for example higher than 99% overall conversion can be achieved with 80% per pass reactant conversion in the oxo unit and 96% reactant recovery in a recovery-recycle unit described below Under such conditions the reactant concentration in the reach ; can be 2-1 times higher than the concentration resulting from the same level (99%) of single pass conversion in the absence of recycle This higher concentration contributes to a proportionally 24 times higher reaction rate, and in the case of the oxo/hydroformylation process of the present invention, it also contributes to an increased catalyst complex stability

REACTANTRECOVERY AND RECYCLE

The use of a recycle of unreacted unsaturated hydrocarbon components is highly desirable in the processes of the present invention to increase the oxo unit productivity and the catalyst life by allowing higher unsaturated hydrocarbon concentrations in the oxo reactor(s) However, feeds having relatively high concentrations of merts and non-storchiometric reactants, such as multicomponent syngas feeds, effectively discourage such a recycle because of the lapid build-up of excess gaseous materials, i.e. inerts (e.g., nitrogen, water vapor, methane, ethane, propane), and excess reactants (typically hydrogen) that would occur in the recycle loop It would be beneficial if a process could be devised to overcome these problems.

Applicants have found that the unreacted unsaturated hydrocarbon components, especially acetylene, can be advantageously recovered from the gaseous effluent of the oxo reactor by scrubbing this "tail gas" with a liquid consisting of the liquid aldehyde product of the oxo reactor This unsaturates-containing liquid can then either be stripped with unsaturates-free syngas to produce a recycle stream of multicomponent syngas that is more concentrated in the unsaturated hydrocarbon than was the tail gas, or preferably, the unsaturates-containing liquid can be recycled directly to the oxo reactor

Applicants have found that solubilities of the unsaturated hydrocarbon components (eg, ethylene, and in particular acetylene) of multicomponent syngas mixtures in certain oxygenated solvents, more particularly C₃-C₅ oxygenated solvents, especially the product aldehyde of the hydroformylation process such as disclosed herein for the conversion of multicomponent syngas mixtures are exceptionally high Furthermore, the solubilities of these unsaturated hydrocarbons are substantially higher than the solubilities of other reactants such as hydrogen, and carbon monoxide, and inerts such as methane, and nitrogen (see Tables 6 and 7 in Example 5) present in multicomponent syngas mixtures used in the process of the piesent invention

Thus another embodiment of the present invention provides a process for the separation or preferential removal ol unsaturated hydrocarbons. especially acetylene from oxo reactor diluents containing same and recycle thereof into the oxo reactor lot further hydroformylation piocessing without build-up ot the aforementioned excess reactants and inerts in the oxo reactor The process provides a method for concentrating and recovering the unsaturated hydrocarbons from the oxo reactor diluent to produce a stream that is enriched in alkyne and olefin and deficient in excess gaseous material tor recycle into the oxo unit without buildup of inerts, and excess components

The recycle and recovery concept of the present invention comprises use of the aldehyde product of hydroformylation as the absorption solvent in a system lot concentrating the unconverted unsaturates in the oxo reactor diluent A simple embodiment of this invention would be the use ot paired absorption and stripping towers In this method, the oxo diluent is led to the bottom of an abruption tower where it is contacted with cold aldehyye to condense out liquid aldehyde and dissolve unsaturated species (particularly acetylene) Oxo tail gas greatly diminished in these components emerges from the top of the absorption tower The unsaturates-containing aldehyde from the bottom of the absorption tower is fed to the top of a stripping tower wherein unsaturates-free gas (such as synthesis gas, hydrogen, nitrogen) is used to strip out the unsaturates into a concentrated vapor phase suitable for recycle to oxo. The unsaturates-free liquid aldehyde product at the bottom of the stripper is divided between recycle to the absorber and a stream which is the aldehyde product of oxo By use of such a scheme, the absorber/stripper is made to serve the three purposes (i) recovering the aldehyde product from the gaseous process effluent, (ii) recovering unsaturates for recycle to oxo, and (iii) removal of unsaturates from the aldehyde product, in which such unsaturates would be unwanted contaminants

A preferred embodiment of the recycle and recovery concept of the present invention accomplishes these same three purposes, but also provides for the recycle of the unsaturated components as solutes in a liquid-phase recycle aldehyde stream An example flow diagram for this embodiment is shown in Figure 3 Into the oxo reactor (31), having a pump-around cooling loop (340), is introduced a multicomponent syngas feed (331) The oxo reactor gaseous or mixed phase diluent (332) is cooled to a temperature at which an amount of aldehyde condenses that is essentially equal to the amount of oxo-produced aldehyde The condensed liquid aldehyde (341) is separated from the remaining gas phase oxo effluent in a flash drum (33) The liquid aldehyde product (341) is introduced into a stripping vessel (34) where it is stripped with an unsaturate-free gas (333) (e g syngas, hydrogen, nitrogen, or light alkanes) to pioduce an unsaturate-free aldehyde product (335) a gaseous efiiuent (342) containing unsaturated hydrocarbons The stripping tower gaseous effluent (342) is combined with the Hash drum (33) vapor and cooled further to puniuce a stieam (334) that o ted to the absorption tower (35) having an upper portion that is at a temperature sutficientlv low to provide reflux (344) of the alkane components of the oxo effluent (eg ethane or propane), shown as cooling of the tower overhead (343) and dium (36) to separate liquid irom vapor This upper portion of the absorber (35) functions as the rectifying section of a distillation towei. reiecling aldehyde from lower boiling components, and resultinti in a substantially aldehyde-free overhead product stream (336) that contains the oxo diluents (eg N_2, methane, ethane, propane) and non-stoichiometric components (eg hydrotieni that boil at temperatures at or below the temperature of the refluxing alkane In the bottom of the tower (35) the liquid phase becomes cold aldehyde that dissolves the highly soluble unsaturated components as if in an absorber At the temperature of the bottom of the tower (35) the solubilities of alkynes and olefins in the liquid phase are very high (see Tables 5 and 6 in Example 5) For example, acetylene concentrations of 10 mol% can be achieved in the acetylene rich aldehyde product at appropriate conditions. This unsaturates-containing liquid stream (337) emerges from the bottom of the tower where it can be pumped as a liquid to substantially higher pressures for recycle to the oxo reactor (31). Once at higher pressure, the unsaturates-containing liquid stream can be heat exchanged (350) to recover any cooling value that it might contain. In this high pressure condition this heat exchange can be accomplished with a minimized concern that unsaturates such as acetylene will separate from the liquid to form a dangerous concentrated phase. Recovery of cooling value can also be employed on other cooled streams (335, 336) exiting the process.

In a further variation on this scheme, the pressure of the oxo eflluent (332) can be increased in pressure prior to the recovery process via a compressor (32). The pressure increase should not increase the partial pressure of the product aldehyde over its saturation limit in order to avoid compressor damage. Furthermore, the partial pressure of acetylene at the high pressure side should be lower than the safety limit of 0.2 MPa. The increased pressure typically should not be higher than 5 MPa in order to avoid excessive equipment cost. Such a pressure increase results in an increase of the partial pressures of the components being separated the product aldehyde and the unconverted C₂ to C₅ monounsaturates. As a result of the higher partial pressures the flash tower 33, and scrubber 35 may be operated at higher temperatures thus potentially reducing the cooling cost of the separation. Furthermore, increasing pressure can carry the added advantage of reducing tower sizes for gas treating and separations. The need and degree of this operational compression step is determined by economic and safety factors. This recycle and recovery process is entirely different from that described in US Patent 3,455.091 in several ways First, US Patent 3, 455, 091 uses high boiling oxo side-products as scrubbing solvents. versus our preferred use of the primary oxo product. Second US Patent 3,455,091 uses the scrubbing system to absorb for recovery purposes the primary-product aldehyde out of the unconverted oxo feed gases, versus our absorption for recycle to oxo of selected unconverted feed components out of other feed components. This recycle and recovery process is also entirely different from that described in US Patent 5.001.274. While US Patent 5,001,274 employs a rhodium catalyst stream to absorb for recycle selected unconverted feed components, the process described herein uses the liquid reaction product. A further difference between the process of the present invention and the aforementioned prior art is that the processed stream is not the effluent of an olefin oxo unit but in fact the eflluent of a different oxo technology in which olefins and alkvnes are co-converted. The processed stream therefore contains chemically different components - C₂ to C₅ alkynes - in high concentration the treatment and recovery of which requrier special process conditions and technology (safety) One of the most important features of the recovery-recycle process of the present invention is that it provides a solution for the safe recovery and recycle of those alkynes, especially of acetylene.

It should be noted that this recycle and recovery process may be used with processes other than the aforementioned and herein described hydroformylation/oxo processes. The recovery and recycle process disclosed herein may be used with other synthesis processes whose reaction products are usable as absorption solvents for unreacted gaseous feed components and which synthesis process is not harmed by the recycle of said products back to the synthesis reactor. For example certain implementations of Fischer-Tropsch ("FT") synthesis can be made to produce oxygenates as products and to consume olefins. in the synthesis gas feed. In such an implementation, the FT oxygenate product can be used as described herein to recover and recycle unconverted olefinic species back to the synthesis reactor. Another example is the variations of alcohol synthesis reactions that consume olefins in the synthesis gas feed and produce higher alcohol products. These are only examples and should not limit in any way the scope of application of the basic concept.

The solvent applied in the unsaturates recovery-recycle process, as it is applied to hydroformylation of multicomponent syngas, is the recovered aldehyde product from the hydroformylation of multicomponent syngas containing C₂-C₅ monounsaturates. Use of the product aldehyde as a solvent presents several advantages the separation of the product aldehyde can be integrated into the unsaturates recovery and recycle proccss saving capital cost, there is reduced need for pin chased solvent and solvent make-up. and reduced product contamination and solvent/product separation problems. An integrated product separation and unsaturates recovery and recycling scheme can offer further advantages relating to the need of use of refrigeration for the effective separation of the product aldehyde. Since both product separation and unsaturates recovery requires the application of low temperatures, the cooling energy can be efficiently utilized in an integrated process such as disclosed herein.

PRODUCT UTILIZATION

C₃ to C₆ aldehydes, which are a desired product of the hydroformylation stage of the present invention, and particularly propanal, have utility as intermediates in the manufacture of many industrial commodity chemicals. Thus, one preferred embodiment of the present invention is its combination with subsequent processing stops that further enhances the value of the aldehyde product. One preferred embodiment of the present invention is the combination of the hydroformylation of a multicomponent syngas with hydrogenation of the aldehyde product of that hydroformylation to produce an alcohol product. Particularly preferred is the production of propanol by this means. An additional preferred embodiment of the present invention is the combination of the hydroformylation of a multicomponent syngas with the oxidation of the aldehyde product of that hydroformylation to produce an organic acid product. Particularly preferred is the production of propionic acid by this means. Hydrogenation and oxidation of the aldehyde to the aforementioned products may be carried out according to procedures known in the art.

An additional preferred embodiment of the present invention is the combination of the hydroformylation of a multicomponent syngas with an aldol condensation step. Aldol condensation is a conversion step that is well known in the art. In this reaction, two aldehydes are joined such that the α-carbon of the first becomes attached to the carbonyl carbon of the second. The result is called an "aldol", which is a β-hydroxy carbonyl compound. Typically, the aldol eliminates H₂O to yield an unsaturated aldehyde. The aldol condensation of two identical aldehydes is called "self-aldol", while the aldol condensation of two different aldehydes is called "cross-aldol" Additional preferred embodiments of this invention include the hydrogenation of so-produced aldols to saturated aldehydes, as well as saturated and unsaturated alcohols. An additional preferred embodiment of this invention is the oxidation of the saturated and unsaturated aldehydes derived from the aldol condensation to corresponding saturated and unsnurated acids. Thus, an additional preferred embodiment of the present invention is the combination of the hydroformylation of a multicomponent syngas with self-aldol of the produced aldehvde to produce an aldol drmer Particularly preferred is the production of 2-methyIpentenal by this means and the subsequent hydrogenation to 2-methylpentanal, and or to 2-methylpentanol as well as the oxidation of the 2-methylpentanal to 2-methylpentanoie acid. An additional preferred embodiment of the present invention is production of multi-methylol alkanes via the cross aldol condensation of formaldehvde with of the aldehydes produced by the hydroformylation of a multicomponent syngas. A further preterred embodiment of the present invention is production of multi-methylol alkanes via cross aldol condensation of formaldehyde with the unsaturated or saturated (hydrogenated) aldehydes produced as aldol dimers of the aldehvde produecd via hydroformvIition of a multicomponent syngas. Typically in this known art. the carbonyl (C. O) group in such a cross-aldol product is chemically or catalylically reduced such that all the oxygen of the multi-methylol alkane is in the hydroxyl form. Particularly preferred are the production of trimethylol ethane by this means (by cross-aldol of formaldehyde with propanal), and the production of 2,2'-dimethylol pentane by this means (by cross-aldol of formaldehyde with 2-methylpentanal). Conversion of aldehydes to the aforementioned products may be carried out according to procedures known in the art.

Thus, the present invention includes a process for the manufacture of alcohols, wherein the aldehydes formed by the hydroformylation of a multicomponent syngas are hydrogenated to form the corresponding alcohols, a process for the manufacture of acids, wherein the aldehydes formed by the hydroformylation of a multicomponent syngas are oxidized to form the corresponding acids; a process for the manufacture of aldol dimers, wherein the aldehydes formed by the hydroformylation of a multicomponent syngas are self-aldolized to form the corresponding dimers, a process for the manufacture of saturated aldehydes, wherein those aldol dimers are hydrogenated to corresponding saturated aldehydes, a process for the manufacture of unsaturated alcohols or acids, wherein the aldol-dimers are hydrogenated or oxidized to form the corresponding unsaturated alcohols or acids, a process for the manufacture of saturated alcohols, wherein t he aldol-dimers are hydrogenated to form the corresponding saturated alcohols, a process for the manufacture of saturated alcohols or acids, wherein the saturated aldehydes produced v ia hydrogenation of the aldol-dimers are hydrogenated or oxidized to form the corresponding saturated alcohols or acids, a pr ocess for the manufacture of multi-methylol alkanes, w herein the aldehydes formed by the hydroformylation of a multicomponent syngas are aluol-conden.sed w ith formaldehyde to form the corresponding multi-methylol alkanes. a proccss f or t he manuf acture of trimethylol et hane, wher ein propanal that is for med by the hydroformylation of a multicomponent syngas is aldol condensed w ith formaldehyde to form the trimethylol et hane, and a process f or t he manufactur e of multi-methylol alkanes, w herein t he aldol-dimers and/or the saturated aldehydes produced therefrom are aldol-condensed w ith formaldehyde to form the corresponding muIti-methylol alkanes.

T his invention can be used to produce the propanal-containing composit ion t hat is used for the production of aldehydes, alcohols, acids, and their derivat iv es, described in EPA 95.300 301.9 and the PCT application based thereon, which are hereby incorporated by reference. Example 1

Apparatus

Experiments were carried out in an Autoclave Engineers' 300 ml stainless steel autoclave. The reactor was connected to a 500 ml high pressure buffer bomb through a regulator valve. Both the reactor and the buffer bomb were equipped with digital temperature and pressure gauges. The autoclave was also equipped with a temperature control unit, and a stirrer with speed control. The total and free volumes of the different parts of the apparatus were measured by gas volumetric method.

Catalyst preparation

The rhodium and phosphine containing solutions were prepared in Vacuum Atmospheres dry boxes under nitrogen or argon. The rhodium was charged either in the form of HRh(CO)(PPh₃)₃, or as Rh(CO)₂(acac), where PPh₃ is iriphenylphosphinc, and acac is the acetylacetonato ligand. Rh(CO)₂(acac) was purchased from Strem Chemicals and was used as received. HRh(CO)(PPh₃)₃ was prepared from Rh(CO)₂(acac) by literature method (G. W. Parshall, Inorg. Synth. 1974, 15, 59). Toluene was distilled from sodium benzophenone under nitrogen. The weight of each component of the toluene solution was measured Methylcyclohexane was used as an internal GC standard. The solution was charged under flow of nitrogen into the autoclave. The unit then was flushed with syngas (H₂/CO = 1) When the catalyst was prepared in situ the autoclave was pressurized to about 0.5 MPa at room temperature then it was healed up to 100 °C, and was kept at that temperature for about 30 mm. Independent experiments demonstrated that under these conditions the rhodium looses the acac ligand by hydrogenation and the formed hydridocarbonyl triphenylphosphino rhodium complex(es) (HRh(CO)_x(PPh₃)_y, x+y 4) catalyze hydroformylation without showing any induction period When HRh(CO)(PPh₃)₃ was used as a Rh source no catalyst preforming was necessary. Hydroformylation of Gas Blend # 1

The reactor containing the solution of the preformed catalyst was flushed and pressurized with Gas Blend #1 containing ethylene, ethane, acetylene, carbon dioxide, hydrogen, methane, carbon monoxide, and nitrogen (composition is given in Table 2) at room temperature. The amount of gas loaded into the reactor was determined by gas volumetric method. The P/Rh ratio in this experiment was 93. The composition of the catalvst charged is given in the footnote of Table 2. The reactor was heated to 110 °C and maintained at r eaction temperature f or two hour s. While the reactor w as at the r eaction temperature , a pressur e dr op indicated that react ion occur red. After two hour s at 1 10 °C, when no f urther pressure dr op was observed, the reactor was chilled to 1 5 °C, and gas and liquid samples were taken. A mass balance was established for the charged materials based on gas chromatography (GC) analyses of the gas and liquid phases. The results are given in Table 2. In the liquid phase the only detected product of the reaction was identified by gas chromatography/mass spectrometry (GC/MS) as propanal. The propanal found in the liquid phase gave a 60 % conversion based on the total amount of ethylene and acetylene loaded into the reactor. Since the experiment was stopped when the oxo reaction ceased the catalyst clearly deactivated before higher conversions could have been achieved . Gas analysis of the final reaction mixture indicated that both unreacted ethylene and acetylene were present at a ratio of acetylene/ethylene of 3.4 at the point when the oxo conversion stopped . The analy sis results showed that a parallel conversion of both ethy lene and acetylene had occurred. The final solution had a dark brown color w hich is associ ated in the experiments disclosed her with a decomposed catalyst.

Example 2

The apparatus, catalyst preparation method, and experimental procedures were the same as in Example 1 . Gas Blend #2, used in this experiment, contained ethylene, ethane, acetylene, carbon dioxide, hydrogen, methane, and carbon monoxide (the composition is given in Table 3). The reaction temperature was 100 °C, and the P/Rh ratio was 300. The composition of the catalyst solution is given in Table 3. After heating the reaction mixture to 100 °C, a fast pressure drop in the autoclave was observed indicating that a gas consuming reaction took place. This pressure drop significantly slowed down after about 45 min reaction time when the reaction was stopped by cooling the reaction mixture to 1 5 °C. After cooling the system gas and liquid samples were taken, and analyzed by GC. The results are given in Table 3. The analyses of both the gas and liquid phases gave a higher conversion (88.5 %) at a 10 °C lower temperature, 14 times lower catalyst concentration, and in a 2.7 times shorter time than what was observed in Example 1 . In addition, the color of the solution sample taken at the end of the experiment was bright orange yellow. An orange yellow color in the herein discussed experiments is associated with an active catalyst system in the conversion of acetylene and ethylene containing multi-component syngas mixtures.

Example 3

This example demonstrates the effect of P/Rh ratio on the hydroformylation of acetylene and ethylene containing MCS oxo feed streams. The preparation and loading procedures of the catalyst solutions were the same as in Example 1 The solvent, tetraethylene glycol dimethyl ether (tetraglyme), was degassed before use. It also served as an internal standard in the GC analyses of the product liquid samples. The solution volume, and the total initial gas charge in each experiment was the same, 70 ml, and 95 mmoles, respectively. The apparatus was the same as in Example 1 except that a volume calibrated, high pressure injection bomb was mounted into the feed line after the high precision pressure regulator between the buffer cylinder and the autoclave. This injection bomb was used to inject known amounts of ethylene/acetylene mixtures into the autoclave. The ethylene, and acetylene charges in each experiment were around 15.4, and 6.4, respectively.

Batch kinetic experiments were carried out at constant 1 MPa total gauge pressure and 120 °C. As the reaction proceeded a constant pressure was maintained by feeding syngas (CO/H₂ = 1) from the volume calibrated high pressure buffer bomb through a high precision regulator valve. The reaction was monitored by reading the pressures in the buffer (measured to an accuracy of 1 kPa) as a function of time (recorded to an accuracy of 1 second). The overall conversions of ethylene and acetylene were determined after each run by GC analyses of the liquid and gas products. The only two products of the reactions detected were propanal as major product and minor amounts of ethane. The overall conversion then was correlated to the total pressure drop and the total gas consumption in moles from the buffer bomb during the experiment. Reaction rates were calculated assuming a linear correlation between the pressure drops and conversion. Catalyst compositions, and results of seven different experiments are shown in Table 4.

Kinetic data in Table 4 demonstrate that the activity of the catalyst increases significantly by increasing the phosphine concentration. The color of the final solutions were orange yellow, except for the run with PPh₃/Rh ratio of 10, which was brown after 120 min reaction time. This color variation indicates that a stable catalyst system is not present at a PPh₃/Rh ratio of 10 in the hydroformylation of acetylene and ethylene containing multi- component syngas feeds. Under the preferred PPh₃/Rh ratios above 30 significant improvement in rate conversion, and stability are achieved.

Example 4

the example demonstrates the effect of H₂/CO ratio on alkene (ethylene) hydroformylation in the presence of a cumulated diene (allene). The preparation and loading procedures of catalyst solutions were the same as in Example 1. The experimental method and the kinetic evaluation of experimental values were the same as in Example 3 except that 15 mmoles of ethylene was connected with 0.13 mmoles of allene and with different amounts of hydrogen to adjust H₂/CO ratios in the autoclave. The catalyst charge was 18.8 μmoles of Rh (277 ppm), and 8.3 mmoles of PPh₃ (3.1 w %) m each experiment.

After injecting allene-ethylene mixtures into the autoclave at 120 °C the reaction first proceeded at a very slow rate. Gas analysis of the gas reaction mixture showed a slow build- up of propylene dining this first slow stage of the reaction. The hydioformylation or ethylene took place only after essentially all (typically 95 to 99%) of the allene charged was converted The length of this first phase of the reaction depended on the H₂/CO nit 10 (see Table 5).

Example 5

Gas solubilities were measured either by gas volumetric method using the same autoclave as in Example I or by ¹H NMR. In the autoclave experiments the solvent was thoroughly degassed in the autoclave before the gas was charged without stirring. After a short temperature equilibration the pressure and temperature in the autoclave was recorded and then the solvent was stirred until no further pressure drop could be observed. From the known gas volume and pressure drop the amount of dissolved gas was calculated. In the ¹H NMR experiments either the solvent (propanal) or hexamethylben/ene served as an internal standard. The values obtained are listed in Table 6.

The experimentally determined (see Table 6) and literature values (see Table 7) reflect high solubilities of ethylene and acetylene in oxygenates, especially in propanal. There is a large difference in solubility between ethylene and acetvlene vs all other major components of typical multicomponent syngas mixtures such as hydrogen, carbon monoxide, and methane. It can also be seen that the solubility difference increases with decreasing temperature.

w ) E. Brunner Ber. Bunsenges. Phys. Chem. 79, S3(7), 7 1 5.

Example 6

The preparation and loading procedures of catalyst solutions were the same as in Example 1. The experimental method and the kinetic evaluation of experimental values were the same as in Example 3, except that 1 5 mmoles of ethylene was coinjected with 0.13 mmoles of one of the following dienes or acetylenes 1 ,3-butadienc, allene, propyne, and acetylene. The catalyst charge was 1 8.8 μmoles of Rh (27.7 ppm), and 8.3 mmoles of PPh₃ (3.1 w. %) in each experiment.

Gas analysis of the gas reaction mixtures indicated a parallel conversion of ethylene with 1 ,3-butadiene, propyne, and acetylene. In the case of ethylene-allene mixtures, h owever, the conversion of ethylene could only start after essentially all the allene lnjected had been hvdrogenated to propylene, as disclosed in Example 4. T he final reaction mixtures contained essentially propanal, ethane, and the hydrogenated product of the competed highly unsaturated component. Thus 1 ,3-butadiene yielded butenes, and allene and propyne yielded propylene At 95 to 98 % ethylene conversion the typical conversions of 1 ,3-butadienc and propyne to the corresponding olefins were ca 60 %. Since the hydrogenation product of acetylene is ethylene its intermediacy could not he detected in the hydroformylation of ethylene-acetylene mixtures. T he observed reaction rates sh o wed a different degree of inhibition on the oxo rate of ethylene by the highly unsatur ated component. Thus, the observed turnover frequencies in ethylene hydroformylation with allene. 1 ,3-butadiene. propyne, and acetylene as coinjected reactants at 33 % ethylene conversion w ere 3 , 5 ,5, 7 , and 9 mol propanal/mol Rh/sec, respecti velv.

Example 7

This example demonstrates the effect that small concentrations of acetylene have in stabilizing the rhodium catalyst against deactivation. The experiment involves two stages, an aging stage and a kinetic measurement stage. The preparation and loading procedures of catalyst solutions were the same as in Example 3, except that the autoclave and buffer bomb volumes are 500 and 325 ml, respectively.

For the aging stage of the experiment, 300 ml of catalyst solution was charged, which solution contained 1400 mmol tetraglyme, 30 mmol triphenylphosphine, and 0.3 mm rhodium (96 ppm). These solutions were heated to 140°C at 1 MPa and contacted with on of three gas streams, (a) syngas (H₂/CO=1) alone, (b) syngas with 5 mol% ethylene, or (c) syngas with 0.51 mol% acetylene. In cases (b) and (c) the gas stream flow was controlled so that the substrate concentration in the effluent was maintained at about 0.5 mol percent. After aging times of 0 (initial solution), 80, 140, and 260 minutes. 30 ml samples of the catalyst solution were withdrawn and set aside.

For the kinetic measurement stage of the experiment, 200 ml of catalyst solution was charged, which solutions were prepared using the 30 ml samples of the aging stage and adding tetraglyme and triphenylphosphine to make a solution containing 860 mmol tetraglyme, 35 mmol triphenylphosphine, and 0.02 mmol rhodium (16 ppm). The experimental method for the kinetic evaluation was the same asin Example 3 ( 1 MPa, 120°C. H₂/CO=1) except that 20 mmoles of ethylene were coinjected with 3 mmoles of acetvlene. The rate (mols oxo second). was found to be first order in ethylene. and a rate constant for each kinetic experiment was calculated as mols oxo per mol ethylene, per wppm Rh, per second. For each aging experiment, rate constants were then normalized as a percent of initial (zero aging) catalyst activity.

A summary of the conditions and results of these catalyst deactivation experiments is shown in Table 8. It is well known that catalyst deactivation is rapid under conditions where substrate (olefin, alkvne) is absent, and this is confirmed in experiment (a) wherein the activity drops 90% in 260 mm at 140ºC. Olefin hydroformylation is commonly run under conditions of low per-pass conversion in order to maintain substrate presence to mitigate this deactivation. Experiment (b) confirms that olefin presence reduces deactivation (now only 50% after 260 mm). but also demonstrates that under the high conversion conditions that would be reflected in a 0.5 mol % exit concentration considerable deactivation occurs. In contrast. experiment (c) demonstrates that low ( 0.5 mol %). concentrations of acetylene dramatically reduce the deactivation (now only 5% after 260 min). Such a preservation of catalyst activity enables operation at higher per-pass conversion as well as higher temperatures

Example 8 This example demonstrates the continuous hydroformulation of mixtures of olefin and cumulated diene, more specifically of ethvlene and allene Experiments were performed in a 500cc Autoclave. Engineers Zipperclave stainless steel autoclave. The autoclave was equipped with a continuous gas feed system, with back pressure control, and with gaseous feed and product characterization via gas chromatography. Catalyst solution was prepared by mixing under nitiogen 210 g of tetiaglyme, 158 g of triphenylphosphine, and 8.8 mg of rhodium (added as Rh(CO)₂(acac). where acac is the acetylacetonato ligand). This corresponds to 39 wppm of Rh, and a P/Rh ratio of 700. Catalyst solution was transferred into the autoclave under nitrogen, the autoclave purged with nitrogen, and then gas flows commenced as indicated in Table 9 Pressure then built up to the 1000 kPa (abs) setting of the back pressure control, after which the autoclave and contents were heated to 90ºC reaction temperature Gas samples were taken after at least 20 hours of continuous reaction

Claims

WHAT IS CLAIMED IS

1 . A process for the production of C₃ to C₆ aldehydes comprising

hydroformylating a mixture containing

(i) C₂ to C₅ olefins and mixtures thereof

and

(ii) C₂ to C₅ alkynes and mixtures thereof

and optionally

(iii) cumulated dienes by reaction with CO and H₂ in the presence of a solution of a rhodium organophosphorus complex catalyst at a concentration of rhodium in solution of from 1 to 1000 ppm by weight

2. A process for the production of C₃ to C₆ aldehydes comprising

hydroformylating a mixture containing

(i) C₂ to C₅ olefins and mixtures thereof

and

(n) C₂ to C₅ alkynes and mixtures thereof

and optionally

(in) cumulated dienes by reaction with CO and H₂ in the presence of a solution of a rhodium organophosphorus complex catalyst at a concentration of rhodium in solution vyherein the ratio of phosphorus to rhodium is greater than 30

3. A process for the production of C₃ to C₆ aldehydes comprising

hydroformylating a mixture containing

(i) C₂ to C₅ olefins and mixtures thereof

and

(i i ) C₂ to C₅ alkynes and mixtures thereof

and optionally

(iii) cumulated di enes by reaction with CO and H₂ in the presence of a solution of a rhodium organophosphorus complex catalyst wherein the catalyst solution has a P/Rh ratio greater than the value R_L wherein:

wherein R_B is the P/Rh ratio sufficient for a catalytically active Rh complex, kPa_TPP is the pKa value for triphenylphosphine, pKa_L is the pKa value for the triorganophosphorus compound, R is the gas constant, and ΔS_B is 35(N-1 ) cal/mole °K, wherein N is the number of P-Rh attachments per ligand molecule, to product the corresponding C₃ to C₆ aldehydes

4. A process according to claim 1 or claim 3 in which the ratio of phosphorus to rhodium is greater than 30

5. A process according to any of the preceding claims in which the

organophosphorus compound is triorganophosphorus

6. A process according to any of the preceding c laims in which the rhodium organophosphorus complex is oil soluble

7 . A process according to any of the precedin g claims in which tho rhodium is low valence

8. A process according to any of the preceding claims in which the food is

multicomponent syngas

9. A process according to any of the preceding claims in which the

hydroformylation is performed at a temperature above 80ºC

10. A process according to any of the preceding c laims in which on average the mixture is in contact with the catalyst for no longer than four hours

11. A process according to any of the preceding c laims in which a total

concentration of coordinatively active P of at least about 0.01 mol/l is used

12. A process according to any of the preceding claims in which a ratio of [P]/p_co of at least 0 1 mmol/l/kPa, where [P] is the total concentration of

coordinatively active phosphorus in the solution, and P_co is the partial pressure of CO is employed 1 3. A process of any of the preceding claims wherein the olefin is essentially ethylene, and the alkyne is essentially acetylene

14. A process according any of the preceding claims in which the mixture also contains dienes

15. A process of any of the preceding claims wherein the partial pressure ratio of H₂/CO is from 1 to 100 the partial pressure ratio of CO/monounsaturates is from 0 5 to 100, and of H₂/monounsaturates is from 0 5 to 100

16. The process of any of the preceding claims wherein the oil soluble

triorganophosphorous ligand is selected from the group consisting of oil soluble triarylphosphines trialkylphosphines, alkyl-diaryl phosphines, aryl- dialkylphosphines, trialkylphosphites and triarylphosphites having at least one phosphorus atom per molecule

17. The process of any of the preceding claims wherein the reaction temperature is from 80°C to 1 80°C the total pressure from about 0.05 to about 5 MPa the partial pressure of carbon monoxiαe up to 50 mol % of the total pressure the mole % of H₂ is from 1 to 98 mole % and mol % of ethylene and acetylene each alone and in combination is from 0.1 to 35 mol %

18. The process of any of the preceding claims in which the molar ratio of olefin to alkyne is at least 2

19. The process of any of the preceding claims wherein the contacting is carried out in at least two reactor stages

20. The process of claim 19 wherein the first stage is optimized at conditions for conversion of olefins in tne presence of alkynes and the second stage is optimized at hydrogenation conditions for conversion of alkynes to olefins

21. A process for recovering unreacted unsaturated hydrocarbons from an effluent stream of a process according to any of the preceding claims, comprising

(a) absorbing the unreacted unsaturated hydrocarbons and the

oxygenated hydrocarbons of the synthesis process effluent stream in solvent wherein said solvent is an unsaturates-depleted stream of the oxygenated product of said synthesis process, and

(b) stripping the unsaturated hydrocarbons from the solvent to produce a first stream concentrated in unsaturates and a second stream of oxygenated product depleted in unsaturates, wherein said unsaturates-depleted stream is the absorption solvent and the synthesis process product

22. The process of claim 21 wherein the absorbing is carried out at a temperature between -100°C and +100°C

23. A process for recovering unreacted unsaturated hydrocarbons from an

effluent stream of a process according to any of claims 1 to 20 comprising

(a) partially condensing the effluent of the synthesis process to produce a liquid condensate enriched in the oxygenated product and a gaseous stream enriched in the low boiling gaseous components

(b) stripping the liquid condensate with an essentially unsaturates-free gas to produce an unsaturates-free oxygenated product and a gaseous stream enriched in unsaturates and low boiling gaseous components,

(c) combining the gaseous streams from step (a) and step (b) and cooling the combined stream,

(d) treating the combined stream from step (c) in an absorber having

reflux of saturated hydi ocarbon soocies at the top, to produce an overhead stream containing the low boiling gaseous components and substantially tree ot syntnesis process product and unsaturated hydrocarbon, and a bottoms steam of synthesis process product containing concentrated absorbed unsaturated hydrocarbon; and

(e) recycling said bottoms streams to the synthesis reactor.

24. The process of claim 23 wherein the bottoms stream of step (e) is pumped to high pressure and heat exchanged with the combined stream from step (c) to recover the cooling value

25. The process of claim 23 or claim 24 wherein the treating of step (d) is carried out at a temperature between -100°C and +100°C.

26 A process for the preparation of a feed stream useful in the process of any of claims 1 to 25 comprising preferentially removing a variable amount of alkynes and multiunsaturates from a gas stream containing at least hydrogen, olefins, alkynes, and multiunsaturates comprising contacting the gas stream with a metal complex-containing stream at a rate sufficient to form adducts of the alkynes and multiunsaturates to be removed, and removing a stream containing the alkyne and multiunsaturate adducts of the metal complex

27 A process according to claim 26 in which the metal complex stream is a liquid or a slurry

28 The process of claim 26 or claim 27 wherein the metal complex is an oil- soluble rhodium complex containing a triorganophosphorous ligand selected from the group consisting of triarylphosphines. tralkylphosphines, alkyl-diaryl phosphines, aryl-dialkylphosphines, trialkylphosphites and tnarylphosphites containing at least one phosphorus atom per molecule

29 The process of claims 26 to 28 wherein the multiunsaturates are selected from the group consisting of C₃-C₅ conjugated and cumulated dienes.

diynes, and enynes, the alkynes are selected from the group consisting of C₂ -C₅ alkynes, and the olefins are selected from the group consisting of C₂- C₅ olefins

30 T he process of claim 29 wherein the gas stream is a multicomponent syngas mixture f urther compr ising one or more ot tho gases selected from the group consisting of CO, CO₂, C ₁ -C₅ alkanes, C ₁ -C₅ oxygenated hydrocarbons, nitrogen, water vapor, helium, and argon

31. The process of any of claims 26 to 30 further comprising a separate

regeneration step wherein the removed alkyne and multiunsaturate adducts of the metal complex are contacted with a hydrogen-rich, CO-depleted gas to form hydrogenated alkynes and multiunsaturates and a stream of

regenerated, multiunsaturates-free metal complex

32 The process of claim 31 wherein the regeneration step contacting is carried out at a H₂/CO partial pressure ratio of at least about 10, a total pressure of from about 0 1 to 50 MPa and a temperature of from about 50 to about 180°C

33 The process of any of claims 26 to 32 wherein the metal complex containing stream is introduced at a rate sufficient to form adducts of the

multiunsaturates without forming adducts of the alkynes

34 A process comprising hydrogenating the aldehyde produced according to any of the preceding claims to form the corresponding alcohol

35 A process comprising oxidizing the aldehyde produced according to any of the preceding claims to form the corresponding acid

36 A process comprising aldolizing the aldehyde produced according to any of the preceding claims to form the corresponding aldol dimer

37 A process according to claim 36 further comprising hydrogenating the aldol dimer to form a saturated aldehyde or saturated alcohol

38 The process according to claim 36 further comprising oxidizing the aldol dimer to form the corresponding unsaturated acid

39. A process comprising oxidizing the saturated aldehyde produced according t claim 37 to form the corresponding saturated acid

40 A process comprising aldol condensing the aldehyde produced according to any of the preceding claims with formaldehyde to form multi-methylol alkanes

41. The process of claim 40 wherein the aldehyde is propanal and the multi- methylol alkane is trimethylol ethane 42. A process comprising further aldol condensing the aldol dimer of claim 36 with formaldehyde to form the corresponding multi-methylol alkane 43. A process comprising further aldol condensing the saturated aldehyde of claim 37 with formaldehyde to form the corresponding multi-methylol alkane