BRPI0708525A2 - process for the preparation of 1,2-propanediol - Google Patents

Abstract

PROCESS FOR THE PREPARATION OF 1,2-PROPANODIOL. The present invention relates to a process for the preparation of 1,2-propanediol, in which a stream containing glycerol, in particular a stream obtained on an industrial scale in the production of biodiesel, is subjected to hydrogenation.

Description

"PROCESS FOR THE PREPARATION OF 1,2-PROPANODIOL"

The present invention relates to a process for the preparation of 1,2-propanediol, wherein a glycerol-containing stream, in particular an industrial-scale stream obtained in the biodiesel preparation, is subjected to hydrogenation.

Decreasing mineral oil reserves and increasing fuel prices are resulting in a growing interest in replacing mineral oil-based fuels for economically and environmentally friendly alternatives. Processes for the production of fuel from fat or oleobiogenic starter mixtures and waste oils obtained, for example, from restaurants and animal fats, have long been known, rapeseed oil currently being predominantly used in Central Europe as a starting material in production. of biogenic fuels. Biogenic oils and fats themselves are less suitable as a motor fuel since they have to be purified in advance by generally complicated methods.

These include the removal of lecithins, carbohydrates and proteins, the removal of oil sludge and the removal of free fatty acids present in relatively large quantities, for example in rapeseed oil. Vegetable oils treated in this way however differ from the technical properties of conventional diesel fuels in several respects. Thus, as a rule they have a higher density than diesel fuel, the rut oil number is lower than that of diesel fuel and the viscosity is several times higher compared to that of diesel fuel. This results in unacceptable deterioration of fuel properties such as non-uniform engine run-off behavior, substantially increased noise emission and, due to higher viscosity, poor atomization and combustion in the combustion chamber. In conventional engines, the use of pure vegetable oils therefore results in coking, associated with increased emission departments. It is well known that these problems can be solved by converting triglycerides (glycerol fatty acid esters) present in the departed biogenic oil and fat mixtures to fatty acid monoalkyl esters, in particular methyl or ethyl esters. These esters, also referred to as "biodiesel", can, as a rule, be used in retrofit diesel engines, often reducing the emission of burnt hydrocarbons and soot particles as compared to normal diesel fuel. Transesterification of triglycerides for biodiesel production also results in glycerol ('10%) which, for reasons of cost efficiency as sustainability, should be used. Therefore, there is a need for effective and economical processes that also allow the use of glycerol obtained in the production of biodiesel. These processes should in particular also be suitable for the use of other glycerol streams on an industrial scale.

US 2,360,844 describes a process for preparing slopes, wherein a crude glyceride is transesterified with C1 -C4 alkanols and the released glycerol is separated from monoalkyl esters. The use of glycerolobtide is not described.

US 5,354,878 describes a process for the preparation of higher fatty acid lower alkyl esters having a residual glycerol lowerotester by transesterification of acid-triglycerides and the use of these esters as diesel fuel.

DE 102 43 700 A1 discloses a semi-pressurization process for the preparation of higher fatty acid alkyl esters, in particular biodiesel, of fatty acid triglyceride starting mixtures comprising free fatty acids by a combination of acid esterification and basic transesterification. Glycerol obtained from natransesterification is partially used as a carrier in the esterification of free fatty acids.

It is known that alcohols having a relatively high hydricity can be converted to alcohols having a lower hydricity by catalytic hydrogenation. Thus, German Patent 524 101 describes such a process in which, among other things, glycerol is subjected to phase hydrogenation in the presence of a hydrogenation catalyst, with considerable excess hydrogen. Specifically, Cr-activated cobalt cobalt catalysts are used for glycerol hydrogenation.

German patent 541 362 describes a process for hydrogenating polyoxy compounds such as, for example, glycerol, the presence of catalysts at elevated temperatures above 150 ° C and superatmospheric under pressure. Specifically, hydrogenation of glycerol is described using a nickel catalyst at a temperature of 200 to 240 ° C and a hydrogen pressure of 100 atm.

R. Connor and H. Adkins, in J. Am. Chem. Sound. 54, 1932, pages 4678-4690, describes the hydrogenolysis of oxygen-containing organic compounds, among others, of glycerol with a concentration of 98% in 1,2-propanediol in the presence of a copper-chromium oxide catalyst.

C. Montassier et al., In Bulletin de la Societe Chimique de France 1989, No. 2, pages 148-155, describe investigations of the reaction mechanism of catalytic hydrogenation of polyols in the presence of various metal catalysts, such as, for example, glycerol. in Raney's uncovering presence.

J. Chaminand et al. In Green Chem. 6, 2004, pages 359-361 describe the hydrogenation of aqueous glycerol solutions at 180 ° C and 80 bar hydrogen pressure in the presence of Cu, Pd and Rh based supported metal catalysts.

DE 43 02 464 A1 describes a process for the preparation of 1,2-propanediol by hydrogenation of glycerol in the presence of a heterogeneous catalyst at pressures from 20 to 300 bar, in particular from 100 to 250 bar, and temperatures from 150 to 320 °. C is a vapor or liquid glycerol being passed through a catalyst bed. Among others, copper chromity, zinc copper oxide, aluminum copper oxide and cobresilicon dioxide are mentioned as catalysts. The use of biodiesel-containing glycogen-containing streams and measures for pretreatment of such currents prior to their use for hydrogenation are not described herein.

EP 0 523 015 describes a process for the catalytic hydrogenation of glycerol for the preparation of 1,2-propanediol and 1,2-ethanediol in the presence of a Cu / Zn catalyst at a temperature of at least 200 ° C. In this process, glycerol is used as an aqueous solution, having a glycerol content of from 20 to 60% by weight, the maximum glycerol content in the working examples being 40% by weight.

WO 2005/095563 describes a low pressure process for converting glycerol to propylene glycol, wherein a stream containing glycerol having a water content of no more than 50% by weight is subjected to catalytic hydrogenation at a temperature in the range of 150 ° C. at 250 ° C and a pressure in the range of 1 to 25 bar.

M. A. Dasari et al., In Appl. Chem. A: General 281, 2005, pages 225-231, describe a process for the hydrogenation of low pressure glycerol in propylene glycol at a temperature of 200 ° C and a hydrogen pressure of 200 psi (13.79 bar) in the presence of a nickel, palladium, platinum, copper or copper chromite catalyst. Different reaction parameters were tested, such as, among others, the glycerolusate water content. It has been found that while increased conversion with decreasing water content, the highest selectivity was achieved in this process under low pressure at a water content of 20% by weight. US 5,616,817 describes a process for the preparation of 1,2 -propanediol by catalytic hydrogenation of glycerol at elevated temperature and superatmospheric pressure, wherein glycerol having a water content of no more than 20% by weight is reacted in the presence of a catalyst comprising 40 to 70% by weight of cobalt, if appropriate. , manganese and / or molybdenum and a low copper content of 10 to 20% by weight. The temperature is in the range of about 180 to 270 ° C and the pressure in the range of 100 to 700 bar, preferably 200 to 325 bar.

It is an object of the present invention to provide a process for the preparation of 1,2-propanediol which permits the hydrogenation of glycerol containing streams with high selectivity and / or low energy consumption, as required, for example, to separate water. The process should be suitable, in particular, for the further processing of industrial scale glycerol streams, such as those obtained in fatty acid detriglyceride transesterification, for the preparation of higher fatty acid alkyl esters.

The invention therefore relates to a process for the preparation of 1,2-propanediol, wherein

a) a glycerol containing stream is supplied and

b) the glycerol-containing stream is subjected to hydrogenation in the presence of a heterogeneous copper-containing catalyst at a temperature of 100 to 320 ° C and a pressure of 100 to 325 bar.

The hydrogenation product obtained in step b) may, if appropriate, be subjected to at least one elaboration step (step c).

In principle, all glycerol-containing streams, including those from industrially performed processes and having the resulting purity therein, are suitable for use in the process according to the present invention. These include in particular glycerol-containing streams for processing oil and / or fat-containing starting materials, for example soap making, fatty acid and fatty acid ester production etc. The glycerol-containing stream provided in step a) is preferably a glycerol-containing stream obtained in the preparation of higher fatty acid alkyl esters by fatty acid detriglyceride transesterification, as obtained in particular in the production of "biodiesel". This embodiment of the process according to the present invention is described in more detail below.

The glycerol containing stream used in step a) preferably has a water content of not more than 30 wt%, preferably not more than 20 wt%. A water content corresponding to glycerol ammonium hydrate (water content 16.3% by weight) or less is particularly preferred. In a special form, a substantially anhydrous containing glycerol stream is used. In the context of the present invention, "substantially anhydrous" is understood to mean a water content of no more than 3 wt%, particularly preferable of no more than 1 wt%. The use of glycerol-containing streams having a water content in the range of up to 30 wt.%, In particular up to 20 wt.%, Enables the preparation of 1,2-propanediol in high yields and with high selectivity in the temperature and pressure range used for hydrogenation. Hydrogenation of non-substantially glycerol-containing streams and in particular of streams having a higher water content than glyceryl monohydrate is also possible at high yields and high selectivity, but due to reduced spacetime production, it is less economical. However, a water content in the range of 3 to 30% by weight may be advantageous for rheological properties during hydrogenation. A special embodiment of the process according to the present invention therefore relates to the use of glycerol-containing streams having a water content in the range of 3 to 30 wt%, preferably 5 to 20 wt%, to reduce viscosity during hydrogenation. Glycerol-containing streams may have at least one other preferably glycerol-miscible organic solvent (and as a result as a water-miscible rule) instead of or in addition to water. The glycerol containing streams provided in step a) preferably have a total dissolving content of no more than 20 wt%, particularly preferably no more than 15 wt%, in particular no more than 10 wt% and especially no more than 10%. 5% by weight. If solvent mixtures comprising water and at least one glycerol or water miscible organic solvent are used, the proportion of the organic solvent is preferably not more than 50% by weight, particularly preferably not more than 20% by weight, based on on the total weight of the solvent. Suitable glycerol-miscible organic solvents are C1 -C4 alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, polyols and their mono edialkyl ethers, cyclic ethers such as dioxane and tetrahydrofuran etc. Suitable solvents are aromatic hydrocarbons, such as benzene, toluene or xylenes. Preferred organic solvents are C1 -C4 alkanols, in particular methanol and / or ethanol and mixtures thereof with water. However, glycerol containing ascents used in step a) preferably do not have organic solvents.

The glycerol-containing streams provided in step a) may be subjected to at least one elaboration step. This includes, for example, at least one purification step to remove unwanted components. This further includes a reduction in water content and / or, if present, organic solvents.

Depending on the origin, glycerol-containing streams may also comprise inorganic salts as unwanted components. These may be removed from the crude glycerol by the elaboration procedures described below. Thermal elaboration (for example using a Sambay evaporator) is particularly suitable for this purpose. Depending on the origin, glycerol-containing streams may also comprise catalyst poisons, ie components that adversely affect hydrogenation by deactivation of the hydrogenation catalyst. These may include, for example, nitrogen-containing compounds such as amines and sulfur-containing compounds such as sulfuric acids, hydrogen sulfide, thio alcohols, thioethers, e.g. e.g. dimethyl sulfide edimethyl disulfide, carbon oxide sulfide, amino acids, e.g. amino acids comprising sulfur and additional nitrogen groups, fatty acids and their salts etc. Catalyst poisons further include halogen compounds, traces of conventional extraction agents, e.g. eg acetonitrile or N-methylpyrrolidone etc. and, if appropriate, arsenic and phosphorus compounds. A frequently present catalyst poison from oil-refining glycerol-containing sources is sulfuric acid, which is used as a catalyst in esterification or transesterification.

For example, thermal elaboration, preferably distillation, adsorption, ion exchange, a membrane separation, crystallization or extraction method or a combination of two or more of these methods may be used to make the glycerol containing streams of step a). Membrane separation methods using membranes of defined pore sizes are especially suitable for reducing water content and / or salt removal. Crystallization is also understood to mean partial freezing of glycerol-containing streams on cooled surfaces. Thus it is possible to remove impurities that accumulate in the solid phase.

In a first embodiment, the containing glycerol stream of step a) is subjected to distillation to reduce water content and / or to remove components that adversely affect catalytic hydrogenation. This can, in principle, be accomplished by conventional distillation methods known to the skilled artisan. Suitable distillation apparatus include distillation columns, such as tray columns, which may be equipped with covers, perforated plates, perforated trays, stacked trims, flushed trims, valves, side removals, etc., evaporators such as thin film evaporators, film evaporators. falling, forced circulation evaporators, Sambay evaporators, etc. and their combinations. Removal of sulfuric acid occurs even as a result of simple distillation, in particular short distillation.

Suitable separation procedures are described in the following documents: Sattler, Klaus: Thermische Trennverfahren, 3rd edition, WileyVCH, 2001; Schlünder EU, Thurner F .: Destination, Absorption, Extraktion, Springer Verlag, 1995; Mersmann, Alfons: ThermischeVerfahrenstechnik, Springer Verlag, 1980; Grassmann P., Widmer F.: Infuhrung in die thermische Verfahrenstechnik, Gruyter, 1997; Weip S., Militzer K.-E., Gramlich K.: Thermische Verfahrenstechnik, Dt. Verlag fur Grundstoffindustrie, Leipzig, Stuttgart, 1993. Reference is made here to these documents.

In another embodiment, the containing glycerol stream of step a) is subjected to catalytic desulfurization, if appropriate in the presence of hydrogen, to reduce the content of sulfur containing compounds, especially sulfur containing aromatic compounds. Suitable desulfurizing agents comprise a metal component, wherein the metals are preferably selected from metals of groups 6, 7, 8, 9, 10, 11 and 12 of the periodic table of elements. The metals are selected in particular from Mo, Ni, Cu, Ag, Zn and their combinations. Other suitable components of desulfurizing agents are doping agents. The metal component may be employed in oxidized form, reduced form and in the form of a mixture comprising reduced and oxidized oxidized constituents. The active components of the desulfurizing agents (metal component (s)) and optionally doping agent (s) may be applied to a support material. Suitable supports are the adsorbents and catalyst supports mentioned below. Preferably, the support material is selected from active carbons, graphites, carbon black, Al2O3, SiO2, TiO2, ZrO2, SiC, silicates, zeolites, terraargylous. (eg, bentonite) and combinations thereof. Application of at least one metal component and optionally other components to a support material may be accomplished by methods known to one skilled in the art, e.g. eg by co-precipitation or impregnation. Desulfurizing agents may be present in the form of a geometric body, e.g. eg in the form of spheres, rings, cylinders, cubes, cuboids or other geometry bodies. Unsupported desulfurizing agents may be shaped by standard forming processes, e.g. eg by extrusion, tableting, etc. The shape of the supported desulfurizing agents is determined by the shape of the support. Desulphurizing agents may be employed, e.g. eg in the form of cylinders, tablets, pellets, caster wheels, rings, stars or compressed extrudates, such as solid extrudates, polylobal extrusions (eg trilobal), hollow extrudates and beehive bodies. A preferred desulfurizing agent comprising copper ezinc in an atomic ratio of 1: 0.3 to 1:10, preferably 1: 0.5 to 1: 3, in particular 1: 0.7 to 1: 1, 5, is preferably used for catalytic desulphurization. A desulphurizing agent comprising 35 to 45 wt% copper oxide, 35 to 45 wt% zinc oxide and 10 to 30 wt% alumina is preferably used. In a preferred embodiment, the desulfurizing agent is a component capable of using as a hydrogenation catalyst in step b). In this regard, reference is made to the following description of the above-mentioned hydrogenation catalysts and processes for their preparation.

In one embodiment of this process variant, glycerol containing streams are brought into contact in at least one desulphurization zone with the desulphurizing agent and then hydrogenated by at least one reaction zone.

It is self-evident to the skilled artisan that the specific configuration and arrangement of the desulfurization and reaction zone (s) can be accomplished in any known manner. It is possible to arrange the desulphurization and reaction zone (s) spatially separated from each other, that is, to separate them structurally from each other by the apparatus configuration or to perform them in one or more common desulphurization / hydrogenation zone (s). .

The copper-zinc desulfurizing agent may be obtained, for example, by a conventional precipitation or co-precipitation method and used in oxidized as well as reduced form.

In a particular embodiment, the copper-zinc sulfurizing agent comprises at least copper, zinc and aluminum, the atomic ratio of copper: zinc: aluminum being in the range of 1: 0.3: 0.05 to 1: 10: 2, preferably from 1: 0.6: 0.3 to 1: 3: 1, and in particular from 1: 0.7: 0.5 to 1: 1.5: 0.9.

For conversion to reduced form, the desulphurization agent may be subjected to a hydrogenation reduction. This is accomplished at about 150 to 350 ° C, preferably about 150 to 250 ° C, in the presence of hydrogen, hydrogen being diluted by an inert gas, such as nitrogen, argon or methane, in particular nitrogen, such that the hydrogen content is 10% by volume or less, preferably 6% by volume or less, in particular from 0.5 to 4% by volume. The copper-zinc desulphurizing agent thus obtained ("reduced form") can be used in this way for desulphurization.

In one embodiment, desulphurization of the glycerol-containing stream is carried out via the oxidized copper-zinc desulphurization agent without hydrogen addition. In one embodiment, the desulphurization of the glycerol-containing stream is carried out by the copper-zinc in oxidized form in the presence of hydrogen.

In another embodiment, the glycerol-containing current desulphurization is carried out by means of the reduced zinc-copper desulphurization agent without the addition of hydrogen.

In another embodiment, the glycerol-containing current desulphurization is carried out by the reduced-zinc copper desulphurization agent in the presence of hydrogen.

Desulphurization is usually carried out within a temperature range of 40 to 200 ° C, in particular from 50 to 180 ° C, especially from 60 to 160 ° C, preferably from 70 to 120 ° C, at a pressure of 1 to 40 bar, particularly from 1 to 32 bar, preferably from 1.5 to 5 bar, especially from 2.0 to 4.5 bar. Desulphurization may be performed in the presence of inert gases such as, for example, nitrogen, argon or methane. As a rule, however, desulphurization is performed without the addition of inert gases.

Usually - if desired - hydrogen having a purity of> 99.9% by volume, preferably> 99.5% by volume, is used here. These purity apply analogously to hydrogen which is used in catalyst activations performed if appropriate.

Usually, the weight ratio of the glycerol-containing hydrogen stream is in the range of 40,000: 1 to 1000: 1, particularly in the range of 38,000: 1 to 5000: 1, in particular in the range of 37,000: 1 to 15,000: 1, preferably in the range of 36,000: 1 to 25,000: 1, especially in the range of 35,000: 1 to 30,000: 1.

The glycerol-containing stream thus desulphurised generally has a sulfur-containing impurity content, especially of aromatic sulfur compounds, of no more than 70 ppb, preferably no more than 50 ppb and the total sulfur content is <200 ppb, preferably <150 ppb. , in particular <100 ppb in all.

The desulphurizing agents described above also make it possible to reduce or remove chlorine, arsenic and / or phosphorus or the corresponding chlorine, arsenic and / or phosphorus containing compounds of the aromatic hydrocarbon or aromatic hydrocarbon mixture.

In another embodiment, the contend glycerol stream of step a) is brought into contact with at least one adsorbent to preempt components that adversely affect catalytic hydrogenation.

Adsorbents generally have a specific surface area, determined according to BET, in the range of about 10 to 2000m2 / g, preferably in the range of 10 to 1500m2 / g, more preferably in the range of 10 to 400m2 / g, especially in the range. range from 60 to 250 m2 / g.

Suitable adsorbents are, for example, active aluminas. They are prepared, for example, from aluminum hydroxide, which is obtainable from aluminum salt solutions by conventional precipitation methods. The active aluminas for the process according to the present invention are also obtainable from aluminum hydroxide gels. For the preparation of such gels, for example, precipitated aluminum hydroxide may be activated by conventional elaboration steps such as filtering, washing and drying and then, if appropriate, milled or agglomerated. If desired, the resulting alumina can then also be subjected to a forming method such as extrusion, granulation, tableting etc. Suitable adsorbents are preferably Alcoa Selexsorb ™ types.

Suitable adsorbents are furthermore alumina-containing solids. These include, for example, so-called clays, which also have aluminas as the main constituent.

Other suitable adsorbents are aluminum phosphates.

Other suitable adsorbents are silicas, which are obtainable, for example, by dehydration and activation of silica gels. Another process for the preparation of silica is flame hydrolysis of silicon tetrachloride. It is possible to vary the desired surface properties of the silica resulting in wide ranges by appropriate variations of the reaction parameters, such as, for example, the stoichiometric composition of the silica mixture. temperature departure.

Other suitable adsorbents are kieselguhrs, which also have silicas as the main constituent. These include, for example, terradiatomeae obtained from silica sediments.

Other suitable adsorbents are titanium bioxides and zirconium bioxides, as described, for example, in Rompp, Chemie-Lexikon, 9th edition (paperback), vol. 6, page 4629 et seq. And page 5156 et seq. And in the literature cited therein. Reference is made herein to its entirety.

Other suitable adsorbents are phosphates, in particular condensed phosphates, such as, for example, fused or calcined phosphates, which have a large active surface area. Suitable phosphates are described, for example, in Rompp, Chemie-Lexikon, 9th edition (freeback) vol. 4, page 3376 and following and in the literature cited there. Reference is made herein to this in its entirety.

Other suitable adsorbents are carbon-containing adsorbents, preferably active carbon. Active charcoal is generally understood herein to mean coal having a porous structure and large internal surface area. For the preparation of active charcoal, materials containing charcoal, animal and / or mineral charcoal are heated, for example, with dehydrating agents, such as zinc chloride or phosphoric acid, which are carbonized by dry distillation and then oxidatively activated. For this purpose, for example, the carbonized material may be treated at elevated temperatures of 700 to 100 ° C with steam, carbon dioxide and / or mixtures thereof.

Use of ion exchangers and / or adsorbing resins is also possible.

The adsorbents are preferably selected from titanium dioxide, zirconium dioxide, silica, kieselguhr, alumina, alumina-containing solids, aluminum phosphates, synthetic natural aluminum silicates, phosphates, carbon-containing adsorbents and mixtures thereof.

Adsorbents generally have a specific surface area determined according to BET, in the range of about 10 to 2000m2 / g, in particular in the range of 10 to 1500 m2 / g and especially in the range of 20 to 600 m2 / g.

For adsorptive removal of unwanted components, particularly components that adversely affect catalytic hydrogenation, the glycerol-containing stream from step a) is brought into contact with at least one adsorbent in an adsorption zone.

In a special embodiment, an adsorbent comprising at least one component also capable of use as a hydrogenation catalyst in step b) is used. The hydrogenation catalysts described in more detail below are referred to herein in their entirety. Combinations of two or more than two adsorbents are also suitable for use as adsorbents. It is possible to use exclusively components also capable of being hydrogenation catalysts, exclusively adsorbents not suitable as hydrogenation catalysts or combinations thereof.

In a preferred embodiment, the same component is used as adsorbent and as a hydrogenation catalyst. If appropriate, one or more other conventional adsorbents, as described above, differing from the hydrogenation catalyst, are further used herein.

In a process configuration, glycerol-containing streams are brought into contact in at least one adsorption zone with the adsorbent and then hydrogenated in at least one reaction zone.

It is self-evident to a person skilled in the art that specific configuration and arrangement of the adsorption and reaction zone (s) can be performed in any known manner. And preferably to arrange the adsorption and reaction zone (s) spatially separated from each other, that is, to structurally separate them by the configuration of the apparatus.

If different adsorbents are used, for example, a first adsorption zone comprising a first adsorbent may be provided in a first adsorption zone of a first reactor separately, i.e. structurally separated from it, for example a second reactor, a second reactor. reaction zone comprising a second adsorbent. Here, the first and / or second adsorbents may comprise at least one component capable of using a hydrogenation catalyst.

In another embodiment, a conventional adsorbent is used together with an adsorbent capable of hydrogenation in a single adsorption zone, for example in stratified form, mixed in the form of a random distribution or in the form of a gradient bed.

Use in the mixed form allows, if appropriate, better temperature control. In the case of a gradient bed, linear and nonlinear gradients may be used. It may be advantageous here to implement the distribution within the bed such that the glycerol containing stream to be hydrogenated is first brought into contact with the adsorbent prior to being brought into contact with the hydrogenating capable adsorbent.

Advantageously, at least two adsorption zones will be arranged such that the glycerol-containing stream to be hydrogenated is brought into contact with a conventional adsorbent in the first adsorption zone and is brought into contact in the second adsorption zone with at least one component capable of use as a hydrogenation catalyst.

The glycerol-containing streams provided in process step a) of the present invention preferably originate from the production of biodiesel. In the context of the present invention, "biodiesel" is understood to mean a mixture of monoalkyl acid ester esters, which may be obtained from starting mixtures containing biogenic oil and / or fat and may be used as fuel in diesel engines.

In principle, all starting mixtures containing oleobiogenic and / or fat are suitable for providing the containing glycerol stream. Oils and fats are generally semi-solid or liquid fatty acid triglycerides, in particular from plant and animal sources, which chemically comprise substantially glyceryl esters of higher fatty acids. Suitable higher fatty acids are fatty or monounsaturated or polyunsaturated acids, preferably having 8 to 40, particularly preferably 12 to 30 carbon atoms. These include, for example, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid. melissic acid, palmitoleic acid, acidolinolinic acid, linolenic acid, stearic acid, elastarestic acid ètc.

Vegetable fats and oils are substantially based on fatty acids having an even number of carbon atoms, while animal fats and oils may also comprise fatty acids having an odd number of carbon atoms, in free or bound form as triglyceride esters. Unsaturated fatty acids, occurring in fatty oils and vegetable oils, are present in useful form, whereas animal fatty acids often have a trans configuration.

In principle, used or unused, unused or purified vegetable, animal or industrial oils or fats or mixtures thereof may be used to provide the glycerol-containing stream of step a). These may comprise proportions of other ingredients, for example free fatty acids. The proportion of free fatty acids is generally from 0% to 50%, e.g. 0.1 to 20% of the starting mixture used for the transesterification of fatty acid triglycerides. Free fatty acids may, if desired, be removed before or after transesterification of fatty acid triglycerides. Salts of these fatty acids (eg alkali metal bones) can be converted to the free acid in advance by acidification with a strong acid, e.g. e.g., HCl. Isolation of free fatty acids is performed, for example, by centrifugation. Preferably, the free fatty acids present in the starting mixture are also converted to alkyl esters. This may be done before, during or after the transesterification of fatty acid triglycerides.

Waste fats and oils suitable for providing the glycerol-containing chain of step a) are fat and / or oleock-containing components, after their recovery from appropriate biogenic starting materials, were first used for other purposes, for example, for technical or food production, and may be chemically modified or unmodified as a result of this use or may have additional ingredients which in particular are associated with such use. These may, if desired, be at least partially removed by transesterification prior to use to provide the glycerol containing stream. Unused fats and oils to provide the glycerol-containing stream of step a) are fat or oil-containing components which have not yet been used for any other purpose after their recovery from the appropriate vegetable or animal departmental materials and which therefore have only ingredients that originate whether from the starting materials or are associated with the recovery of the starting materials. Ingredients other than fatty acid triglycerides (and, if appropriate, free fatty acids) may also, if desired, also be partially removed from these starting materials by transesterification prior to use to provide the glycerol containing stream.

For purification and / or enrichment, unused or unused fats or oils may be subjected to removal of unwanted ingredients such as lecithins, carbohydrates, proteins, oil sludge, water etc.

Vegetable oils and fats are those which originate predominantly from vegetable starting materials such as seeds, roots, leaves or other suitable plant parts. Animal fats or oils originate predominantly from animal starting materials such as animal organs, tissues or other body parts or body fluids such as milk. Industrial oils and fats are those which have been obtained in particular from animal or vegetable starting materials and treated for finishers. Used or unused, unpurified or purified oils and / or fats and / or fats used in accordance with the invention are selected in particular from the group consisting of soap filler, brown grease, tallow, industrial lard, frying oils, animal fat, edible fat, crude vegetable oils, crude animal oils or fats or mixtures thereof.

"Soap load" is understood to mean a byproduct obtained in the processing of vegetable oils, in particular an edible oil refinery byproduct, which is based on soybean, rapeseed or sunflower oil. The soap filler has a ratio of about 50% to 80% free fatty acids.

"Brown grease" is understood to mean an individual producer containing animal fat, which has a proportion of more than 15% to 40% free fatty acids. "Yellow grease" comprises from about 5% to 15% free fatty acids.

"Industrial tallow" and "industrial lard" are understood to mean animal fats that are produced for industrial purposes and are obtained after drying or wet melting process, for example from animal killing waste. Industrial tallies are classified as emanipulated according to their acid number, the fatty acid content, for example from 1 to 15 to 20% by weight and in some cases even higher depending on their origin.

"Animal fats" include, in particular, fat-containing waste products obtained from the use of bodies of vacuum cattle, pigs, fish and marine mammals, eg solar stearin, a solid residue that remains after the lard oil has been forced out. pork dabanha.

The glycerol-containing stream of step a) is preferably provided with crude vegetable oils as a starting material. It is possible to start from unpurified crude vegetable oils, i.e. from liquid or solid compositions, which are obtained from vegetable starting materials, for example by compression, which have not been treated other than by sedimentation in usually customary periods and centrifugation or filtering, in particular. Mechanical forces, such as gravitational force, centrifugal force or pressure, are used to separate oil from solid constituents. Such unpurified crude vegetable oils may also be vegetable oils obtained by extraction if their properties do not differ or differ significantly only from the corresponding vegetable oils obtained by means of decompression. The proportion of fatty acids in non-purified vegetable fats and oil differs and is, for example, from about 0 to 20%, such as, for example, from 0.1 to 15%.

Before being used for transesterification, vegetable oils can of course undergo one or more elaboration steps as described in more detail below. Thus, purified vegetable oils, for example raffinates or semi-raffinates, of the aforementioned vegetable oils may also be used as starting materials.

A vegetable oil or fat which is preferably selected from rapeseed oil, palm oil, rapeseed oil, soybean oil, sunflower oil, cottonseed oil, palm kernel oil and coconut fat and mixtures thereof is preferably used to provide the current containing glycerol of step a). Particularly preferably used is rapeseed oil or a mixture containing rapeseed oil.

Animal fat or oil is preferably selected from milk fat, wool fat, beef tallow, lard, fish oils, blubber etc. and mixtures thereof are also suitable for providing the glycerol containing stream of step a). Prior to their use for transesterification, these animal fats and oils may also be subjected to one or more preparation steps, as further described below.

Preferably, the provision of the glycerol-containing step step a) comprises the following steps:

(al) providing a starting mixture containing biogenic fat and / or oil;

(a2) transesterification of the fatty acid triglycerides in the starting mixture with at least one C1-C9 monoalcohol and, where appropriate, esterification of the free fatty acids present in the divided mixture with formation of an esterification mixture;

(a3) separation of the esterification mixture to give at least one biodiesel enriched fraction and at least one glycerol enriched fraction released in the esterification;

a4) if appropriate, purification of the glycerol enriched fraction.

Step al)

In one embodiment, the provision of the mixture containing biogenic fat and / or oil in step (a) comprises at least one purification step. For purification, the fat and / or oil starting mixture may be subjected to at least one purification process commonly used for fats and oils, such as clarification, filtration, bleaching earth treatment or alkali acids treatment for separation of problematic impurities, such as proteins, phosphatides and iodines and a combination of at least two of these purification steps.

Step a2)

At least one C1 -C9 monoalcohol, in particular at least one C1-C4 monoalcohol is preferably used for transesterification of fatty acid triglycerides. The use of methanol or ethanol is preferred.

Transesterification of fatty acid triglycerides may be performed by acid catalysis or preferably basic. Suitable acids are, for example, mineral acids such as HCl, H2SO4 or H3PO4.

At least one base is preferably used as a catalyst. Said base is preferably selected from alkali metal hydroxides such as NaOH and KOH, alkaline earth metal hydroxides such as Ca (OH) 2, C1 -C6 alkaline and alkaline earth metal alkanolates such as NaOCH3, KOCH3, Na (OCH2CH2) and Ca (OCH 2 CH 2) 2 and mixtures thereof. Naa, KOH or NaOCH 3 is particularly preferably used, most preferably NaOCH 3.

The amount of the base used is usually in the range of from 0.1 to 10% by weight, in particular from 0.2 to 5% by weight, based on the amount of fatty acid triglycerides used.

The base is preferably used in the form of an aqueous or alcoholic solution, in particular preferably alcoholic. The solvent already used for triglyceride alcohololysis is advantageously used as a base solvent. The NaOCH3 solution in methanol is preferably used for transesterification.

The transesterification is preferably carried out at a temperature of about 20 to 150 ° C, in particular from 30 to 95 ° C.

Transesterification is performed in apparatus customary for this purpose and known to the person skilled in the art. In a proper derealization form, transesterification is performed continuously. The transesterification is preferably performed on at least one column, the transesterification mixture obtained simultaneously being subjected to a separation. In general, a higher boiling phase which is enriched as a basic catalyst with unconverted monoalcohol and glycerol formadone transesterification is obtained and a lower boiling phase which is enriched with the transesterification product is obtained. If the transesterification product still contains triglycerides which have not undergone transesterification, they may also be separated and further transesterified at the first or another transesterification stage.

The last transesterification mixture is then transferred to a drying unit, residual amounts of water again removed. After drying in the drying apparatus, the desired end product biodiesel is present in purified form and can be used directly as fuel.

If the fat and / or oil-containing starting mixture used to provide the glycerol-containing stream in step a) comprises free fatty acids, they may preferably be subjected to esterification to convert into biodiesel-suitable esters.

Free fatty acids are preferably transesterified with the same C1-C9 monoalcohol as was used for transesterification of fatty acid triglycerides. Esterification of free fatty acids may be performed before, during or after transesterification of fatty acid triglycerides. In a preferred embodiment, esterification of free fatty acids is performed prior to transesterification of acid-triglycerides.

Esterification of free fatty acids may be performed by basic or preferably acid analysis. Suitable acids are the above-mentioned mineral acids such as HCl, H2SO4 or H3PO4, p-toluene sulfonic acid etc. The esterification is preferably carried out at a temperature of from about 20 to 95 ° C, in particular from 40 to 80 ° C.

Esterification is carried out in customary paraffin apparatus and known to the skilled artisan. These include agitated vessels and / or columns which, if desired, are connected to form cascades. The esterification of free fatty acids is preferably performed in at least one esterification apparatus designed as a column, the esterification mixture obtained simultaneously being subjected to separation. In a suitable embodiment, esterification is performed in the presence of a dragging agent to facilitate separation.

Step a3)

During or after transesterification and / or esterification, the esterification mixture is separated to give a fraction enriched with C1-C9 monoalcohol esters and at least a glycerol-enriched fraction released on transesterification. Separation is preferably carried out by conventional distillation methods known to the person skilled in the art. Suitable distillation apparatus are those mentioned above.

Step a4)

The fraction obtained after separation of the glycerol-enriched step (a3) esterification mixture may, if appropriate, be subjected to at least one elaboration step. This includes, for example, the removal of unwanted components, such as salts, and components that adversely affect catalytic hydrogenation or the removal of water and, if present, the organic solvent. Reference is made to the above statements about these elaboration steps in their entirety.

Catalysts used in the process according to the present invention may be unsupported catalysts or supported catalysts.

They may be used in the form of catalysts of uniform composition, impregnated catalysts, coated catalysts and precipitated catalysts.

In principle, a large number of catalysts containing copper, which may additionally comprise at least one other major group I, II or III, IV, V element, or lanthanide subgroup I, II, IV, V, VII or VIIIe (IUPAC) : groups 1 to 15 and lanthanides) are suitable, in particular Ca, Mg, Al, La, Ti, Zr, Cr, Mo, W, Mn, Ni, Co, Zn and their combinations.

A special embodiment of catalysts which are particularly advantageous for use in the process according to the present invention comprises skeletal or metal sponge catalysts, such as those referred to as "Raney catalysts". These include, in particular, copper-containing Raney copper alloys in the form of a Raney catalyst. Raney catalysts, whose metal component comprises at least 95%, in particular at least 99% copper, are preferred. Processes for preparing Raney catalysts are known to the skilled person and are described, for example, in DE-A-4335 360, DE-A-43 45 265, DE-A-44 46 907 and EP-A-842 699.Raney copper can be prepared in a manner known per se by treating copper-aluminum alloys with alkali metal hydroxides. A suitable Raney catalyst for use in the process according to the present invention is obtainable, for example, by preparing a mixture of at least one copper-containing catalyst alloy and at least one binder, the decatalyst alloy comprising copper and, if appropriate, at least a catalytically active catalyst other and a leachable component, if appropriate with addition of wetting agents and / or additives such as molding aids, lubricants, plasticizers and / or pore-forming, homogenization of this mixture and molding to provide desired molding, calcination of the molding and activating the catalyst precursor thereby obtained by partial or complete leaching of the leachable component and, if appropriate, final washing of the prepared catalyst.

Another special embodiment of catalysts which are particularly advantageously used in the process according to the present invention comprises catalysts consisting of oxidizable copper form and, if appropriate, additionally in elemental form. The hydrogenation catalyst used in step b) then preferably comprises at least 23% by weight, particularly preferably at least 35% by weight of oxidizable and / or elemental copper, based on the total catalyst base.

A process frequently used for the preparation of such catalysts comprises the impregnation of support materials with solutions of the catalyst components, which are then converted to the catalytically active state by heat treatment, decomposition or reduction.

Another suitable process for preparing decatalysts comprises precipitating one catalyst component or co-precipitating two or more catalyst components. Thus, a copper compound, optionally at least one other metal compound / or an additive, is precipitated and subjected to subsequent drying, calcination and forming to produce a shaped catalyst body. Precipitation may be performed in the presence of a non-supporting material. Suitable starting materials for precipitation are metal salts and metal complexes. As a copper compound for precipitation it is a known principle to use all Cu (I) and / or Cu (II) salts which are soluble in the solvents used for support application, eg nitrates, carbonates, acetates, oxalates or complexes. Ammonium Particular preference is given to the use of copper nitrate. The catalytically active component of the catalyst may further comprise, in addition to a copper compound, other elements as additive components, e.g. eg metals, non-metals and their compounds. These preferably include a metal groups 4 to 15 and the lanthanides. These preferably include metals such as La, Ti, Zr, Cu, Mo, W, Mn, Re, Co, Ni, Cu, Ag, Au, Zn, Sn, Pb, As, Sbe Bi. Preferably, an aqueous medium is used for precipitation.

Suitable aqueous media are substances or mixtures which are liquid under the process conditions and contain at least 10 wt%, preferably at least 30 wt% and in particular at least 50 wt% water. The non-water part is preferably selected from inorganic or organic substances, which are at least partially water soluble or at least partially water miscible. For example, non-water substances are selected from organic solvents, C1-C22 alkanols, in particular methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, pentanols and hexanols, C4-C8cycloalkyl ethers, such as tetrahydrofurans, pyranes, dioxanes and trioxanes, C1 -C12 dialkyl ethers such as dimethyl ether, dibutyl ether and methyl butyl ether. Aqueous medium preferably contains less than 40%, in particular less than 30% and particularly preferably less than 20% organic solvent. In preferred embodiments of the process of the present invention, the aqueous medium is essentially free of organic solvents.

Precipitation can be induced by known methods, e.g., cooling a saturated solution, adding a precipitating agent etc. Suitable precipitating agents are e.g. acids, bases, reducing agents etc. Precipitation may be induced by the addition of an acid or base to the aqueous medium containing the copper compound and optionally other compounds. Suitable acids are mineral acids such as HCl, H2SO4 and H3PO4. The base is preferably selected from metal oxides, metal hydroxides, in particular alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, metal carbonates, in particular alkali metal and alkaline earth metal carbonates, e.g. lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate, nitrogen bases, in particular ammonia, primary, secondary and tertiary amines.

Examples of reducing agents are carboxylic acids, such as formic acid, citric acid, lactic acid, tartaric acid and, in particular, carboxylic acid salts, preferably alkali metal, alkaline earth metal, ammonium and C1-C10 alkylammonium salts, phosphorus acid or hypophosphorus, salts of phosphorus or hypophosphoric acid, in particular alkali metal or alkaline earth metal, C1-C10 alkanols such as methanol, ethanol and isopropanol, sugars such as aldoses and ketoses in the form of monosaccharides, disaccharides and oligosaccharides, in particular glucose, fructose and lactose, aldehydes such as formaldehyde, borohydrogen compounds such as boron hydrides, boranes, metal borane and borane complexes, e.g. diborane, sodium borohydride and aminoboranes, in particular trimethylaminoborane, hydrazine and aminoboranes, in particular trimethylaminoborane, hydrazine and alkylhydrazines, such as methylhydrazine, hydrogendothionites and dithionites, in particular sodium epotassium hydrogen dithionites, potassium zinc dithionites, and sulfites, in particular sodium and potassium hydrogen sulfites, sodium sulfites, potassium and calcium, hydroxylamine and urea and mixtures thereof.

For example, catalysts comprising nickel and copper as well as other metals as active constituents on a silica support are suitable for hydrogenation. Such catalysts are described, for example, in DE-A 26 28 987. The active material of these catalysts comprises in particular from 40 to 80% by weight of nickel, from 10 to 50% by weight of copper and from 2 to 10% by weight of nickel. manganese.

EP-A-O 434 062 discloses hydrogenation catalysts obtainable by reduction of a precursor comprising oxides of copper, aluminum and at least one other metal selected from magnesium, zinc, titanium, zirconium, tin, nickel and cobalt.

Hydrogenation catalysts, which are described in DE 10218 849 and comprise from 0.1 to 10 wt.% Of chromium, calculated as Cr2O3, from 0.1 to 10 wt.% Of calcium, calculated as CaOx and from 5 to 20%. Copper weight, calculated as CuO, deposited on a silica-bearing material and based in each case on the total weight of the calcined catalyst, are also suitable.

DE-A-40 21 230 describes copper oxide / zirconium catalysts, the ratio of copper atoms to zirconium atoms, expressed as a weight ratio, from 1: 9 to 9: 1.

DE-A-4,028,295 describes copper / manganese hydrogenation catalysts.

EP-A-5 52463 describes hydrogenation catalysts in a first embodiment, the oxide form substantially corresponding to the composition CuaAlbZrcMndOx, the following ratios being applicable: a> 0; b> 0; c> / = 0; d> 0; a> b / 2; b> a / 4; a> c; a> d; and χ is the number of oxygen ions that is required to preserve electroneutrality per formula unit. According to another embodiment, the catalyst according to the present invention comprises a lower proportion of alumina. The catalyst according to this embodiment substantially corresponds to the composition CuaAlbZrcMndOx, the following ratios being applicable: a> 0; b = a / 40 a a / 4; c> / = 0; d> 0; a> c; a = 0.5 of 0.95d and χ is the number of oxygen ions that are required to preserve electron neutrality per unit of formula.

WO 2006/005505 discloses molded catalyst bodies which are particularly advantageous for use in the process according to the present invention. These catalysts can be produced by a process in which

(i) an oxide material comprising copper oxide, aluminum oxide and at least one of lanthanum, tungsten, molybdenum, titanium or zirconium oxides, preferably given to delanthanum and / or tungsten oxides, is made available.

(ii) powdery metallic copper, copper flakes, powdery cement or a mixture thereof with graphite may be added to the oxidic material and

(iii) the resulting mixture of (ii) is formed to form a catalyst shell or catalyst extrudate having a diameter of / or a height h of <2.5 mm, catalyst balls having a diameter d of <2, 5 mm or hive catalyst having a diameter Γζ of <2,5 mm.

Among lanthanum, tungsten, molybdenum, titanium or zirconium oxides, lanthanum oxide is preferred. The composition of the oxide material is generally such that the proportion of copper oxide is in the range of 40 to 90% by weight, the proportion of lanthanum, tungsten, molybdenum, titanium or zirconium oxides is in the range of 0 to 50% by weight and The aluminum oxide ratio is up to 50% by weight, in each case based on the total weight of the above mentioned oxide constituents, with these three oxides together comprising at least 80% by weight of the oxide material after calcination and cement not being included as part of the oxide material in the above sense.

In a preferred embodiment, the oxidic material comprises

(a) copper oxide in a fixed ratio of 50 <χ> 80 wt%, preferably 55> χ> 75 wt%,

(b) aluminum oxide in a ratio in the range of 15 <y> 35 wt%, preferably 20> 30 wt%, and

(c) at least one of the lanthanum, tungsten, molybdenum, titanium or zirconium oxides, preferably lanthanum and / or tungsten oxides,

in a proportion in the range of 2 <ζ <20 wt%, preferably 3> ζ> 15 wt%,

in each case based on the total weight of the oxide material after calcination, where 80 <χ + y + ζ <100, in particular 95 <x + y + z <100.

Preferred catalysts comprise the following metals in oxide form, reduced form (elemental form) or a combination thereof. Metals that are stable in more than one oxidation state may be employed entirely in one of the oxidation states or a combination of different oxidation states: CuCu , TiCu ZrCu5MnCu, AlCu, Ni, MnCu, Al, at least one other selected metal from La, W, Mo, Mn, Zn, Ti, Zr, Sn, Ni, CoCu, Zn, ZrCu, Cr, CaCu, Cr, CCu , Al, Mn, optionally Zr

Especially preferred catalysts comprise the following metals: CuCu, Ti

Cu5Al

Cu, al, la

Ass, Al, Zn

Cu, Zn, Zr

Ass, Al, Mn

Cu, Cr, C

Virtually all prior art support materials as advantageously used in the preparation of supported catalysts, for example SiO2 (quartz), porcelain, magnesium oxide, titanium dioxide, silicon carbide, TiO2 (rutile, anatase), ZrO2, Al2O3 (alumina), aluminum silicate, steatite (magnesium silicate), zirconium silicate, cerium silicate or mixtures of these materials may be used as a backing material for the catalysts according to the present invention. Preferred support materials are alumina and silica. Silica materials of different origin, for example, pyrogenically produced silicas or silicas produced by a chemical method, such as silica gels, precipitated or silica aerogels, can be used as silica support material for the preparation of the catalyst (for the preparation of various SiO2 partition materials cf.: W. Büchner; R. Schliebs; G. Winter; H. H. Büchel: lndustrielle Anorganische Chemie; 2nd edition, pages 532-533, VCHVerlagsgesellschaft, Weinheim 1986).

Catalysts may be present in the form of a corpogeometric, e.g. eg in the form of spheres, rings, cylinders, cubes, cuboids or other geometrical bodies. Unsupported catalysts may be shaped by standard methods, e.g. eg extrusion, tableting, etc. The shape of the supported catalysts is usually determined by the shape of the support. In an alternative, the support may be subjected to a conformation process prior to or after application of the catalytic reactive compound (s) or a precursor thereof. Catalysts may be employed, e.g. eg in the form of cylinders, tablets, inserts, wagon wheels, rings, stars or extruded, such as solid extrudates, polylobal extrusions (eg trilobal), hollow extrudates and honeycomb bodies.

Catalyst particles generally have an average (wider) diameter value of 0.5 to 20 mm, preferably 1 to 10 mm. These include, for example, tablet catalysts, for example, having a diameter of 1 to 7 mm, preferably 2 to 6 mm and a height of 3 to 5 mm, rings having, for example, an external diameter of 4 to 7 mm. preferably 5 to 7 mm, a height of 4 to 7 mm, preferably 2 to 5 mm and a bore diameter of 2 to 3 mm, or filaments of different lengths having a diameter of, for example, 1.0 to 5 mm. Such formats may be obtained in a manner known per se by tableting, extrusion molding or extrusion. For this purpose, conventional adjuvants, for example, lubricants such as graphite, polyethylene oxide, cellulose or fatty acids (such as stearic acid) and / or casting aids and reinforcing agents such as glass fibers, asbestos or silicon carbide may be used. be added to the catalyst material.

A special embodiment of supported catalysts comprises coated catalysts. Coated catalysts are also preferably suitable for the process according to the present invention. Coated catalysts comprise a catalytic material applied as a coating on a support. They may be present in the form of spheres, rings, cylinders, cubes, cuboids or other geometric bodies. Regardless of the type and composition of the catalytically active material, the coated catalyst particles can in principle be provided by bringing the support into contact with a liquid binder and the catalytically active material by applying a layer of the material to the support and then, if appropriate, partially removing it. become agglutinating. In order to provide the catalyst particles, the catalytically active material is already applied in its prepared catalytically active form, for example as calcined mixed oxide. Suitable processes for the preparation of coated catalysts are described, for example, in DE-A-29 09 671 and EP-A-714 700. According to the last mentioned process, the support is first moistened with the liquid binder, a layer of material. The active catalyst is then attached to the surface of the moistened support body by bringing it into contact with dry, finely divided active catalyst material and, if appropriate, the liquid binder is then partially removed. In a special embodiment, the steps of dampening the carrier into contact with the catalyst material and removing the liquid binder are repeated once or several times until the desired layer thickness of the coated catalyst is achieved.

Another special embodiment of supported catalysts comprises catalysts prepared by impregnation methods. For this purpose, supported catalysts comprise catalysts prepared by impregnation methods. For this purpose, catalytically active catalyst components or their precursor compounds may be applied to the support material. In general, aqueous salt solutions of the components, for example aqueous solutions of their halides, sulfates, nitrates etc. are applied to impregnate the support material. The copper component may also be applied, for example, as an aqueous solution of its amine complex salts, for example, as [Cu (NH3) 4] SO4 solution or as [Cu (NH3) 4] (NO3) 2. , appropriate in the presence of sodium carbonate in the support material.

Of course, copper amine complexes other than those mentioned by way of example can also be used with the same success for catalyst preparation.

Impregnation of the carrier material with the parent compound precursors of the catalytically active components may be carried out at one stage or in a plurality of stages. Impregnation may be performed on conventional impregnation apparatus, for example impregnation drums. After drying and / or calcination, the prepared catalyst is then obtained. Drying of the impregnated catalyst moldings may be carried out continuously or in batches, for example in belt or tray ovens. Drying can be carried out in a gas stream, for example in a gas stream or a nitrogen stream. Depending on the applied pressure it is generally carried out at temperatures of 50 to 200 ° C, preferably from 80 to 150 ° C. Pre-dried calcination of the catalyst, if appropriate, is generally carried out at temperatures of 200 to 800 ° C, preferably from 500 to 700 ° C. Calcination, such as drying, can be performed continuously or in batches, for example in belt or tray ovens. Calcination may be performed at atmospheric or reduced pressure and / or in a gas stream, for example in an air stream or hydrogen stream. A pretreatment with hydrogen or hydrogen-comprising gases, generally under conditions that meet the hydrogenation conditions, serves for the preliminary reduction / activation of the hydrogenation catalyst. However, the catalyst may also be reduced in situ under the conditions specified in the case of hydrogenation, preferably under pressure (e.g., at a hydrogen pressure of about 100 to 325 bar).

In hydrogenation, the resulting glycerol and 1,2-propanediol are preferably present in the liquid phase.

Catalysts may be arranged, for example, in a fixed bed or may be used as a suspension. Hydrogenation can therefore be performed, for example, by the slow bed procedure or liquid phase procedure. For liquid phase hydrogenation, catalysts are preferably used in finely divided form, e.g. as a powder in suspension. In slow phase hydrogenation, catalysts are used as moldings, as described above, for example in the form of cylinders, tablets, pads, wagon wheels, rings, stars or extruded tablets, such as solid extrusions, polylobal extrusions, hollow extrusions and beehive bodies. . Excess hydrogen is preferably circulated, and a small portion may be discharged as waste gas to remove inert materials. A reactor or a plurality of reactors may be used which may be connected in series or in parallel with one another.

The hydrogenation temperature of step b) is preferably from 150 to 300 ° C, in particular from 175 to 250 ° C.

The reaction pressure in step b) is preferably from 140 bar to 250 bar.

The molar ratio of hydrogen to glycerol is preferably from 2: 1 to 500: 1, preferably from 3: 1 to 100: 1.

The spatial velocity of the catalyst in the continuous procedure is preferably from 0.1 to 1, more preferably from 0.2 to 0.6, and in particular from 0.3 to 0.6 kg of glycerol to be hydrogenated per kg (catalyst) per H.

The conversion based on glycerol is preferably at least 90%, in particular at least 95%. The selectivity based on 1,2-propanediol is preferably at least 85%, particularly preferably at least 90% in the process according to the present invention. Often even higher selectivities of up to 95% or more can be achieved.

Hydrogenation is conveniently performed continuously.

The hydrogenation discharge substantially comprises 1,2-propanediol.

Other constituents are, among others, methanol, ethanol, n-propanol, isopropanol, 1,3-propanediol, glycerol, ethylene glycol and water. The hydrogenation discharge can then be elaborated by conventional methods known to the person skilled in the art. For example, thermal elaboration, preferably distillation, adsorption, ion exchange, a membrane separation, crystallization or extraction method or a finger combination or more of these methods may be used. Preferred is a distillation preparation. This can in principle be performed by conventional distillation methods known to the skilled person in the art. Suitable distillation apparatus comprises distillation columns, such as tray columns, which may be equipped with lids, perforated plates, perforated trays, stacked trims, dumped trims, valves, side removals, etc. evaporators such as thin film evaporators, falling film evaporators, forced circulation evaporators, Sambay evaporators etc. and their combinations. Glycerol still present in the hydrogenation charge may be recycled to the hydrogenation stage, if appropriate, after being distilled off.

The invention is explained in more detail with reference to the following non-limiting examples.

Examples

Glycerol of the pharmaceutical glycerol and pure glycerol qualities from Biodiesel Schwarzheide GmbH was used as feedstock for catalyst evaluation experiments. Table 1 shows the analytical data of glycerol used.

Table 1

<table> table see original document page 38 </column> </row> <table>

Glycerol analysis of feed loading and discharge is performed by gas chromatography (data in% GC per area).

HP 5890-2 sampler device

Range: 2

Column: 30 m DBWax; Film thickness: 0.25 μπι Sample volume:

Carrier Gas:

Fluid rate

injector temperature:

Detector:

Temperature Detector:

Temperature program:

1 μl

Helium

100 ml / min

240 ° C

FID (flame ionization detector)

250 ° C

min at 40 ° C, 10 ° C / min at 240 ° C 15 min at

240 ° C

Total working time 45 minCatalysts containing copper of different compositions were tested (see table 2).

Table 2: Summary of Catalysts Tested

<table> table see original document page 39 </column> </row> <table>

* for B, but higher calcination temperature (from 400 to 500 ° C)

** by Aldrich

The catalysts were activated for 10 h at a temperature of 200 ° C and a hydrogen pressure of 50 bar before the reaction.

General method for batch batch catalyst testing

Pharmaceutical glycerol having a water content of 20% was used. The catalyst was initially placed in a 0.31 min autoclave and the autoclave was closed and was tested for leaks at 200 bar N2 at room temperature. Catalyst extrudates were used in the form of moldings and extrudates were comminuted in advance for the preparation of catalyst suspensions.

Then the autoclave was depressurized and the activation of catalyst performed. For this purpose, 50 bar H2 were forced at room temperature, heating was then performed at an internal temperature of 200 ° C and the temperature was maintained for about 10 h without agitation. After cooling to 30 ° C and subsequent inertization with N2, the The autoclave was evacuated and the reaction solution was aspirated.

For the glycerol reaction, 50 bar H2 were forced at room temperature and the reaction mixture was heated to 215 ° C with co-operation (700 to 1000 rpm speed). The resulting autoclave pressure was supplemented with H2 at the desired final pressure of 200 bar. The hydrogen consumed in the reaction was replenished. The time of the experiments was 10 hours. After the end of the experiment, the autoclave was cooled to room temperature and depressurized. The analysis of samples and discharges was performed by gas chromatography by integration of peak areas (% per area). The results are shown in table 3.

Table 3: Comparison of fixed bed catalyst and de-suspension procedures

<table> table see original document page 40 </column> </row> <table> General method for continuous hydrogenation using fixed delight catalysts

Pharmaceutical glycerol was used, having a water content of 10%. The experiments were performed in a laboratory apparatus continuously operated at 200 to 240 bar. Experimental series 9 to 11 were operated to simulate the main reactor with liquid circulation in the liquid phase procedure. In each case 70 ml of the catalysts were used.

The unit structure and process description are described below:

The unit consists of a 75 ml R1 tubular reactor (internal = 12 mm, L = 800 mm), having three liquid heated heating zones, which is operated by the liquid phase procedure. If necessary, a flow of liquid, which is operated with flow control (Danfoss) via an HPLC pump, can be connected. All parts of the unit are made of metal and designed for an operating pressure of up to 250 bar.

The glycerol solution (aqueous, 90% concentration) is continuously measured, regulated by a scale within the reactor R1 and reacted under defined conditions (pressure, temperature, catalyst spatial velocity) with hydrogen to provide the desired product. Hydrogen is supplied by 50 l steel cylinders, which are compressed to the required pressure by means of a compressed air operated compressor. The desired reaction pressure is established via pressure control (P2) in the waste gas stream and the required amount of hydrogen is fed into the flow-controlled reactor R1 via a mass flow meter (Hi-Tec). Liquid reactor discharge is level controlled (container B2) via an HPLC pump and collected in the discharge container (B5). Gaseous reactor discharge is passed via a buffer vessel (B4) and depressurized via a pressure-controlled Recco valve (P2). In experimental series 15, reactions were continued in a modified unit (slow-flow main flow reactor main reactor). , downstream of the reactor without liquid circulation in the liquid phase procedure). In all experiments, the catalyst was stable, no catalyst loss occurred as a result of so-called "leaching".

Table 4: Results of continuous experiments (best fit of experimental record)

<table> table see original document page 42 </column> </row> <table>

LR = liquid recycling (circulation) from reactor outlet to inlet reactor

Claims (13)

Process for the preparation of 1,2-propanediol, characterized in that d) a glycerol-containing stream is provided and b) the glycerol-containing stream is subjected to hydrogenation in the presence of a heterogeneous copper-containing catalyst at a temperature of 100 to 320 °. C and a pressure of 100 to 325 bar. Process according to claim 1, characterized in that a glycerol-containing stream obtained in the preparation of the higher fatty acid alkyl esters by transesterification of fatty acid triglycerides is provided in step a). Process according to Claims 1 and 2, characterized in that the glycerol-containing stream having a water content of no more than 30 wt%, preferably no more than 20 wt%. Process according to either of Claims 1 and 2, characterized in that the glycerol-containing stream is substantially anhydrous. Process according to any one of the preceding claims, characterized in that, in step a), the glycerol-containing chain is subjected to elaboration by at least one elaboration process, which is selected from thermal elaboration, adsorption, ion exchange, membrane separation, crystallization, extraction or a combination of two or more of these processes. Process according to any one of the preceding claims, characterized in that, in step a) the stream containing glycerol is subjected to distillation to reduce water content and / or to remove components which adversely affect catalytic hydrogenation. Process according to any one of the preceding claims, characterized in that, in step a), the stream containing glycerol is subjected to catalytic desulphurization, if appropriate, in the presence of hydrogen to reduce the content of sulfur-containing compounds, especially aromatic compounds. containing sulfur. Process according to any one of the preceding claims, characterized in that, in step a), the stream containing glycerol is brought into contact with at least one adsorbent for removal of components which adversely affect catalytic hydrogenation. Process according to Claim 8, characterized in that the adsorbent comprises at least one component capable of use as a hydrogenation catalyst in step b). Process according to any one of the preceding claims, characterized in that the provision of the containing glycerol stream of step a) comprises the following steps: al) providing a starting mixture containing biogenic fat and / or oil, a2) transesterification of the triglycerides of fatty acids present in the starting mixture with at least one C1-C9 monoalcohol and, if appropriate, esterification of the free fatty acids present in the partitioned mixture with formation of an esterification mixture, a) separation of the esterification mixture to obtain at least one enriched fraction. with C1-C9 monoalkyl esters and at least one glycerol-enriched fraction released on transesterification, a4) if appropriate, purification of the glycerol-enriched fraction. Process according to any one of claims 1 to 10, characterized in that the hydrogenation catalyst used in etapab) is Raney catalyst. Process according to any one of claims 1 to 10, characterized in that the hydrogenation catalyst used in etapab) comprises at least 23 wt.%, Preferably at least 35 wt.% Copper, in oxidic and / or elemental form. based on the total weight of the catalyst. A process according to any one of claims 1 to 10, characterized in that the hydrogenation catalyst used in etapab) comprises the following metals, each in oxide or elemental form or a combination thereof: Cu, Cu, TiCu, ZrCu, MnCu, AlCu, Ni, MnCu, Al, at least one other selected metal from La, W, Mo, Mn, Zn, Ti, Zr, Sn, Ni, Co Cu, Zn, ZrCu, Cr, CaCu, Cr, CCu, Al, Mn, optionally Zr