EA044340B1 - METHOD FOR OBTAINING HIGHER FATTY ALCOHOLS - Google Patents

Abstract

The invention relates to a method for producing higher fatty alcohols, comprising a three-stage synthesis in a reactor. The first stage involves a reaction between triethylaluminum (TEA) and ethylene in the presence of a promoting additive of the general form RnAlCl3.n, where R is an alkyl radical with an even number of carbon atoms, and η is from 0 to 1. RnAlCU-nB is used in an amount of 3 to 35 mol.% relative to TEA in an aliphatic or aromatic hydrocarbon solvent with a boiling range of 60 to 300°C to form aluminum alkyls. The second stage involves oxidation of the resulting aluminum alkyls to produce aluminum alkoxides. The third stage involves hydrolysis of the aluminum alkoxides to produce a mixture of higher fatty alcohols. The technical result is the development of a method for producing higher fatty alcohols with a content of target fractions of C1 and C2 of at least 16 and 14%, respectively, without the use of catalysts based on transition metals at the growth stage.

Description

Description of the invention

The invention relates to a method for producing higher fatty alcohols (HFAs), namely to producing a mixture of higher fatty alcohols from ethylene, with a narrow distribution of target fractions in favor of alcohols C ₁₂ , C ₁₄ , which are used for the production of surfactants for household and industrial needs: foam stabilizers , additives for lubricating oils. The demand for these alcohols is many times greater than the demand for alcohols with other chain lengths.

It is known that about half of the higher fatty alcohols in industry are obtained from ethylene in three ways:

The Alfol process is known, which has found wide industrial application and has been described many times in the technical literature (Noweck K. Fatty alcohols // Ullmann's Encyclopedia of Industrial Chemistry. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, - 2012. - V. 31, No. 11. - P. 124; 10.1002/14356007.al0_277.pub2) [1]. This method is based on the interaction of TEA with ethylene under a pressure of 120 atm and at a temperature of 120°C, resulting in the formation of aluminum alkyls, which are then subjected to oxidation at 5 atm and 50°C to form alkoxides, which are then hydrolyzed at 90°C. The Alfol process is based on technology patented by Karl Ziegler and Hans-Georg Gellert (US 2699457, publ. 1955.01.11) [2], which consists in the polymerization of ethylene in the presence of an activator with the general formula Me(R) _n , in which Me is one metal of the third group (aluminum, gallium, indium and beryllium). The use of Et ₃ Al (TEA) has gained practical importance.

The main disadvantage of the known method is that in the Alfol process a mixture of even higher fatty alcohols with a wide Poisson distribution is formed, which reduces the yield of the target fractions C ₁₂ , C ₁₄ and produces a large number of by-products.

It is known that Ethyl Corp. An improved technology has been patented (US 3391175, publ. 1968.07.02; US 3391219, publ. 1968.07.02) [3], which makes it possible to obtain a narrower distribution of alcohols along the chain length with a maximum content of _C12 , _C14 fractions. In a well-known process, the principle of isolating a fraction of aluminum alkyls with a short chain length and putting them into recycling with a reaction of displacement of short-chain substituents on the aluminum atom to longer alkenes with the release of short-chain alkenes was implemented. Transalkylation occurs at a temperature of 180-200°C and a pressure of 3.5 MPa. This method is introduced into the industry under the name Epal process.

The disadvantage of this known method is the complexity of the technological process, its multi-stage nature, and the high temperature of the process.

A number of patents have been devoted to ways to improve the process at the chain propagation stage using additional catalytic additives.

Thus, in a later patent of BP Corp North America Inc (patent US5233103, published 1993.08.03) [4], the method was improved by using a cobalt-containing catalyst at the stage of the displacement reaction in an amount from 5 to 100 ppm. Next, the production of VLS was carried out according to the following scheme: olefins formed as a result of the displacement reaction are removed from the reaction mixture, then the oxidation of higher aluminum trialkyls is carried out, followed by the hydrolysis of aluminum alkoxides at the final stage of the process with the formation of higher linear alcohols.

In addition to the complexity of the technological process, the disadvantage of this method is the contamination of the product with cobalt compounds, which is an unfavorable factor that limits the possibility of using the product.

Another way to modernize the process using transition metal catalysts was proposed by Ethyl Corp. (patent US 2962513 A, publ. 1960.11.29) [5]. In the proposed method, triethylaluminum directly enters into a displacement reaction with higher α-olefins to produce higher aluminum alkyls. Compounds based on salts and oxides of Group VIII metals, as well as manganese, titanium and copper are used as catalysts for the process.

The cobalt catalyst for the chain propagation stage is also known from EP 0577020, publ. 2001.08.08 [6], which proposed a method for producing higher fatty alcohols. The method is characterized in that the displacement reaction catalyzed by cobalt compounds involving higher α-olefins and lower aluminum trialkyls is carried out at a pressure below atmospheric pressure, so that the displaced olefins are removed from the reaction mixture simultaneously with the formation of higher aluminum trialkyls. At the final stage, the latter undergo oxidation and hydrolysis with the formation of VLS.

It is known that transition metals as a catalytic additive were used in the method proposed by Shell Internationale Research Maatschappij (patent GB 1004108 A) [7], where the use of non-terminal olefins was proposed as a feedstock for the production of primary alcohols. Primary alcohols are obtained by oxidation of aluminum alkyl compounds obtained as above. The resulting aluminum alkoxides are then hydrolyzed. In an example, the reaction product from a mixture of non-terminal octenes is oxidized by bubbling in air and then hydrolyzed with 10% hydrochloric acid to produce 1-octanol after separation and purification.

The disadvantages of this known method are the toxicity of transition metals, the complete removal of which from the product is a complex process.

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There is a known method patented by Shell Oil Company (US 8017811, publ. 13/09/2011) [8], which consists in the hydroformylation of olefins in the presence of a cobalt-based catalyst modified with organophosphine. The process is carried out in a reactor with two reaction zones. The advantage of this method is the low pressure at which the product is formed, as well as the high proportion of linear alpha alcohols. At the same time, the resulting alcohols have an odd number of carbon atoms in the hydrocarbon radical.

The disadvantages of this method are also the complexity and multi-stage nature of the technology, as well as the complexity of preparation and toxicity of a catalyst based on a cobalt compound with an organophosphine ligand.

The use of alkyl halides for the production of aluminum alkyls is described in US 2931820, publ. 1960.04.05 [9]. In the known method, aluminum alkyls are prepared by the reaction of aluminum with primary alkyl halides in the presence of an inert solvent and the subsequent reaction of the resulting aluminum alkyl sesquihalide with an alkali metal. As a result, aluminum and an aluminum alkyl solution are formed.

A known method for producing linear primary monoalcohols from patent RU 2291848, publ. 01/20/2007 [10]. The invention relates to a method for producing alcohols, including the synthesis of olefins under Fischer-Tropsch reaction conditions, followed by hydroformylation and isolation of a mixture of alcohols. From the Fischer-Tropsch synthesis products with a cobalt catalyst, a hydrocarbon fraction containing 10-45 wt.% linear olefins is separated by distillation, which is subjected to hydroformylation with carbon monoxide and hydrogen in the presence of a catalyst based on a cobalt source and a substituted or unsubstituted monophosphabicycloalkane ligand. The molar ratio of hydrogen and carbon monoxide ranges from 1.0 to 5.0. This is followed by the stages of hydrogenation and distillation. The technical result is the production of a composition containing linear alcohols C ₇ -C ₁₂ of at least 60 wt.% with a high reaction rate and high selectivity of the process.

The disadvantages of this known method are that this method does not allow the selective production of even-numbered alcohols. In addition, the complexity of the hardware design; high energy costs for maintaining the technological parameters of the hydroformylation and hydrogenation process - high pressure and temperature; disadvantages associated with the use of a catalyst are deactivation, losses due to entrainment with the reaction mass, the need to separate the catalyst from the reaction mixture, and deposits of the metal catalyst on the walls of the reaction equipment.

A known method for producing higher fatty alcohols is from patent RU 2378244, publ. 01/10/2010 [11]. The method for producing higher fatty alcohols (HFAs) involves the interaction of the hydrocarbon fraction Gio-Cis with hydrogen peroxide in the presence of a solvent. In this case, the process is carried out at 2050°C, at a molar ratio of the hydrocarbon fraction C ₁₀ -C ₁₈ and hydrogen peroxide (1.0-13.0): 1, on a catalyst - titanium-containing zeolite, loaded in an amount from 0.1 to 70 g /l of the reaction mass, which after the synthesis stage is subjected to atmospheric rectification to remove the solvent, and vacuum rectification to separate the unreacted hydrocarbon fraction C _1o -C _1s returned to the synthesis stage in the form of distillate and commercial higher fatty alcohols. Typically, a titanium-containing zeolite with MFI, MEL or β-zeolite topology, with a titanium content of 0.1 to 9.5%, is used as a catalyst. The method makes it possible to obtain high-yield high-yield liquids with reduced energy costs for their isolation.

The disadvantage of the known method is that the known invention solves a different technical problem than the proposed invention. The known method does not solve the problem of forming a hydrocarbon radical of the required length with an even number of carbon atoms.

The authors of the proposed invention consider the source of information given in the prior art to be the closest prototype [1].

The technical objective of the invention is to develop a method for producing higher fatty alcohols with a content of target fractions C ₁₂ and C ₁₄ of at least 16 and 14%, respectively, without the use of catalysts based on transition metals at the growth stage.

This technical result is achieved by the fact that the method for producing higher fatty alcohols includes a three-stage synthesis in a reactor, where:

in the first stage, a reaction occurs between triethylaluminum (TEA) and ethylene in the presence of a promoting additive to form aluminum alkyls;

at the second stage, the resulting aluminum alkyls are oxidized to produce aluminum alkoxides;

at the third stage, the hydrolysis of aluminum alkoxides is carried out to obtain a mixture of higher fatty alcohols, while at the first stage the reaction between TEA and ethylene occurs in the presence of a promoting additive, of the general type - R _n AlCl ₃ _ _n , where R is an alkyl radical with an even number of carbon atoms , selected from the range: ethyl, hexyl, octyl, and n is from 0 to 1. In this case, R _n AlCl ₃ _ _n is used in an amount from 3 to 35 mol.% relative to TEA in an aliphatic or aromatic hydrocarbon solvent with a temperature range - 2 044340 boiling zone from 60 to 300°C. In the proposed method, the reaction between TEA and ethylene in the presence of a promoting additive occurs at a temperature of 90-125°C and a pressure of 80-140 atm for 4-7 hours.

In this case, the oxidation of aluminum alkyls is carried out as follows: dried air is supplied to the reactor at a pressure of 1-5 atm in flow mode, then the reactor is heated to a temperature of 30-55°C, then a catalyst solution based on a titanium (IV) compound, for example titanium tetraisopropylate, is added .

In the proposed method, aluminum alkoxides are removed from the reactor and subjected to aqueous hydrolysis.

Disclosure of the invention

The stated technical problem of the invention is solved by using, in the production of VLS from ethylene and triethylaluminum at the stage of growth of an organoaluminum compound, as a promoting additive a chemical compound of the general formula - R _n AiCi ₃ _ _n , providing a narrower distribution of alcohols along the length of the carbon chain, where R is an alkyl radical with an even number of carbon atoms, and n is from 0 to 1, in an amount from 3 to 35 mol.% relative to triethylaluminum.

In this case, the promoting additive of the above formula can be selected from a number of compounds: AiCl ₃ ; _EtAiCl2 ; QHnACb; C6H1 ₃ AiCl ₂ .

Obtaining VZhS is carried out as follows.

At the first stage, a solution of triethylaluminum in an aliphatic or aromatic hydrocarbon solvent is loaded into a batch reactor in an inert atmosphere, and the compound R _n AiCi ₃ _ _n is added there in an amount from 3 to 35 mol.% relative to TEA. Then ethylene is supplied under a pressure of 80-140 atm, the reaction is carried out at a temperature of 90-125°C for 4-7 hours. At lower temperatures and pressures, the yield of target alcohols dropped sharply. At temperatures above 125°C, the proportion of olefins as by-products increased significantly.

The promoting additive in the form of the compound R _n AiCi ₃ _ _n , added in an amount from 3 to 35 mol.% at the first stage of the synthesis of aluminum alkyls due to the reaction between ethylene and TEA, was selected experimentally.

With less than 3 mol.% introduction of the promoting additive, the declared technical effect of the yield of the target product is not achieved.

The resulting aluminum alkyls are converted into higher fatty alcohols through the process of oxidation and hydrolysis. Oxidation is carried out in the same high-pressure reactor as the chain propagation step. Oxidation is carried out in two stages. At the first stage, dried air is supplied to the reactor at a pressure of 1-5 atm in flow mode. The reactor is heated to a temperature of 30-55°C. In the second stage, a catalyst solution based on a titanium (IV) compound, for example titanium tetraisopropylate, is added. The second stage is carried out at the same temperature and pressure.

The second oxidation product, aluminum alkoxides, is removed from the reactor and placed in a distillation cube to remove the solvent. The target fractions are then subjected to aqueous hydrolysis. A portion of an aqueous solution acidified with HCl or H2SO4 to pH 7 to 1 is slowly added to the reaction mixture. For better separation, the mixture is mixed with the addition of a non-polar organic solvent (for example, nefras) and heated to a temperature of 60°C. After separation of the layers, the organic phase is removed and the aqueous (inorganic layer) is washed 2-3 times with the above-mentioned non-polar hydrocarbon solvent. If necessary, the organic phases are combined for a second distillation. The resulting organic fraction contains even linear α-alcohols.

A significant difference between the proposed invention and its closest analogue [1] is the use of the compound R _n AiCi ₃ _ _n as a promoting additive, providing a narrower distribution of alcohols along the length of the carbon chain, as well as providing an increase in the yield of target fractions relative to other fractions.

The advantages of the proposed method compared to the prototype [1] are:

high selectivity for target fractions C ₁₂ , C ₁₄ ;

a more flexible range of technological conditions, allowing to obtain target products C ₁₂ , C ₁₄ with high yield.

The invention is illustrated by a figure that shows a diagram of a method for producing VLS from ethylene and TEA using the claimed promoting additive.

The implementation of the proposed method for obtaining high-quality liquids is illustrated by the following examples of specific implementation.

Example 1.

VLS was produced in a laboratory setup in a batch reactor. A solution of 10 ml of 40% triethylaluminum in a Nefras-P1-63/75 solvent in an inert atmosphere was placed in a reactor, 1.0 ml of EtAlCl2 was added. Then, ethylene was supplied at a pressure of 105 atm. and a temperature of 115°C for 5 hours. After this, air was supplied to the reactor for 5 hours at a pressure of 3.5 atm and heating in the range of 30-55°C. Then a solution of tetraisopropyl titanate (100 μl) was added and

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Claims (12)

oxidation was continued for another 4 hours under similar conditions. After oxidation, the resulting mixture of alkoxides was separated, the solvent was removed, and hydrolysis was performed to obtain VLS. The distribution of alcohols was determined by chromatographic method. Examples 2 and 3. Similar to example 1 and differ in a reduced proportion of the promoting additive EtAlCl ₂ . (table). Nefras-A-150/330 was used as an organic solvent. It has been shown that the promoting effect of the additive is maintained when its proportion relative to TEA is reduced down to 3 mol.% (Example 3). Examples 4 and 5. Similar to example 1 and differ in changed pressure (table). It has been shown that the promoting additive EtAlCl ₂ works in a wide pressure range from 80 to 140 atm. Xylene was used as an organic solvent. With decreasing pressure, the distribution of alcohols shifted towards low molecular weight ones (example 5), and with increasing pressure, the peak distribution of alcohols along the length of the carbon radical shifted, on the contrary, towards heavier alcohols (example 4). Examples 6-8. Similar to example 1 and differ in changed temperature (table). It has been shown that the promoting additive EtAlCl ₂ works in a wide range of conditions from 90 to 125°C. Heptane was used as an organic solvent. With decreasing temperature, the distribution of alcohols shifted towards low molecular weight ones (example 7), and with increasing temperature, the peak distribution of alcohols along the length of the carbon radical shifted, on the contrary, towards heavier alcohols (example 6). Examples 9-11. Similar to example 1 and differ in the use of AlCl ₃ and solutions of C ₆ H ₁₃ AlCl ₂ and C ₈ H ₁₇ AlCl ₂ as a promoting additive. Hexane was used as an organic solvent. It has been shown that by varying the alkyl radical and even in its absence, the necessary effect of a promoting additive is achieved. The table shows the results of using a promoting additive with the general formula R _n AlCl ₃ -n, in an amount from 3 to 35 mol.% relative to triethylaluminum under the stated technological parameters and conditions of the formula of the proposed method. No. Promoting additive Amount of additive, g Pressure, atm Temperature, °C Yield Ci ₂ , wt.% Yield Cm, wt.% 1. EtAlCl ₂ , 1.2 105 115 30 24 2. EtAlCl ₂ , 0.6 105 115 27 22 3. EtAlCl ₂ , ο,ι 105 115 18 15 4. EtAlCh 1.2 140 115 15 28 5. EtAlCh 1.2 80 115 25 12 6. EtAlCl ₂ 1.2 105 125 17 25 7. EtAlCh 1.2 105 90 16 10 8. EtAlCh 1.2 140 90 26 18 9. AlCh 1.2 105 115 27 21 10. SbN1zA1S1 ₂ 1.6 105 115 22 17 11. C ₈ Hi ₇ A1C1 ₂ 2.0 105 115 23 19 12. prototype 105 115 16 14 The proposed method is not described in any information source, which allows us to talk about its novelty. Analysis of known developments in the field of technology under study and comparison of them with the developed invention shows that it does not clearly follow from the prior art, therefore, it meets the condition of patentability - inventive step and can be used in industry and other fields of technology, therefore, it meets the condition of patentability - industrially applicable, i.e. meets all necessary conditions for patentability. CLAIM 1. The method for producing higher fatty alcohols is a three-stage synthesis in a reactor, where: in the first stage, a reaction occurs between triethylaluminum (TEA) and ethylene in the presence of a promoting additive to form aluminum alkyls; at the second stage, the resulting aluminum alkyls are oxidized to produce aluminum alkoxides; -