RU2799940C1 - Method for producing higher fatty alcohols - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for producing higher fatty alcohols, including a three-stage synthesis in a reactor. At the first stage, a reaction occurs between triethylaluminum (TEA) and ethylene in the presence of a promoting additive of a general form – R_nAlCl_3-n, where R is an alkyl radical with an even number of carbon atoms, and n is from 0 to 1, whereas R_nAlCl_3-n is used in an amount of 3 to 35 mol.% relative to triethylaluminum in an aliphatic or aromatic hydrocarbon solvent with a boiling point range of 60 to 300° C to form aluminium alkyls. At the second stage, the resulting aluminium alkyls are oxidized to obtain aluminium alkoxides. At the third stage, hydrolysis of aluminium alkoxides is carried out to obtain a mixture of higher fatty alcohols.

EFFECT: development of a method for obtaining higher fatty alcohols with a content of target C₁₂ and C₁₄ fractions of at least 16% and 14%, respectively, without the use of catalysts based on transition metals at the growth stage.

4 cl, 1 dwg, 1 tbl, 11 ex

Description

The invention relates to a method for producing higher fatty alcohols (HFA), namely, to obtaining a mixture of higher fatty alcohols from ethylene, with a narrow distribution of target fractions in favor of C ₁₂ , C ₁₄ alcohols, which are used for the production of surfactants for domestic and industrial needs: foam stabilizers, additives for lubricating oils. The need for these alcohols many times exceeds the demand for alcohols with a different chain length.

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 repeatedly described 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.a10_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 oxidized at 5 atm and 50°C to form alkoxides, which are then hydrolyzed at 90°C. The "Alfol process" is based on a 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 target fractions C ₁₂ , C ₁₄ and gives a large amount of by-products.

It is known that Ethyl Corp. patented improved technology (US 3391175, publ. 1968.07.02; US 3391219, publ. 1968.07.02) [3], which allows to obtain a narrower distribution of alcohols along the chain length with a maximum content of C ₁₂ , C ₁₄ fractions. carrying out the displacement reaction of short-chain substituents at the aluminum atom to longer alkenes, with the release of short-chain alkenes. Transalkylation occurs at a temperature of 180-200°C and a pressure of 3.5 MPa. This method has been commercialized under the name "Epal process".

The disadvantages of the known method are the complexity of the process, multi-stage, as well as the high temperature of the process.

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

So, in a later patent of BP Corp North America Inc (Patent US 5233103, publ. 1993.08.03) [4], the method was improved by using a cobalt-containing catalyst at the stage of the displacement reaction in an amount of from 5 to 100 ppm. Further, the production of HFA was carried out according to the following scheme: olefins formed as a result of the displacement reaction are removed from the reaction mixture, then higher trialkyl aluminum is oxidized, followed by 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 limiting the possibility of using the product.

Another process upgrade using transition metal catalysts has been proposed by Ethyl Corp. (patent US 2962513A, publ. 1960.11.29) [5]. In the proposed method, triethylaluminum directly reacts 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 process catalysts.

A cobalt chain growth step catalyst is also known from EP 0577020, publ. 2001.08.08 [6], which proposes a method for obtaining higher fatty alcohols. The method is characterized in that the cobalt-catalyzed displacement reaction involving higher α-olefins and lower aluminum trialkyls is carried out at subatmospheric 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 HFAs.

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

The disadvantages of the known method is the toxicity of transition metals, the complete purification of which the product is a complex process.

There is a method patented by Shell Oil Company (US 8017811, publ. 09.13.2011) [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 technology, as well as the complexity of preparation and toxicity of the catalyst based on a cobalt compound with an organophosphine ligand.

The use of alkyl halides to obtain aluminum alkyls is described in US 2931820, publ. 1960.04.05 [9]. In a known process, aluminum alkyls are obtained by reacting aluminum with primary alkyl halides in the presence of an inert solvent and then reacting the resulting aluminum alkyl sesquihalide with an alkali metal. As a result, aluminum and aluminum alkyl solution are formed.

A known method for producing linear primary monoalcohols from patent RU 2291848, publ. January 20, 2007 [10]. The invention relates to a method for producing alcohols, including the synthesis of olefins under the conditions of the Fischer-Tropsch reaction, followed by hydroformylation and isolation of a mixture of alcohols. From the Fischer-Tropsch synthesis products with a cobalt catalyst, a hydrocarbon fraction is separated by distillation with a linear olefin content of 10-45 wt.%, 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 is from 1.0 to 5.0. This is followed by hydrogenation and distillation steps. EFFECT: obtaining a composition with a content of linear alcohols C ₇ -C ₁₂ of at least 60 wt.% with a high reaction rate with high selectivity of the process.

The disadvantages of the known method is that this method does not allow selective production of even alcohols. In addition, the complexity of hardware design; high energy costs for maintaining the technological parameters of the process of hydroformylation and hydrogenation - high pressure and temperature; the 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, the deposition of a metal catalyst on the walls of the reaction apparatus.

A known method for obtaining higher fatty alcohols from patent RU 2378244, publ. 01/10/2010 [11].

The method for obtaining higher fatty alcohols (HFA) includes the interaction of the C ₁₀ -C ₁₈ hydrocarbon fraction with hydrogen peroxide in the presence of a solvent. In this case, the process is carried out at 20-50°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 of 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 returned to the synthesis stage fraction C ₁₀ -C ₁₈ in the form of a distillate and commercial higher fatty alcohols. As a rule, a titanium-containing zeolite with an MFI, MEL or β-zeolite topology is used as a catalyst, with a titanium content of from 0.1 to 9.5%. The method makes it possible to obtain HFS with a high yield at reduced energy costs for their isolation.

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

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

The technical objective of the invention is to develop a method for obtaining higher fatty alcohols containing target fractions C₁₂ and C₁₄ not less than 16% and 14%, respectively, without the use of catalysts based on transition metals at the growth stage.

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

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

in the second stage, the resulting aluminum alkyls are oxidized to obtain aluminum alkoxides;

at the third stage, 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, the general form is R_nAlCl_3-n,

where R is an alkyl radical with an even number of carbon atoms, selected from the series: ethyl, hexyl, octyl, and n is from 0 to 1,

while using R _n AlCl _3-n in an amount of from 3 to 35 mol.% relative to triethylaluminum in an aliphatic or aromatic hydrocarbon solvent with a boiling temperature range of 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 fed into the reactor at a pressure of 1-5 atm in a flow mode, then the reactor is heated to a temperature of 30-55 ° C, then a catalyst solution based on a titanium (IV) compound is added, for example, titanium tetraisopropylate.

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

Disclosure of the essence of the invention

The set technical problem of the invention is solved by using the chemical compound of the general formula - R_nAlCl_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 of from 3 to 35 mol.% with respect to triethylaluminum.

While promoting the additive of the above formula, can be selected from a number of compounds: AlCl ₃ ; EtAlCl ₂ ; C ₈ H ₁₇ AlCl ₂ ; C ₆ H ₁₃ AlCl 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, the compound R _n AlCl _3-n is added there in an amount of 3 to 35 mol.% relative to triethylaluminum. 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 R _n AlCl _3-n compound, added in an amount of 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 is not achieved the claimed technical effect of the output of the target product.

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

The product of the second oxidation, which is aluminum alkoxides, is removed from the reactor and placed in a still to remove the solvent. Target fractions are then subjected to aqueous hydrolysis. A portion of the aqueous solution acidified with HCl or H ₂ SO ₄ to pH 7 to 1 is slowly added to the reaction mixture. For better separation, the mixture is stirred with the addition of a non-polar organic solvent (eg nefras) and heated to a temperature of 60°C. After separation of the layers, the organic phase is taken off and the aqueous (inorganic layer) is washed 2-3 times with the aforementioned non-polar hydrocarbon solvent. If necessary, the organic phases are combined for a second distillation. The resulting organic fraction contains even linear α-alcohols.

The essential difference of the present invention from the closest analogue [1] is the use of the compound R _n AlCl _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 with the prototype [1] are:

- high selectivity for target fractions C ₁₂ , C ₁₄ ;

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

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

Examples of specific implementation of the method

Example 1 VFS was obtained on a laboratory plant 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 ml of EtAlCl was added₂. Then provided the supply of ethylene at a pressure of 105 atm and a temperature of 115°C for 5 hours. After that, air was supplied to the reactor for 5 hours at a pressure of 3.5 atm and heated in the range of 30-55°C. Then a solution of tetraisopropyl titanate (100 µl) was added and the oxidation continued for another 4 hours under similar conditions. After oxidation, the resulting mixture of alkoxides was separated, the solvent was removed, and subjected to hydrolysis to obtain VFS. The distribution of alcohols was determined by the chromatographic method.

Examples 2 and 3, similar to example 1, are distinguished by a reduced proportion of promoting additives EtAlCl ₂ . (Table 1). Nefras-A-150/330 was used as an organic solvent. It was shown that the promoting effect of the additive is retained when its proportion relative to TEA is reduced down to 3 mol.% (Example 3).

Examples 4 and 5, similar to example 1, differ in the changed pressure (Table 1). It has been shown that the promoting additive EtAlCl ₂ operates in a wide pressure range from 80 to 140 atm. Xylene was used as an organic solvent. With a decrease in pressure, the distribution of alcohols shifted towards low molecular weight ones (example 5), and with an increase in the distribution peak of alcohols along the length of the carbon radical, on the contrary, it shifted towards heavier alcohols (example 4).

Examples 6, 7, 8, similar to example 1, differ in the changed temperature (Table 1). It has been shown that the EtAlCl ₂ promoting additive works in a wide range of conditions from 90 to 125°C. Heptane was used as an organic solvent. With a decrease in temperature, the distribution of alcohols shifted towards low molecular weight ones (example 7), and with an increase in the peak of the distribution of alcohols along the length of the carbon radical, on the contrary, it shifted towards heavier alcohols (example 6).

Examples 9, 10, 11, similar to example 1, differ in the use of AlCl ₃ as a promoting additive and solutions of C ₆ H ₁₃ AlCl ₂ , C ₈ H ₁₇ AlCl _2. Hexane was used as an organic solvent. It has been shown that by varying the alkyl radical, and even in its absence, the desired effect of the promoting additive is achieved.

Table 1 shows the results of using a promoting additive with the general formula R _n AlCl _3-n, in an amount of from 3 to 35 mol.% with respect to triethylaluminum at the stated technological parameters and conditions of the proposed method.

Table 1 No. Promoting Supplement Amount of additive, g Pressure, atm Temperature, °C Output C ₁₂ , wt.% Yield C ₁₄ , wt.% 1. EtAlCl ₂ , 1.2 105 115 thirty 24 2. EtAlCl ₂ , 0.6 105 115 27 22 3. EtAlCl ₂ , 0.1 105 115 18 15 4. EtAlCl ₂ 1.2 140 115 15 28 5. EtAlCl ₂ 1.2 80 115 25 12 6. EtAlCl ₂ 1.2 105 125 17 25 7. EtAlCl ₂ 1.2 105 90 16 10 8. EtAlCl ₂ 1.2 140 90 26 18 9. AlCl ₃ 1.2 105 115 27 21 10. C ₆ H ₁₃ AlCl ₂ 1.6 105 115 22 17 eleven. C ₈ H ₁₇ AlCl 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". An analysis of known developments in the studied field of technology and their comparison with the developed invention shows that it does not explicitly follow from the prior art, therefore, it meets the patentability condition - “inventive step” and can be used in industry and other fields of technology, therefore, it meets the patentability condition - “industrially applicable”, i.e. meets all the necessary conditions for patentability.

Claims (9)

1. A method for producing higher fatty alcohols, including three-stage synthesis in a reactor, where at the first stage, a reaction occurs between triethylaluminum (TEA) and ethylene in the presence of a promoting additive with the formation of aluminum alkyls; in the second stage, the resulting aluminum alkyls are oxidized to obtain aluminum alkoxides; at the third stage, hydrolysis of aluminum alkoxides is carried out to obtain a mixture of higher fatty alcohols, characterized in that at the first stage, the reaction between TEA and ethylene occurs in the presence of a promoting additive, the general form is R_nAlCl_3-n, where R is an alkyl radical with an even number of carbon atoms, and n is from 0 to 1, while using R _n AlCl _3-n in an amount of from 3 to 35 mol.% relative to triethylaluminum in an aliphatic or aromatic hydrocarbon solvent with a boiling temperature range of 60 to 300°C. 2. The method according to p. 1, characterized in that 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. 3. The method according to p. 1, characterized in that use promoting additives R_nAlCl_3-n, where R is an alkyl radical selected from the series: ethyl, hexyl, octyl. 4. The method according to claim 1, characterized in that the oxidation of aluminum alkyls is carried out as follows: dried air is fed into the reactor at a pressure of 1-5 atm in a flow mode, then the reactor is heated to a temperature of 30-55 ° C, then a catalyst solution based on a titanium (IV) compound is added, for example, titanium tetraisopropoxide.