EP1501915A1

EP1501915A1 - METHOD FOR PRODUCING C sb 4 /sb -C sb 12 /sb FATTY ACIDS

Info

Publication number: EP1501915A1
Application number: EP03722564A
Authority: EP
Inventors: Georg Fieg; Ulrich SCHÖRKEN; Sabine Both; Ingomar Mrozek; Norbert Klein; Albrecht Weiss; Levent YÜKSEL; Ralf Otto; Carolin Meyer
Original assignee: Cognis Deutschland GmbH and Co KG; Cognis IP Management GmbH
Current assignee: Cognis IP Management GmbH
Priority date: 2002-05-08
Filing date: 2003-04-29
Publication date: 2005-02-02
Also published as: JP2005524759A; DE10220525A1; WO2003095596A1; AU2003229744A1; US20060057689A1

Abstract

The invention relates to a method for producing C4-C12 fatty acids, according to which: (a) C4-C12 fatty acid methyl esters are, in one stage, completely or partially hydrolyzed with water in the presence of enzymes and with the continuous removal of methanol; (b) the hydrolysate is separated into an organic and an aqueous/alcohol phase, and; (c) the organic phase containing fatty acids and (in the event of partial hydrolysis) fatty acid methyl esters releases non-converted fatty acid methyl esters. A removal of methanol directly from the reaction feedstock leads to increased conversions.

Description

Process for the preparation of C ₄ -C ₂ fatty acids

Field of the Invention

The invention is in the field of oleochemical raw materials and relates to a biotechnological process for the production of short-chain fatty acids from the corresponding methyl esters.

State of the art

In oleochemistry, fatty acid methyl esters with different chain length distributions are produced. When long-chain fatty acid methyl esters are separated off by distillation, so-called preliminary fatty acid methyl esters are formed, which are different mixtures of C ₄ to C ₁₂ methyl esters and are often used directly in further transesterification reactions. The resulting derivatives are of poor quality due to the impure raw material. Alternatively, the fatty acid methyl esters are therefore first split and the fatty acids released are then esterified. The chemical hydrolysis takes place in the presence of acidic catalysts, such as, for example, alkylbenzenesulfonic acids, known from international application WO 94/14743. The process therefore results in the formation of sulfuric acid, which leads to massive corrosion in the systems and contaminates the products with high metal contents. In addition, the yield of these processes is not yet optimal. Another problem is the environmentally friendly disposal of the catalysts.

The object of the present invention was therefore to provide an improved process for the production of short-chain fatty acids from their methyl esters, which reliably avoids the disadvantages of the prior art mentioned. In particular, the fatty acids should be obtained in high purity and high yields and the process should operate under mild conditions. Description of the invention

The invention relates to a process for the preparation of C ₄ -C ₁₂ fatty acids, in which

(a) C ₄ -C ₁₂ fatty acid methyl ester completely or partially hydrolyzed in one step in the presence of enzymes with water with continuous removal of methanol

(b) the hydrolyzate is separated into an organic and an aqueous / alcoholic phase,

(c) and the organic phase containing fatty acids and (in the case of partial hydrolysis) fatty acid methyl esters freed from unreacted fatty acid methyl esters.

Surprisingly, it was found that enzymatic hydrolysis with continuous removal of methanol leads to fatty acids which are free of undesired by-products. High yields are achieved, the process works under mild conditions and with catalysts that meet all requirements for environmental compatibility. If the methanol removal takes place continuously directly from the hydrolysis reactor during the hydrolysis process, a much faster reaction is achieved in a one-step process.

hydrolysis

The hydrolysis of the fatty acid methyl esters is preferably carried out at mild temperatures in the range from 20 to 80 ° C., preferably 30 to 70 ° C. and particularly preferably 35 to 60 ° C. with continuous removal of methanol under vacuum, the preferred temperature being the optimum activity of the enzymes used is specified. The lipases and / or esterases are usually used in free or immobilized form. Typical examples of suitable enzymes, which are not intended to be limiting, are lipases and / or esterases of microorganisms selected from the group formed by Alcaligenes, Aspergillus niger, Candida antarctica A, Candida antarctica B, Candida cylindracea, Chromobacterium viscosum, Rhizomucor miehei, Penicilium camenberti, Penicilium roqueforti, Porcine pancreas, Pseudomonas cepacia, Pseudomonas fluorescens, Rhizopus javanicus, Rhizopus oryzae, Thermomyces lanugenosus (see Example 1). Lipases and esterases from the organisms Alcaligenes, Candida, Chromobacterium, Rhizomucor, Pseudomonas, Rhizopus and Thermomyces are preferred. The enzymes are usually used as dilute suspensions or aqueous concentrates. The lipases / esterases can also be used immobilized on carrier material and reused in repeated batches.

A batch mode of operation is suitable as the hydrolysis method, in which a constant water content is usually set in the range of 30-70% by weight in the reactor by metering in water. The reaction is usually carried out at a temperature of 30-50 ° C. and below 100 mbar, preferably 50 to 70 mbar (Examples 2, 3, 4 and 6).

Another suitable method is a batch hydrolysis process in which water is fed in continuously and a methanol / water is permanently stripped off. With this procedure, the water content in the reactor is usually low (0-20% by weight). The reaction is usually carried out at a temperature of 50-70 ° C. and below 100 mbar, preferably 50 to 70 mbar (Examples 7 and 8).

Processes in which the methanol removal is spatially and / or temporally separated from the hydrolysis reaction work significantly worse. Such a disadvantageous method is described in JP05317063.

Examples of less suitable methods are methanol removal in a separate reaction vessel (Example 9) and methanol removal via a dephlegmator or e.g. Falling film evaporators (Example 10), in which the organic and aqueous phases are continuously returned to the hydrolysis reactor. An example of the temporal separation of methanol removal and hydrolysis is described in Examples 11 and 12. A multi-stage process according to this scheme leads to lower yields of short-chain fatty acids.

workup

Following the hydrolysis, the aqueous / alcoholic phase is separated from the organic phase and the latter is worked up, i.e. unreacted methyl ester removed from the product of value.

Different cleavage rates are obtained depending on the duration of the hydrolysis. The reaction can be stopped early, for example in the range of a conversion of 60% by weight, so that the subsequent separation of fatty acids and fatty acid methyl esters by distillation must take place. However, it can also only be at over 90% by weight, preferably above 95 % By weight are ended, or even continued up to 99% by weight, so that, as in the latter case, no subsequent separation is necessary. The removal of the unreacted methyl ester is preferably carried out in a distillation column with packed internals, it having proven advantageous to feed the feed between the lifting and stripping sections of the column. At temperatures in the range from 70 to 100 ° C. and a reduced pressure of 10 to 50 mbar, the methyl esters are taken off at the top of the column and can be returned to the reaction. Shorter-chain fatty acids and low-boiling impurities can be sucked off via the pump and released into the exhaust air, which is why a subsequent condensation is recommended. The resulting fatty acids have a purity of at least 95% by weight.

Examples

Example 1:

Selection of suitable lipases for the hydrolysis of short-chain fatty acid methyl esters

15 batches, each with 4 g of C8 fatty acid methyl ester (caprylic acid methylate) and 6 g of water in a sealable reaction vessel, are provided with a stirring fish and stirred in parallel on a multi-stirring plate at room temperature. Commercially available lipases or esterases according to the table below are added to the batches. Samples are taken after a reaction time of 2 h and 24 h. The organic phase containing fatty acid methyl ester and enzymatically hydrolyzed fatty acid is separated and analyzed.

Table 1

Lipases and esterases used

Enzyme organism manufacturer mg / batch

Chirazyme L-10 Alcaligenes sp. Romans 40

Lipase A Aspergillus niger Amano 40

Novozym 868 Candida antarctica A Novozym es 40

Novozym 525 Candida antarctica B Novozymes 40

Lipomod 34 Candida cylindracea Biocatalysts 40

Lipase LP Chromobacterium viscosum Asahi Kasei 4

Novozym 388 Rhizomucor miehei Novozymes 40

Lipase G Penicilium camenberti Amano 40

Lipase R Penicilium roqueforti Amano 40

Lipase L115P Porcine pancreas Biocatalysts 40

Lipase PS Pseudomonas cepacia Amano 40

Lipase AK Pseudomonas fluorescens Amano 40

Lipomod 36 P Rhizopus javanicus Biocatalysts 40

Lipase F-AP 15 Rhizopus oryzae Amano 40

Lipolase Ti 100 Thermomyces lanugenosus Novozymes 40

The implementation of the reaction was examined by determining the acid number. Table 2

Sales with different enzymes after 2 and 24 h reaction time

Enzyme sales [2 h reaction] Sales [24 h reaction]

Chirazyme L-10 18.4% 33.7%

Lipase A 0.9% 8.8%

Novozym 868 2.4% 8.3%

Novozym 525 27.3% 34.7%

Lipomod 34 22.9% 31.4%

Lipase LP 23.9% 36.1%

Novozym 388 1 18.5% 26.1%

Lipase G 1.6% 19.7%

Lipase R 0.9% 2.0%

Lipase L115P 4.0% 12.9%

Lipase PS 16.3% 27.4%

Lipase AK 11.6% 28.3%

Lipomod 36 P 8.5% 24.5%

Lipase F-AP 15 12.7% 12.3%

Lipolase Tl 100 18.4% 24.1%

All lipases and esterase tested have a hydrolysis activity of short-chain fatty acid methyl esters. After the screening, lipases and esterases from the organisms Alcaligenes, Candida, Chromobacterium, Rhizomucor, Pseudomonas, Rhizopus and Thermomyces are preferred.

Example 2:

Cleavage of Short Chain Fatty Acid Methylesters under Continuous MeOH

distance

2800 g of water, 1200 g of fatty acid methyl ester and 40 ml of Lipolase (Thermomyces Lipase, Novozymes) are introduced into a temperature-controlled double-jacket reactor with a Sulzer column attached. The reaction is carried out at a reactor temperature of 35 ° C. and a vacuum of 60 mbar. The reflux / decrease ratio at the top of the column is set to 12: 2. The stirrer speed is set to 300 rpm. After 5 hours, 40 ml of Lipolase and 500 ml of water are added.

The implementation of the reaction was examined by determining the acid number.

Table 3

Sales with continuous methanol removal after different

response times

The amount of distillate contained and thus removed from the reaction equilibrium was determined in the distillate.

Table 4

Conversion with continuous removal of methanol - amount of distillate removed from the reaction equilibrium after different reaction times

When the reaction was complete, <0.2% methanol was found in the aqueous phase of the reaction mixture. Example 3:

Cleavage of Short Chain Fatty Acid Methylesters under Continuous MeOH

distance

2800 g of water, 1200 g of fatty acid methyl ester and 40 ml of Novozym (Candida antarctica B lipase, Novozymes) are introduced into a temperature-controlled double-jacket reactor with a Sulzer column attached. The reaction is carried out at a reactor temperature of 35 ° C. and a vacuum of 60 mbar. The return / decrease ratio at the column head is set to 12: 2. The stirrer speed is set to 300 rpm. After 24 h, 300 g of water are metered in. The reaction of the reaction was examined by determining the acid number.

Table 5

Sales with continuous removal of methanol after different reaction times

Example 4:

Cleavage of Short Chain Fatty Acid Methylesters under Continuous MeOH

Removal with immobilized lipase

350 g of water, 350 g of fatty acid methyl ester and 35 g of immobilized novozym (Candida antarctica B lipase, Novozymes adsorbed on polypropylene carrier, enzyme load of 200 mg technical liquid preparation per g carrier) are introduced into a heated flask with a dephlegmator attached. The reaction is carried out at a reactor temperature of 35 ° C. and a vacuum of 60 mbar. Water is continuously metered into the batch at about 0.75 ml / min, so that the reactor volume remains constant over the course of time. The implementation of the reaction was examined by determining the acid number.

Table 6

Sales with continuous removal of methanol with immobilized lipase after different reaction times

Example 5:

Investigation of the stability of immobilized lipase in the cleavage of short-chain fatty acid methylates

Candida antarctica B lipase (Novozym 525, Novozymes), which was previously adsorbed on polypropylene carrier, is used for the stability analysis. Investigations are carried out at room temperature, 50 ° C, 60 ° C and 70 ° C. For this purpose, the immobilized lipases are stirred in a mixture of short-chain fatty acid methyl esters (mixture of C6-C10 fatty acids, 50% by weight) and water (50% by weight) until a reaction equilibrium is established. The immobilized enzyme is filtered off at intervals (see table Results) and fresh fatty acid methyl ester and water are added. The respective hydrolysis rate is determined.

The reaction was examined by determining the acid number after a reaction time of 4 h. Table 7

Turnover with different immobilized lipase stored at different times

temperatures

Storage time Sales (RT) Sales (50 ° C) Sales (60 ° C) Sales (70 ° C)

1st week 28.6% 32.7% 33.0% 34%

2nd week 28.8% 33.4% 33.5% 7.4%

3rd week 29.7% 33.2% 34.1% 4.5%

6th week 25.0% 29.1% 30.9% 4.9%

Week 13 26.1% 15.2% 13.2% 4.5%

Week 16 26.5% 7.2% 6.5% 2.5%

The half-life of the enzyme is about 12 weeks at 50 ° C, about 10 weeks at 60 ° C, about 1 week at 70 ° C and over 16 weeks at room temperature.

Example 6:

Hydrolysis of short-chain fatty acid methylesters on a pilot scale with immobilized

Lipase in repeated batches

25 kg of water, 20 kg of fatty acid methylate Edenor Me C 6 - 10 and 2.5 kg of immobilized novozyme (Candida antarctica B lipase, novo zymes are adsorbed on polypropylene carrier, enzyme load 200 mg technical liquid preparation per g Carrier). The reaction is carried out at an internal reactor temperature of 45 ° C. and a vacuum of 60 mbar. The stirrer speed is set to 150 rpm. Since a methanol / water distillate is obtained under the conditions mentioned, continuous water must be metered into the batch so that the reactor filling volume remains constant over the course of time. After completion of the reaction, the reaction mixture is discharged from the kettle, the immobilized enzyme being retained in the reactor via a built-in sieve.

The turnover of each batch is compared after 12 hours. The implementation of the reaction was examined by determining the acid number. Table 8

Sales with continuous removal of methanol on a pilot scale

Even after 40 batches, the immobilized enzyme shows no loss of activity in the selected parameters, which was correlated with the degree of conversion.

Example 7:

Continuous hydrolysis of short-chain fatty acid methyl esters with stripping of water and methanol

200 g of fatty acid methyl ester, 20 g of water and 10 g of Candida antarctica B lipase immobilized on polypropylene are placed in a heated flask. The reaction is carried out with a distillation bridge at 60 mbar and a temperature of 60 ° C. Water is continuously pumped into the flask at a flow rate of 0.25 ml / min. In a second approach, water is pumped into the flask at a flow rate of 0.5 ml / min. The water content in the flask is below 20% during the entire reaction time. The implementation of the reaction was examined by determining the acid number.

Table 9

Sales with stripping of water and methanol after different reaction times

Example 8:

200 g of fatty acid methyl ester, 20 g of water and 10 g of Candida antarctica B lipase immobilized on polypropylene are placed in a heated flask. The reaction is carried out with a distillation bridge at 60 mbar and a temperature of 70 ° C. Water is continuously pumped into the flask at a flow rate of 0.75 ml / min. The water content in the flask is below 20% during the entire reaction time. The reaction was investigated by determining the acid number.

Table 10

Sales with stripping of water and methanol after different reaction times

Example 9:

Continuous cleavage of short chain fatty acid methylates with separation of

Splitting process and removal of methanol

350 ml of fatty acid methyl ester, 350 ml of water and 35 g of immobilized Candida antarctica B lipase are placed in a heated flask. The hydrolysis reaction is carried out at 35 ° C. The reaction mixture is continuously pumped into a second flask which is heated to 120 ° C. At a vacuum of 740 mbar, methanol is continuously removed in this flask. The reaction mixture from flask 2 is continuously pumped back into the reaction flask at the same flow rate. Water is metered into the reaction flask so that the reaction volume remains constant.

Result:

The implementation of the reaction was examined by determining the acid number.

Table 11

Sales with separation of the splitting process and methanol removal after different

response times

The hydrolysis reaction is significantly slower than with a continuous methanol withdrawal directly from the reaction flask. Example 10:

Continuous cleavage of short chain fatty acid methylates with separation of

Splitting process and removal of methanol

350 ml of fatty acid methyl ester, 350 ml of water and 35 g of immobilized Candida antarctica B lipase are placed in a heated flask. The hydrolysis reaction is carried out at 45 ° C. The reaction mixture is continuously pumped through a dephlegmator heated to 110 ° C. At a vacuum of 740 mbar, methanol is continuously removed and the remaining reaction mixture drips back into the reaction flask. Water is metered in to keep the reaction volume constant. The implementation of the reaction was examined by determining the acid number.

Table 12

response times

The hydrolysis reaction is significantly slower than with a continuous methanol withdrawal directly from the reaction flask.

Example 11:

Multistage cleavage of short chain fatty acid methylates by exchanging the

Water phase without continuous methanol withdrawal

7.5 g of fatty acid methyl ester, 12.5 g of water and 0.1 g of Lipolase (Thermomyces Lipase, Novozymes) are reacted in a stirred vessel at room temperature. After 18 h, 26 h and 41 h, the water phase is separated by separation from the organic phase. se removed. 12.5 g of water and 0.1 g of Lipolase are added after each phase change.

The implementation of the reaction was examined by determining the acid number.

Table 13

Sales with multi-level splitting after different reaction times

Example 12:

Two-stage cleavage of short-chain fatty acid methylates

540 g of a C ₈ precursor fatty acid methyl ester were placed in a stirring apparatus with a capacity of 3 l, 1260 g of water and 16.2 ml of lipolase concentrate were added and the mixture was stirred at 37 ° C. at a speed of 300 rpm. The hydrolysis was followed by sampling. After 16 h the hydrolysis was stopped, the first hydrolyzate thus obtained was transferred to a centrifuge and separated into an aqueous / alcoholic phase (containing water, methanol and enzymes) and an organic phase which contained the fatty acid formed and the unreacted methyl ester, Cut. The organic phase was returned to the reactor, 1260 g of water and 16.2 ml of fresh enzyme were added. The mixture was then subjected to a second hydrolysis again at 37 ° C. Here too, the progress of the reaction was monitored by sampling. The results are summarized in Table 1. Table 14

Turnover hydrolysis of primary fatty acid methyl esters (figures in% by weight)

The second hydrolyzate, which contained 67.1 fatty acid and 30.8% by weight of unreacted methyl ester, was again separated into an aqueous / alcoholic and an organic phase by centrifugation. The latter was placed between a lifting and stripping section in a rectification column with packed internals and distilled at 85 ° C. and 20 mbar. After 6 h, during which shorter-chain and low-boiling impurities were sucked off via the pump, a C ₈ fatty acid with a purity of greater than 95% by weight was obtained.

Example 13:

Comparison of the various enzymatic processes for the hydrolysis of short-chain fatty acid methyl esters

Comparison of the methods from Examples 4, 7, 9, 10, 11.

Example 4 describes a hydrolysis process with continuous removal of methanol at a constant water content in the reactor.

Example 7 describes a hydrolysis process with continuous removal of methanol, in which water is continuously stripped from the reaction vessel. The water content in the reaction vessel is low,

Example 9 describes a hydrolysis process with continuous methanol removal, in which the methanol removal and the hydrolysis reaction are spatially separated. Example 10 describes an alternative hydrolysis process with continuous methanol removal, in which the methanol removal and the hydrolysis reaction are spatially separated.

Example 11 describes a hydrolysis process without continuous removal of methanol under vacuum, in which methanol is removed from the equilibrium by separating the aqueous phase.

Table 15

Comparison of different procedures

The comparison of the processes clearly shows that a methanol removal directly from the reaction batch provides the best sales. A spatial separation of the hydrolysis and methanol removal with continuous methanol withdrawal in a separate vessel or a temporal separation of hydrolysis and methanol removal via e.g. Phase separation does not lead to satisfactory results.

Claims

claims

1. A process for the preparation of C ₄ -C ₂ fatty acids, in which

(a) C ₄ -C ₂ -fatty acid methyl ester completely or partially hydrolyzed in one step in the presence of enzymes with water with continuous removal of methanol

(c) and the organic phase containing fatty acids and (in the case of partial hydrolysis) fatty acid methyl esters of unreacted fatty acid methyl esters.

2. The method according to claim 1, characterized in that one carries out the hydrolysis at temperatures in the range from 20 to 80 ° C.

3. Process according to claims 1 and / or 2, characterized in that lipases and / or esterases are used as enzymes in free or immobilized form.

4. The method according to claims 1 to 3, characterized in that lipases and / or esterases selected from the group of microorganisms which is formed by Alcaligenes, Aspergiilus niger, Candida antarctica A, Candida antarctica B, Candida cylindracea, Chromobacterium viscosum, Rhizomucor miehei, Penicilium camenberti, Penicilium roqueforti, Porcine pancreas, Pseudomonas cepacia, Pseudomonas fluorescens, Rhizopus javanicus, Rhizopus oryzae, Thermomyces lanugenosus.

5. The method according to at least one of claims 1 to 4, characterized in that one carries out the hydrolysis to a degree of splitting of 60 to 99 wt .-%.

6. The method according to at least one of claims 1 to 5, characterized in that a constant water content in the range of 30 to 70% by weight is set in the reactor during the hydrolysis.

7. The method according to at least one of claims 1 to 5, characterized in that during the hydrolysis in the reactor a water content in the range of 0 to 20 wt.% In the reactor.