HU204885B - Process for alcoholysis of natural triglycerides - Google Patents

Abstract

Alcoholysis of natural, previously opt. deacidified tri:glycerides is carried out with an 1.5-10 fold excess of 1-4C alcohols in the presence of 0.5-10% additive contg multivalent-metal-alcoholates and fatty acid soaps. The reaction is completed by the addn of an alkaline catalyst, at 60-130 deg. C.

Description

The present invention relates to the alcoholysis of natural triglycerides with low molecular weight alcohols.

Esters of low-molecular-weight alcohols with naturally occurring fatty acids are commercially available intermediates, plastic solvents, plasticizers, starting materials for many compounds such as surfactants, soap products, higher molecular weight fatty acid alkyl esters. Recently, the use of methyl and ethyl esters of fatty acids as an alternative Diesel engine has become significant.

In the processes for preparing the above fatty acid alkyl esters, the reaction of the triglyceride with a C 1-4 aliphatic saturated primary alcohol is carried out in the presence of an acid or alkali catalyst under substantially anhydrous conditions. The reaction mixture may contain mono-, di-, triglycerides, monoalkyl ester, glycerol and excess alcohol, depending on the proportion of the various components present in the reaction mixture.

The target product alkyl fatty acid esters and glycerol are prepared from this reaction mixture.

No. 2,271,619. In the process of the US patent, the starting material can be any purified fat (e.g., coconut oil, cocoa butter, fish oil), the catalyst used is an alkali metal hydroxide (NaOH, KOH), in an amount of 0.1-0.5% relative to the glyceride. the amount of alcohol (methanol, ethanol) is 1.2-1.75 times the equivalent value of the glyceride. The reaction temperature chosen is about the boiling point of the alcohol used. Upon completion of the reaction, the phases are separated. The upper ester phase is washed with water followed by vacuum distillation and the glycerol lower phase is vacuum distilled to recover glycerol. The disadvantage of the process is that it is restricted to the treatment of highly purified, deacidified and anhydrous fats 3, the excess alcohol dissolved in the ester phase becomes useless when diluted in aqueous washing, or can be recovered by a separate technological step and the degree of esterification is below the expected value. 4

Nos. 2,462,369, 2,462,370, 2,478,008, 2,383,579, and 2,383,580. According to U.S. Patents, alcoholysis can be made more economical if, at the end of the reaction, deactivation of the catalyst renders the reaction irreversible in the direction of product formation, removing the excess alcohol from the reaction mixture (eliminating the need for a separate concentration step). The esterification and glycerol phases are separated after combined vacuum distillation purification.

The above processes are more effective than before, but have not eliminated the product yield and catalyst capacity reduction effects of impurities present in the fat (free fatty acids, moisture).

Nos. 2,462,371 and 2,383,596. US procedures are exploring a further opportunity for further product yields by pre-treating fats. To fix the free fatty acids, the crude oil is first extracted with a mixture of alcohol (methanol + ethanol) and then the transesterification is carried out by alkaline catalysis in two steps: first the partial esterification of the glyceride to mono- or 60 diglycerides followed by addition of reaction.

No. 3,020,612. In the German patent process, the low molecular weight alcohol reaction of the previously treated triglycerides with an alkaline catalyst is also carried out in two steps. The crude transesterification product formed in the first step separated from glycerol is subjected to a second alcoholysis and this reaction mixture is washed several times with a suitable amount of water to purify the alkyl fatty acid ester.

The process, with its long reaction time and still incomplete conversion, has the disadvantage of diluting the second-stage alcohol and the glycerol formed with water, which is a loss or can be concentrated in a separate, uneconomical step to a degree of usability. A further yield reducing factor is the aqueous emulsion middle emulsion layer which has to be separated.

) Another way of improving the alcoholysis of triglycerides is the preparation of fat, which not only binds the free fatty acids but also converts them to the ester, thus increasing the yield of the ester phase.

A convenient solution is to pass the fat and the alcohol to be used through a cation exchange column where the free fatty acids that make up the fat are esterified. The ester water produced, the presence of which may impair the effect of pretreatment, can be advantageously utilized in the treatment of various alkali metal fatty acid salts. This possibility was recognized in U.S. Patent No. 845,142. inventors of Japanese patent.

In our research to increase the fat-alcoholysis efficiency, we have discovered that the use of various polyvalent metal alcoholate compounds is beneficial in influencing the reaction. Based on this discovery, we have developed a method by which the industrialized alcoholysis of any vegetable and animal fat can be easily accomplished. The yields and the degree of esterification of the reaction products are close to theoretical values

According to the invention, the triglycerides of natural origin, purified as necessary by a prior deacidification treatment, are reacted with 1.5 to 10, preferably 1.7 to 5.0 times, excess C 1-4 aliphatic alcohols in the presence of an additive, and then 0.2 to 0.8. by weight, the reaction mixture is worked up in a known manner; after separation of glycerol and ester as needed, the soapy phase is partially used for another reaction. The additive consists of polyvalent metal alcoholate and fatty acid soap having a weight percentage of triglyceride of 0.5 to 10, preferably 2.7 to 4.0.

As the soap component of the additive, the Na salt of a C12-C18 fatty acid, preferably the soap phase formed in the previous reaction, is added to the total additive.

It is used in an amount of 50-90% by weight, preferably 70-80% by weight.

As the metal alcoholate component of the additive, Ti (OR) 4 and / or Al (OR) 3, where R = C 3 -C 4 aliphatic primary or secondary alkyl, may be used in an amount of from 10 to 50, preferably 15 to 30% by weight.

The process of the invention makes it possible to produce products with an esterification degree greater than 96% and a yield greater than 97% due to the presence of the additive.

The effectiveness of the process is also illustrated by the following examples.

Examples

Example 1

To the rapeseed oil (580 g, 6.5 mg KOH / g, 0.2 wt% water) was added 140 g of methanol, and the reaction mixture was applied to a 55-60 ° C column packed with VARION-KSM cation exchange resin. After a residence time of 45 minutes, transfer to a 1000 ml flask with thermometer, mechanical stirrer, electric heating and esterification flask, add 1.6 g of fatty acid soap and 1.3 g of aluminum mono-sec-butylate diisopropylate through the addition. the mixture is vigorously stirred for 5 minutes. Subsequently, 2.9 g of NaOH catalyst were weighed and the system was heated to reflux temperature of the alcohol where it was stirred for an additional hour. At the end of the alcoholysis, 3.7 g of cc was added to inhibit the catalyst. H ₂ SO 4 and then the mixture was stripped of methanol by distillation. The remaining reaction mixture separates into phases which are separated and purified by distillation. The target product has an esterification degree of 96.3% and a yield of 97.2%.

Example 2

Example 1 is repeated except that 2.9 g of aluminum mono-sec-butylate diisopropylate are added at the same time as 1.6 g of fatty acid soap. As a result of the alcoholysis, the degree of esterification was 96.8% and the yield 97.7%.

Example 3

Example 1 is repeated except that the amount of aluminum mono-sec-butylate diisopropylate added is 5.8 g. The resulting esterification rate was 97.5% and the yield 98.5%.

Example 4

After thawing with 500 g of 24.6 mg KOH / g acid beef tallow, 160 g of methanol are added and the column of Example 1 is pretreated with a residence time of 70 minutes. The reaction mixture was charged into the flask of Example 1, 25 g of fatty acid soap and 25 g of aluminum mono-sec-butylate diisopropylate were added, followed by 4 g of NaOH after stirring for 5 minutes. In the following, the procedure of Example 1 is followed. The esterification degree of the target product is 97.8% and the yield is 98.4%.

Example 5

500 g of pork fat (4.5 mg KOH / g acid) are melted, 210 g of ethanol are added and the pre-treatment of Example 1 is carried out. Then, 10 g of soap and 7.5 g of mono-isopropoxy-tri-n-butoxy titanate and finally 4 g of KOH are added to complete the alcoholysis according to Example 4. The product has an esterification degree of 97.0% and a yield of 97.9%.

Example 6

500 g of 2.9 mg of KOH / g of coconut fat are thawed and 240 g of n-propanol are added. After pre-treatment on the ion exchange column of Example 1, alcoholization of the flask of Example 1 was carried out by adding 10 g of fatty acid soap, 5.5 g of monoisopropoxy-tri-n-butoxytitanate and 2.5 g of NaOH. The degree of esterification was 97.4% and the yield was 98.0%.

Example 7

Example 1 is repeated except that 8 g of soap and 3.2 g of aluminum mono-sec-butyl diisopropylate are added after pre-treatment to 400 g of 1.7 mg KOH / g of acidic sunflower oil after pretreatment. After stirring for 5 minutes, another 2 g of NaOH was added. The target product has an esterification degree of 97.0% and a yield of 97.6%.

Example 8

The flask of Example 1 was charged with 500 g of rapeseed oil of 0.2 mg KOH / g, 100 g of methanol, 1.5 g of fatty acid soap and 1.0 g of aluminum mono-sec-butylate diisopropylate. The mixture was stirred at 60 ° C for 5 min and then 1.0 g NaOH was added. In the following, the procedure of Example 1 is followed. The resulting esterification rate was 97.2% and the yield 98.4%.

Claims (3)

PATENT CLAIMS CLAIMS 1. A process for the alcoholysis of triglycerides of natural origin, purified by a prior deacidification treatment, comprising reacting the triglycerides with C1-10 aliphatic alcohols, preferably in an excess of 1.7-5.0 times, in the presence of an additive. 2 to 0.8% by weight of an alkaline catalyst, preferably by adding NaOH at a temperature of 60 to 130 ° C, preferably at the boiling point of the alcohol, and then working up the reaction mixture in a known manner, preferably deactivating the catalyst the excess aliphatic carbon alcohols are distilled off, the glycerol and the ester are separated by separation of the phases, the soap phase is partially used for a further reaction, characterized in that the additive consists of polyhydric metal alcoholate and -10, preferably 2.7-4.0. Process according to claim 1, characterized in that the soap component of the additive comprises the addition of the Na salt of a C12-C18 fatty acid, preferably the soap phase formed in the previous reaction, to the whole additive. It is used in an amount of 50-90% by weight, preferably 70-80% by weight. 3. The process of claim 1, wherein the additive is a metal alcoholate component Ti (OR) 4 and / or Al (OR) j is an aliphatic primary or secondary alkyl group having from 3 to 4 carbon atoms in the range of 10 to 50, preferably 15 to 30% by weight, based on the total weight of the additive.