SK239991A3 - Method of adjustment of methylesters of high fatty acids - Google Patents

Abstract

Methylesters of higher fatty acids are acquired by preesterification of triacylglycerols by methanol in presence of alcalic catalyst. Innorganic catalyst is after reaction preferential in created glycerol phase but it occurs in mass 0,02 to 0,06 per cent of weight also in methylester phase as noncombustible surplus. At its removing are the methylesters mixed with strong mineral acid in small mole excess towards present alkali, than this excess of mineral acid is liquidated by ammonia and excess of ammonia is striped by air. By invention method is possible to prepare ash-free methylesters of high fatty acid, straight available as fuel for diesel engines.

Description

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Process for treatment of higher methyl esters

Technical field

The present invention relates to a process for the treatment of higher fatty acid methyl esters prepared by the transesterification of triacylglycerols with methanol in the presence of an alkali catalyst to remove inorganic substances from the methyl esters.

The state of the art

Methyl esters of higher fatty acids are obtained by pre-impregnation of natural triacylglycerols with methanol in the presence of alkali metal compounds as catalyst. or alkali metal carbonates of sodium and potassium in the reaction mixture are in the form of salts of higher fatty acids, methoxides, glycerolates and other similar compounds, or even in their original form. C, two liquid phases are formed in the reaction mixture, the ester phase and the glycerol phase. The alkali metal compounds present are preferably concentrated in the polar environment of the glycerol phase, but a small amount thereof remains soluble in the ester phase and constitutes the essence of the ash. The potassium compounds have a higher solubility than the sodium compounds. Water scrubbing or ion exchange on a suitable ion exchanger is used to remove or reduce the alkali metal content of the methyl esters. The disadvantage of aqueous washing is the possibility of forming tough, difficult-to-break emulsions as well as ester hydrolysis associated with increased acidity and reduced ester stability. The disadvantages of ion exchangers are their low productivity and high cost.

SUMMARY OF THE INVENTION

The process according to the invention consists in mixing the methyl / esters with an appropriate amount of a strong mineral acid in a small molar excess relative to the alkali present, then the excess mineral acid is disposed of with ammonia and the excess ammonia is stripped off with air.

The process of the invention has several advantages. It reliably provides virtually ashless fuel for diesel engines. Free fatty acids that are released from the decomposition of any alkaline soaps present by mineral acid are bound by ammonia in the form of ammonium salts of fatty acids. These remain in methyl esters, but are incinerable without ash. The use of readily removable ammonia to bind the excess mineral acid allows the mineral acid to be metered in without the need for analytical determination of the alkali content of the methyl esters. The excess ammonia is simply removed from the methyl esters by air stripping. The consumption of chemicals relative to the volumes of methyl esters processed is minimal. The process is environmentally safe, potassium or sodium and mono-ammonium salts of phosphoric or sulfuric acids can be used as fertilizers. The use of concentrated reagents practically does not allow water to enter the system, or only in negligible amounts. Ammonia is preferably used in the gaseous state, but can also be supplied in the form of 25% by weight. The aqueous ammonium hydroxide solution is admixed to 1 kg of methyl esters of 6 to 18 millimoles of monobasic mineral acid after completion of the transesterification of the triacylglycerols with methanol, separation of the glycerol phase and preferably removal of the methanol present by distillation or stripping containing 0.02 to 0.04% by weight of ash. , for example HCl, or an equivalent amount of a polybasic mineral acid, for example or ^SO 2, at a temperature of 40 to 70 ° C. After stirring for 2 to 10 minutes, 3 to 20 millimoles of ammonia per kg of methyl esters are introduced into the reaction mixture, representing 0.14 to 0.34 g of NHg as ammonia gas, or

0.56 to 1.36 g of 25% ammonium hydroxide. The mixture is further stirred for 2 to 10 minutes and then any unreacted ammonia is stripped with air.

An example of an embodiment of the invention

To 1 kg of mixed fatty acid methyl esters with an ash content of 0.027 wt%, which represents 8.7 millimoles of Na, 0.35 g of HgPO4 85%, which is 9.1 ml of the equivalent of acid, was added at 55 ° C. The mixture was stirred for 5 min and then 0.68 g of 25% ammonium hydroxide, 10 millimoles of NH4, was added. After stirring for 5 min, the mixture was stripped with air. As described, ashless mixed methyl esters of higher fatty acids were obtained.

Industrial usability

The higher fatty acid methyl esters treated by the process of the invention are useful as ashless fuel for diesel engines. Fuel produced from renewable vegetable or animal products is usable in conventional diesel engines without their treatment and is more environmentally friendly than conventional oil fuel,

Claims (1)

PATENT CLAIMS Process for treating ash-containing higher fatty acid esters prepared by the esterification of triacylglycerols with methanol in the presence of an alkali catalyst to remove ash, characterized in that mono-or polybasic mineral acid in a molar acid / alkali ratio of 1: 1 to 1: 1 is added to the methyl esters. 5 and the reaction mixture is stirred at 40 to 70 ° C for 2 to 10 minutes, then ammonia is introduced into the reaction mixture in a molar acid / ammonia ratio of 1: 1 to 1: 1.4 and after stirring for 2 to 10 minutes stripes through the air.