Zubenko S. Alkaline synthesis, physicochemical and operational properties of butyl esters of fatty acids on the basis of oil’s triglycerides.

Alkaline synthesis, physicochemical and operational properties of butyl esters of fatty acids on the basis of oil’s triglycerides. A high-efficient anhydrous catalyst potassium butoxide on the basis of potassium hydroxide by azeotropic dehydration with butyl alcohol, was obtained. Technologically acceptable conditions for carrying out the process of alkaline butanolysis on potassium butoxide (the ambient temperature, the catalyst amount 1.4-2.0 wt%, the molar ratio of alcohol to oil 4÷6:1 and the stirring duration 5-15 min), which allows obtaining higher than 90 % yield of esters and separation of products, was found. The composition of products was determined using the methods of gas chromatography, IR-spectroscopy and acid-base titration. The excessive stability of reaction system during alkaline butanolysis of oils at the presence of water is explained by the effect of two types of stabilizers, being surfactants (potassium soaps) and mono(di)glycerides, which contributes to the formation of high-stable reverse microemulsions. It was established, that during butanolysis the glycerol layer, containing two components, which are glycerol and potassium glyceroxide, is formed. The ways of formation of the latter were considered. The mechanism of butanol molecule activation and further transformations, when potassium butoxide is used as catalyst, was proposed. The developed method of one-stage synthesis was tested in oil transesterification by a mixture of ethyl and butyl alcohols. High yields of a mixture of fatty acid alkylesters and the proper separation of products were achieved. Adequate mathematical models of the influence of the molar ratio of reagents and the ratio between alcohols on most important process parameters (esters yield, separation degree and composition of products) were built. It has been established that butyl esters meet the requirements for biocomponents of diesel fuel by a number of physicochemical and operating characteristics (viscosity, density, cloud point, cold filter plugging point, cetane number). The motor bench tests showed that the mixture fuels based on butyl and ethyl esters are similar by their power characteristics, being almost not inferior to petroleum diesel fuel, while exceeding it by environmental performance. Scope – petrochemistry.