Chapter 1 - Synthesis of Biodiesel Fuel in Supercritical Lower Alcohols with and without Heterogeneous Catalysts (Thermodynamics, Phase and Chemical Equilibriums, Experimental Studies)

Abstract

Thermodynamic data (critical parameters, enthalpy, entropy) were calculated for mono-, di-, and triglycerides of fatty acids (palmitic, oleic, and linoleic), free fatty acids, and methyl esters of fatty acids, which are involved in transesterification of vegetable oils with lower alcohols. Phase diagrams of the reaction mixtures were calculated and reaction conditions providing supercritical state of the reaction mixture were selected for transesterification of triglycerides in various lower alcohols. The chemical equilibria of the methanol transesterification of simple and mixed fatty acid triglycerides were studied in a wide range of temperatures, pressures, and ratios of initial components, including the region of the supercritical state of the reaction mixture. Calculation of the phase equilibrium and equilibrium composition of the reaction products obtained by transesterification of triglycerides and vegetable oils with lower alcohols allowed selection of the optimal reaction conditions for practical applications. Transesterification reactions of rapeseed oil in supercritical methanol in a flow reactor over a wide range of variation of the methanol/oil ratio, pressure, and contact time were studied. Conditions ensuring selectivity and a high degree of rapeseed oil conversion were found. Experiments to study this reaction in the presence of zeolite heterogeneous catalyst were performed.