Biodiesel-transesterification of biological oils with liquid catalysts: Thermodynamic properties of oil-methanol-amine mixtures

New catalysts and environmentally benign processes allow generation of biodiesel with improved properties at competitive costs. Different amine-based liquid catalysts are screened with respect to conversion rates. Experimental investigations of the complex phase behavior between methanol, different oils, and catalysts as reactants and methyl ester and glycerol as products are the key to define suitable process conditions for reaction and product recovery. An optimized procedure results in a conversion higher than 98% in a one-stage operation. By using sodium- or potassium-free catalysts, soap formation is avoided and glycerol and methyl ester separate rapidly. Effluents of washing water are minimized or even avoided.