Lewis and Brönsted basic active sites on solid catalysts and their role in the synthesis of monoglycerides

Solid Brönsted base catalysts show higher activity and much higher specific rate than reported Lewis basic hydrotalcite catalyst for transesterification of oleic acid methyl ester with glycerol. The selectivity of the former for monoglycerides is higher because of the lower deactivation of the catalyst, which allows the transesterification of diglycerides to occur at longer reaction times. Calcined Li-Al hydrotalcites give higher activity than MgO or Al-Mg hydrotalcites because of the stronger Lewis basicity of the former. All of the solid Lewis basic catalysts have the same selectivity to monoglyceride regardless of the base strength, a selectivity lower than that of Brönsted basic solid catalysts.