The exceptional activity of a phosphazenium hydroxide catalyst incorporated onto silica in the transesterification of tributyrin with methanol

摘要

A phosphazenium hydroxide catalyst incorporated onto silica showed exceptional activity in the transesterification of tributyrin with methanol and could be used repeatedly without suffering any appreciable deactivation.rnBiodiesel produced by the transesterification of triglyceride with a lower alcohol is a carbon-neutral fuel without the net emission of CO_2 and also a sustainable transportation fuel without using petroleum sources. Homogeneous base catalysts, such as potassium and sodium hydroxides, are mainly employed in the transesterification of vegetable oil and animal fat with methanol because of their high activity and convenience. However, the post-treatment of biodiesel products to neutralize the remaining base and wash out salts are relatively expensive, thereby lowering the feasibility of biodiesel. Although several heterogeneous catalysts, such as zeolites, alkali earth oxides and hydrotalcites, have been applied as base catalysts for transesterification, their low activities and inconvenient pre-treatments limit their application.