Transesterification of vegetable oils over a phosphazenium hydroxide catalyst incorporated onto silica

Abstract

The catalytic activity of a phosphazenium hydroxide (PzOH) catalyst incorporated onto silica (PzOH/SiO 2) was investigated in the transesterification of vegetable oils with methanol. The PzOH stably incorporated onto silica (SiO 2) maintained its basicity and converted methanol molecules to methoxide ions. The PzOH/SiO 2 catalyst exhibited high activity in the transesterification of palm, corn, grape seed, and soybean oils (S-oil) with methanol, achieving ~ 90% conversion at 75 °C with a catalyst loading of 0.2 g per 4.8 ml of S-oil. Although the accumulation of organic materials on PzOH/SiO 2 reduced its activity, this accumulation was effectively removed by washing with methanol. The high activity of PzOH/SiO 2 was responsible for its strong basicity and for the free mobility of the PzOH moiety.