Hydrolysis of palm olein catalyzed by solid heteropolyacids

Abstract

AbstractThe hydrolysis activity of superacids on palm olein, including tungstophosphoric acid and molybdophosphoric acid and their partially ion‐exchanged cesium (Cs) salt, were investigated and compared with macroporous cation‐exchanged resin and aluminum‐incorporated mesoporous molecular sieve. The activities of the superacids supported on the resin and silica were also determined. The reactions were carried out in a stirred batch reactor with continuous steam injection at temperatures from 140 to 180°C. The reaction kinetics, obtained by regression, are first order with respect to TG of the superacids and Cs salts. Of the catalysts studied, the superacids loaded onto cation‐exchanged resins were the most active on a weight basis. However, in terms of the turnover number per acid site, the Cs salt of tungstophosphoric acid had 13 times the activity of the cation‐exchanged resin. The original superacids had lower activities than the Cs salts in terms of their turnover number. The observations are qualitatively in line with the higher acid strengths of the catalysts, as confirmed by the low activity of the aluminum silicate mesoporous molecular sieve, which is known to have a high concentration of low‐to moderate‐strength acid sites. The activation energy of the reaction with the Cs salts was ∼49 kJ mol−1. This is rather low as compared to that catalyzed by the cation‐exchanged resin.