Biodiesel synthesis via esterification and transesterification over a new heterogeneous catalyst comprising lacunary silicotungstate and MCM-41

Mono-vacant silicotungstate anchored to MCM-41 was synthesized by a direct post-synthesis grafting method and characterized by BET surface area measurements, FT-IR, Si-29 MAS NMR, XRD and TEM. The catalytic application of the material was established for acid catalyzed synthesis of biodiesel via esterification of oleic acid and transesterification of different edible and non-edible oils such as waste cooking oil, jatropha oil, sunflower oil, cotton seed oil and mustard oil. A kinetic study was carried out for the esterification of oleic acid and it was found that esterification of oleic acid follows first order kinetics with the calculated activation energy E-a = 49.8 kJ mol(-1) and pre-exponential factor A = 8.7 x 10(4) min(-1). The expected mechanism for the biodiesel synthesis via esterification and transesterification has also been proposed.