Biodiesel synthesis by transesterification using coal-based solid acid catalyst

Abstract

The medium metamorphic degree of bituminous coal with high oxygen content and low ash content is selected as the carbon carrier to prepare an efficient carbon-based solid acid catalyst through partial carbonization and sulfonation approach, and then is employed to catalyze transesterification of palm oil with methanol for biodiesel production. The strength of catalyst is characterized by Hammett inductor method. The reaction parameters are optimized by single factor method. Results demonstrate that the prepared catalyst possesses the Hammett acid strength range of 0.8<H0<3.3. The maximum biodiesel yield of 97.8% is obtained at catalyst dosage of 6 wt.%, transesterification temperature of 160 °C, molar ratio of methanol to palm oil of 18 and stirring rate of 1000 rpm for 8 h. Moreover, the catalyst exhibits satisfactory activity in catalyzing simultaneous esterification and transesterification when 20 wt.% oleic acid is added to palm oil.