Development of a New Solid Catalyst for Biodiesel Production Using Local Vegetable Resources, Adapted to the Contexts of the West African Countries

Abstract

African countries are increasingly interested in biofuels to provide access to energy. The development of local technologies using local resources for biodiesel production can be a promising solution. This work is a first step towards the development of a simple process of transesterification of vegetable oil using local resources. The aim of this study is to explore new solid catalysts made of a potassium phase supported on char, for the production of biodiesel by transesterification of vegetable oil with ethanol. Catalysts were prepared by impregnating shea nut shells with four selected potassium precursors KCl, KOH, K2CO3, and KNO3, and then pyrolyzed. The thermal behaviour of the impregnated biomass as well as the potassium crystalline phase in the catalysts were investigated. The effects of the type of potassium precursor, pyrolysis temperature and the amount of catalyst on the conversion of oil to ethyl ester were analyzed. Results showed that increasing pyrolysis temperature enhanced the conversion of oil. Catalysts obtained from KOH and K2CO3 precursors displayed better activity than the other catalysts. The catalytic activity was found to be related to a K2CO3 crystalline phase. For conditions of transesterification at 10 wt% of catalyst, a reaction temperature of 70 °C and only 10 min reaction time, ethyl ester contents were 97.6 wt% for KOH and 99.1 wt% for K2CO3 based catalysts. Both catalysts allowed a good ethyl-ester yield in soft temperature and pressure conditions, and in a short time.