Recycling heterogeneous catalyst waste in biodiesel production using methanol and hydrochloric acid: A case study on the washing effect with lauric acid as raw material

Abstract

The widespread use of heterogeneous catalysts for biodiesel production has led to the generation of substantial waste. Therefore, it was needed to reduce the solid waste catalyst in the biodiesel industry by exploring the reuse of catalysts. This study focused on the reactivation of used catalysts through the esterification of lauric acid using Amberlyst CM-4 catalyst, with pre-treatments involving methanol washing and HCl reactivation. Gas chromatography was employed to analyze lauric acid and methyl ester while Scanning Electron Microscope provided insights into the pore conditions of the fresh catalyst and used catalyst and Brunauer Emmett Teller provided information into surface area and pore condition. In this study, it was examined how many times the Amberlyst catalyst could be used to catalyze lauric acid to become biodiesel. The limitation of this capability is catalyst conversion above 80 %. The results showed that optimal conditions for biodiesel production were reached at a reaction temperature of 60 °C, a reaction time of 120 minutes, and an agitation rate of 500 rpm, yielding 93.7 % conversion for the used catalyst and 98.5 % for the fresh counterpart. The Amberlyst catalyst can be used up to seven times, because the results still provide a conversion above 80 %. After this catalyst does not provide a conversion above 80 %, then this catalyst is washed with methanol and activated using HCl. The results obtained show that this catalyst can still be used four more times. Hence, the results of this research can be applied to reduce industrial waste and reduce the costs of making biodiesel from fatty acids.