Biodiesel production using heterogeneous catalyst based on volcanic ash of Mount Sinabung

Abstract

This study applied volcanic ash of Mount Sinabung (VAMS) as a heterogeneous catalyst in biodiesel production. Volcanic ash can be regarded as a result of natural calcination of the soil at eruption site. It contains metal oxides which suggests a high potential for catalyst development. The purpose of this study was to characterize VAMS and was further tested as heterogeneous catalyst in transesterification reaction. VAMS was analyzed for its morphology and elemental content, functional group by using Scanning Electron Microscopy – Energy Dispersive Spectroscopy (SEM-EDS), and Fourier Transform Infrared (FTIR) Spectroscopy, respectively. The results of SEM analysis showed that VAMS is more orderly and porous than the soil of Mount Sinabung. Pore formation during calcination is estimated to be decomposition of organic matter in the inner pores. As such, VAMS is already activated and the pore can serve as a reaction site. EDS analysis showed that VAMS contains Si, K, Mg, and Na. These elements are the active ingredients responsible for catalyzing the transesterification. FTIR results further confirmed the presence of the metal oxide groups. Treated waste cooking oil (TWCO) and methanol were used as reactants. The amount of catalyst used, reaction time and TWCO to methanol molar ratio (TMR) were varied. Resulting biodiesel was analyzed for its physical properties include methyl ester concentration, density, viscosity, and flash point. The best result was obtained at 60°C, 6 wt% catalyst load, TMR of 1:9 and reaction time of 2 h, yielding 99,58% ester purity and 99.54% yield. The biodiesel characteristics met the Indonesia standard (SNI). Based on the results, VAMS can be used as heterogeneous catalyst in biodiesel production.