PROCESS OPTIMIZATION OF BIODIESEL PRODUCTION USING ALKALINE CATALYSTS

Abstract

The most commonly used method for biodiesel preparation is via transesterification of vegetable oil using alkalinecatalysts. Biodiesel yield and oil conversion are affected by operating conditions including the catalyst formulation andconcentration. Application of alkaline catalysts can also lead to undesired soap formation. This study evaluated the alkalinecatalyst effects on biodiesel yield and soap formation in transesterifying methanol and canola oil at different catalystconcentrations, reaction temperatures, and methanol-to-oil molar ratios. Four different alkaline catalysts, i.e., potassiumhydroxide, sodium hydroxide, potassium methoxide, and sodium methoxide, were studied and compared on molar basisthrough a 4-factor 3-level experimental design. It was observed that methoxide catalysts led to better biodiesel yields thanhydroxide catalysts. The methoxide catalysts not only accelerated the reaction but also elevated the conversion equilibrium.Based on statistical optimization, the operating conditions for maximizing biodiesel yield and minimizing soap formationwere potassium methoxide as catalyst at 0.2 mol/mol (1.59%wt), reaction temperature of 50.C, and methanol-to-oil molarratio of 4.5:1. Experimental verification gave 95.8% biodiesel yield and 0.75%wt soap.