Production of Fuel Quality Ethyl Ester Biodiesel: 1. Laboratory-Scale Optimization of Waste Frying Oil Ethanolysis, 2. Pilot-Scale Production with the Optimal Reaction Conditions

Abstract

In this study, to produce fuel quality biodiesel, optimization of homogeneous alkaline-catalyzed ethanolysis reaction of waste frying oil was performed. In the first stage of the study, laboratory-scale experiments were carried out to determine the appropriate alkaline catalyst type. Ethanolysis reactions were initially conducted with hydroxide catalysts (KOH and NaOH), but glycerol phase separation could not be obtained. Therefore, alkoxide catalysts (CH3OK and CH3ONa) were used and glycerol phase separation could be obtained with the reaction conditions of ethanol:feedstock molar ratio of 6:1, 1.40 wt% CH3ONa, 75 °C and 4 h. The product yield, viscosity and density were 91.24%, 4.89 mm2s−1, and 880.8 kgm−3, respectively. In the second stage, to increase the yield, optimization experiments were performed and the yield was increased to 99.08% while viscosity and density were almost the same with the reaction conditions of ethanol:feedstock molar ratio of 8:1, 1.40 wt% CH3ONa, 45 °C and 2 h. In the third and the last stage, pilot-scale ethyl ester production was carried out with the optimal reaction conditions. In the pilot-scale ethanolysis, yield decreased to 91.0% because of saponification and emulsification, but the produced ethyl ester biodiesel fuel met the European Biodiesel Fuel Standard (EN 14214:2013).