A NOVEL CONTINUOUS-FLOW REACTOR USING REACTIVE DISTILLATION FOR BIODIESEL PRODUCTION

Abstract

The production of biodiesel through batch and existing continuous-flow processes requires the use of a muchhigher excess alcohol, typically 100%, than the stoichiometric molar requirement in order to drive the transesterificationreaction to completion. This excess alcohol must be recovered in a separate process, which involves additional capital andoperating costs. In this study, a novel reactor system using reactive distillation (RD) was developed and investigated forbiodiesel preparation from canola oil and methanol. The goal was to significantly reduce the use of excess methanol whilemaintaining a high methanol:glyceride molar ratio inside the RD reactor by recycling a small amount of methanol within thesystem. Reactant conversion rate and product yield were used as the criteria for the reactor evaluation. The effect of themethanol:glyceride ratio was studied on a laboratory-scale perforated-tray RD reactor system. Product parameters such asmethyl ester content, glycerides, and methanol content were analyzed. Preliminary results showed that the RD reactor witha methanol:glyceride ratio of 4:1 (molar), in which the use of methanol was cut down by 66%, gave a satisfactory biodieselyield and oil conversion rate at a column temperature of 65C. Total reaction time in the pre-reactor and RD column wasabout 3 min, which is 20 to 30 times shorter than in typical batch processes. The productivity of the RD reactor system wasabout 6.6 m3 biodiesel per m3 reactor volume per hour, which is 6 to 10 times higher than that of batch and existingcontinuous-flow processes.