Reactive Distillation toward an Ecoefficient Process of Continuous Biodiesel Manufacture from Waste Oil: Pilot-Scale Experiments and Process Design

The objective of the present work is to find a potential way for a great decrease in the biodiesel production energy requirement and CO₂ emission from the aspects of the reactor and process. Here, for the first time, a series of pilot-scale reactive distillation (RD) experiments were conducted using the cation-exchange resin catalysts and used for biodiesel synthesis from esterification of soybean oil deodorized distillate with methanol. The reaction kinetics was also investigated at different temperatures and mole ratios of methanol to free fatty acids (FFAs). Moreover, a rigorous biodiesel synthesis model of the RD process, based on the kinetics obtained in this work, was developed and validated on the basis of experimental data. The developed modeling can be used to optimize the process and design parameters while also providing a foundation guide for industrial applications. The results demonstrated that the use of RD technology increases the conversion of FFA to 99% and keeps energy consumption and CO₂ emission at a low level. Furthermore, the RD technology over cation-exchange resin catalysts will open a new path to develop a better process for biodiesel synthesis from waste oil to reduce the production energy consumption, decrease CO₂ emission, and thus further increase the commercial competitiveness of this green fuel.