Producing Biodiesel from Waste Cooking Oil with Catalytic Membrane Reactor: Process Design and Sensitivity Analysis

Biodiesel demand increases steadily while using virgin oil as feedstock leads to food–energy competition. Application of conventional biodiesel process using waste cooking oil (WCO) as the alternative feedstock is limited due to the sensitivity of alkali catalysts to free fatty acids (FFA) and the need for glycerol and water washings. This work proposes and conceptually designs a catalytic membrane reactor process to overcome those mentioned limitations. Multiple components in the FFA and WCO were considered in the process design to better demonstrate practical situations and possible technical challenges. Its technical challenges and economic feasibility as well as sensitivities of key process parameters are also evaluated. Results show that the membrane reactor process has a high potential for commercial implementations and economically attractive because it avoids problems associated with the conventional process. Despite being the most sensitive parameter, FFA content of 30 wt% reduces the economic potential by only 5%, demonstrating the robustness of the developed CMR process. Better separation techniques and higher membrane selectivity toward biodiesel still need to be developed in the future to realize and improve the process.