Advances in calcium oxide mediated catalytic biodiesel production: A paradigm shift in complying with UN's SDG7

Abstract

The growing concerns over global warming and the finite nature of fossil fuel resources have spurred interest in biodiesel as promising alternative towards carbon-neutral economy. Substituting petro-diesel with biodiesel could trigger to a remarkable decline in environmental pollution. Amidst several customary processes, transesterification is ascertained to be a globally well-adopted cost-competent and scalable method of biodiesel manufacturing. Nevertheless, transesterification faces many challenges particularly with homogeneous catalysis, such as catalyst separation and formation of wastewater. Calcium oxide (CaO) as a heterogeneous catalysts have gained momentum of interest. However, it has still some bottlenecks in scaling-up.

The current review delves into the use of CaO-based catalyst in biodiesel synthesis over the previous fifteen years addressing a critical need for improvement in catalytic activity through regeneration of reused catalyst to promote sustainable development goals (SDG7) of the United Nations. It also digs deeper into exploring possible mechanisms that cause catalyst deactivation to enable designing catalyst synthesis and ensure resistance to leaching and deactivation; advocating the need of kinetic and thermodynamic analysis, which have impact on the reaction process; evaluating the life cycle assessment (LCA), and the practical applications of the findings. The review also underscores the paucity of sufficient data for comparing the environmental impacts of biodiesel production using CaO-mediated catalysts. There is still a remarkable lacuna in the literature pertaining to the CaO-based cost analysis to make biodiesel production economical. Furthermore, it suggests that future research should focus on developing catalysts that can efficiently regenerate themselves in a single step.