Biodiesel production under a microwave-assisted approach using a glycerol-derived Zn bifunctional catalyst

Abstract

Biodiesel production still relies heavily on homogeneous catalysts and edible oils, which leads to costly production and purification steps. Heterogeneous bifunctional catalysts have emerged as promising alternatives as they can be easily recovered and reused, in addition to tolerating low-grade feedstocks. Moreover, biodiesel production generates a substantial amount of crude glycerol as a byproduct, which creates a crucial need for valorisation strategies. Herein, to overcome these challenges, a zinc oxide-glycerol-based material was synthesized and employed as a bifunctional catalyst for the conversion of acidified corn oil into biodiesel via a microwave-assisted approach. Physicochemical characterization revealed a flower-like mesoporous structure and the presence of ZnO as the main active phase. Reaction parameters, including oil-to-methanol molar ratio, catalyst loading, temperature, and reaction time, were optimized to determine conditions that maximize conversion efficiency, achieving the highest conversion of 94.5% at 150 °C for 1.5 hours using a 5 wt% catalyst loading and a 1 : 24 oil-to-methanol molar ratio. Furthermore, reusability studies showed that the material remains stable for up to five reaction cycles. Our findings highlight the potential of using glycerol as a precursor for the synthesis of heterogeneous catalysts and offer a circular and economically viable alternative for biodiesel production, rendering it more sustainable.