Synthesis and characterization of heterogeneous catalysts (MgO, CaO/Zeolite-Y) via hydrothermal method for biodiesel production

The global energy crisis and increasing greenhouse gas emissions have driven the development of sustainable energy alternatives, among which biodiesel has gained considerable attention. However, conventional biodiesel production is often limited by homogeneous catalysts that suffer from separation difficulties, low reusability, and secondary waste generation. In this work, heterogeneous MgO and CaO supported Zeolite-Y catalysts were synthesized via a hydrothermal method to enhance metal dispersion and catalyst stability. Structural characterization by XRD confirmed the preservation of the Faujasite-Y framework after metal incorporation, whereas SEM and SEM–EDX analyses revealed a typical octahedral morphology and uniform distribution of MgO and CaO on the Zeolite surface. Acidity measurements verified the availability of active sites suitable for transesterification. The catalysts were evaluated in sono-transesterification of waste cooking oil with methanol at 65 °C for 2 h. MgO/Zeolite-Y achieved a biodiesel yield of 63.824%, while CaO/Zeolite-Y exhibited superior catalytic performance with a yield of 79.344%. The produced biodiesel complied with SNI 7182:2015 and ASTM D6751 standards. These results indicate that CaO/Zeolite-Y is a promising heterogeneous catalyst for biodiesel production, demonstrating superior performance compared to MgO/Zeolite-Y under optimised reaction conditions.