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Abstract
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The urgent global demand for sustainable energy solutions necessitates the development of high-performance, environmentally benign catalysts for biodiesel production. We present the design and synthesis of a novel solid base catalyst, K2CO3@SBA-15, utilizing Diatomaceous Earth, an abundant biogenic material, as a renewable silica precursor. This strategic material innovation not only valorizes an underutilized natural resource but also offers a scalable, low-cost pathway for producing mesoporous supports with high structural integrity. The tailored catalyst exhibits exceptional properties, as confirmed by comprehensive characterization techniques (XRD, FT-IR, Raman, CO2-TPD, SEM, TEM, TGA, and XPS). When applied to the transesterification of waste cooking oil (WCO), the catalyst achieved a remarkable 97.6% biodiesel yield under mild conditions (45°C, 120min, 9:1 methanol-to-oil ratio). Kinetic modeling revealed a low activation energy of 31.18kJmol−1, while thermodynamic analysis indicated an endothermic, associative transition state mechanism (ΔH#=+28.58kJmol−1; ΔS#=−190.04Jmol−1K−1). Reusability studies demonstrated superior catalytic stability, with performance sustained over multiple cycles, particularly upon post-use calcination. Minimal potassium leaching, confirmed by ICP analysis, underscores the long-term durability of the system. Furthermore, the synthesized biodiesel met all critical fuel standards (ASTM D6751, EN 14214), validating its commercial viability. This work establishes a new paradigm in biodiesel catalysis by integrating naturally sourced materials, rational catalyst design, and mechanistic insight to deliver a high-efficiency platform for clean fuel production. The approach offers a compelling blueprint for next-generation catalysts aimed at decarbonizing liquid fuel technologies.
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