Designing an economical and environmentally friendly catalyst for production of biodiesel is crucial yet a challenging aspect for advancing renewable energy applications. To accomplish this, the present research elucidates the fabrication of a highly efficient novel heterogeneous catalyst by utilizing CaO derived from waste chicken eggshells and a metal–organic framework (MOF)@layered double hydroxide (LDH) (CLD-HK) for the sustainable microwave-assisted transesterification of soybean oil (SO), achieving a biodiesel yield of 99.78 ± 0.6 % within just 60 min. The remarkable catalytic performance is primarily ascribed to the strong basicity of CaO and LDH, along with the unsaturated sites contributed by the MOF, which create accessible active sites for effective substrate adsorption and effective coordination with triglycerides. This synergy results in excellent catalytic performance of the CLD-HK catalyst. Kinetic studies revealed an activation energy (Ea) of 29.50 kJ/mol, significantly lower than previous reported values, demonstrating high energy efficiency. Various parametric studies revealed that the reaction adhered to pseudo-first-order model with a rate constant of 0.07495 min−1. A plausible reaction mechanism for the transesterification of SO was proposed based on the various characterization results. Furthermore, 1HNMR, 13C NMR, FT-IR and GC–MS analyses validated the conversion of SO to fatty acid methyl esters (FAME), with the produced biodiesel meeting the ASTM standards. The life cycle cost analysis (LCCA) estimated the unit production cost at merely $0.42/kg, highlighting the commercial viability of this biowaste-based catalyst. This approach not only valorizes waste materials but also offers a sustainable and cost-effective alternative to petroleum-based diesel.

中文翻译：

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用于微波辅助生物柴油合成的废蛋壳衍生的 CaO/金属有机骨架@LDH：热力学、机理见解和生命周期成本分析


设计一种经济且环保的生物柴油生产催化剂对于推进可再生能源应用至关重要，但也是一个具有挑战性的方面。为了实现这一目标，本研究利用来自废弃鸡蛋壳的 CaO 和金属有机框架 （MOF） @layered双氢氧化物 （LDH） （CLD-HK） 制备了一种高效的新型非均相催化剂，用于大豆油 （SO） 的可持续微波辅助酯交换反应，在短短 60 分钟内实现 99.78 ± 0.6% 的生物柴油收率。卓越的催化性能主要归因于 CaO 和 LDH 的强碱性，以及 MOF 贡献的不饱和位点，这些位点为有效底物吸附和与甘油三酯的有效配位创造了可接近的活性位点。这种协同作用使 CLD-HK 催化剂具有出色的催化性能。动力学研究表明，活化能 （Ea） 为 29.50 kJ/mol，明显低于以前报告的值，表明能源效率高。各种参数研究表明，该反应遵循速率常数为 0.07495 min-1 的准一级模型。基于各种表征结果，提出了一种合理的 SO 酯交换反应机制。此外，1HNMR、13C NMR、FT-IR 和 GC-MS 分析验证了 SO 向脂肪酸甲酯 （FAME） 的转化，生产的生物柴油符合 ASTM 标准。生命周期成本分析 （LCCA） 估计单位生产成本仅为 0.42 美元/千克，凸显了这种基于生物废物的催化剂的商业可行性。 这种方法不仅使废料增值，而且还为石油基柴油提供了一种可持续且具有成本效益的替代品。