Facile fabrication of heteropolyacid/bimetallic Bi/Ce-MOFs hybrid catalyst for sustainable biodiesel synthesis

Metal-organic frameworks (MOFs) are promising heterogeneous catalysts or catalyst support materials for biodiesel production due to their high surface area, tunable porosity, and diverse morphology. However, developing bimetallic MOFs that combine easy scalability, high stability, and good catalytic activity that are beneficial for large-scale synthesis and applications is still highly desirable. Herein, a fascinating bimetallic Bi/Ce-MOFs (Bi/Ce-BTC) supported heteropolyacid (HPMo) was constructed by a simple hydrothermal synthesis strategy, and its catalytic performance was evaluated in the esterification of oleic acid. A comprehensive characterization of the composite material's structure, composition, and properties was performed using various techniques (XRD, FTIR, N₂ physisorption, SEM-EDS, TG, NH₃-TPD, Py-FTIR, and XPS). These characterization techniques thoroughly confirm the successful impregnation of HPMo on the Bi/Ce-BTC, and it possesses a relatively large specific surface area, meso-porosity, high acidity capacity, and synergistic catalytic effect between the substrates. Catalytic experiments demonstrated that HPMo@Bi/Ce-BTC exhibited the best catalytic performance, achieving 92.7% conversion of oleic acid under optimal reaction conditions. Remarkably, the catalyst could be easily reused six times with an acceptable oleic acid conversion (79.3%). In addition, the kinetic analysis of the esterification reaction by HPMo@Bi/Ce-BTC catalyst showed pseudo-first-order kinetics, with activation energies found to be 60.9 kJ/mol. Overall, the employment of bimetallic MOFs for impregnation of active species paves a potential way for broad applications in sustainable chemical processes.