Immobilization of thiol-functionalized ionic liquids onto the surface of MIL-101(Cr) frameworks by S–Cr coordination bond for biodiesel production

A novel functionalized MOF heterogeneous catalyst (MIL-101(Cr) @MBIAILs), 2-Mercaptobenzimidazole ILs with electron-rich –SH groups immobilized onto the surface of the well-defined MIL-101(Cr) frameworks, was constructed and fabricated by the S–Cr coordination bond on the basis of the facile post-synthetic modification strategy. The heterogeneous catalyst was measured by XRD, FTIR, SEM, TEM, TGA, EA and N₂ adsorption–desorption, and the catalytic behavior of the catalyst was assessed by the esterification about oleic acid and methanol as a model reaction. The results showed that MBIAILs have been successfully immobilized onto the surface of MIL-101(Cr) frameworks by S–Cr coordinate bonds. More importantly, the conversion of oleic acid just decreased from 91.0% to 82.1% when the catalyst had been reused six times. This exhibited the prepared catalyst had superior catalytic behavior and excellent reusability.