Selective Mesitylene Oxidative Coupling Reaction by Metastructured Electrocatalyst Comprised of Carbonaceous Scaffold Coated with Pd Derived from Zeolitic Imidazole Framework

Abstract

Electrocatalysis plays a vital role in industrial processes like electrohydrodimerization of acrylonitrile, anodic substitution and addition, electrolytic oxidative/reductive coupling and electrolysis of heterocyclic compounds. Electrocatalysts with suitable size and shape selectivity for reactants, reactant intermediates and products increase their selectivity. Zeolites are the most common vehicles for size-/shape-selective heterogeneous catalysts, but their lack of electronic conductivity vitiates their use in electrocatalysis. In this context, we explore the effectiveness of carbon derived from the zeolitic imidazole framework (ZIF), which possesses both electronic conductivity and structural selectivity for electrocatalytic oxidative coupling of mesitylene to bimesityl. Co-ZIF synthesized by facile solvothermal method was heated in an inert atmosphere and acid-leached to remove Co in order to generate C-based structured material. Further, Pd acting as a catalyst was deposited inside the pore walls of the obtained C scaffold by electroless deposition to derive pore sizes ranging between the molecular size of the particular product. Controlling the pore size of metastructured electrocatalyst at ~ 16 A allows only bimesityl formation, and restricts any larger sized by-product. Metastructured electrocatalyst showed ~ 18 times higher selective conversion for the desired bimesityl production than the planar Pd film electrocatalyst, demonstrating the potential of the proposed approach.