LAUSR

Abstract The micropore of the pristine NaY zeolite limits the number of active center Cu+ as well as the diffusion of reactant and product molecules, meanwhile, owing to its small size of hexagonal prisms and sodalite cages as compared to the kinetic diameter of the reactants leads to the low Cu+ utilization, which is not conductive to the oxidative carbonylation of methanol over CuY zeolite. In this work, the NaY zeolite with abundant mesopore was obtained without evident sacrifice of framework Al by sequential H4EDTA-NaOH treatment. The hexagonal prisms and sodalite cages were broken during the H4EDTA-NaOH sequential treatment process resulting in the formation of mesopores, which facilitated the exchange of Cu(NH3)42+ with Na+ and improved the accessibility of Cu+ to reactant molecules. Moreover, the extracted Al species from the framework of NaY by H4EDTA treatment gradually reinserted back into the framework of NaY zeolite during the subsequent alkali treatment with the increased NaOH concentration, which improved the number of available exchanged sites with Cu(NH3)42+. Hence, the number of accessible active center Cu+ was significantly improved. Besides, the formation of mesopores promoted the diffusion of reactants and product molecule. The obtained results indicate that modification of NaY by sequential H4EDTA-NaOH treatment is an effective strategy to enhance the catalytic performance of CuY for oxidative carbonylation reaction.