Slow pyrolysis of Cu/Co-Co Prussian blue analog to enhance catalytic activity and selectivity in epoxidation of styrene

Abstract

High-performance Prussian blue analog (PBA) derivative catalysts can be developed by slow pyrolysis of PBA at low temperature, which makes the materials generate cyano vacancies. Through the pyrolysis treatment, a series of Cu/Co-Co PBA derivatives were prepared and used as catalysts for the epoxidation of styrene. Cu/Co-Co PBA-250, obtained by slow pyrolysis at 250 ℃, showed the highest catalytic performance for the epoxidation of styrene, with 99% of styrene conversion. The superior catalytic performance is responsible for its large specific surface area and abundant metal active sites which generated by cyano vacancies. Meanwhile, the face-centered cubic structure and the confinement effects of CN− on metal cations were still maintain during the pyrolysis process. The DFT and control experiment confirmed that tBuOO·radical was the active species responsible for epoxidation of styrene and the convert of Cu2+ to Cu+ may be an important reason for its excellent selectivity.