Bimetal oxide CuO/Co3O4 derived from Cu ions partly-substituted framework of ZIF-67 for toluene catalytic oxidation

A MOF-templated method is developed to prepare bimetal oxide CuO/Co3O4 by in situ pyrolysis of Cu2+ partly-substituted ZIF-67 precursor. The physicochemical properties of CuO/Co3O4 are studied by various characterizations such as X-ray diffraction, Raman analysis, transmission electron microscope, scanning electron microscope, N-2 adsorption-desorption measurement, X-ray photoelectron spectroscope, O-2 temperature-programmed desorption, H-2 temperature-programmed reduction, etc. Comparison with CuO, Co3O4 and Mix-CuO/Co3O4, 90 % of both toluene conversion and mineralization over CuO/Co3O4 are fulfilled at around 229 degrees C under the condition of 1000 ppm toluene and weight hour space velocity =20,000 mL/(g h), which is promoted more than 40 degrees C. The better catalytic performance of CuO/Co3O4 attributes to high mutual dispersion of two oxides, porous structure, lower temperature reducibility, abundant lattice defects, more active oxygen species, higher Co3+/Co2+ and O-latt/O-ads molar ratios. Meanwhile, CuO/Co3O4 exhibits a better catalytic stability at different conversions and a good tolerance to 10 vol.% of water vapour. The investigation of temperature-dependent active oxygen species and in-situ DRIFTS results reveal that toluene oxidation on CuO/Co3O4 obeys Mars van Krevelen mechanism.

Automated summary

A bimetal oxide CuO/Co3O4 catalyst was synthesized using a MOF-templated method, showing excellent catalytic performance at low temperatures, good stability, and tolerance to water vapor. The superior performance is attributed to the high dispersion of the two oxides, porous structure, and abundant active oxygen species.