Heterobimetallic CoCeOx derived from cobalt partially-substituted Ce-UiO-66 for chlorobenzene efficient catalytic destruction

Abstract

Here, a metal–organic framework (MOF)-templated strategy was applied to synthesize the CoCeOx bimetallic catalysts by calcining Co partially-substituted Ce-UiO-66. It is indicated that the substituted Co limited Ce cations in Ce-UiO-66 framework, which affects its growth and structure crystallinity to some extent. After pyrolysis treatment, the derived bimetallic oxide (CoCeOx-M) can basically keep the octahedral structure and the surface area is much higher than the bulk metal composite oxide (CoCeOx-B) prepared by traditional coprecipitation. Results reveal that CoCeOx-M performs the best chlorobenzene degradation capacity, superior stability and vapor tolerance compared with those of CeO2-M (derived from Ce-UiO-66) and CoCeOx-B. At the same time, it is favorable to inhibit the formation of CO during the oxidation reaction. The superior catalytic performance of CoCeOx-M is attributed to a good dispersion of metal cations, high surface area and active oxygen concentration, and good redox property. Moreover, the formation of organic byproducts especially chlorinated organics can be obviously prohibited over CoCeOx-M compared with that of CeO2-M. Mechanism study reveals that chlorobenzene dissociates on the surface of CoCeOx-M to form carboxylates such as acetate species, maleate and phenolate before finally oxidized into CO2, H2O, and HCl. The present work poses new insights into the fabrication of efficient catalysts for industrial CVOC purification.