In situ synthesis of MOF-derived CuCoOx with enhanced catalytic activity and moisture resistance for aromatic VOCs combustion: The role of bimetallic oxide interactions on the catalytic mechanism

The impact of water vapor on the catalytic oxidation of VOCs is inevitable in the treatment of industrial waste gases. The presence of water vapor usually inhibits the catalytic oxidation. Therefore, the development of water-resistant, efficient and stable catalysts is of great significance for the control of VOCs. Herein, CuCoOx catalysts were prepared by pyrolysis of in situ synthesized CuCo-ZIF. Meanwhile, a range of Cu-Co bimetallic oxide catalysts were obtained by pyrolysis of Cu/Co-ZIFs synthesized by common strategies for the comparison in the oxidation of aromatic VOCs under humidity conditions. CuCoOx exhibited higher catalytic activity and stability under high moisture conditions compared with CuCoOx-IE (MOF precursors synthesized by ion exchanging) and CuO/Co3O4 (MOF precursors synthesized by mixing). The T90 of toluene was 209 °C under the reaction conditions of 1000 ppmv toluene, 40,000 mL g−1h−1 WHSV and 5 vol% H2O. The improved catalytic performance of CuCoOx was ascribed to more surface lattice defects and enriched active oxygen species, which originated from the enhanced interactions between Cu and Co species. The surface active oxygen species on CuCoOx were either derived from the adsorbed gaseous oxygen, or generated via the reaction of O2 with type III H2O adsorbed on oxygen vacancies. Thus, the presence of H2O accelerated the ring-opening of benzoates and attenuated the competitive adsorption of H2O and VOCs. This study affords new ideas for the construction of efficient and water-tolerant bimetallic oxide catalysts for the degradation of VOCs under moisture conditions.