Catalytic Oxidation of Dichloromethane over the Zeolitic Imidazolate Framework-Derived HZSM5@Co3O4 Catalyst Synthesized through Two-Step Pyrolysis: Efficient Synergy of Acidity and Redox Properties.

Developing efficient and stable catalysts remains a significant challenge for the degradation of chlorinated volatile organic compounds (CVOCs). In this work, a novel one-pot method was developed to synthesize the HZSM5@Co series of catalysts, aiming to combine the high redox properties of Co3O4 derived from zeolitic imidazolate framework (ZIF) with the excellent acidity of HZSM-5 to achieve enhanced activity and stability for dichloromethane degradation. The optimized 0.5HZSM5@Co-N500A350 catalyst, synthesized via a two-step pyrolysis method using N2 and air, exhibited excellent catalytic activity, low CH3Cl selectivity, and outstanding stability. Characterization results revealed that this superior performance stems from a dual synergistic effect: the ZIF-67 pyrolysis strategy inhibits the coverage of acidic sites in HZSM-5 by Co3O4, thus preserving more active acid centers. Concurrently, the two-step pyrolysis yields highly dispersed Co3O4 nanoparticles with smaller particle sizes and more abundant oxygen vacancy defects, which significantly boosts the redox capacity. This study provides valuable insights into the design of efficient, environmentally friendly catalysts for removing CVOCs.