Catalytic oxidation of 1,2-dichloroethane over three-dimensional ordered meso-macroporous Co₃O₄/La_0.7Sr_0.3Fe_0.5Co_0.5O₃: Destruction route and mechanism

Three-dimensional ordered meso-macroporous La_0.7Sr_0.3Fe_0.5Co_0.5O₃ (3DOM LSFCO)-supported Co₃O₄ catalysts were designed and prepared via a PMMA-templating strategy for the total oxidation of 1,2-dichloroethane (1,2-DCE). The physicochemical properties of all synthesized samples were characterized by XRD, FE-SEM, TEM, HAADF-STEM, low-temperature N₂ sorption, XPS, H₂-TPR, and in situ FT-IR. The introduction of Co₃O₄ increases the generation rate of oxygen vacancy, playing a crucial role in adsorption and activation of oxygen species. The special 3DOM structure of perovskite-type oxide promotes 1,2-DCE molecules to effectively and intimately contact with the surface adsorbed oxygen over supported catalysts and further accelerates the redox process. Compared with pure LSFCO, all the Co₃O₄ supported catalysts show superior catalytic performance with reaction rate increases from 5.53 × 10⁻¹² to 2.29 × 10⁻¹¹ mol g⁻¹ s⁻¹ and E_a decreases from 74.7 to 22.6 KJ mol⁻¹. Amongst, the 10Co₃O₄/3DOM LSFCO catalyst exhibits the best catalytic activity, highest resistance to chlorine poisoning and lowest by-products concentration because of the largest amount of surface adsorbed oxygen. CO₂, CO, HCl, and Cl₂ are the main oxidation productions, while some typical reaction intermediates such as vinyl chloride, 1,1,2-trichloroethane and trichloroethylene are also observed, especially over the 3DOM LSFCO sample. Furthermore, the reaction mechanism of 1,2-DCE oxidation over obtained catalysts was proposed based on the results of gas chromatography, in situ FT-IR, and on-line MS. It is believed that the Co₃O₄/3DOM LSFCO are promising catalysts for the total removal of chlorinated volatile organic compounds.