Catalytic ozonation of dichloromethane at low temperature and even room temperature on Mn-loaded catalysts

Abstract

Five Mn-loaded catalysts were synthesized on γ-Al₂O₃, TiO₂, ZrO₂, nano γ-Al₂O₃ and nanoZrO₂ supports. The catalytic ozonation of DCM (dichloromethane) was evaluated under industrial conditions (i.e., temperature, O₃ input, H₂O and SO₂ content). According to results, >90% DCM conversion without O₃ residue was achieved for all samples at 120 °C and an O₃/DCM ratio of 6. At 20–120 °C, the highest Mn³⁺ content, abundant surface oxygen species and more weak acid sites led to the best performance of Mn/nanoAl₂O₃ (M/A-II). At 20 °C and 120 °C, 80% and 95% DCM can be degraded respectively on M/A-II at 20 °C with matched surface oxygen species and acidity. An O₃/DCM ratio of 6 was optimal for performance and economy. For the effects of complex exhaust, both H₂O and SO₂ deactivated M/A-II. The H₂O-induced deactivation was recoverable and also removed surface-deposited chlorine-containing species, enhancing the HCl selectivity. Finally, the Cl equilibrium of the reaction was comprehensively analyzed.