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

Five Mn-loaded catalysts were synthesized on γ-Al 2 O 3 , TiO 2 , ZrO 2 , nano γ-Al 2 O 3 and nanoZrO 2 supports. The catalytic ozonation of DCM (dichloromethane) was evaluated under industrial conditions ( i.e. , temperature, O 3 input, H 2 O and SO 2 content). According to results, >90% DCM conversion without O 3 residue was achieved for all samples at 120 °C and an O 3 /DCM ratio of 6. At 20-120 °C, the highest Mn 3+ content, abundant surface oxygen species and more weak acid sites led to the best performance of Mn/nanoAl 2 O 3 (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 O 3 /DCM ratio of 6 was optimal for performance and economy. For the effects of complex exhaust, both H 2 O and SO 2 deactivated M/A-II. The H 2 O-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.