Low temperature catalytic elimination of dichloromethane over manganese oxides catalysts with ozone assistance

Abstract

This paper synthesized MnO2 catalysts with different crystal structures including α-, β-, γ-, and δ-phase for catalytic ozonation of CH2Cl2. Among them, δ-MnO2 exhibited superior activity (100 % mineralization rate for 100 ppm of CH2Cl2 at 120 °C under O3/DCM of 12.5) as well as decent stability and potential of multi-pollutants collaborative degradation, which was attributed to its abundant oxygen vacancies and mobile lattice oxygen species. Compared with traditional catalytic oxidation, O3 assistance facilitated the contact between reactants and catalyst and suppressed the accumulation of products, thus effectively reducing energy barrier of reaction. The evolution of intermediates from transient reaction studies during catalytic ozonation and oxidation further proved O3 introduction facilitated dechlorination. This study presents an efficient crystalline-engineering MnO2 for catalytic ozonation and verifies the superiority of catalytic ozonation.