Catalytic decomposition has been considered as a promising method for ozone (O3) pollution abatement. In practical application, the competitive adsorption of water usually causes severe poisoning of the O3 decomposition catalyst. Herein, the promoting effect of post nitric acid (HNO3) treatment of birnessite-type manganese dioxide (MnO2) on gaseous O3 removal in humid stream at room temperature was investigated in this study. Various characterization techniques and the Density Functional Theory (DFT) calculation were used to clarify the underlying mechanism. In sharp contrast with the as-synthesized MnO2, whose O3 conversion dropped fast to ~10% within 30-min reaction, the HNO3-treated sample (H-MnO2) exhibited a stable O3 removal efficiency of ~60% within 24 h for 115 ppm of O3 with 50% of relative humidity under a high space velocity of 600 L/g/h at room temperature. Two consecutive steps were involved in gaseous O3 decomposition, i.e. adsorption and decomposition. According to the characterization results, larger amount of acid sites and oxygen vacancies combined with their superior humidity tolerance facilitates the adsorption and subsequent decomposition of O3 in humid stream. Moreover, the DFT calculation demonstrates that the O3 adsorption energy was increased and the H2O adsorption energy was decreased over the H-MnO2 compared with the as-synthesized sample.

Dramatically stable birnessite-type MnO2 for gaseous ozone decomposition in humid stream at room temperature: Effects of post nitric acid treatment

254th National Meeting (2017)

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