Heat treatment of MnCO3: An easy way to obtain efficient and stable MnO2 for humid O3 decomposition

Abstract

The competitive water adsorption in the practical environment usually causes severe deactivation of the O3 decomposition catalysts. In this study, MnCO3 was used as precursor to prepare efficient and stable MnO2 catalyst for gaseous O3 decomposition in humid stream. The sample S-300, prepared by calcining MnCO3 at 300 °C for 6 h, exhibited 63% (80%) of removal efficiency for 120 (43) ppm of O3 under a high space velocity of 600 L g−1 h−1 and 50% (40%) of relative humidity at 25 °C, which is superior to the commercial O3 scrubber (oxide compound of Cu and Mn) and α-MnO2. However, even lower or higher treatment temperature did not further promote humid O3 decomposition. Thorough characterizations, especially by the temperature programmed and in situ DRIFTs experiments, demonstrate that the large amount of active oxygen vacancies and strong Lewis-acid sites together with the easy recovery of the occupied oxygen vacancies and weak interaction with water molecules accounted for the excellent O3 decomposition activity in humid stream. Besides, the developed pores by thermal decomposition of MnCO3 might also facilitate O3 removal. This study provides an easy and rational design of affordable and efficient catalysts for environmental application.