Removing Surface Hydroxyl Groups of Ce-Modified MnO2 To Significantly Improve Its Stability for Gaseous Ozone Decomposition

Stratospheric ozone (O3), which slips into the cabin through the air-supply system in a commercial airliner, is detrimental to human health around the world. For gaseous O3 abatement, catalytic decomposition is an effective method. However, catalyst deactivation is one of the main obstacles to its practical application. In this study, a new deactivation mechanism involving the surface hydroxyl group of catalyst is found by investigating the effects of heat treatment of cerium-modified todorokite-type manganese dioxides (Ce–MnO2) on O3 decomposition, which will contribute to the development of more active and stable O3 decomposition catalysts in the future work. The in situ DRIFT study indicates that gaseous O3 reacted with surface hydroxyl groups to form surface adsorbed water, which occupied the catalytically active sites (i.e., oxygen vacancies) leading to the catalyst deactivation. Calcination at 300 °C greatly removed surface hydroxyl groups while keeping oxygen vacancies almost unchanged at the same time; thus the as-obtained catalyst showed greatly improved stability, keeping ∼98% of removal efficiency for ∼115 ppm of O3 within 5 h under a very high space velocity of 1200 L g–1 h–1 at room temperature.