Unravelling the intrinsic synergy between Pt and MnOx supported on porous calcium silicate during toluene oxidation

Abstract

Developing efficient catalysts that enhance electronic interactions between active metal sites is a promising strategy for removing volatile organic compounds (VOCs). Herein, we report the preparation of a series of novel porous–calcium–silicate-supported (PCS-supported) Pt–MnO_x bimetallic catalysts for the catalytic oxidation of toluene. The 0.1Pt–5MnO_x/PCS catalyst showed excellent catalytic activity, exhibiting the lowest temperature (237 °C) for 90% toluene conversion (T₉₀), the highest CO₂ selectivity (94.29%), and excellent long-term stability and water resistance, which is primarily ascribable to strong electronic interactions between Pt and MnO_x species. Partial electron transfer from MnO_x to Pt through Pt–O–Mn bonds results in the formation of electron-rich Pt⁰ and Mn⁴⁺ species, thereby improving the active oxygen species content and enhancing low-temperature reducibility. The in situ DRIFTS technique proved that the possible reaction path of toluene combustion is toluene → benzaldehyde → benzoic acid → maleic anhydride → carbon dioxide and water. This study is expected to provide new insight into the relationship between electronic interactions and the catalytic performance of bimetallic catalysts toward VOCs.