Investigation on the Reaction Mechanism of Methane Oxidation over MgAl2O4‐Supported Single‐Atom Catalyst Prepared at High Temperature

Abstract

AbstractStability and reactivity of single‐atom catalysts (SACs) are the points of concern in catalysis, especially under the harsh conditions, such as at elevated temperatures in oxidizing conditions. Previous work showed that thermally stable Pt1 SAC supported on K‐modified MgAl2O4 prepared by a vapor‐phase self‐assembly mechanism (Pt1/K/MgAl2O4) showed better performance than a Pt/MgAl2O4 nanocatalyst in catalytic CH4 oxidation (Chem, 2022, 8, 731–748). However, the detailed reaction mechanism remains unclear, which preventing the further development of single‐atom catalysts for CH4 oxidation. Herein, the sintering resistance behaviour of the Pt1/K/MgAl2O4 catalyst, was investigated by means of density functional theory (DFT) calculations, and it was found that the catalytic CH4 oxidation takes place via the Mars‐van Krevelen (MvK) mechanism, similar to that on conventional oxides. This viewpoint is further verified by experiments. Additionally, other noble metals (Au, Ir and Ru) and alkali elements (Na and Cs) are also investigated and it is found that the alkali types also affect the catalytic performance. This work clarifies the reaction mechanism of CH4 oxidation on metal SAC supported on MgAl2O4 synthesized at high temperature, providing a chance to manipulate the performances of metal SAC in CH4 oxidation.