Resolving the Types and Origin of Active Oxygen Species Present in Supported Mn-Na<sub>2</sub>WO<sub>4</sub>/SiO<sub>2</sub> Catalysts for Oxidative Coupling of Methane
Sagar Sourav, Yixiao Wang, Daniyal Kiani, Jonas Baltrušaitis, Rebecca Fushimi, Israel E. Wachs
Abstract
The involvement of lattice oxygen species is important toward oxidative coupling of the methane reaction (OCM) over supported Mn-Na2WO4/SiO2 catalysts, but there is no consensus regarding the types, role, and origin of lattice oxygen species present in supported Mn-Na2WO4/SiO2 catalysts, which hinders the understanding of the OCM reaction network. In the present study, by utilizing the temporal analysis of products technique, we show that supported Na2WO4/SiO2 catalysts possess two different types of oxygen species, dissolved O2 and atomic O, at an OCM-relevant temperature. The addition of Mn-oxide to this catalyst increases the total amount and release rate of dissolved O2 species and improves C2 selectivity of both dissolved O2 and atomic lattice O species.