Separation of MnWO <i> _x </i> and NaWSiO <i> _x </i> Phases Boosts Oxidative Coupling of Methane

Abstract

Abstract The oxidative coupling of methane (OCM) is an attractive approach for methane transformations, but achieving a satisfactory combination of activity and selectivity remains challenging, even with the promising Mn–Na 2 WO 4 /SiO 2 catalyst. Herein, we demonstrate that nanoscale separation of Mn‐based and Na 2 WO 4 ‐based phases results in a highly efficient catalyst, achieving a remarkable 79% selectivity for C 2 –C 3 hydrocarbons at a 32% CH 4 conversion at 775 °C, outperforming most previously reported catalysts. Our studies reveal that MnWO x phases with adjustable surface Mn/W ratios and redox activities are more effective for the selective activation of O 2 , thereby enhancing the OCM of CH 4 . The assembly of MnWO x and Na 2 WO 4 /SiO 2 components in nanoscale proximity significantly promotes the formation of C 2 –C 3 hydrocarbons by suppressing deep oxidation. We propose a bifunctional mechanism involving the transfer of active oxygen species from MnWO x to Na 2 WO 4 /SiO 2 , which induces selective activation and coupling of CH 4 on the Na 2 WO 4 /SiO 2 surface.