Enhanced oxidative coupling of methane over Mn2O3–Na2WO4/TS-1 catalysts by the Ti induced synergistic effect between Mn2O3 and Na2WO4

Abstract

Oxidative coupling of methane (OCM) can directly convert natural gas into C₂ hydrocarbons (C₂H₄ and C₂H₆). The Mn₂O₃–Na₂WO₄/SiO₂ catalyst, owing to its high OCM performance and thermostability at high temperatures, has become a promising OCM catalyst. The synergy and dispersion of Na₂WO₄ and Mn₂O₃ are important factors in improving OCM performance, and the selection of the support has a significant impact on their dispersion and interaction. To enhance the synergistic effect and dispersion of Na₂WO₄ and Mn₂O₃, a TS-1 support doped with varying amounts of Ti was selected for the Mn₂O₃–Na₂WO₄/xTS-1 (Na–W–Mn/xTS-1) catalyst preparation. The characterization results showed that Ti addition promoted Na₂WO₄ dispersion and enhanced interactions between Na₂WO₄ and Mn₂O₃. Moreover, Ti doping effectively promoted the generation of active oxygen species and increased the conversion of methane, thereby increasing the C₂ yield. The Na–W–Mn/8%TS-1 catalyst exhibited the highest OCM performance, with a 20.0% C₂ yield and 46.8% CH₄ conversion. The enhanced OCM performance may be caused by the increased dispersion of Na₂WO₄ and Mn₂O₃ induced by the atomic-level Ti doping in the TS-1 support, which promoted their interaction and increased the number of lattice oxygen species.