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.