Studies on the structure and catalytic performance of S and P promoted Na-W-Mn-Zr/SiO2 catalyst for oxidative coupling of methane

A series of Na-W-Mn-Zr/SiO2 catalysts promoted by different contents of S or/and P were prepared and investigated in oxidative coupling ofmethane to clarify the effect of S and P on the Na-W-Mn-Zr/SiO2 catalyst. From the characterization results, it is found that the addition of Sand P to the Na-W-Mn-Zr/SiO2 catalyst helps the formation of active phases, such as -cristobalite, Na2WO4, ZrO2, and Na2SO4. Moreover,the addition of S and P increases the concentration of surface-active oxygen species by improving the migration of active components fromthe bulk phase to the surface of the catalyst. According to the activity test, impressive methane conversion and C2 hydrocarbons yield wereobtained at a low temperature of 1023 K over the six-component Na-W-Mn-Zr-S-P/SiO2 catalyst, which contained 2 wt% S and 0.4 wt% Psimultaneously. The deactivation of Na-W-Mn-Zr-S-P/SiO2 was due to the loss of surface active components.