Effect of TiO₂on the Performance of Mn/Na₂WO₄Catalysts in Oxidative Coupling of Methane

The oxidation coupling of methane (OCM) has received attention as a direct route to produce C2 chemicals. Although the OCM is energetically more efficient than the conventional process, however, it provides relatively low C2 yield and CH4 conversion at lower temperatures. In this study, TiO2 and Ce were used as a support and a promoter to facilitate CH4 conversion by providing more available oxygen species in the Mn/Na2WO4-based catalysts. Additionally, the performance of TiO2-supported catalysts was compared with that of the conventional Mn/Na2WO4/SiO2 catalyst. Various techniques including X-ray diffraction, X-ray photoelectron spectroscopy, and H2 temperature-programmed reduction were conducted to evaluate the effect of TiO2 and Ce. The 1.9 % Mn-5% Na2WO4-5% Ce/TiO2 showed the best performance, with a maximum C2 yield of 26.1% at 775 °C and the CH4/O2 ratio of 2. This yield was higher than that of the Mn/Na2WO4-based catalysts examined in this study, indicating that TiO2 is a promising support for OCM catalysts.