Effect of TiO₂ on the Performance of Mn/Na₂WO₄ Catalysts 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.