Effect of the particle blending-shaping method and silicon carbide crystal phase for Mn-Na-W/SiO₂-SiC catalyst in oxidative coupling of methane

Supported Mn-Na-W on silica is a benchmark catalyst for oxidative coupling of methane due to its appropriate ethylene yields. Here we compare eight catalysts with the same active phase (Mn-Na-W) and variable support composition or particle blending-shaping method to evaluate the effect of the support. First, we explore the different preparation methods (impregnation, ball milling, and spray-drying), concluding that spray-drying leads to a promising selective catalyst. Then, we compare different SiC crystal phases (α+β and β), keeping the same composition and shaping method (spray-drying). The catalyst with α+βSiC crystal phase has significantly more activity than the β one in 30 h reaction runs. Finally, we assess the effect of process conditions to improve the yields (15 % at 800°C) of the most promising catalyst: spray-dried and with α+βSiC. The roles of the blending-shaping method and SiC crystal phase are explained by the induced differences in oxidation behavior and active phase distributions.