Acetylene formation via oxidative coupling of methane over monolithic Pt/Al2O3 and Pt/ZrO2 catalysts

Abstract

This study investigates the influence of key operational parameters – including space velocity, feed gas dilution with nitrogen, and the carbon-to-oxygen (C:O) ratio – on monolithic Pt/Al₂O₃ and Pt/ZrO₂ catalysts for the oxidative coupling of methane (OCM). Optimal operating conditions were identified that yielded high C₂ selectivities, with a notably large share of acetylene. Under ideal conditions, a Pt/ZrO₂ catalyst achieved a maximum C₂ selectivity of 11.3 %, with 84 % acetylene contribution and approximately 90 % methane conversion. Zirconia was found to be a superior support material compared to alumina in terms of catalyst stability and longevity. A number of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were applied and revealed significant morphological and structural changes in both catalyst types, induced by the harsh reaction conditions with temperatures exceeding 1200 °C. These findings contribute to the advancement of more robust catalyst formulations and optimized process conditions for the OCM reaction.