Sustainable Catalysis: Methane Oxidation Over Non-Noble Metal Supported Catalysts

Abstract

The increasing global demand for energy, the depletion of fossil fuel reserves, and growing environmental concerns necessitate the exploration of alternative energy sources and the development of advanced technologies for the efficient utilization of natural gas and other fossil fuel derivatives. Despite efforts to transition toward renewable energy, fossil fuels continue to dominate the global energy landscape. Among them, natural gas stands out as the most economical option, possessing the highest hydrogen-to-carbon (H/C) ratio, which contributes to its cleaner combustion profile. As a result, natural gas consumption is projected to increase steadily in the coming years. However, methane (CH4), the primary component of natural gas is a potent greenhouse gas with a global warming potential over 20 times greater than that of CO2, making its controlled oxidation a subject of significant research interest. Traditionally, noble metal-based catalysts such as palladium (Pd) and platinum (Pt) have shown excellent activity and selectivity for methane oxidation [3]. However, their high cost and limited availability restrict their feasibility for large-scale applications. Recently, non-noble metal-supported catalysts have emerged as promising alternatives due to their low cost, greater availability, and tunable catalytic behavior. In this study, nickel (Ni)-based catalysts were synthesized in-house and evaluated for their methane oxidation performance. The catalytic activity was tested under a gas mixture containing 2600 ppm CH4, approximately 8% O2, with nitrogen as the balance gas, at a Gas Hourly Space Velocity (GHSV) of 70,000 h-1. Various catalyst supports were investigated, including CeO2, ZrO2, SiO2, and their binary and ternary mixtures. The Ni-based mixed oxide catalysts demonstrated significant methane oxidation activity, and their performance was benchmarked against a Pd/Al2O3 catalyst, which served as the reference. Further studies are planned to evaluate the performance of these catalysts under more realistic conditions, particularly in the presence of water vapor (H2O) and carbon dioxide (CO2). Additionally, the surface morphology and physicochemical properties of the synthesized catalysts were characterized using a range of analytical techniques to better understand their structure-activity relationships.