(405d) Conversion of Methane to Methanol and Ethanol in a Single Reactor

Methane is the most abundant resource of organic carbon. However, many methane reserves are in remote locations, where the economy of scale for steam reformers cannot be realized and distances to chemical plants are too large for efficient transportation through pipelines.

To provide an option for converting methane to liquid intermediates, we developed a bi-functional catalyst that combines Lewis acidic NiO clusters with a redox active ceria-zirconia (CZ) support. Methane is activated on Lewis acid sites, and under the right conditions, surface methyl or methoxy groups can couple to higher alkyl/alkoxy chains. In the presence of steam, the surface groups can be hydrolyzed to alcohols. Specifically, methanol and ethanol were detected in our study. The redox active CZ support activates O₂ to enable a net selective oxidation reaction, providing a thermodynamic driving force. Besides alcohols, CO₂ and H₂ are formed as by-products. Importantly, formation of alcohols occurs at 450 °C under steady state conditions with a turnover frequency of at least 50 h^-1. This is a clear improvement from previously reported catalysts, which required a high-temperature calcination step for every turnover. The nature and synergy of active sites as well as the mechanism of the reaction will be discussed.