UCLA

The rise in greenhouse gas emissions over the past few decades has led to the introduction of global policies and legislation to promote carbon control. Methane contributes to (how much percent) of the total emissions and plays a critical role in rising temperatures. Technologies like dry methane reforming, steam methane reforming, and Fischer-Tropsch synthesis are common in industrial methane conversion. These technologies are expensive to initiate and maintain and re-release carbon dioxide into the atmosphere. Biological species, methanotrophs in particular, consume methane and produce commodity products such as methanol, formic acid, and formaldehyde efficiently. In this work, a manganese(oxy)hydroxide (MnOx) catalyst inspired by the functionality and components of methanotrophs is synthesized. The catalyst’s ability in activating the C-H bond in methane and its performance in the electrochemical partial oxidation of methane to methanol is investigated. The applied potentials and control of mass transport is observed to have a significant effect on the selective production of methanol. Under low and high applied overpotentials, MnOx is selective towards methanol production. At intermediate applied overpotentials, the catalyst is selective towards acetate production. Furthermore changing rotation speeds leads to changes in mass transport that affects the product selectivity between methanol and acetate. The stability of the catalyst is probed with scanning electron microscopy (SEM) and chronoamperometry control experiments and catalyst degradation after two hours of operation is indicated. Thus, tuning the effects of applied potential, mass transport, and catalyst stability is important to optimize the conversion of methane to value-added products. Our results suggest that by controlling these effects and using the bioinspired MnOx as a catalyst we electrochemically convert methane to various products.