Methane is most commonly known as a ubiquitous cleaner energy source, while also being a potent greenhouse gas. It is produced from both natural sources, such as wetlands and large bodies of water, and anthropogenic sources, such as natural-gas reservoirs and livestock. At the same time, methane is a source of many important feedstock chemicals, including blue hydrogen and methanol, which is used for the production of plastics, paints and fuels.
The most common way methane is converted to methanol is by an indirect methane conversion process, which is both energy intensive and has a high CO2 footprint. Scientists have increasingly sought to figure out a direct conversion of methane to methanol, which has the potential to be more energy efficient and more promising for industrial chemical processes.
Researchers from the Energy Storage and Distributed Resources Division (ESDR) at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Department of Chemical and Biomolecular Engineering at UC Berkeley partnered with scientists and engineers at the University of Texas at Austin as well as Shell International Exploration and Production Inc. to offer their analysis of the electrochemical oxidation of methane to methanol in membrane electrode assemblies (MEAs).
MEAs are composed of the membrane, the catalyst layers, and gas diffusion layers, and they have successfully been used for fuel cells, electrolyzers and other energy-conversion technologies. “An electrochemical approach may be an option to better control the partial oxidation of methane while still having the potential for scale-up operations,” said Julie Fornaciari, a graduate student at UC Berkeley and an affiliate in ESDR at Berkeley Lab.
In their analysis, the research team explores various configurations of the MEAs to determine which would be most optimal for methanol production via an electrochemical route. They also discuss the metrics for evaluating the performance of MEAs in order to make it possible for scientists to draw comparisons between studies.
The research team, co-led by Berkeley Lab’s Senior Scientist Adam Weber and Senior Faculty Scientist Alexis Bell, offers a systematic approach for how to better study and develop the use of MEAs for partial oxidation of methane. If MEAs prove to be a successful energy-efficient method in the partial oxidation of methane, the impact on industrial chemical processes and the environment could be significant.
“As renewable assets come on-line and the cost of renewable electrons comes down, electrochemical processes using green feedstocks such as renewably produced electrons will provide decarbonization of industrial chemical processes that until now have used thermal routes, a concept we have termed the Electrochemical Refinery or a power to products paradigm,” said Weber. “One such process is converting methane to methanol, where the low-temperature electrochemical route has distinct advantages compared to the thermochemical one and the electrochemical route.”