Among fossil resources, natural gas - especially methane (its chief component) – is the most attractive feedstock for producing a wide range of hydrocarbon-based commodity chemicals. As the world’s leading methane producer, and with vast reservoirs of shale methane, as well as the future availability of a significant amount of biogas methane, the U.S. is in position to lead the world in a methane-to-chemicals revolution. Unfortunately, existing methane conversion processes are energetically inefficient, resulting in significant carbon dioxide (CO2) emissions. One promising alternative to existing processes for methane activation is low temperature, aqueous electrochemical conversion as promoted by catalysts. When paired with renewable energy sources, like wind and solar, electrocatalytic processes can theoretically achieve completely CO2-free production of chemicals and fuels from methane. To that end, the project investigates various electrocatalytic methane reaction pathways, with the eventual goal of enabling the development of inexpensive, efficient, and economical fuels and chemicals, such as methanol.
Specifically, the project will combine two high-level scientific aims to investigate five known pathways to create the surface-active oxygen species needed to enable the methane-to-methanol reaction. The first aim focuses on identifying the types of activated oxygen species and the effects of electrochemical potential on reaction selectivity and activity. For each active oxygen pathway, the second aim focuses on identifying the rate determining step by combining in-situ characterization of the surface species during reaction with electrochemical data. Together the two aims combine standard electrochemical techniques with surface enhanced infrared spectroscopy, isotope labeling and GC/MS product characterization to uncover the rate, selectivity, and reaction order for each pathway. To enable the five pathways, only 3 different catalysts are needed: oxidized polycrystalline Pt, RuO2 and NiO:ZrO2. The number of catalyst chemistries and form factors are purposely limited, to promote a depth of understanding that can inform further development of additional catalysts that have even greater activity towards methane activation and selectivity for methanol formation. The fundamental understanding generated through the scientific aims will be fed directly to two undergraduate-led engineering activities, allowing for strong integration of research and education. Laboratory-based undergraduate research will focus on integrating down-selected catalysts into new reactor schemes. Additionally, undergraduate senior design teams will focus on designing the supporting balance-of-plant around the new reactors, and performing preliminary techno-economic assessments of various configurations. Finally, the project will be balanced by several hands-on outreach programs to under-represented high-school students.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
