Collaborative Research: EAGER: CET: Plasma-Catalytic Pyrolysis of Methane to Make Carbon-Free Hydrogen

This EArly-concept Grants for Exploratory Research (EAGER) award is made in response to Dear Colleague Letter 23-109, as part of the NSF-wide Clean Energy Technology initiative. Hydrogen is a versatile energy carrier that offers a path to a carbon-neutral economy. However, the most useful form of hydrogen, H2, is not abundant and instead hydrogen atoms are mostly found bonded to other elements, such as to carbon in hydrocarbons or to oxygen in water.

Currently, 95% of the global H2 supply is produced by transforming methane from natural gas via the steam-methane reforming reaction that produces 5.5 tons CO2 per ton of H2. Electron-driven chemical reactions harnessing renewable electricity to produce H2 would be transformative for clean energy technology in the 21st century. While water electrolysis can leverage renewable energy for H2 production, producing H2 directly from methane is much less energy intensive and can lead to the co-production of high-value carbon materials, which would significantly decrease the cost of hydrogen.

This research effort examines the scientific principles underlying a new approach to produce H2 as a carbon-free energy carrier from methane—a distributed and economically-essential asset in the U.S.—with no CO2 emissions. The process concurrently produces carbon fibers, versatile structural materials with applications ranging from civil infrastructure to consumer products.

The project will involve interdisciplinary education and training of a post-doctoral researcher, and doctoral and undergraduate students. Outreaching activities will include the promotion of STEM careers to underrepresented minorities, organization of the 2025 US Low Temperature Plasma School and documenting best practices for design and operation of lab scale plasma reactors.

This project will provide key insights into chemical and physical rate processes and into fluid flow configurations to support the creation of electricity-driven plasma-catalytic process using microwave excitation with efficiencies exceeding electrolysis, to make carbon-free hydrogen and solid carbon fibers from natural gas. The project’s approach will leverage the highly selective nature of catalytic processes on surfaces and non-equilibrium electron-induced plasma reactions to enable catalytic chemistry at conditions far from equilibrium.

This project will evaluate the hypothesis that interfacing microwave plasma with catalysts enables the suppression of unselective gas phase recombination and nucleation in favor of selective surface recombination reactions towards carbon fibers. This means controlling recombination chemistry on timescales of radical lifetimes which are likely in the order of 100 microseconds or less.

The activation of strong C-H bonds in methane will significantly enhance the rate and conversion of methane pyrolysis at a volumetric scale in the gas phase but these short-lived plasma-derived intermediates must be transported to the two-dimensional catalytic surface. Thus, the interaction of plasmas with catalytic surfaces for methane pyrolysis involves time and length-scales that span orders of magnitudes and involve flux and reactivity of both short-lived intermediates as well as solid state nucleation and growth phenomena.

This research will integrate in-situ diagnostics, catalyst science, and computational modeling to identify and understand physical phenomena at reaction and transport time and length scales appropriate to describe and facilitate plasma-catalyst interactions for methane pyrolysis to produce H2 and carbon fibers.

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.