Zeolite Nanosheet on Hydrogen Permeable Membrane: Coupling Catalysis with Hydrogen Removal in Non-oxidative Direct Methane Conversion

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1264599 LiuThe non-oxidative direct methane conversion (NDMC) to more valuable and easily transportable chemicals and fuels has remained a grand challenge due to the intrinsic kinetic and thermodynamic constraints. A recent report by the US Energy Information Administration envisions inexpensive and abundant natural gas as a raw material that can significantly impact the chemical and energy supplies of the world. A membrane reactor composed of a metal/zeolite (Mo/ZSM5) catalyst and a hydrogen (H2) permeable membrane has the potential to overcome these kinetic and thermodynamic barriers. The essential feature of the membrane reactor is that Mo species within spatially constrained ZSM5 channels containing Broensted acid sites activate methane to form carbon chains while concurrently restricting the carbon chain length; the H2 permeable membrane continuously removes H2 product to increase conversion relative to feed equilibrium limitations. The key objective of this research is to fabricate and describe novel tubular membrane reactors composed of ZSM5 lamellar catalysts and thin H2 permeable ceramic membranes. A focus of the research is controlling the ZSM5 crystal size by assembly of ZSM5 nanosheets and ceramic membranes to optimize methane (CH4) reaction kinetics and H2 separation in NDMC. Preliminary data show that activity of Mo/ZSM5 and H2 permeation through the ceramic membrane depends strongly on the ZSM5 crystal size and membrane thickness, respectively. A cross-disciplinary strategy will be used to control NDMC and create new and potentially transformative ways of converting reactant methane gas to high value-added fuels and chemicals. Broader Impacts: The development of efficient NDMC membrane reactors may lead to new thermochemical processes to meet the demand for high-energy density fuels from methane gas. The project integrates research on zeolite chemistry, solid state ioincs, chemical catalysis, and separation processes with an education and outreach component designed to highlight the importance of chemical engineering relevant to energy conversion. Education will be enhanced by developing a new course based upon PIs' research interests in materials, catalysis, separation, and energy, by recruiting and mentoring undergraduate students from underrepresented communities in research activities, and by outreach programs for K-12 students near the University of Maryland.