Structured Catalytic Membrane Reactor for Sustainable Hydrogen Production

Development of sustainable routes to “blue hydrogen,” clean burning H2 that is derived from fossil sources and is combined with CO2 capture and sequestration, provides a technological bridge between a world mostly powered by coal, petroleum, and natural gas to one powered by solar and wind. This research will advance modular technology located at the natural gas well, extracting hydrogen from the natural gas (methane), while enabling CO2 sequestration and boosting natural gas production. This technology cost effectively utilizes the vast domestic natural gas resources while minimizing emissions of greenhouse gases, fortifying the nation’s energy security, and strengthening its economy. The project subject aligns with ongoing activities for broadening participation of students from underrepresented groups at the University of Houston, a serving institution for Hispanic, Asian, and Pacific Islanders, in the emerging fields of distributed conversion of natural gas and decarbonization of the chemical and energy industries. Students working on this project will be well positioned for employment in industry and academe during the energy transition. The project will address fundamental membrane, catalyst and reactor issues during coupled generation, separation, and purification of H2 in a structured catalytic membrane reactor (SCMR). The project goal is to overcome two fundamental barriers of this potentially breakthrough technology: (1) Synthesis of a H2 transport membrane that reliably meets target flux (> 0.01 mole H2/m2 s) and permselectivity [H2/(CH4+CO2) > 100] at elevated total pressure and temperature, and (2) Design and development of a compact, structured catalytic membrane reactor that meets the targets for volumetric productivity (10 mol H2/m3 s) and purity (90% H2) for a range of feed compositions and flow rates. The multi-layer catalytic membrane reactor combines a catalytic layer (Pt-Pd/Al2O3 or Ni/Al2O3) with a H2 permselective microporous membrane (CoO-SiO2), both coated onto the porous walls of a conductive, robust monolith substrate (SiC), to carry out steam reforming of methane with in situ H2 separation and purification. The central hypothesis is that the catalytic membrane reactor, so constituted, overcomes steam reforming equilibrium constraints and kinetic inhibition through in situ H2 removal, producing a purified H2 permeate stream that serves as a low-carbon energy carrier, and a pressurized CO2 retentate stream for localized sequestration and enhanced gas production. The research deliverable entails convergence to a membrane that has a feasible combination of permselectivity, flux, and resilience under application-relevant conditions and a membrane reactor that has the design attributes to couple natural gas reforming with H2 removal. The project scope spans membrane synthesis and characterization, including membrane permeation measurements and bench-scale reactor performance experiments, in parallel with reactor analysis and modeling. Project findings will be incorporated into a course under development on hydrogen process and reaction engineering. Several aspects of the proposed research has broader application, including: (i) coupled catalytic reaction and membrane transport; (ii) spatially-resolved concentration and temperature measurements; (iii) design and control of reactors with coupled endothermic and exothermic reactions; and (iv) analysis and design of modular reactors. 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.