"Selective Reverse Water-Gas Shift Catalysis at Intermediate Temperature and Elevated Pressure for Power-to-Liquid Fuel Production"
Long-haul aviation, maritime shipping, and heavy freight transport are among the hardest sectors to decarbonize because the energy densities required for practical operation are beyond the reach of batteries or liquid hydrogen. Power-to-liquid (PtL) synthesis, converting renewable electricity, water, and captured CO₂ into drop-in hydrocarbon fuels, offers a scalable alternative unconstrained by feedstock availability (like biomass). A promising PtL architecture couples the reverse water-gas shift reaction (RWGS), which converts CO₂ and H₂ into CO-rich syngas, with Fischer-Tropsch synthesis, which converts syngas to yield naphtha, jet fuel, and diesel. The central challenge in this chain is selective RWGS catalysis at intermediate temperatures (500–750°C) and elevated pressures (5–30 bar), the regime most compatible with upstream electrolyzers and downstream synthesis units, where a competing methanation reaction favors undesired methane production and existing catalysts fall short.
Here I will discuss my work addressing this challenge across process modelling, techno-economic analysis, and experimental catalyst development and evaluation. I will first present an Aspen Plus process modelling study examining how RWGS reactor selectivity and operating conditions influence hydrogen utilization, energy efficiency, and fuel production cost in an integrated RWGS + Fischer-Tropsch system. I will then describe the development of dispersed alkali metal carbonate catalysts and their performance under intermediate-temperature, elevated-pressure conditions relevant to process integration, including activity, selectivity, and long-term stability measurements. Finally, I will present a mechanistic investigation into the structural changes as associated activity change for these catalysts at the upper end of the intermediate-temperature regime, supported by operando synchrotron X-ray diffraction and thermodynamic analysis, and introduce a new catalyst design motivated by that understanding.