(217h) Reactive Water Sorbents for Sorption Enhanced Reverse Water Gas Shift

The conversion of CO₂ to transport fuels with hydrogen has the potential of the integration of CO₂ capture and energy storage and conversion. In particular, the production of methanol and dimethyl ether (DME) fuels is a very interesting one. The synthesis of methanol and DME directly from CO₂ suffers, however, from very low equilibrium conversion. As a consequence, multiple (recycle) steps should be included in the process. Synthesis of methanol and DME with CO enriched feed greatly improves the conversion. Therefore, an alternative to the direct synthesis of DME from reaction of CO₂ is to convert first CO₂ to CO, via reverse water-gas shift (RWGS). The RWGS is an endothermic equilibrium reaction, and the equilibrium lies on the product side only at very high temperatures. The conversion at lower temperatures, i.e. 250 - 350 °C can be greatly enhanced if reaction product water is selectively removed. Here, first proof-of-concept is presented of the successful design of a multifunctional reactive sorbent for sorption-enhanced reverse water-gas shift (SE-RWGS, here designated as ‘COMAX’), which combines CO₂ activation and water adsorption functionalities in an integrated reactive sorbent. Near complete selectivity to CO was achieved from atmospheric pressure up to at least 29 bar, i.e. the highest pressure studied in the experimental campaign, with stoichiometric and excess quantities of hydrogen in the COMAX feed, the latter in view of the potential use of syngas mixtures. An outlook towards cycle design and process integration for the production of (aviation) fuel will be presented. The successful integration of catalytic activity and water adsorption capacity into a single particle opens opportunities in the further intensification of sorption-enhanced reactions for CO₂ conversion.