Reactive Water Sorbents for the Sorption-Enhanced Reverse Water–Gas Shift

Sorption-enhanced reverse water–gas shift (SE-RWGS, here designated as ‘COMAX’) was studied with bifunctional reactive sorbents. First proof-of-concept is presented of the successful design of a multifunctional reactive sorbent, which combines CO2 activation and water adsorption functionalities in an integrated reactive sorbent, i.e. the active phase is loaded on the carrier that provides surface area for dispersion of the active (Pt, Cu) phase as well as H2O sorption capacity. 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. This selectivity was obtained with stoichiometric and excess quantities of hydrogen in the (RWGS) COMAX feed, the latter in view of the potential use of syngas mixtures. The newly developed bifunctional material bears important additional advantage for scaling up of the COMAX process, because it avoids the mixing of catalyst and adsorbent materials that differ in properties such as hardness. Evidently, the key parameter for optimizing the COMAX process is the working adsorption capacity of the system and (multi-column) cycle design. Improving the capacity can be done by optimizing the reactive adsorption conditions and by optimizing the regeneration method.