The effect of sorbent regeneration enthalpy on the performance of the novel Swing Adsorption Reactor Cluster (SARC) for post-combustion CO2 capture

Abstract

The recently proposed SARC concept combines a temperature swing and a vacuum swing to efficiently regenerate a CO2 capture sorbent. A heat pump is used to facilitate the temperature swing by transferring heat from the exothermic carbonation to the endothermic regeneration reaction. This study uses combined reactor and power plant simulations to investigate an interesting trade-off presented by the SARC concept: sorbents with higher regeneration enthalpies will require more heat transfer between carbonation and regeneration, but also allow for a smaller temperature swing, thus enabling the heat pump to transfer this heat more efficiently. Studies showed that the optimal process efficiency is achieved at a sorbent regeneration enthalpy in the range of 100–150 kJ/mol, thus avoiding the need for novel sorbents with very low regeneration enthalpies. Simulation results also highlighted another interesting feature of the SARC concept: the generally undesired adsorption of water vapour by the sorbent does not reduce the overall SARC efficiency because the release of water vapour under regeneration enhances the pressure swing. Finally, a central composite design was conducted to fully understand the SARC behaviour when using sorbents with different regeneration enthalpies. These insights are important for optimal sorbent selection for the SARC concept in future studies.