Sorption-enhanced water gas shift reaction by in situ CO2 capture on an alkali metal salt-promoted MgO-CaCO3 sorbent

CO 2 capture and sequestration is one of the viable solutions to reduce the CO 2 emissions from fossil fuel combustion, and sorption-enhanced water gas shift (SEWGS) is a promising technology for pre-combustion CO 2 capture. In this study, a novel alkali metal salt (AMS)-promoted MgO-CaCO 3 sorbent was applied to the SEWGS process, and this sorbent exhibited fast sorption rate, high capacity and good stability in 30 CO 2 capture cycles. Catalyst and sorbent particles were arranged in a layer-by-layer alternating configuration in the reactor. The effects of operating conditions such as temperature, pressure and initial H 2 O/CO molar ratio were investigated, and the thermodynamic equilibrium analyses of the CO 2 sorption on AMS-promoted MgO-CaCO 3 and the SEWGS process in the layered configuration were carried out, based on which the optimization of the reactor configuration was performed. A high-purity H 2 (99.4% in dry basis) was experimentally achieved in the SEWGS process at 573 K, 12 atm and an initial H 2 O/CO molar ratio of 1.5 with a three catalyst/sorbent layered configuration, and the cyclic stability was demonstrated over 10 consecutive SEWGS cycles.