Sorption-enhanced steam-methane reforming: CaO–CaCO3 capture technology

Calcium oxide (CaO) has been investigated in the context of CO2 capture. In its application for the sorption-enhanced steammethane reforming process (SE-SMR), CO2 is captured in a sorption mode through the formation of CaCO3, at which stage, the conversion of CH4 to H2 is also enhanced. Subsequently, the CO2 is released in a separate desorption mode where the CaCO3 is calcined to CaO. In a combined system modeling and experimental approach a sweet-spot in operational conditions has been determined in terms of adsorption–reaction and desorption temperature and pressure. Additionally the required performance in terms of cyclic capacity has been determined in relation to system efficiency. Long term cyclic capacity under sweet-spot conditions has been demonstrated in a lab-scale experiment in excess of 200 loading cycles, with stabilization of cyclic capacity occurred after 100 cycles, and above the required minimum of 15% of the thermodynamic capacity. Increasing the adsorption temperature above 600 ∘C reactivated the CaO–CaCO3 sorbent system.