Extremely Low Energy Penalty for Co-Removal of H₂S and CO₂ from IGCC Gas

By coupling CALF-20 on ZIF-7 via in situ crystallization in the confined micrometer-sized pores of poly(acrylates), a novel composite, namely, CALF-20-on-ZIF-7@poly(acrylates), has been synthesized for the simultaneous removal of CO2 and H2S from IGCC feed gas. Within this coupled crystal, CALF-20, known for its strong adsorption capacity and excellent stability toward CO2 and H2S, serves as the outer layer crystal to shift the adsorption/desorption hysteresis loop of inner ZIF-7 to beyond atmosphere pressure. Under high pressure, CO2 and H2S are automatically adsorbed. Upon reducing the pressure to the atmospheric level, CO2 is automatically released, while H2S remains temporarily due to its high adsorption energy. After about 150 cycles of CO2 adsorption/desorption of the kilogram-scale composite, H2S approaches saturation and is then removed by vacuuming. Since the content of H2S in IGCC feed gas is trivial, the total energy consumption for the composite regeneration is 0.16 MJ/kg (CO2). After 600 consecutive cycles, the CO2 adsorption capability of the composite decreases by 0.41%, demonstrating excellent cyclic stability.