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

Abstract

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.