High efficient pre-combustion CO2 capture by using porous slurry formed with ZIF-8 and isoparaffin C16

Abstract

Integrated gasification combined cycle (IGCC) power generation has drawn more and more attention because of the increasing demand for zero CO2 emission. H2/CO2 mixture with middle/higher pressure like IGCC gas is usually separated by using low energy consumption physical absorption approach. Here, for upgrading traditional physical absorbents, we report a new porous slurry formed with ZIF-8 and isoparaffin C16 to raise CO2 capture capacity and selectivity. The properties and sorption behaviors of this slurry have been experimentally investigated, and the content of ZIF-8 is optimized as 20 wt%. The optimized slurry exhibits low viscosity (11.02–2.75 mPa·s when temperature ranges from 273.15 to 303.15 K), sufficiently high sorption speed, low CO2 sorption heat (9.39–18.47 kJ/mol, decreasing with increasing CO2 loading). More importantly, the slurry exhibits much higher CO2 sorption capacity (e.g., 3.39 mol/L/MPa at 0.1 MPa and 273.15 K, vs. 2.48 mol/L/MPa for dimethyl ethers of polyethylene glycol (DEPG) and 2.22 mol/L/MPa for propylene carbonate (PC)) and selectivity over H2 (17.4–205, which could be one time higher than DEPG and three times higher than PC). The recyclability of this slurry system is also excellent. The 98% sorption capacity is recovered by vacuuming for 5 min without heating, showing that the easy sorption-desorption cycle can be completed only via pressure swing. We believe ZIF-8/isoparaffin C16 slurry would be a promising alternative to existing commercial CO2 absorbent for separating IGCC gas with higher efficiency and lower energy cost.