Enhancing CO2 separation for pre-combustion capture with hydrate formation in silica gel pore structure

This communication reports the enrichment of the hydrate phase with CO2 in gas hydrates formed from a CO2 and H2 gas mixture when using silica gels to form the hydrate. Phase composition analysis showed that the CO2 concentrations in the retrieved gas from hydrates were in the range of 96.5 and 98.7 mol% at the range of 6.0–9.2 MPa at 274.15 K in 100 nm silica gel. 13C NMR spectra supplemented the phase composition analysis and suggested that CO2 molecules occupy 93% of small cages and 100% of large cages in the hydrate phase. It is noted that the obtained CO2-rich hydrate, by implementing a silica gel pore structure, has a composition of (0.14H2/1.86 CO2)S·(6CO2)L·46H2O, which provides the quite promising idea of separating CO2 from an industrial gas containing H2 such as shifted synthesis gas, for pre-combustion capture.