Hydrate-based pre-combustion carbon dioxide capture process in the system with tetra-n-butyl ammonium bromide solution in the presence of cyclopentane

摘要

Effects of 0.29 mol% tetra-n-butyl ammonium bromide (TBAB) solution in conjunction with cyclopentane (CP) on the hydrate-based pre-combustion CO_2 capture are investigated by the measurements of the gas uptakes, CO_2 separation efficiencies and induction time of the hydrate formation at the different temperature-pressure conditions. The results show that the volume of the TBAB has an effect on the CO_2 separation and the induction time, and the addition of the CP into the TBAB solution remarkably enhances the CO_2 separation and shortens the induction time. The system with the CP/TBAB solution volume ratio of 5 vol% and TBAB solution/reactor effective volume ratio of 0.54 is optimum to obtain the largest gas uptake and the highest CO_2 separation efficiency at 274.65 K and 4.0 MPa. Compared to the results with tetrahydrofuran (THF) as an additive [1], the gas uptake is enhanced by at least 2 times and the induction time is shortened at least 10 times at the similar temperature-pressure condition. In addition, the CO_2 concentration in the decomposed gas from the hydrate slurry phase reaches approx­imately 93 mol% after the first-stage separation at 274.65 K and 2.5 MPa. The gas uptakes of more than 80 mol% are obtained after 400 s at the temperature range of 274.65-277.65 K and the pressure range of 2.5-4.5 MPa.