Experimental Study on CO2 Capture from Simulated Flue Gas with an Adsorption-Hydration Method

As global warming intensifies, it has become urgent to reduce greenhouse gas emissions. In this work, an adsorption-hydration method was employed to separate carbon dioxide (CO2) from simulated flue gas by dispersing 1.0 mol % aqueous tetrahydrofuran solution in activated carbon, which resulted in the formation of hydrates. The hydrate phase equilibrium data was measured for determining the appropriate operating conditions. Four activated carbons (1(#), 2(#), 3(#), and 4(#)) with different particle sizes were used as dispersion media under the condition of the same water content. Wet activated carbon 2(#) (50.0 wt % water content) showed the best performance. After separation, the CO2 concentration in equilibrium gas phase decreased from 20.86 to 3.07 mol %, and its recovery reached 90.35% at 274.15 K and 2.302 MPa. Then, the effects of water content and initial gas-solid ratio were examined. The results demonstrated that the variations in water content within the range 20.81-60.43 wt % had almost no effect on the adsorption process at 274.15 K and an initial pressure of 3.5 MPa. However, excess water lowered the hybrid separation efficiency. At a certain water content, there existed an optimum initial gas-solid ratio, which was favorable for CO2 recovery. The recycling of wet activated carbons was conducted, and the results indicated that their working capacities did not change after recycling. This study contributes to better understanding of CO2 capture from flue gas with an adsorption-hydration method and also offers the optimization of an adsorption-hydration process.