CO2 removal from natural gas by moisture swing adsorption

With the mission of negative emission, moisture swing sorbents are developing fast in recent years, thanks to their low energy consumption and simple operating system. The sorbent was proposed to capture CO2 directly from ambient air, while its low energy-cost nature underpins carbon capture from a variety of other gas streams with larger CO2 concentrations. The present study exploits the moisture swing process for capturing industrial process CO2, and the CO2 removal from natural gas is used for demonstration. Compared to capturing CO2 from the air, the adsorption capacity is promoted significantly as the CO2 concentration in the gas mixture is much higher (1–20%). A stable cyclic capacity with ∼1.0 mmol/g is obtained, which is comparable to that of aqueous/solid amine sorbents. Moreover, a moisture swing process flow is developed for CO2 removal from natural gas, and an energy consumption analysis of the moisture swing process is conducted with comparison to the traditional amine scrubbing technique. We find that the energy consumption of the moisture swing decarbonization process (∼187.38 kJ/Sm3) is less than half that of the methyl diethanolamine solution method (954–1304 kJ/Sm3), which strongly supports the moisture swing process as a promising method for capturing industrial process CO2. © 2021 Institution of Chemical Engineers