Water-Gas Shift Reaction to Capture Carbon Dioxide and Separate Hydrogen on Single-Walled Carbon Nanotubes

In view of the increasingly severe global warming and ocean acidification caused by CO₂ emissions, we report a new procedure, named "reactive separation", to capture CO₂. We used advanced Monte Carlo and molecular dynamics methods to simulate the water-gas shift reaction in single-walled carbon nanotubes. We found that (11,11) carbon nanotubes with a diameter of 0.75 nm have the best ability to capture CO₂ generated in the water-gas shift reaction. When the feed water-gas ratio is 1:1, the pressure is 3 MPa, and the temperature is 473 K, the storage capacity of CO₂ reaches 2.18 mmol/g, the molar fraction of CO₂ and H₂ inside the carbon nanotube is 0.87 and 0.09, respectively, the conversion of CO in the pore is as high as 97.6%, and the CO₂/H₂ separation factor is 10.3. Therefore, utilizing the reaction and separation coupling effect of carbon nanotubes to adsorb and store the product CO₂ formed in the water-gas shift reaction, while separating the generated clean energy gas H₂, is a promising strategy for developing novel CO₂ capture technologies.