On the development of Vacuum Swing adsorption (VSA) technology for post-combustion CO2 capture

A metal-organic framework, UiO-66, has been evaluated as adsorbent in a post-combustion vacuum swing adsorption (VSA) process. Equilibrium isotherms of the most relevant gases (CO2 and N2) as well as breakthrough curves measured using synthetic flue gas containing 15 mol% CO2 without and with 9 mol% water vapor are reported. Based on the breakthrough data, a six step one-column VSA cycle is designed and the effects of adsorption and CO2 rinse times used on the CO2 recovery and CO2 purity are examined. With the chosen process configuration and cycle design CO2 purities around 60% and CO2 recoveries up to 70% are achieved. 50 cycle adsorption-desorption experiments show that the cyclic CO2 capacity is reduced by approximately 25% in the presence of water vapor. No reduction in cyclic capacity is observed with increased cycle number; there is rather a slight increase in cyclic capacity with cycle number indicating that a cyclic steady state still not has been reached after 50 cycles.