Effect of water content on separation of CO2/CH4 with active carbon by adsorption-hydration hybrid method

An adsorption-hydration hybrid method was adopted to separate CO2/CH4 gas mixture using active carbon as adsorbent. The influence of water content and initial gas-solid ratio on the separation performance of CO2/CH4 mixture and the capacity of the recycled wet material were investigated. The experimental results show that when the water contents are 19.23 and 30.41 wt%, the adsorption-hydration hybrid method presents obvious advantage over single adsorption method. The molar fraction of CH4 can be enriched from 77.08% to 85.41% at the equilibrium pressure of 4.01 MPa for system with water content of 30.41 wt%. However, the separation performance for system with water content of 10.97 wt% is more likely to fall than rise due to no hydrate forms. Compared with the systems with fresh wet active carbon, the similar separation effect of CO2/CH4 could be attained with recycled wet material when under the same operation conditions. The property of the active carbon is stable confirmed from the scanning electron microscope measurements after it undergoes adsorption-hydration and desorption-hydrate dissociation process.