Application of carbon fibre composites to CO2 capture from flue gas

Abstract

The application of large sized honeycomb structured monolithic carbon fibre composites (HMCFC) to CO2 capture was evaluated experimentally using simulated flue gas in 2.0m long, large sized adsorption column. The average adsorption capacity of pure CO2 on the HMCFC, was 11.9wt% (mass uptake) at ambient temperature and pressure. With a simulated flue gas (at 298K) consisting of 13vol% CO2 (partial pressure 13kPa), 5.5% of O2 and the balance N2, the CO2 capture efficiency during the adsorption breakthrough study was found to be over 98%. After adsorption, thermal regeneration that was applied at 398K without any inert gas purge to recover the adsorbed gas, resulted in a desorbed CO2 gas concentration of up to 100%, but with a CO2 recovery of less than 20% while vacuum regeneration (up to 30kPa) yielded less than 5% CO2. However, combined thermal and vacuum regeneration was found to be an effective CO2 desorption strategy to achieve very high CO2 recovery and purity. Also, after the flue gas adsorption step, when the adsorbents were flushed with specific quantitites of CO2, more concentrated CO2 in the desorbed gas was obtained. Under optimum operating conditions, the desorbed gas exhibited a CO2 concentration of 100% with recovery from the input flue gas of over 97%. The carbon fibre composite adsorbents showed very good mechanical stability, and were unaffected by water from moisture condensation during regeneration experiments with repeated heating and cooling.