Adsorption properties and performance of CPO-27-Ni/alginate spheres during multicycle pressure-vacuum-swing adsorption (PVSA) CO2 capture in the presence of moisture

CPO-27-Ni/alginate spheres have been prepared and evaluated for post-combustion CO2 capture using both dry and moist synthetic flue-gas in a multicycle pressure-vacuum swing adsorption (PVSA) cycle. Single component equilibrium isotherms of the adsorbent spheres give estimated CO2/N2 and H2O/CO2 selectivities of 24 and 7 at 323 K for the actual gas composition (around 9 kPa H2O, 28 kPa CO2, rest N2, ptot=200 kPa). The PVSA cycle used consists of four steps; an adsorption step, a counter-current blowdown step, a counter-current purge step and, finally, a counter-current pressurization step. The results from single column testing show that the presence of moist in the flue gas reduces the CO2 working capacity somewhat (around 15%), however, even when beginning the cyclic PVSA run with an adsorbent completely saturated with water, an apparent steady state performance is reached in which the CO2 working capacity still is significant and stable over more than 100 cycles. The results are interpreted as a consequence of the counter-current blowdown and purge steps carried out in dry nitrogen.