Performance of Na2O promoted alumina as CO2 chemisorbent in sorption-enhanced reaction process for simultaneous production of fuel-cell grade H2 and compressed CO2 from synthesis gas

The performance of a novel thermal swing sorption-enhanced reaction (TSSER) concept for simultaneous production of fuel-cell grade hydrogen and compressed carbon dioxide as a by-product from a synthesis gas feed is simulated using Na2O promoted alumina as a CO2 chemisorbent in the process. The process simultaneously carries out the water gas shift (WGS) reaction and removal of CO2 from the reaction zone by chemisorption in a single unit. Periodic regeneration of the chemisorbent is achieved by using the principles of thermal swing adsorption employing super-heated steam purge.Recently measured equilibrium and kinetic data for chemisorption and desorption of CO2 on the promoted alumina using conventional column dynamic tests as well as new experimental data demonstrating the concept of sorption-enhanced WGS reaction using the material are reviewed. The simulated performance of the TSSER process employing this material as a chemisorbent is compared with the process performance using K2CO3 promoted hydrotalcite as the chemisorbent. The promoted alumina exhibited (i) ∼15% lower H2 productivity at a slightly reduced CO to H2 conversion, and (ii) comparable compressed CO2 productivity at a higher CO2 recovery, albeit at a relatively lower product pressure. However, the steam duty for regeneration of the chemisorbent was reduced by ∼50% for the promoted alumina.