N-doped mesoporous alumina for adsorption of carbon dioxide.

N-doped mesoporous alumina has been synthesized using chitosan as the biopolymer template. The adsorbent has been thoroughly investigated for the adsorption of CO2 from a simulated flue gas stream (15% CO2 balanced with N2) and compared with commercially available mesoporous alumina procured from SASOL, Germany. CO2 adsorption was studied under different conditions of pretreatment and adsorption temperature, inlet CO2 concentration and in the presence of oxygen and moisture. The adsorption capacity was determined to be 29.4 mg CO2/g of adsorbent at 55 degrees C. This value was observed to be 4 times higher in comparison to that of commercial mesoporous alumina at a temperature of 55 degrees C. Basicity of alumina surface coupled with the presence of nitrogen in template in synthesized sample is responsible for this enhanced CO2 adsorption. Adsorption capacity for CO2 was retained in the presence of oxygen; however moisture had a deteriorating effect on the adsorption capacity reducing it to nearly half the value.