Adsorptive removal of CO2 on Nitrogen-doped porous carbon derived from polyaniline: Effect of chemical activation

Nitrogen-doped porous carbons (NDCs) with high surface areas were prepared using a nitrogen containing polymer (polyaniline) as precursor with H3PO4, ZnCl2 and KOH activation. The effects of activation conditions on the structure of adsorbents and CO2 adsorption were also investigated. The porous structure and surface chemical composition of microporous carbon were analyzed and characterized by N-2 adsorption-desorption, elemental analysis (CHNS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The effect of temperature on CO2 adsorption was studied at 298, 308 and 318 K on the prepared adsorbents activated by H3PO4, KOH and ZnCl2. Among activating agents studied, H3PO4 was the best activator for the structure development whereas the N-doped porous carbon obtained by ZnCl2 had high CO2 adsorption capacity of 3.54 mmol/g at ambient temperature and pressure with CO2 heat of adsorption energy of 55 kJ/mol at lower surface coverage. The selectivity of CO2 over N-2 by H-2,650, Zn-2,500 and K-1,650 (CO2: N-2 = 015:0.85, 298 K, 1 bar), predicted by the ideal adsorbed solution theory (LAST) model, were attained 13.65, 26.32 and 6.41, respectively. The multi advantages of these sorbents such as low cost, easy synthesis, lower heat of adsorption, high CO2 uptake capacity and high CO2/N-2 selectivity prove the suitability of nitrogen-doped carbons for CO2 capture.