Removal of H₂S And CO₂ from gas mixtures by adsorption on polymer-based adsorbents for hydrogen production: A computational chemistry approach

For the purification of gases in the hydrogen production and fuel cell applications, it is necessary to fundamentally understand the adsorption mechanism and effect of the amine types in the polymer on the adsorption performance. A computational chemistry approach of the adsorption of CO₂ and H₂S on PEI with different amine types was conducted on the basis of a designed tetramer of ethylenimine. The adsorption conformations of CO₂ and H₂S on the primary, secondary, and tertiary amines were examined, and the pseudo heats of adsorption on the different sites were estimated. The adsorption affinity on the amine depended on both the coordination number of the N atom with C atoms and the steric hindrance, and the linear PEI was better adsorbent than the branch PEI for adsorptive separation of CO₂ and H₂S from the gas mixtures. The adsorption mechanism and effect of the amine types were discussed by a combination of the computational and experimental results. This is an abstract of a paper presented at the 231st ACS National Meeting (Atlanta, GA 3/26-30/2006).