TEPA-supported sorbents for CO2 capture from biogas

Biogas, derived from anaerobic fermentation of organic wastes (crop residues, animal manure, municipal sewage), is a valuable renewable energy carrier. The enrichment of methane in biogas, to have a fuel with higher calorific value, can be achieved by removal of carbon dioxide; the resulting methane can be burned as such to produce heat, used as fuels of spark ignition engines or gas turbines to recover electricity or combined heat and power, used as a fuel of direct biogas fuel cells or converted to syngas or hydrogen by steam reforming of methane to feed hydrogen fuel cells . Adsorption technology over a range of porous solid is a widely applied energy-efficient and cost-effective method to CO2 removal; in particular the adsorption/desorption on the immobilized amine sorbents has been considered as one of the most promising approaches. In a previous investigation we have found that sorbents based on tetraethylenepentamine (TEPA) impregnated on active carbon exhibit, under similar conditions, higher CO2 uptake than PEI (polyethylenimine) based sorbents. The objective of the present study was to further investigate the effect of TEPA loading, CO2 concentration in the feed, flow rate, separation selectivity from simulated biogas streams on the sorption capacity. In addition, three kinetic model were used to fit the adsorption process.