Sorbents with high efficiency for CO2 capture based on amines-supported carbon for biogas upgrading

Sorbents for CO2 capture have been prepared by wet impregnation of a commercial active carbon (Ketjen-black, Akzo Nobel) with two CO2-philic compounds, olyethylenimine (PEI) and tetraethylenepentamine (TEPA), respectively. The effects of amine amount (from 10 to 70 wt.%), CO2 concentration in the feed, sorption temperature and gas hourly space velocity on the CO2 capture performance have been investigated. The sorption capacity has been evaluated using the breakthrough method, with a fixed bed reactor equipped with on line gas chromatograph. The samples have been characterized by N2 adsorption-desorption, scanning electron microscopy and energy dispersive X-ray (SEM/EDX). A promising CO2 sorption capacity of 6.90 mmol/gsorbent has been obtained with 70 wt.% of supported TEPA at 70°C under a stream containing 80 vol% of CO2. Sorption tests, carried out with simulated biogas compositions (CH4/CO2 mixtures), have revealed an appreciable CO2 separation selectivity; stable performance was maintained for 20 adsorption-desorption cycles