Amine-modified mesocellular silica foams for CO2 capture

Three mesocellular silica foam (MCF) materials with different window sizes were prepared and functionalized with polyethyleneimine (PEI) for use as CO2 adsorbents. The as-prepared adsorbents were characterized by XRD, TEM, SEM, nitrogen adsorption/desorption and thermogravimetric (TG) analyses. CO2 capture was performed in a fixed bed reactor operated at atmospheric pressure. The results showed that the CO2 adsorption capacity increased with the window size of the MCF substrates. MCF material that had the largest window size exhibited the largest CO2 uptake of 152.0 mg/g of adsorbent (304.0 mg/g of PEI) with a 50 wt% PEI loading under the conditions of 15.1% (v/v) CO2 in N2 at 75 °C and atmospheric pressure. It is one of the highest capture capacities per gram of PEI reported in the literature thus far under the above conditions used. Repeated adsorption/desorption cycles revealed that the MCF modified by PEI is a good adsorbent for CO2 with good cyclic stability.