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 152.0mg/g of adsorbent (304.0mg/g of PEI) with a 50wt% 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.