Development of Amine-Functionalized Silica Foams with Hierarchical Pore Structure for CO2 Capture

A novel mesocellular silica foam (MCF) support were synthesized, which has different pore volumes and two different sizes of windows on the spherical cells. Tetraethylenepentamine (TEPA)-functionalized MCF adsorbents were then prepared for CO2 capture. The effects of support structure, capture temperature, SO2, and NO2 on the CO2 capture were investigated. The results show that the hierarchical window structure can improve the dispersion of amine species in the silica foams. In situ diffuse reflectance infrared Fourier transform spectroscopy results indicate that more adsorption sites can be exposed in the pores at high temperature for CO2 capture. The MCF-TEPA60% has the optimal capture amount of 4.75 mmol/g with 15 vol % CO2 at 75 °C. The SO2 and NO2 have a negative influence on the adsorption and regeneration properties of adsorbent due to the production of byproducts. However, the MCF-0.8-TEPA60% can maintain outstanding carbon dioxide adsorption capacity during 10 regeneration cycles.