Adsorption characteristics of carbon dioxide on organically functionalized SBA-15

Aminosilane-modified SBA-15 was prepared by grafting various aminosilanes on mesoporous silica SBA-15, and its adsorption characteristics towards carbon dioxide were examined. The amount of carbon dioxide adsorbed was almost the same for both in the presence and in the absence of water vapor. It was found that the efficiency of adsorption, defined as the number of adsorbed carbon dioxide molecules per nitrogen atom of aminosilane-modified SBA-15, increased with increasing the surface density of amine. Infrared spectroscopy revealed that carbon dioxide was adsorbed on aminosilane-modified SBA-15 through the formation of alkylammonium carbamate in the presence and in the absence of water vapor. It was suggested that amine pairs, on which carbon dioxide was adsorbed through formation of alkylammonium carbamate, increased with increasing surface density of amine. In addition, influence of amine structure on the adsorption capacity has also been discussed.