Enhanced CO2 capture by functionalization of SBA-15 with APTES and l-lysine

Abstract

In this study, amine-based CO2 sorbents were synthesized after functionalizing SBA-15 mesoporous materials. Mesoporous SBA-15 was characterized and functionalized by APTES as an alkanolamine, L-lysine as an amino acid and a combination of both. CO2 adsorption tests were performed at 1.6 and 2 bar to estimate the carbon dioxide (CO2) uptake on the sorbents. As expected, CO2 adsorption capacity (mmol/g) increases with pressure. Based on the elemental analysis of the sorbents and the results of Fourier transform infrared spectroscopy (FTIR), a proposal was made of the possible chemical reactions that may occur in order to describe the experimental results. It is important to mention that the pretreatment prior to the CO2 adsorption tests plays a key role for the application of amine-functionalized mesoporous silica. The presence of water conditions the formation of carbonic acid and carbonate adsorbed on the surface and, consequently, the CO2 adsorption capacity of the sorbent. APTES and l-lysine loaded onto mesoporous SBA-15 exhibited the highest CO2 adsorption capacity (4.53 mmol/g) at 2 bar and room temperature. After reloading the sorbents with APTES and Lysine, no improvements in the CO2 absorption capacity were observed.