Surface engineered silica mesospheres – A promising adsorbent for CO2 capture

Abstract

Carbon dioxide adsorption capacities of amine modified sol-gel SiO2 mesospheres were evaluated. The sorbents were prepared from readily available sodium metasilicate via sol-gel process. Three amines were used for surface modification purpose, namely Tetraethylenepentamine (TEPA), Tetraethylenepentamine acrylonitrile (TEPAN) and a mixture of Aminopropyltrimethoxysilane (APTMS) coupled with the two amines individually. The sorbents were characterized and carbon dioxide adsorption studies at 50 and 75 °C were conducted. CO2 adsorption isotherms of the functionalized samples at both the temperatures showed that the sorbents coupled with APTMS gave better adsorption performance than with individual amines. The sample with mixture of APTMS and TEPA showed the best performance among the samples studied with a CO2 adsorption capacity of 3.26 mmol g-1 at 75 °C. The TEPAN immobilized sorbents exhibited faster kinetics at both the temperatures of 50 and 75 °C; henceforth it appears that in addition to the amine content present in the sample, effective distribution of the amines on the surface and inside the pores that are accessible to CO2 determine the actual working capacity of the adsorbent.