Quantifying CO2 adsorption motifs in functionalized mesoporous silica using solid-state NMR

Le résumé fourni par la source

The rapid rise in atmospheric CO2 concentration necessitates the development of efficient carbon capture technologies to achieve carbon neutrality. The CO2 adsorption-based separation using porous materials, especially silica offers a cost effective and reusable solution. In this study, we investigated the immobilization of polyethyleneimine onto mesoporous silica, which is well known for its CO2 adsorption. A systematic series of samples with PEI loadings of 20, 30, 40, 50, and 60 wt % was synthesized and analyzed. Solid-state NMR spectroscopy is a unique tool to probe the non-covalent interactions between the silica surface and imine groups, both during the CO2 adsorption and in the presence of moisture. The solid-state NMR results reveal significant peak shifts and line broadening at 40 wt % loading, indicating the onset of PEI agglomeration. The complementary computational calculations support these experimental observations indicating the formation of carbamic acid species characterized by a resonance at 164 ppm. These insights into the molecular level interactions provide a platform for designing the high-performance amine functionalized adsorbents for carbon capture applications.

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