Organoamines-grafted on nano-sized silica for carbon dioxide capture

• Commercially available and more cost effective support has been used for the synthesis of the new adsorbents.
• Amine compounds are chemically bonded to the support preventing amine leaching and minimizing their environmental and health hazard.
• More cost effective regeneration step due to significantly lower heat capacity (≈0.73 J g−1 °C−1) compared with aqueous solutions.
• First example of one step grafting of trimethoxysilylpropyl-polyethyleneimine onto silica for the synthesis of CO2 adsorbent materials.
• Enhanced graft densities were obtained by the saturation of the silane agents with CO2 before grafting to the surface.

Organoamine–inorganic hybrid adsorbent materials were synthesized by covalent immobilization of alkylaminotrimethoxysilanes and polyethyleneiminetrimethoxysilane onto fumed silica (nanosilica). The obtained silica–organic hybrid materials were characterized by thermogravimetry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) confirming the successful grafting of the amine derivatives to silica and their surface area measured using Brunauer–Emmett–Teller method (BET). The influence of reaction conditions on the graft density of organoamines was investigated and it was found that the saturation of the silane coupling agents with carbon dioxide prior to surface modification resulted in higher graft densities. Carbon dioxide uptake of the obtained hybrid materials were determined by thermogravimetric analysis at room temperature as well as higher temperatures resulting in CO2 adsorption capacities from 32.4 to 69.7 mg g−1 adsorbent.

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