Facile co-precursor sol-gel synthesis of a novel amine-modified silica aerogel for high efficiency carbon dioxide...

Massive amount of CO₂ emission, which could cause climate change, has been recognized as a serious environmental issue. Chemical adsorption is generally considered as a promising technology for CO₂ capture in low CO₂ partial pressure. Physical properties and chemical components of the adsorbent are important to CO₂ adsorption performance. To address structure limitation and complicated preparation process of the conventional adsorbent, herein, we reported a rapid and simple route to synthesis amine-modified silica aerogel monolith by co-precursor sol-gel method. Microstructure and the surface functional groups of the amine-modified silica aerogel could be easily manipulated. The products were characterized by SEM, XPS, NMR, in situ DRIFT and CNS elemental analyzer. The amine-modified silica aerogel exhibited good physical properties and demonstrated excellent CO₂ adsorption performance. The density, porosity and BJH pore volume of the amine-modified silica aerogel were 0.12 g/cm³, 94.5% and 2.39 cm³/g, respectively. The maximum static and dynamic adsorption capacities of CO₂ on the amine-modified silica aerogel were 2.2 mmol/g and 5.59 mmol/g under anhydrous and humid mixed gas conditions, respectively. The as-prepared aerogel also showed good cyclic ability for CO₂ adsorption and desorption. The CO₂ adsorption on the amine-modified silica aerogel is by the formation of carbamate through a two-step zwitterion mechanism. This easily prepared amine-modified silica aerogel could be a promising adsorbent for CO₂ capture.