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

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.