Amine hybrid aerogel for high-efficiency CO2 capture: Effect of amine loading and CO2 concentration

The objective of this research was to develop a high-performance CO2 adsorbent by a simple, cost-effective and environmental-friendly route based on amine hybrid aerogel. A new amine hybrid titania/silsesquioxane composite aerogel (AHTSA) was prepared by a one-pot sol-gel process followed by supercritical drying (SCD). The wet gel was obtained by orderly mixing all the reactants in a container without adding any catalyst. SCD was conducted without contaminant emission. Effects of amine loading and CO2 concentration on pores structure and CO2 adsorption performance of AHTSA were investigated. Higher amine loading leads to lower specific surface area and mesopore volume of AHTSA, due to the increase of large pores and diminishment of mesopores when increasing the amine loading. Resulting from the sharp decrease of the surface area, overdosing of the amine precursor negatively affects the surface amine content of AHTSA and thus reduces its CO2 adsorption capacity. High CO2 concentration favors the CO2 adsorption capacity and rate as concentrated CO2 favors the CO2 diffusion in the pore space of the adsorbent, enhances the interaction between CO2 and surface amine groups. The dry CO2 adsorption capacity of AHTSA increases from 1.64, 4.19 to 6.66 mmol/g when the CO2 concentration of the mixture gas varies from ∼400 ppm (air), 1% to 10%. Short adsorption halftime and high amine efficiency of AHTSA with different CO2 concentrations reveal that AHTSA is a dynamic and effective adsorbent for CO2 capture, even direct air capture.