Effect of Pore Structure of Supports on CO2 Adsorption of Tetraethylenepentamine/Carbon Aerogels Prepared by Incipient Wetness Impregnation Method

Carbon aerogels (CA) with a wide range of pore parameters were synthesized through a sol-gel process and by varying the R/C mass ratios of initial mixtures. Tetraethylenepentamine (TEPA)/CA sorbents were prepared by incipient wetness impregnation method, which is more gentle, for CO2 adsorption measurement. The results showed that the TEPA/CA sorbents displayed high CO2 uptake up to 4.1 mmol/g at 75 degrees C under 10% (v/v) CO2/N-2 flow with fast adsorption and desorption kinetics. Larger pore volume instead of higher specific surface area of CA is beneficial for gas transfer into the pores of sorbents and good for CO2 adsorption capacity of the sorbents. Moreover, a proper mesopore size (24.7 nm) of CA was found to be important in influencing CO2 adsorption capacity of TEPA/CA sorbents. In addition to pore volume and pore size, it was found that the original surface morphology of CA plays a vital role in the CO2 adsorption capacity of TEPA/CA sorbents as well by inducing CA treated by 3% nitric acid. The adsorption kinetics of sorbents were primarily influenced by the pore size of CA, namely that larger pore size (even over mesopore range) promotes the CO2 diffusion inside the pores of sorbents. Insight into the role of porous support from this work could help in the further design of applicable and high-performance amine-modified sorbents.