Impacts of nano-scale pore structure and organic amine assembly in porous silica on the kinetics of CO_(2) adsorptive separation

Nano structure including pore structure and amine assembly is critical for improving sorption and desorption kinetics for adsorptive CO_(2) separation.The present work delineates(1)the influence of the nano-scale pore structure of amine-functionalized solid sorbents,and(2)effect of changing the assembly of amine molecules on surface of nano-porous SiO_(2) on the rates of adsorption and desorption of CO_(2).50PEI-MSN sorbent with inverted cone-shaped pores was prepared by using mesoporous silica nanospheres(MSN)with inverted cone-shaped pores for the loading of polyethyleneimine(PEI).Co-structure-directing(CSD)method was used to synthesize the sorbent with arranged amine assembly at nano-scale(2N-CSD).By comparison with 50PE卜SBA15 as a benchmark sorbent,both sorbents have improved sorption and desorption kinetics.There are significant effects of nano pore structure and amine assembly on the sorption and desorption kinetics.The inverted cone-shaped pores in MSN allow loading polymeric amines in their narrower ends and leaving larger pore mouths open for the transport of CO_(2);50PEI-MSN shows a maximum sorption rate of 81.4 mg·g^(-1)·min^(-1) with average sorption rate of 25.4mg·g^(-1)·min^(-1) at 80℃ which are 34%and 59%higher than the corresponding values for 50PEI-SBA15;a maximum desorption rate of 38.4mg·g^(-1)·min^(-1) with average desorption rate of 11.8 mg·g^(-1)·min^(-1) ramping from 30 to 95℃ which are 37%and 156%higher than the corresponding values for 50PEI-SBA15.The arranged monolayer-like amine assembly on surface of nanoporous SiO_(2) likely provides high amine sorption sites through improved accessibility of amine,and 2N-CSD shows a maximum sorption rate of 60.5 mg·g^(-1)·min^(-1),with average sorption rate of 12.8mg·g^(-1)·min^(-1) at 300C which are 108%and 205%higher than the corresponding values for 50PEI-SBA15;a lower maximum desorption rate of 9.7 mg g'1min"1 and average desorption rate of 9.8mg·g^(-1)·min^(-1) ramping from 30 to 95℃ which is 250%higher than the corresponding value for 50PEI-SBA15.The present work demonstrates the importance of tailoring nano-scale pore structure and amine assembly for significantly improving sorption and desorption kinetics of adsorptive CO_(2) separation.