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Diffusion kinetics of CO 2 in amine‐impregnated MIL‐101, alumina, and silica adsorbents
Author(s) -
Gelles Teresa,
Rezaei Fateme
Publication year - 2020
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.16785
Subject(s) - sorption , adsorption , microporous material , desorption , kinetics , diffusion , mesoporous material , amine gas treating , mesoporous silica , chemical engineering , chemistry , materials science , polymer chemistry , organic chemistry , catalysis , thermodynamics , physics , quantum mechanics , engineering
CO 2 sorption kinetics of poly(ethylenimine) (PEI)‐impregnated MIL‐101, γ‐alumina, and UVM‐7 silica were investigated by the zero‐length column technique for the purpose of understanding the effect of amine content, adsorbent porosity, and adsorption temperature on CO 2 sorption rates. Each of the adsorbents was impregnated with three different amine contents (20, 35, and 50 wt%) and the effective diffusion time constants were determined at 25°C. For each respective adsorbent, it was found that increasing the amine content results in diminished diffusion rates. Additionally, it was found that the pore size of the support has a profound effect on diffusional kinetics, where microporous MIL‐101 yielded substantially slow desorption rates upon amine‐functionalization compared to mesoporous γ‐alumina. PEI‐impregnated UVM‐7 silica was further investigated at 50 and 75°C in order to provide insight into the effect of temperature on sorption kinetics. The results indicated that PEI‐impregnated UVM‐7 exhibited faster sorption kinetics at higher temperatures. Upon desorption, PEI‐UVM‐7 silica exhibited two distinct regions of mass‐transfer control that occur at different sorption times. This is best explained by first the occurrence of surface diffusion followed by diffusion out of the bulky PEI polymer chains. The findings of this study provide novel kinetic characterizations on promising amino‐adsorbents for carbon capture applications.