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In Situ Infrared Study of the Role of PEG in Stabilizing Silica‐Supported Amines for CO 2 Capture
Author(s) -
Tanthana Jak,
Chuang Steven S. C.
Publication year - 2010
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201000090
Subject(s) - sorbent , carboxylate , chemistry , adsorption , peg ratio , polyethylene glycol , fourier transform infrared spectroscopy , infrared spectroscopy , inorganic chemistry , hydrogen bond , nuclear chemistry , organic chemistry , chemical engineering , molecule , finance , engineering , economics
The CO 2 capture capacity, adsorption mechanism, and degradation characteristics of two sorbents, silica‐supported tetraethylenepentamine (TEPA/SiO 2 ) and polyethylene‐glycol‐modified TEPA/SiO 2 (PEG/TEPA/SiO 2 ), are studied by diffuse reflectance infrared Fourier transform spectroscopy and mass spectrometry. The CO 2 capture capacities of TEPA/SiO 2 and PEG/TEPA/SiO 2 are determined to be 2087 and 1110 μmol CO 2 g −1 sorbent, respectively. Both sorbents adsorb CO 2 as hydrogen‐bonding species, NH 2 O, and carbamate/carboxylate species. The CO 2 adsorption half‐time increases with the number of CO 2 capture cycles. Infrared results suggest that the increased adsorption half‐time is a result of diffusion limitation, caused by accumulation of TEPA and PEG species on the surface of the sorbent particles. The degradation of TEPA/SiO 2 is found to correlate with the accumulation of carboxylate/carbamic species. The addition of PEG decreases the degradation rate of the sorbent and slows down the formation of carboxylate species. These carboxylate species can block CO 2 capture on amine (NH 2 /NH) sites. The stabilizing role of PEG on TEPA/SiO 2 can be attributed to hydrogen‐bonding between TEPA (NH 2 /NH)and PEG (OH).