Infrared study of CO 2 sorption over "molecular basket" sorbent consisting of polyethylenimine-modified mesoporous molecular sieve

Xiaoxing Wang, Viviane Schwartz, Jason C. Clark, Xiaoliang Ma, Steven H. Overbury, Xiaochun Xu, Chunshan Song

Research output: Contribution to journalArticle

282 Citations (Scopus)

Abstract

An infrared study has been conducted on CO 2 sorption into nanoporous CO 2 "molecular basket" sorbents prepared by loading polyethylenimine (PEI) into mesoporous molecular sieve SBA-15. IR results from DRIFTS showed that a part of loaded PEI is anchored on the surface of SBA-15 through the interaction between amine groups and isolated surface silanol groups. Raising the temperature from 25 to 75°C increased the molecular flexibility of PEI loaded in the mesopore channels, which may partly contribute to the increase of CO 2 sorption capacity at higher temperatures. CO 2 sorption/desorption behavior studied by in situ transmission FTIR showed that CO 2 is sorbed on amine sites through the formation of alkylammonium carbamates and absorbed into the multiple layers of PEI located in mesopores of SBA-15. A new observation by in situ IR is that two broad IR bands emerged at 2450 and 2160 cm -1 with CO 2 flowing over PEI(50)/SBA-15, which could be attributed to chemically sorbed CO 2 species on PEI molecules inside the mesopores of SBA-15. The intensities of these two bands also increased with increasing CO 2 exposure time and with raising CO 2 sorption temperature. By comparison of the CO 2 sorption rate at 25 and 75°C in terms of differential IR intensities, it was found that CO 2 sorption over molecular basket sorbent includes two rate regimes which suggest two distinct steps: rapid sorption on exposed outer surface layers of PEI (controlled by sorption affinity or thermodynamics) and the diffusion and sorption inside the bulk of multiple layers of PEI (controlled by diffusion). The sorption of CO 2 is reversible at 75°C. Comparative IR examination of the CO 2 sorption/desorption spectra on dry and prewetted PEI/SBA-15 sorbent revealed that presorbed water does not significantly affect the CO 2-amine interaction patterns.

Original languageEnglish (US)
Pages (from-to)7260-7268
Number of pages9
JournalJournal of Physical Chemistry C
Volume113
Issue number17
DOIs
StatePublished - Apr 30 2009

Fingerprint

baskets
Polyethyleneimine
sorbents
Molecular sieves
absorbents
Carbon Monoxide
Sorbents
sorption
Sorption
Infrared radiation
Amines
amines
Desorption
desorption
Temperature
Carbamates
affinity
surface layers
flexibility

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Wang, Xiaoxing ; Schwartz, Viviane ; Clark, Jason C. ; Ma, Xiaoliang ; Overbury, Steven H. ; Xu, Xiaochun ; Song, Chunshan. / Infrared study of CO 2 sorption over "molecular basket" sorbent consisting of polyethylenimine-modified mesoporous molecular sieve. In: Journal of Physical Chemistry C. 2009 ; Vol. 113, No. 17. pp. 7260-7268.
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abstract = "An infrared study has been conducted on CO 2 sorption into nanoporous CO 2 {"}molecular basket{"} sorbents prepared by loading polyethylenimine (PEI) into mesoporous molecular sieve SBA-15. IR results from DRIFTS showed that a part of loaded PEI is anchored on the surface of SBA-15 through the interaction between amine groups and isolated surface silanol groups. Raising the temperature from 25 to 75°C increased the molecular flexibility of PEI loaded in the mesopore channels, which may partly contribute to the increase of CO 2 sorption capacity at higher temperatures. CO 2 sorption/desorption behavior studied by in situ transmission FTIR showed that CO 2 is sorbed on amine sites through the formation of alkylammonium carbamates and absorbed into the multiple layers of PEI located in mesopores of SBA-15. A new observation by in situ IR is that two broad IR bands emerged at 2450 and 2160 cm -1 with CO 2 flowing over PEI(50)/SBA-15, which could be attributed to chemically sorbed CO 2 species on PEI molecules inside the mesopores of SBA-15. The intensities of these two bands also increased with increasing CO 2 exposure time and with raising CO 2 sorption temperature. By comparison of the CO 2 sorption rate at 25 and 75°C in terms of differential IR intensities, it was found that CO 2 sorption over molecular basket sorbent includes two rate regimes which suggest two distinct steps: rapid sorption on exposed outer surface layers of PEI (controlled by sorption affinity or thermodynamics) and the diffusion and sorption inside the bulk of multiple layers of PEI (controlled by diffusion). The sorption of CO 2 is reversible at 75°C. Comparative IR examination of the CO 2 sorption/desorption spectra on dry and prewetted PEI/SBA-15 sorbent revealed that presorbed water does not significantly affect the CO 2-amine interaction patterns.",
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Infrared study of CO 2 sorption over "molecular basket" sorbent consisting of polyethylenimine-modified mesoporous molecular sieve. / Wang, Xiaoxing; Schwartz, Viviane; Clark, Jason C.; Ma, Xiaoliang; Overbury, Steven H.; Xu, Xiaochun; Song, Chunshan.

In: Journal of Physical Chemistry C, Vol. 113, No. 17, 30.04.2009, p. 7260-7268.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Infrared study of CO 2 sorption over "molecular basket" sorbent consisting of polyethylenimine-modified mesoporous molecular sieve

AU - Wang, Xiaoxing

AU - Schwartz, Viviane

AU - Clark, Jason C.

AU - Ma, Xiaoliang

AU - Overbury, Steven H.

AU - Xu, Xiaochun

AU - Song, Chunshan

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N2 - An infrared study has been conducted on CO 2 sorption into nanoporous CO 2 "molecular basket" sorbents prepared by loading polyethylenimine (PEI) into mesoporous molecular sieve SBA-15. IR results from DRIFTS showed that a part of loaded PEI is anchored on the surface of SBA-15 through the interaction between amine groups and isolated surface silanol groups. Raising the temperature from 25 to 75°C increased the molecular flexibility of PEI loaded in the mesopore channels, which may partly contribute to the increase of CO 2 sorption capacity at higher temperatures. CO 2 sorption/desorption behavior studied by in situ transmission FTIR showed that CO 2 is sorbed on amine sites through the formation of alkylammonium carbamates and absorbed into the multiple layers of PEI located in mesopores of SBA-15. A new observation by in situ IR is that two broad IR bands emerged at 2450 and 2160 cm -1 with CO 2 flowing over PEI(50)/SBA-15, which could be attributed to chemically sorbed CO 2 species on PEI molecules inside the mesopores of SBA-15. The intensities of these two bands also increased with increasing CO 2 exposure time and with raising CO 2 sorption temperature. By comparison of the CO 2 sorption rate at 25 and 75°C in terms of differential IR intensities, it was found that CO 2 sorption over molecular basket sorbent includes two rate regimes which suggest two distinct steps: rapid sorption on exposed outer surface layers of PEI (controlled by sorption affinity or thermodynamics) and the diffusion and sorption inside the bulk of multiple layers of PEI (controlled by diffusion). The sorption of CO 2 is reversible at 75°C. Comparative IR examination of the CO 2 sorption/desorption spectra on dry and prewetted PEI/SBA-15 sorbent revealed that presorbed water does not significantly affect the CO 2-amine interaction patterns.

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