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Bacsik Z, Atluri R, Garcia-Bennett AE, et al. Temperature-induced uptake of CO2 and formation of carbamates in mesocaged silica modified with n-propylamines. Langmuir. 2010;26(12):10013-24doi: 10.1021/la1001495.
Bacsik, Z., Atluri, R., Garcia-Bennett, A. E., & Hedin, N. (2010). Temperature-induced uptake of CO2 and formation of carbamates in mesocaged silica modified with n-propylamines. Langmuir : the ACS journal of surfaces and colloids, 26(12), 10013-24. https://doi.org/10.1021/la1001495
Bacsik, Zoltán, et al. "Temperature-induced uptake of CO2 and formation of carbamates in mesocaged silica modified with n-propylamines." Langmuir : the ACS journal of surfaces and colloids vol. 26,12 (2010): 10013-24. doi: https://doi.org/10.1021/la1001495
Bacsik Z, Atluri R, Garcia-Bennett AE, Hedin N. Temperature-induced uptake of CO2 and formation of carbamates in mesocaged silica modified with n-propylamines. Langmuir. 2010 Jun 15;26(12):10013-24. doi: 10.1021/la1001495. PMID: 20218553.
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Langmuir. 2010 Jun 15;26(12):10013-24. doi: 10.1021/la1001495.

Temperature-induced uptake of CO2 and formation of carbamates in mesocaged silica modified with n-propylamines.

Langmuir : the ACS journal of surfaces and colloids

Zoltán Bacsik, Rambabu Atluri, Alfonso E Garcia-Bennett, Niklas Hedin

Affiliations

  1. Department of Materials and Environmental Chemistry, Berzelii Center EXSELENT on Porous Materials, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.

PMID: 20218553 DOI: 10.1021/la1001495

Abstract

Adsorption-mediated CO(2) separation can reduce the cost of carbon capture and storage. The reduction in cost requires adsorbents with high capacities for CO(2) sorption and high CO(2)-over-N(2) selectivity. Amine-modified sorbents are promising candidates for carbon capture. To investigate the details of CO(2) adsorption in such materials, we studied mesocaged (cubic, Pm3n symmetry) silica adsorbents with tethered propylamines using Fourier transform infrared (FTIR) spectroscopy and volumetric uptake experiments. The degree of heterogeneity in these coatings was varied by either cosynthesizing or postsynthetically introducing the propylamine modification. In situ FTIR spectroscopy revealed the presence of both physisorbed and chemisorbed CO(2) in the materials. We present direct molecular evidence for physisorption using FTIR spectroscopy in mesoporous silica sorbents modified with propylamines. Physisorption reduced the CO(2)-over-N(2) selectivity in amine-rich sorbents. Samples with homogeneous coatings showed typical CO(2) adsorption trends and large quantities of IR-observable physisorbed CO(2). The uptake of CO(2) in mesocaged materials with heterogeneous propylamine coatings was higher at high temperatures than at low temperatures. At higher temperatures and low pressures, the postsynthetically modified materials adsorbed more CO(2) than did the extracted ones, even though the surface area after modification was clearly reduced and the coverage of primary amine groups was lower. The principal mode of CO(2) uptake in postsynthetically modified mesoporous silica was chemisorption. The chemisorbed moieties were present mainly as carbamate-ammonium ion pairs, resulting from the quantitative transformation of primary amine groups during CO(2) adsorption as established by NIR spectroscopy. The heterogeneity in the coatings promoted the formation of these ion pairs. The average propylamine-propylamine distance must be small to allow the formation of carbamate-propylammonium ion pairs.

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