We have located links that may give you full text access.
Temperature-induced uptake of CO2 and formation of carbamates in mesocaged silica modified with n-propylamines.
Langmuir : the ACS Journal of Surfaces and Colloids 2010 June 16
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.
Full text links
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app