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NMR Studies of Cooperative Effects in Adsorption


Reference:

Hitchcock, I., Chudek, J. A., Holt, E. M., Lowe, J. P. and Rigby, S. P., 2010. NMR Studies of Cooperative Effects in Adsorption. Langmuir, 26 (23), pp. 18061-18070.

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Official URL:

http://dx.doi.org/10.1021/la103584k

Abstract

The conversion of gas adsorption isotherms into pore size distributions generally relies upon the assumption of thermodynamically independent pores. Hence, pore-pore cooperative adsorption effects, which might result in a significantly skewed pore size distribution, are neglected. In this work, cooperative adsorption effects in water adsorption on a real, amorphous, mesoporous silica material have been studied using magnetic resonance imaging (M RI) and pulsed-gradient stimulated-echo (PGSE) NMR techniques. Evidence for advanced adsorption can be seen directly using relaxation time weighted M RI. The number and spatial distributions of pixels containing pores of different sizes filled with condensate have been analyzed. The spatial distribution of filled pores has been found to be highly nonrandom. Pixels containing the largest pores present in the material have been observed to fill in conjunction with pixels containing much smaller pores. POSE NMR has confirmed the spatially extensive nature of the adsorbed ganglia. Thus, long-range (>= 40 mu m) cooperative adsorption effects, between larger pores associated with smaller pores, occur within mesoporous materials. The NMR findings have also suggested particular types of pore filling mechanisms occur within the porous solid studied.

Details

Item Type Articles
CreatorsHitchcock, I., Chudek, J. A., Holt, E. M., Lowe, J. P. and Rigby, S. P.
DOI10.1021/la103584k
DepartmentsFaculty of Engineering & Design > Chemical Engineering
Faculty of Science > Chemistry
RefereedYes
StatusPublished
ID Code22222

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