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Title: Porous texture and surface character dehydroxylated and rehydroxylated MCM-41 mesoporous silicas -- Analysis of adsorption isotherms of nitrogen gas and water vapor

Abstract

Four samples of MCM-41 mesoporous silicas whose average pore diameters are 2.4, 2.8, 3.2, and 3.6 nm were prepared using sodium orthosilicate and cationic surfactants of [CH{sub 3}(CH{sub 2}){sub n}N(CH{sub 3}){sub 3}]X (n = 11, 13, 15, 17). These four samples were calcined at 1123 K in vacuo to obtain the dehydroxylated samples, which were further rehydroxylated at 298 K to obtain the rehydroxylated samples. The adsorption isotherms of nitrogen gas (77 K) for the 12 MCM-41 mesoporous silicas are of Type IVc, giving no adsorption hysteresis. On the other hand, the first adsorption isotherms of water vapor (298 K) for the dehydroxylated MCM-41 samples are quite different from those of nitrogen gas, giving the remarkable adsorption hysteresis. The second water isotherms for the rehydroxylated MCM-41 samples are of Type IV, showing slight hysteresis. Using the nitrogen isotherms, the relation between the pore size and carbon chain length of the surfactant has been determined, and the effect of dehydroxylation and rehydroxylation on the porous texture has been examined. Using the first and second water isotherms, the adsorption model of physisorbed waters adsorbed on the surface silanol groups has been proposed. From the pore size distribution curves of nitrogen and water,more » the presence of constrictions in the cylindrical pores has been predicted.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Kwansei Gakuin Univ., Nishinomiya (JP)
OSTI Identifier:
20080256
Resource Type:
Journal Article
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 225; Journal Issue: 2; Other Information: PBD: 15 May 2000; Journal ID: ISSN 0021-9797
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; SILICATES; HYDROXYLATION; ADSORPTION ISOTHERMS; NITROGEN; WATER VAPOR

Citation Formats

Naono, Hiromitu, Hakuman, Masako, Tanaka, Takashi, Tamura, Nobuki, and Nakai, Kazuyuki. Porous texture and surface character dehydroxylated and rehydroxylated MCM-41 mesoporous silicas -- Analysis of adsorption isotherms of nitrogen gas and water vapor. United States: N. p., 2000. Web. doi:10.1006/jcis.2000.6777.
Naono, Hiromitu, Hakuman, Masako, Tanaka, Takashi, Tamura, Nobuki, & Nakai, Kazuyuki. Porous texture and surface character dehydroxylated and rehydroxylated MCM-41 mesoporous silicas -- Analysis of adsorption isotherms of nitrogen gas and water vapor. United States. doi:10.1006/jcis.2000.6777.
Naono, Hiromitu, Hakuman, Masako, Tanaka, Takashi, Tamura, Nobuki, and Nakai, Kazuyuki. Mon . "Porous texture and surface character dehydroxylated and rehydroxylated MCM-41 mesoporous silicas -- Analysis of adsorption isotherms of nitrogen gas and water vapor". United States. doi:10.1006/jcis.2000.6777.
@article{osti_20080256,
title = {Porous texture and surface character dehydroxylated and rehydroxylated MCM-41 mesoporous silicas -- Analysis of adsorption isotherms of nitrogen gas and water vapor},
author = {Naono, Hiromitu and Hakuman, Masako and Tanaka, Takashi and Tamura, Nobuki and Nakai, Kazuyuki},
abstractNote = {Four samples of MCM-41 mesoporous silicas whose average pore diameters are 2.4, 2.8, 3.2, and 3.6 nm were prepared using sodium orthosilicate and cationic surfactants of [CH{sub 3}(CH{sub 2}){sub n}N(CH{sub 3}){sub 3}]X (n = 11, 13, 15, 17). These four samples were calcined at 1123 K in vacuo to obtain the dehydroxylated samples, which were further rehydroxylated at 298 K to obtain the rehydroxylated samples. The adsorption isotherms of nitrogen gas (77 K) for the 12 MCM-41 mesoporous silicas are of Type IVc, giving no adsorption hysteresis. On the other hand, the first adsorption isotherms of water vapor (298 K) for the dehydroxylated MCM-41 samples are quite different from those of nitrogen gas, giving the remarkable adsorption hysteresis. The second water isotherms for the rehydroxylated MCM-41 samples are of Type IV, showing slight hysteresis. Using the nitrogen isotherms, the relation between the pore size and carbon chain length of the surfactant has been determined, and the effect of dehydroxylation and rehydroxylation on the porous texture has been examined. Using the first and second water isotherms, the adsorption model of physisorbed waters adsorbed on the surface silanol groups has been proposed. From the pore size distribution curves of nitrogen and water, the presence of constrictions in the cylindrical pores has been predicted.},
doi = {10.1006/jcis.2000.6777},
journal = {Journal of Colloid and Interface Science},
issn = {0021-9797},
number = 2,
volume = 225,
place = {United States},
year = {2000},
month = {5}
}