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Title: Mesoporous titanosilicate molecular sieves prepared at ambient temperature by electrostatic (S{sup +}I{sup -}, S{sup +}X{sup -}I{sup +}) and neural (S{degree}I{degree}) assembly pathways: A comparison of physical properties and catalytic activity for peroxide oxidations

Abstract

Hexagonal mesoporous titanosilicates with distinguishable framework charges and textural mesoporosity, namely, Ti-MCM-41 and Ti-HMS, were prepared at ambient temperature by electrostatic and neutral assembly processes, respectively. Titanium incorporation at the 2 mol % level for both materials was accompanied by increases in lattice parameters and wall thicknesses, but the framework pore sizes remained unaffected. Cross-linking of the anionic framework of as-synthesized Ti-substituted MCM-41 prepared by electrostatic S{sup +}I{sup -} and S{sup +}X{sup -}I{sup +} assembly pathways (where S{sup +} is a quaternary ammonium surfactant and I{sup -} and I{sup +} are ionic silicon precursors) was enhanced significantly by Ti substitution, as judged by {sup 29}Si MAS NMR. The neutral framework of as-synthesized Ti-HMS formed by S{degree}I{degree} assembly (where S{degree} is a primary amine and I{degree} is a neutral silicon precursor) exhibited the same high degree of cross-linking as the unsubstituted silica analog. UV-vis and XANES spectra for the calcined forms of Ti-MCM-41 and Ti-HMS indicated (i) the presence of site-isolated Ti species in the framework, (ii) predominantly tetrahedral coordination for Ti, along with some rehydrated five- and six-coordinated sites, and (iii) Ti siting that was virtually independent of the framework assembly pathway. 35 refs., 5 figs., 3 tabs.

Authors:
; ; ;  [1];  [2];  [3]
  1. Michigan State Univ., East Lansing, MI (United States)
  2. Univ. of Hamburg (Germany)
  3. Lawrence Livermore National Lab., CA (United States)
Publication Date:
OSTI Identifier:
420824
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 118; Journal Issue: 38; Other Information: PBD: 25 Sep 1996
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 40 CHEMISTRY; MOLECULAR SIEVES; SYNTHESIS; X-RAY DIFFRACTION; NMR SPECTRA; STYRENE; OXIDATION; POROUS MATERIALS; ELECTROSTATICS; TITANIUM SILICATES; TITANIUM COMPOUNDS; PHYSICAL PROPERTIES; CATALYSTS; PEROXIDES

Citation Formats

Zhang, W, Wang, J, Tanev, P T, Pinnavaia, T J, Froeba, M, Lawrence Livermore National Lab., CA, Univ. of California, Livermore, CA, Wong, J, and Univ. of California, Livermore, CA. Mesoporous titanosilicate molecular sieves prepared at ambient temperature by electrostatic (S{sup +}I{sup -}, S{sup +}X{sup -}I{sup +}) and neural (S{degree}I{degree}) assembly pathways: A comparison of physical properties and catalytic activity for peroxide oxidations. United States: N. p., 1996. Web. doi:10.1021/ja960594z.
Zhang, W, Wang, J, Tanev, P T, Pinnavaia, T J, Froeba, M, Lawrence Livermore National Lab., CA, Univ. of California, Livermore, CA, Wong, J, & Univ. of California, Livermore, CA. Mesoporous titanosilicate molecular sieves prepared at ambient temperature by electrostatic (S{sup +}I{sup -}, S{sup +}X{sup -}I{sup +}) and neural (S{degree}I{degree}) assembly pathways: A comparison of physical properties and catalytic activity for peroxide oxidations. United States. https://doi.org/10.1021/ja960594z
Zhang, W, Wang, J, Tanev, P T, Pinnavaia, T J, Froeba, M, Lawrence Livermore National Lab., CA, Univ. of California, Livermore, CA, Wong, J, and Univ. of California, Livermore, CA. Wed . "Mesoporous titanosilicate molecular sieves prepared at ambient temperature by electrostatic (S{sup +}I{sup -}, S{sup +}X{sup -}I{sup +}) and neural (S{degree}I{degree}) assembly pathways: A comparison of physical properties and catalytic activity for peroxide oxidations". United States. https://doi.org/10.1021/ja960594z.
@article{osti_420824,
title = {Mesoporous titanosilicate molecular sieves prepared at ambient temperature by electrostatic (S{sup +}I{sup -}, S{sup +}X{sup -}I{sup +}) and neural (S{degree}I{degree}) assembly pathways: A comparison of physical properties and catalytic activity for peroxide oxidations},
author = {Zhang, W and Wang, J and Tanev, P T and Pinnavaia, T J and Froeba, M and Lawrence Livermore National Lab., CA and Univ. of California, Livermore, CA and Wong, J and Univ. of California, Livermore, CA},
abstractNote = {Hexagonal mesoporous titanosilicates with distinguishable framework charges and textural mesoporosity, namely, Ti-MCM-41 and Ti-HMS, were prepared at ambient temperature by electrostatic and neutral assembly processes, respectively. Titanium incorporation at the 2 mol % level for both materials was accompanied by increases in lattice parameters and wall thicknesses, but the framework pore sizes remained unaffected. Cross-linking of the anionic framework of as-synthesized Ti-substituted MCM-41 prepared by electrostatic S{sup +}I{sup -} and S{sup +}X{sup -}I{sup +} assembly pathways (where S{sup +} is a quaternary ammonium surfactant and I{sup -} and I{sup +} are ionic silicon precursors) was enhanced significantly by Ti substitution, as judged by {sup 29}Si MAS NMR. The neutral framework of as-synthesized Ti-HMS formed by S{degree}I{degree} assembly (where S{degree} is a primary amine and I{degree} is a neutral silicon precursor) exhibited the same high degree of cross-linking as the unsubstituted silica analog. UV-vis and XANES spectra for the calcined forms of Ti-MCM-41 and Ti-HMS indicated (i) the presence of site-isolated Ti species in the framework, (ii) predominantly tetrahedral coordination for Ti, along with some rehydrated five- and six-coordinated sites, and (iii) Ti siting that was virtually independent of the framework assembly pathway. 35 refs., 5 figs., 3 tabs.},
doi = {10.1021/ja960594z},
url = {https://www.osti.gov/biblio/420824}, journal = {Journal of the American Chemical Society},
number = 38,
volume = 118,
place = {United States},
year = {1996},
month = {9}
}