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

Journal Article · Wed Sep 25 04:00:00 EDT 1996 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja960594z· OSTI ID:420824

Zhang, W; Wang, J; Tanev, P T; Pinnavaia, T J ^[1]; Froeba, M ^[2]; Wong, J ^[3]

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1. Michigan State Univ., East Lansing, MI (United States)
2. Univ. of Hamburg (Germany)
3. Lawrence Livermore National Lab., CA (United States)

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.

• OSTI ID: 420824
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 38 Vol. 118; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
CATALYSTS
ELECTROSTATICS
MOLECULAR SIEVES
NMR SPECTRA
OXIDATION
PEROXIDES
PHYSICAL PROPERTIES
POROUS MATERIALS
STYRENE
SYNTHESIS
TITANIUM COMPOUNDS
TITANIUM SILICATES
X-RAY DIFFRACTION