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Title: Hydrothermal and postsynthesis surface modification of cubic, MCM-48, and ultralarge pore SBA-15 mesoporous silica with titanium

Abstract

The authors describe the introduction of titanium centers to cubic MCM-48 was hydrothermally prepared with a gemini surfactant that favors the cubic phase and leads to a high degree of long-range pore ordering. This phase was chosen due to its high surface area (1100--1300 m{sup 2}/g) and its three-dimensional, bicontinuous pore array. SBA-15, synthesized with a block copolymer template under acidic conditions, has a surface area from 600 to 900 m{sup 2}/g and an average pore diameter of 69 {angstrom}, compared to 24--27 {angstrom} for MCM-48. Alkoxide precursors of titanium were used to prepare samples of Ti-MCM-48 and Ti-SBA-15. The authors have detailed the bulk and molecular structure of both the silica framework and the local bonding environment of the titanium ions within each matrix. X-ray powder diffraction and nitrogen adsorption shows the pore structure is maintained despite some shrinkage of the pore diameter at high Ti loadings by grafting methods. UV-visible and Raman spectroscopy indicate that grafting produces the least amount of Ti-O-Ti bonds and instead favors isolated tetrahedral and octahedral titanium centers. High-resolution photoacoustic FTIR spectra demonstrated the presence of intermediate range order within the silicate walls of MCM-48, established the consumption of surface silanols to form Si-O-Timore » bonds by grafting, and resolved the characteristic IR absorbance at 960 cm{sup {minus}1}, occurring in titanium silicates, into two components. All three spectroscopic techniques, including in situ Raman, reveal the reactive intermediates formed when the materials are contacted with hydrogen peroxide.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of California, Santa Barbara, CA (US)
OSTI Identifier:
20075547
Resource Type:
Journal Article
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 12; Journal Issue: 4; Other Information: PBD: Apr 2000; Journal ID: ISSN 0897-4756
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; TITANIUM SILICATES; CATALYST SUPPORTS; PORE STRUCTURE; SURFACE AREA; HYDROTHERMAL SYNTHESIS

Citation Formats

Morey, M S, O'Brien, S, Schwarz, S, and Stucky, G D. Hydrothermal and postsynthesis surface modification of cubic, MCM-48, and ultralarge pore SBA-15 mesoporous silica with titanium. United States: N. p., 2000. Web. doi:10.1021/cm9901663.
Morey, M S, O'Brien, S, Schwarz, S, & Stucky, G D. Hydrothermal and postsynthesis surface modification of cubic, MCM-48, and ultralarge pore SBA-15 mesoporous silica with titanium. United States. https://doi.org/10.1021/cm9901663
Morey, M S, O'Brien, S, Schwarz, S, and Stucky, G D. 2000. "Hydrothermal and postsynthesis surface modification of cubic, MCM-48, and ultralarge pore SBA-15 mesoporous silica with titanium". United States. https://doi.org/10.1021/cm9901663.
@article{osti_20075547,
title = {Hydrothermal and postsynthesis surface modification of cubic, MCM-48, and ultralarge pore SBA-15 mesoporous silica with titanium},
author = {Morey, M S and O'Brien, S and Schwarz, S and Stucky, G D},
abstractNote = {The authors describe the introduction of titanium centers to cubic MCM-48 was hydrothermally prepared with a gemini surfactant that favors the cubic phase and leads to a high degree of long-range pore ordering. This phase was chosen due to its high surface area (1100--1300 m{sup 2}/g) and its three-dimensional, bicontinuous pore array. SBA-15, synthesized with a block copolymer template under acidic conditions, has a surface area from 600 to 900 m{sup 2}/g and an average pore diameter of 69 {angstrom}, compared to 24--27 {angstrom} for MCM-48. Alkoxide precursors of titanium were used to prepare samples of Ti-MCM-48 and Ti-SBA-15. The authors have detailed the bulk and molecular structure of both the silica framework and the local bonding environment of the titanium ions within each matrix. X-ray powder diffraction and nitrogen adsorption shows the pore structure is maintained despite some shrinkage of the pore diameter at high Ti loadings by grafting methods. UV-visible and Raman spectroscopy indicate that grafting produces the least amount of Ti-O-Ti bonds and instead favors isolated tetrahedral and octahedral titanium centers. High-resolution photoacoustic FTIR spectra demonstrated the presence of intermediate range order within the silicate walls of MCM-48, established the consumption of surface silanols to form Si-O-Ti bonds by grafting, and resolved the characteristic IR absorbance at 960 cm{sup {minus}1}, occurring in titanium silicates, into two components. All three spectroscopic techniques, including in situ Raman, reveal the reactive intermediates formed when the materials are contacted with hydrogen peroxide.},
doi = {10.1021/cm9901663},
url = {https://www.osti.gov/biblio/20075547}, journal = {Chemistry of Materials},
issn = {0897-4756},
number = 4,
volume = 12,
place = {United States},
year = {Sat Apr 01 00:00:00 EST 2000},
month = {Sat Apr 01 00:00:00 EST 2000}
}