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Degree

PHD, Kent State University, College of Arts and Sciences / Department of Chemistry, 2009.

Abstract

Ordered mesoporous inorganic nanocomposite materials were synthesized by using soft- and hard-templating strategies. Ordered mesoporous silicas (OMSs) were obtained by soft templating, whereas ordered mesoporous carbons (OMCs) and mesoporous mixed metal oxides were prepared by hard templating. Also, post-synthesis modification of OMSs was carried out by deposition of mixed metal oxides, carbon and nickel. The resulting materials were characterized by nitrogen and argon adsorption, thermogravimetric analysis, small angle X-ray scattering, powder X-ray diffraction, scanning and transmission electronic microscopy, elemental analysis, temperature programmed desorption and diffuse reflectance Fourier transform infrared spectroscopy. The first part of this dissertation is devoted to the optimization of experimental conditions such as time, temperature, pH and salt addition for the synthesis of several OMSs: SBA-15, SBA-16 and FDU-1. The size of ordered mesopores, surface area and pore volume of the aforementioned OMSs were tailored by adjusting the synthesis time and temperature as well as by combining solvent extraction and calcination for the template removal. A further improvement of SBA-16 and FDU-1 was achieved by using low acid concentration and adding NaCl addition, which resulted in OMSs with large cage diameters and uniform pore openings. Subsequently, the SBA-15 and SBA-16 materials were employed as hard templates for the synthesis of OMCs, using iron chloride as a catalyst for in situ polymerization of pyrrole. After carbonization and silica dissolution, the nitrogen-doped OMCs with tunable mesopores, graphitic domains and magnetic iron-iron carbide nanoparticles were obtained. Also, the pore walls of SBA-15 were modified with 2, 3-dihydroxy naphthalene, which was converted into thin carbon film. The impregnation of the resulting SBA-15-carbon nanocomposites with nickel salts afforded materials with “pea-pod” distribution of nickel nanoparticles. In addition, the pore walls of SBA-15 were modified with metal alkoxides of Al, Ti, and Zr by using a partially hydrolytic sol-gel process, which depending on the experimental conditions resulted in the deposition of thin films and nanoparticles of these oxides. Finally, OMCs were used as hard templates for the synthesis of mesoporous iron-doped alumina-titania mixed oxides, which exhibited high Lewis acidity and partially retained the structural symmetry of the templates used.

Subject Headings

Chemistry; Materials science

Keywords

SBA-15; SBA-16; FDU-1; ordered mesoporous silicas; ordered mesoporous carbons; mesoporous mixed metal oxides; nitrogen adsorption; ordered mesoporous materials

Committee / Advisors

Mietek Jaroniec, PhD (Advisor)
Anatoly K. Khitrin, PhD (Committee Member)
Hanbin Mao, PhD (Committee Member)
Lien-Chy Chien, PhD (Committee Member)
John J. Portman, PhD (Committee Chair)

Pages

210p.

Document number: kent1258990927
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=kent1258990927

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