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Title: Preparation of monodispersed microporous SiO{sub 2} microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst

Abstract

A novel and simple method for the synthesis of monodispersed microporous SiO{sub 2} microspheres with high specific surface area was developed by hydrolysis of tetraethoxysilane (TEOS) in a water-ethanol mixed solution and using dodecylamine (DDA) as hydrolysis catalyst and template. The as-prepared products were characterized with differential thermal analysis-thermogravimetry, scanning electron microscopy, high-resolution transmission electron microscopy, small angle X-ray diffraction and nitrogen adsorption. The effects of experimental conditions including hydrolysis temperatures, calcination temperature and concentrations of TEOS and DDA on the morphology and pore parameters of the as-prepared SiO{sub 2} microspheres were investigated and discussed. The results showed that hydrolysis temperature and concentrations of TEOS and DDA are important parameters for the control of size and morphology of particles. The specific surface area and specific pore volume of the as-prepared SiO{sub 2} microspheres increased with increasing DDA concentration and calcination temperature. DDA may act not only as a good hydrolysis catalyst but also as a template for the formation of monodispersed SiO{sub 2} microspheres with high specific surface area. This research may provide new insight into the synthesis of monodispersed microporous SiO{sub 2} microspheres. -- Graphical abstract: Monodispersed microporous SiO{sub 2} microspheres with high specific surface area were prepared bymore » hydrolysis of tetraethoxysilane (TEOS) using dodecylamine (DDA) as hydrolysis catalyst and the effects of experimental conditions on the morphology and pore parameters of the as-prepared SiO{sub 2} microspheres were investigated and discus0009s.« less

Authors:
 [1];  [2];  [2]
  1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi road 122, Wuhan 430070 (China). E-mail: jiaguoyu@yahoo.com
  2. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi road 122, Wuhan 430070 (China)
Publication Date:
OSTI Identifier:
20784853
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 179; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2005.10.036; PII: S0022-4596(05)00491-3; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CALCINATION; DIFFERENTIAL THERMAL ANALYSIS; HYDROLYSIS; MICROSPHERES; SCANNING ELECTRON MICROSCOPY; SILICON OXIDES; SPECIFIC SURFACE AREA; SYNTHESIS; THERMAL GRAVIMETRIC ANALYSIS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Yu Jiaguo, Zhao Li, and Cheng Bei. Preparation of monodispersed microporous SiO{sub 2} microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst. United States: N. p., 2006. Web.
Yu Jiaguo, Zhao Li, & Cheng Bei. Preparation of monodispersed microporous SiO{sub 2} microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst. United States.
Yu Jiaguo, Zhao Li, and Cheng Bei. Sun . "Preparation of monodispersed microporous SiO{sub 2} microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst". United States. doi:.
@article{osti_20784853,
title = {Preparation of monodispersed microporous SiO{sub 2} microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst},
author = {Yu Jiaguo and Zhao Li and Cheng Bei},
abstractNote = {A novel and simple method for the synthesis of monodispersed microporous SiO{sub 2} microspheres with high specific surface area was developed by hydrolysis of tetraethoxysilane (TEOS) in a water-ethanol mixed solution and using dodecylamine (DDA) as hydrolysis catalyst and template. The as-prepared products were characterized with differential thermal analysis-thermogravimetry, scanning electron microscopy, high-resolution transmission electron microscopy, small angle X-ray diffraction and nitrogen adsorption. The effects of experimental conditions including hydrolysis temperatures, calcination temperature and concentrations of TEOS and DDA on the morphology and pore parameters of the as-prepared SiO{sub 2} microspheres were investigated and discussed. The results showed that hydrolysis temperature and concentrations of TEOS and DDA are important parameters for the control of size and morphology of particles. The specific surface area and specific pore volume of the as-prepared SiO{sub 2} microspheres increased with increasing DDA concentration and calcination temperature. DDA may act not only as a good hydrolysis catalyst but also as a template for the formation of monodispersed SiO{sub 2} microspheres with high specific surface area. This research may provide new insight into the synthesis of monodispersed microporous SiO{sub 2} microspheres. -- Graphical abstract: Monodispersed microporous SiO{sub 2} microspheres with high specific surface area were prepared by hydrolysis of tetraethoxysilane (TEOS) using dodecylamine (DDA) as hydrolysis catalyst and the effects of experimental conditions on the morphology and pore parameters of the as-prepared SiO{sub 2} microspheres were investigated and discus0009s.},
doi = {},
journal = {Journal of Solid State Chemistry},
number = 1,
volume = 179,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • SiO{sub 2}/TiO{sub 2} composite microspheres with microporous SiO{sub 2} core/mesoporous TiO{sub 2} shell structures were prepared by hydrolysis of titanium tetrabutylorthotitanate (TTBT) in the presence of microporous silica microspheres using hydroxypropyl cellulose (HPC) as a surface esterification agent and porous template, and then dried and calcined at different temperatures. The as-prepared products were characterized with differential thermal analysis and thermogravimetric (DTA/TG), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption. The results showed that composite particles were about 1.8{mu}m in diameter, and had a spherical morphology and a narrow size distribution. Uniform mesoporous titania coatings on the surfaces of microporousmore » silica microspheres could be obtained by adjusting the HPC concentration to an optimal concentration of about 3.2mmolL{sup -1}. The anatase and rutile phase in the SiO{sub 2}/TiO{sub 2} composite microspheres began to form at 700 and 900 deg. C, respectively. At 700 deg. C, the specific surface area and pore volume of the SiO{sub 2}/TiO{sub 2} composite microspheres were 552 and 0.652mLg{sup -1}, respectively. However, at 900 deg. C, the specific surface area and pore volume significantly decreased due to the phase transformation from anatase to rutile.« less
  • Thermally stable supported metal catalysts can be prepared by matching the metal particle size to the average pore diameter. Preparative variables aimed at achieving this match are presented. In the 3-8 pH range, blank silica gels prepared using tetraethoxysilane (TEOS) were observed to have BET surface areas of 350-800 m{sup 2}/g and mesoporous structures with an average pore diameter of between 4 and 25 nm at a constant H{sub 2}O/TEOS ratio of 10. Silica aerogels have comparable BET surface areas, larger pore diameters, and pore volumes than xerogels. In the case of supported Pt catalysts prepared by sol-gel synthesis, themore » effect of preparative variables, including metal precursor, metal loading, reactant stoichiometries, and solvent removal, have been studied. The use of Pt(AcAc){sub 2} resulted in average pore diameters which could be varied in the 4-20-nm range by adjusting the H{sub 2}O/TEOS ratio during synthesis. BET surface areas in the 500-800 m{sup 2}/g and metal dispersions of 50-85% can be achieved. The H{sub 2}/n-hexane reaction was studied on these catalysts. Catalytic activities were found to be comparable or slightly superior to supported metal catalysts prepared by traditional methods. 26 refs., 10 figs., 11 tabs.« less
  • Specific surface area of molybdena in MoO/sub 3//SiO/sub 2/ catalysts, determined by the oxygen adsorption method, showed 101-107 sq m/g for catalysts containing 4.8-13.0% molybdena, compared with 50.8-56.7 sq m/g for unsupported molybdena. The particle size for the 13% molybdena catalyst was 69 A., compared with 25 A. for a 15% molybdena catalyst on alumina, which interacts more strongly with the molybdena. X-ray diffraction data of the 13% molybdena/silica catalyst showed 203 A. owing to the greater effect of large particles in this method. The equivalent molybdena areas for the silica-supported catalysts increased from approx. 7 sq m/g for themore » 4.8% molybdena catalyst to approx. 15 sq m/g for the 13% molybdena catalyst which corresponded to a low coverage (131 sq m/g silica area).« less
  • Oxygen chemisorption has been used for determination of the specific molybdena area in a series of MoO/sub 3/ (4.8 to 13.0 wt%)/SiO/sub 2/ catalysts. The experiments were carried out gravimetrically with samples quantitatively reduced to MoO/sub 2/. MoO/sub 2/ samples with a high surface area (50 to 80 m/sup 2/ g/sup -1/) were used to determine a factor for relating oxygen chemisorption to equivalent molybdena area. In the range 77 to 195/sup 0/K, temperature had no effect on the amount of chemisorbed oxygen on both unsupported and supported samples. The equivalent molybdena areas in the supported samples correspond to relativelymore » low coverages of the silica surface. The particle size deduced from oxygen chemisorption for reduced MoO/sub 3/(13.0%)/SiO/sub 2/ was 69 A, higher than that of 25 A for a reduced MoO/sub 3/ (15%)/Al/sub 2/O/sub 3/ catalyst, in agreement with the weaker interaction with silica. A higher value (approx. = 200 A) is calculated from x-ray diffraction line broadening.« less