Acid and Alkaline Sol-Gel Synthesis of Amorphous Aluminosilicates, Dry Gel Properties, and Their Use in Probing Sol Phase Reactions

Witte, Bruno M. De; Uytterhoeven, Jan B.

doi:10.1006/jcis.1996.0371

Cited by 28 publications

(11 citation statements)

References 18 publications

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“…It is seen that one of the advantages of the new synthesis method is that the samples' pore size distribution can be maintained constant over a wide range of Si/Al ratios. This property is quite different from the literature results, which showed that the pore size distribution changes with the Si/Al molar ratio . Moreover, the new synthesis method also yields larger specific surface area.…”

Section: Resultscontrasting

confidence: 98%

Ultrasonic Synthesis of Silica−Alumina Nanomaterials with Controlled Mesopore Distribution without Using Surfactants

et al. 2002

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A novel sol-gel process has been developed for the synthesis of amorphous silica-aluminas with controlled mesopore distribution without the use of organic templating agents, e.g., surfactant molecules. Ultrasonic treatment during the synthesis enables production of precursor sols with narrow particle size distribution. Atomic force microscopy analysis shows that these sol particles are spherical in shape with a narrow size distribution (i.e., 13-25 nm) and their aggregation during the gelation creates clusters containing similar sized interparticle mesopores. A nitrogen physiadsorption study indicates that the mesoporous materials containing different Si/Al ratios prepared by the new synthesis method has a large specific surface area (i.e., 587-692 m 2 /g) and similar pore sizes of 2-11 nm. Solid-state 27 Al magic angle spinning (MAS) NMR shows that most of the aluminum is located in the tetrahedral position. A transmission electron microscopy (TEM) image shows that the mesoporous silica-alumina consists of 12-25 nm spheres. Additionally, high-resolution TEM and electron diffraction indicate that some nanoparticles are characteristic of a crystal, although X-ray diffraction and 29 Si MAS NMR analysis show an amorphous material.

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Section: Resultscontrasting

confidence: 98%

Ultrasonic Synthesis of Silica−Alumina Nanomaterials with Controlled Mesopore Distribution without Using Surfactants

et al. 2002

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“…While alkylation of aromatic hydrocarbons by olefins was convincingly reported [9], Corma et al [10], Calemma et al [11] and Peratello et al [12] found that MSA (mesoporous alumina-silica) catalysts are highly suitable acidic components for the preparation of supported metal bi-functional catalysts applied in hydroisomerization, hydrocracking and olefins oligomerization. Among the reported MSA mesoporous syntheses by sol-gel and reaction conditions controlling parameters such as pore size, structure, distribution, hydrothermal stability and the density of acid sites [13,14] various templates and pore regulating agents such as tetra alkyl ammonium cation and tetra alkyl ammonium hydroxide [15][16][17] were reported as effective for such tasks.…”

Section: Introductionmentioning

confidence: 99%

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

Saber

Gobara

2014

Egyptian Journal of Petroleum

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The present work aims at obtaining a suitable and selective catalyst for catalytic dehydrogenation reactions through designing pore structures of silica-containing alumina nanocomposites by optimizing silica content in the structure. In this trend, series of silica-containing alumina nanocomposites with different molar ratios Al 2 O 3 /SiO 2 were prepared by the solvothermal method. According to surface characterization of silica-containing alumina nanocomposites, the sample with the highest molar ratio of Al 2 O 3 /SiO 2 (2.06) showed mesoporous structure with selective pore sizes of 3.7 and 4.6 nm. In addition, it had a high surface area value of 308 m 2 /g. Furthermore, SEM and TEM images of the same sample showed ultra fine sized particles in the nano size (7-17 nm). Dehydrogenation catalysts, as developed structures, were then achieved by loading 0.6 wt.% platinum metal over the prepared nanocomposites. Performances of the prepared nanocatalysts were investigated via the dehydrogenation of a model compound namely; cyclohexane. Experimental results showed that the Pt catalyst supported on the silica-containing alumina nanocomposites with the highest molar ratio of Al 2 O 3 /SiO 2 , is an efficient and selective catalyst toward the dehydrogenation reaction. This was revealed in terms of 100% selectivity of this catalyst toward the conversion of cyclohexane at all ranges of temperatures with the conversion reaction being temperature dependent. Practically, the total conversion of cyclohexane increased with increasing reaction temperature and reached 100% at 450°C while the prepared catalyst demonstrated absolute selectivity. ª 2014 Production and hosting by Elsevier B.V. on behalf of Egyptian Petroleum Research Institute.

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“…How different Si/Al ratios affect the strength and other properties of the hardened binder is difficult to estimate, unless using one and the same material with different Si/Al ratios but the same extent and kinetic of dissolution. Therefore, model investigations of aluminosilicate gels were done occasionally [7][8][9][10]. (2) A blend of raw materials changes the Si/Al ratio in summary.…”

Section: Introductionmentioning

confidence: 99%

Condensation of aluminosilicate gels—model system for geopolymer binders

Buchwald

Zellmann

Kaps

2011

Journal of Non-Crystalline Solids

108

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Acid and Alkaline Sol-Gel Synthesis of Amorphous Aluminosilicates, Dry Gel Properties, and Their Use in Probing Sol Phase Reactions

Cited by 28 publications

References 18 publications

Ultrasonic Synthesis of Silica−Alumina Nanomaterials with Controlled Mesopore Distribution without Using Surfactants

Ultrasonic Synthesis of Silica−Alumina Nanomaterials with Controlled Mesopore Distribution without Using Surfactants

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

Condensation of aluminosilicate gels—model system for geopolymer binders

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