Preparation from metal sols

Amorphous silica has also been mentioned as a starting metal oxide material for the preparation of particulate mesoporous membranes. These membranes were prepared from commercial sols, Ludox (DuPont) or Cecasol (Sobret), and coated on a macroporous a-alumina support [35]. In contrast to crystalline membrane materials such as alumina, titania or zirconia, the evolution of pore size with temperature of amorphous silica membranes was revealed to be more sensitive to drying conditions than to firing temperature (Table 7.1). When heat-treated for several hours at 800°C the silica top layer transformed from an amorphous state to cristobalite. 

Yamada, N. Yoshinaga, L Katayama, S., Formation Behavior and Optical Properties of Transparent Inrganic-Organic Hybrids Prepared from Metal Alkoxides and Polydimethylsiloxane. J. Sol-Gel Sci. Technol. 2000,17,123-130. Lebeau, R. Maquet, J. Sanchez, C. Beaume, F. Laupretre, F., Structural and Dynamical Studies of Hybrid Siloxane-Silica Materials. J. Mater. Chem. 1997,... 

Stanic V, Etsell TH, Pierre AC, et al. (1997) Metal sulfide preparation from a sol-gel product and sulfur. J Mater Chem 7 105-107... 

Current and potential applications of films prepared by sol-gel processing are numerous (1,61) and they are expected to grow in the future. Table 5.10 summarizes some possible applications of films and coatings prepared from metal alkoxide solutions (69). 

It is necessary to note that, if heating is applied for the homogenization of solutions prepared from metal alkoxides together with metal carboxylates, it is necessary to control very thoroughly the thermal conditions to insure the reproducibility in subsequent sol-gel... 

Kaji H., Nakanishi K., Soga N. Polymerization indnced phase separation in silica sol-gel systems containing formamide. J. Sol-Gel Sci. Tech. 1993 1 35-16 Kamiya K., Sakka S. Stmctnre and propoties 0fTiO2-SiO2 glasses prepared from metal alkoxides. 

Yamada N., Yoshinaga I., Katayama S. Formation behavior and optical properties of transparent inorganic-organic hybrids prepared from metal alkoxides and polydimethylsiloxane. J. Sol-Gel Sci. Technol. 2000 17 123-130... 

A gel is defined as a hydrous metal aluminosihcate prepared from either aqueous solutions, reactive soflds, colloidal sols, or reactive aluminosihcates such as the residue stmcture of metakaolin and glasses. 

Alumina, zirconia, or zinc hybrids with poly(tetramethylene oxide)s were prepared by means of the conventional sol-gel method starting from metal... 

Summary Materials containing uniform, nanometer-sized metal particles homogeneously dispersed in a Si02 matrix, with a variable metal loading, were prepared by the sol-gel processing starting from metal salts, alkoxysilanes of the type X(CH2)nSi(OR)3 and, optionally, Si(OR)4. 

A review of preparative methods for metal sols (colloidal metal particles) suspended in solution is given. The problems involved with the preparation and stabilization of non-aqueous metal colloidal particles are noted. A new method is described for preparing non-aqueous metal sols based on the clustering of solvated metal atoms (from metal vaporization) in cold organic solvents. Gold-acetone colloidal solutions are discussed in detail, especially their preparation, control of particle size (2-9 nm), electrophoresis measurements, electron microscopy, GC-MS, resistivity, and related studies. Particle stabilization involves both electrostatic and steric mechanisms and these are discussed in comparison with aqueous systems. 

A new class of heterogeneous catalyst has emerged from the incorporation of mono- and bimetallic nanocolloids in the mesopores of MCM-41 or via the entrapment of pro-prepared colloidal metal in sol-gel materials [170-172], Noble metal nanoparticles containing Mex-MCM-41 were synthesized using surfactant stabilized palladium, iridium, and rhodium nanoparticles in the synthesis gel. The materials were characterized by a number of physical methods, showed that the nanoparticles were present inside the pores of MCM-41. They were found to be active catalysts in the hydrogenation of cyclic olefins such as cyclohexene, cyclooctene, cyclododecene, and... 

The initial interaction of Ru3(CO)i2 with the surface of several oxides has been extensively studied by EXAFS and IR spectroscopy [70,100]. Representative studies of materials prepared from Ru3(CO)i2 and zeolites ]101, 102] or MCM-41 related supports [97] have also been reported. Ru/Si02 has also been prepared by the sol-gel method, using Ru3(CO)i2 and tetramethoxysilane as precursors [98] spheroidal metal particles homogeneously dispersed into the sihca matrix with a size range from 1 to 4nm were obtained after decarbonylation at 573 K under He, followed by H 2-treatment. 

Positively-charged hydroxide sols can be prepared from many metals. To produce a colloidal solution from the precipitate, a process termed peptization, a solution of the salt, itself, is not... 

Cesium chloride [7647-17-8] M 168.4, m 645°, b 1303°, d 3.99. Soluble in H2O but can be purified by crystn from HbO (sol in g per cent 162.3(0.7°), 182.2(16.2°) and 290(at bp 119.4°)] and dried in high vac. Sol in EtOH and is deliquescent, keep in a tightly closed container. [Handbook of Preparative Inorganic Chemistry (ed Brauer) Vol I 951 1963]. For further purification of CsCl, a cone aqueous soln of the practically pure reagent is treated with an equivalent weight if I2 and CI2 bubbled into the soln until pptn of CsC I ceased. Reciystn yields a salt which is free from other alkali metals. It is then decomposed to pure CsCl on heating. [JACS 52 3886 1930]. Also rerystd from acetone-water, or from water (0.5ml/g) by cooling in CaC /ice. Dried at 78° under vacuum. 

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