X silica

Spherical particles in the micrometric size range of mesoporous MSU-X silica were obtained with nonionic PEO-based surfactant by a new, easy and highly reproducible synthesis pathway leading to Micelle Templated Structures (MTS) with large surface area and narrow pore size distribution. First results on their adsorption properties show that they could be used for HPLC applications. 

Whatever the nature of the template, among possible applications such as catalysts, grafting supports, or filtration medium, the use of MTS for chromatography applications has been claimed for years. However, this latter application requires the ability to synthesize homogeneous batches of spherical particles with a mean diameter at least equal to 5 pm. Such particles were observed only once, in a pH-dependent synthesis of MCM-41 particles, performed by Yang, Ozin and co-workers [1], Most of the time, the synthesis of submicrometer-size particles of MCM-41 or MCM-48 materials was only reported [2-4], We present the synthesis of MSU-X silica with perfectly controlled size and shape suitable for chromatography applications. 

In the wide field of possible applications for MTS, the use of their properties of adsorption and steric selectivity is still to be explored. However, such applications require well-defined particles, especially spherical particles in the micrometric range. The synthesis of MSU-X silica that exhibits these shapes allowed us to test their properties in adsorption HPLC. Non polar solvent such as hexane are suitable to allow a significant separation. Further analyses and testing for size exclusion separation processes are under progress. 

A comparison of the effects of heat and steam on the activity and selectivity of three types of commercial cracking catalysts is illustrated in Table X. Silica-alumina is the most active initially and has the greatest heat stability in the absence of steam, but it is the most susceptible to... 

Figure 1. Rate of sorption of aged 4 X I O 7 plutonium on 230-/x silica grains at pH 7 and 0.1 M ionic strength...

Gem quality beryls are aquamarine (blue), emerald (green), and golden beryl. Likewise, amethyst is a violet-colored silica, and sapphire (blue) and ruby (red) are alumina. Yet pure beryl (Be)At3Sif,0 x) silica (Si03). and alumina (AUOd are colorless. Explain. 

Aflatoxins (metabolites of Aspergillus flavus which are among the most potent known inducers of tumours) Aflatoxins in extracts from grain samples infested with Aspergillus flavus Adsorption SIL-X silica Isopropyl ether/ tetrahydrofuran (88 12)... 

Mesoporous MSU-X silica tuned for filtration and chromatography applications... 

Mesoporous MSU-X silica was synthesized with a two-step pathway, that allowed us to get a high control degree on both the final material shape and the porous size distribution. These materials were developed and tested for separating applications, including HPLC chromatography and ultrafiltration membranes. Both applications show that the specific structure of the Micellar Templated Structures exhibits a new behavior in the separation applications, compared with other materials. They are explained by the combined effect of the silica nature and the specific cylindar pore shape. 

P-05 - The double-step synthesis of MSU-X silica decoupling the assembly mechanism... 

Methyl-modified MSU-1 mesostructures were prepared by one-pot strategy. The microstructure and the interfacial characteristic were measured with N2 sorption, IR, SiNMR, SEM, TEM, TGA and SAXS. The results showed that methyl groups have been incorporated into MSU-X silica framework and the surface and texture properties of the resultant materials varied with the amount of incorporated methyl groups. 

Leigh, J., Wang, H., Bonin, A., Peters, M., and Ruan, X., Silica-induced apoptosis in alveolar and granulomatous cells in vivo. Environ. Health Perspect, 105 (Suppl. 5), 1241-1245, 1997. 

EN 366 (70) contains two test methods. The first (Method A) allows visual assessment of any changes that take place when the specimen is exposed to radiant heat, while Method B determines the protective effect of the test material. The source of radiant heat is a series of si.x silica carbide rods, and the test heat flux is chosen according to the intended end use of the material from the range of low intensity (5-10 kW m"), medium intensity (20 and 40 kW/m ), and high intensity (80 kW/m"). A heat transmission factor is calculated from the temperature rise of a calorimeter positioned against the reverse side of the specimen. 

CH3)2COSiX3 (X = silica gel matrix) Photolysis of isopropanol adsorbed on silica gel/ Silica gel EPR/ 77 6H(jS) 2.07 68Bobl... 

Silica surface Silica surface Silica surface X Silica surface... 

It should be noted that the structure of C/silica and C/X/silica surfaces can be complex not only with respect to their topography but also to their chemical composition due to the availability of H, O, etc., atoms in surface groups, new noncarbon phases (oxide or metal as in the case of carbonization of acetylacetonates of Ni and Co), which can affect the adsorption energy of polar and nonpolar adsorbates. 

Zhang, Y. Fei, J. Yu, Y Zheng, X. Silica Immobilized Ruthenium Catalyst used for Carbon Dioxide Hydrogenation to Formic Acid (I) The Effect of Functionalizing Group and Additive on the Catalyst Performance Catal. Commun. 2004, 5,643-646. 

Fig. 8.12 Amount of acid sites of the SixZri-xOisupports in comparison with the Fe oxide covered surfaces, determined by 2-phenylethylamine probe (S, pure silica, and SZ-X, silica-zirconia oxides with 5 < X < 45 zirconia mass concentration) (from Ref [23])...

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