01865nas a2200241   4500008004100000022001400041245009100055210006900146260007400215300001200289490000700301520101100308653002301319653002301342653001401365653001901379653002501398653002401423100002101447700002201468700001801490856011501508       2009                        eng d  a0928-070700aSynthesis of Si-MCM-41 from ternary SiO2-CTAOH-H2O system via dry gel conversion route0 aSynthesis of SiMCM41 from ternary SiO2CTAOHH2O system via dry ge  aVAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDSbSPRINGERcAUG  a244-2500 v513 a<p>Steam assisted dry gel conversion method was employed for the synthesis of Si-MCM-41 from ternary SiO2:CTAOH:H2O systems wherein fumed silica was used as a source of silica. The influence of synthesis time, molar ratios of CTAOH/SiO2 in dry gel and the water content at the bottom of autoclave on the quality and formation of mesophases has been investigated. Powder XRD, N-2 adsorption-desorption, TEM and hydrothermal stability test were the techniques used for sample characterization. Keeping molar ratio of CTAOH/SiO2 constant, shorter synthesis time, lower unit cell parameter and d spacing were observed when steam assisted dry gel conversion method was employed in place of conventional hydrothermal method. There exists an optimum lower limit for water content at the bottom of autoclave for reducing the synthesis period. Keeping synthesis temperature and CTAOH/SiO2 molar ratio fixed, Si-MCM-41 with improved hydrothermal stability was obtained by steam assisted dry gel conversion route.</p>10aDry gel conversion10apowder diffraction10aSi-MCM-4110aSol-gel growth10aStructural stability10aTextural properties1 aTaralkar, U., S.1 aNiphadkar, P., S.1 aJoshi, P., N.  uhttp://library.ncl.res.in/content/synthesis-si-mcm-41-ternary-sio2-ctaoh-h2o-system-dry-gel-conversion-route-002426nas a2200241   4500008004100000022001400041245013100055210006900186260006900255300001200324490000800336520150300344653002001847653002301867653002601890653001101916100002801927700002701955700002601982700002202008700002502030856012902055       2009                        eng d  a0254-058400aTin-silicalite-1: synthesis by dry gel conversion, characterization and catalytic performance in phenol hydroxylation reaction0 aTinsilicalite1 synthesis by dry gel conversion characterization   aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcMAR  a344-3490 v1143 a<p>Tin-silicalite-1 (Sn-MFI) has been successfully synthesized by dry gel conversion (DGC) method. The influence of various synthesis parameters such as crystallization time, temperature, water content at the bottom of autoclave, molar ratios of (TPA)(2)O/SiO(2) and SiO(2)/SnO(2) in dry gel on the crystallization kinetics and physico-chemical properties of Sn-MFI materials has been investigated. Powder-X-ray diffraction (XRD),XPS,AAS, DRUV-vis and SEM techniques were employed as characterization tools. Time-dependent studies revealed that, the progressive crystallization of Sn-MFI depend not only on the synthesis time but also on the other various synthesis parameters. Increase in the crystallization temperature, water content at bottom of autoclave (TPA)(2)O/SiO(2) and SiO(2)/SnO(2) molar ratios in dry gel resulted in the lowering of overall crystallization period. A good correspondence between the chemical composition of the surface and the bulk indicated the uniform distribution of Sn(4+) ions. The presence of these ions in tetrahedral coordination has been indicated by DRUV-vis spectral studies. Although, not better but comparable activity has been shown by Sn-MFI prepared by dry gel conversion method with Sn-MFI prepared by conventional hydrothermal crystallization method in the hydroxylation of phenol reaction. Increase in concentration of isolated Sn(4+) ions led to increase in phenol conversion and H(2)O(2) efficiency. (c) 2008 Elsevier B.V. All rights reserved.</p>10acrystallisation10aDry gel conversion10amicroporous materials10aSn-MFI1 aNiphadkar, Prashant, S.1 aKotwal, Mehejabeen, S.1 aDeshpande, Shilpa, S.1 aBokade, Vijay, V.1 aJoshi, Praphulla, N.  uhttp://library.ncl.res.in/content/tin-silicalite-1-synthesis-dry-gel-conversion-characterization-and-catalytic-performance-0