02373nas a2200241   4500008004100000022001400041245014100055210006900196260007300265300001200338490000700350520148000357653001401837653001101851653001601862653003201878653001401910100001601924700002001940700001801960700002101978856013201999       2007                        eng d  a1387-181100aOne step synthesis of chromium-containing periodic mesoporous organosilicas and their catalytic activity in the oxidation of cyclohexane0 aOne step synthesis of chromiumcontaining periodic mesoporous org  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB  a334-3440 v993 a<p>Chromium-containing ethane-bridged hybrid mesoporous materials (Cr-PMO) with uniform hexagonal arrangement were synthesized by two different synthesis routes using 1,2-bis(triethoxysilyl)ethane (BTEE) and tetraethyl orthosilicate (TEOS) as silica sources and alkyltrimethyl ammonium salts (ATMA) as surfactants. Powder X-ray diffraction, TEM, N-2 adsorption-desorption, FT-IR, in situ FT-Raman, UV-ViS, XPS, Si-29 MAS NMR and C-13 CP MAS NMR were used to probe the mesoporous structure and the nature of chromium sites in the hybrid catalyst matrix. PXRD, TEM and N-2 adsorption-desorption analysis showed that the original hexagonal structure of the materials is maintained after chromium substitution, while FT-Raman, UV-Vis and XPS analysis showed that chromium atoms exist in a highly dispersed state. The catalytic performance of the chromium-containing hybrid samples was tested in the liquid-phase oxidation of cyclohexane with aqueous hydrogen peroxide (H2O2) and non-aqueous tert-butylhydroperoxide (TBHP) as oxidants. The hybrid materials exhibited better catalytic activities and were more stable than the conventional Cr-MCM-41 catalyst. The higher catalytic activity of the new chromium-containing molecular sieves is attributed to the improved hydrophobicity of the materials and to the complementary structural features that facilitates the accessibility of cyclohexane to the active framework chromium sites. (c) 2006 Elsevier Inc. All rights reserved.</p>10aCr-MCM-4110aCr-PMO10aCyclohexane10ahybrid mesoporous materials10aOxidation1 aShylesh, S.1 aSrilakshmi, Ch.1 aSingh, A., P.1 aAnderson, B., G.  uhttps://library.ncl.res.in/content/one-step-synthesis-chromium-containing-periodic-mesoporous-organosilicas-and-their-catalytic02083nas a2200253   4500008004100000022001400041245011500055210006900170260005700239300001200296490000800308520123300316653001401549653001601563653001801579653001801597653001401615100001801629700001501647700001601662700001401678700001301692856012401705       2009                        eng d  a1011-372X00aCatalytic aerobic oxidation of cyclohexane and ethyl benzene over chromium-containing mesoporous organosilicas0 aCatalytic aerobic oxidation of cyclohexane and ethyl benzene ove  a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcOCT  a492-4990 v1323 a<p>Chromium-containing ethane-bridged hybrid periodic mesoporous organosilicas (Cr-PMO) were synthesized using 1,2-bis(triethoxysilyl) ethane (BTEE) and tetraethyl orthosilicate (TEOS) as silica sources and alkyltrimethyl ammonium salts as surfactants by two different synthesis routes. PXRD and N(2) adsorption-desorption analysis shows that the original structure of the materials is maintained after chromium substitution while spectroscopic study proves the incorporation of chromium in the frame wall positions and show the existence of Cr(2)O(3) species in the mixed silica source (BTEE-TEOS) synthesized chromium samples. The catalytic activity of the newly developed chromium samples was evaluated in the liquid phase oxidation of cyclohexane and ethylbenzene using air as an oxidant. Further, the Cr-PMO samples exhibited better cyclohexane conversion and cyclohexanone selectivity than the conventional Cr-MCM-41 and other metal-containing MCM-41 samples. The exceptional activity of the new chromium-containing molecular sieves is attributed to the hydrophobicity of the materials and to the complementary structural features that facilitates the accessibility of substrate to the active framework chromium sites.</p>10aCr-MCM-4110aCyclohexane10aEthyl benzene10aOrganosilicas10aOxidation1 aSingh, A., P.1 aTorita, N.1 aShylesh, S.1 aIwasa, N.1 aArai, M.  uhttps://library.ncl.res.in/content/catalytic-aerobic-oxidation-cyclohexane-and-ethyl-benzene-over-chromium-containing-0