02396nas a2200301   4500008004100000022001400041245009500055210006900150260007300219300001000292490000800302520135400310653002301664653001701687653004501704653001801749653001901767653002001786653004101806100002301847700002101870700001701891700001801908700001801926700001501944700001701959856011801976       2009                        eng d  a0926-860X00aCharacterization of clay intercalated cobalt-salen catalysts for the oxidation of p-cresol0 aCharacterization of clay intercalated cobaltsalen catalysts for   aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV  a16-230 v3703 a<p>The intercalation of cobalt-salen complexes into the interlamelar spaces of montmorillonite clay was investigated by various characterization studies. The ``neat'' cobalt-salen complex showed a weight loss at 368 degrees C while the weight loss for the corresponding intercalated complex was observed at much higher temperature of 492 degrees C due to decomposition of the complex. The thermal stabilization observed was due to the host-guest interaction of clay and metal complex and thus confirmed the intercalation. The XANES spectrum of Co(salen)-mont sample revealed the change of symmetry from the tetrahedral in plane to the octahedral structure having an axial bonding of oxygen to the cobalt, indicating that cobalt atoms in Co(salen)-mont were coordinated axially with the lattice oxygen of montmorillonite. Both XANES and EXAFS results indicated that cobalt atoms in Co(salen)-mont form two additional Co-O bonds with a bond length of 0.199 nm by the intercalation while retaining the Co-salen structure. Co-salen intercalated into the montmorillonite clay showed the highest activity for the air oxidation of p-cresol, giving 88% selectivity to the oxidation products. Effects of NaOH concentration and various solvents on the conversion and selectivity patterns also have been studied. (C) 2009 Elsevier B.V. All rights reserved.</p>10aCobalt-oxygen bond10aCobalt-salen10aExtended X-ray absorption fine structure10aIntercalation10aLattice oxygen10aMontmorillonite10aX-ray absorption near edge structure1 aKshirsagar, V., S.1 aGarade, Ajit, C.1 aMane, R., B.1 aPatil, K., R.1 aYamaguchi, A.1 aShirai, M.1 aRode, C., V.  uhttps://library.ncl.res.in/content/characterization-clay-intercalated-cobalt-salen-catalysts-oxidation-p-cresol-001946nas a2200229   4500008004100000022001400041245009200055210006900147260007300216300001200289490000700301520114400308653002701452653002001479653001201499653001601511100001401527700002101541700001501562700001701577856012201594       2013                        eng d  a0169-131700aMetal cation-exchanged montmorillonite clay as catalysts for hydroxyalkylation reaction0 aMetal cationexchanged montmorillonite clay as catalysts for hydr  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR  a141-1460 v743 a<p>Several solid acid catalysts were prepared by exchanging metal cations such as Zn2+, Fe3+ and Al3+ with montmorillonite clay. Among these, Al-montmorillonite showed the highest acidity determined by the pyridine-IR as well as NH3-TPD methods. A systematic comparison of the performance of these catalysts along with parent montmorillonite was carried out for the hydroxyalkylation of p-cresol with formaldehyde to give 2, 2'-methylenebis (4-methyl phenol) (DAM). It was found that the activity of these catalysts was in accordance with the increase in acidity of parent montmorillonite after the exchange of cations in the order of Zn2+, Fe3+ and Al3+. The selectivity pattern was also influenced by the exchanged cations. Since Al-montmorillonite showed the highest conversion of 51% with 98% selectivity to DAM, the effects of various reaction parameters, namely, mole ratio, catalyst concentration, temperature, reaction time on conversion and selectivity pattern were also studied using the same catalyst This catalyst also showed an excellent stability as evidenced by its eight times reuse. (C) 2012 Published by Elsevier B.V.</p>10aCations-exchanged clay10aMontmorillonite10aNH3-TPD10aPyridine-IR1 aJha, Ajay1 aGarade, Ajit, C.1 aShirai, M.1 aRode, C., V.  uhttps://library.ncl.res.in/content/metal-cation-exchanged-montmorillonite-clay-catalysts-hydroxyalkylation-reaction-0