01884nas a2200253   4500008004100000022001400041245011800055210006900173260007300242300001200315490000800327520094000335653002301275653002301298653002701321653002301348653002101371653002401392100001501416700001901431700002401450700002801474856012801502       2006                        eng d  a0926-860X00aTransesterification of cyclic carbonates with methanol at ambient conditions over tungstate-based solid catalysts0 aTransesterification of cyclic carbonates with methanol at ambien  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP  a108-1140 v3123 a<p>Dimethyl carbonate synthesis with 80 mol% yield is achieved through transesterification of ethylene carbonate with methanol at ambient conditions (RT and atmospheric pressure) using alkali and alkaline-earth tungstates as solid catalysts. The catalysts are efficient even at the sub-ambient temperatures. Reactions under CO2 pressure indicate that CO2 atmosphere retards the transesterification reaction completely below 100 degrees C. Experimental conditions of 150 degrees C and 3.4 MPa CO2 pressure are required to obtain maximum DMC yield of 71 mol%. Synthesis of DMC by one-pot synthesis using epoxide, CO2 and methanol is not as effective as that by two-step method with the present catalyst system. Raman and IR spectra of methanol-interacting tungstates indicate the formation of a methoxide ion species adsorbed at the catalyst surface as one possible reaction intermediates. (C) 2006 Elsevier B.V. All rights reserved.</p>10aDimethyl carbonate10aethylene carbonate10aheterogeneous catalyst10aRaman spectroscopy10asodium tungstate10atransesterification1 aSankar, M.1 aNair, Madhavan1 aMurty, K., V. G. K.1 aManikandan, Palanichamy  uhttps://library.ncl.res.in/content/transesterification-cyclic-carbonates-methanol-ambient-conditions-over-tungstate-based-001617nas a2200241   4500008004100000022001400041245007700055210006900132260007100201300001400272490000700286520077800293100001701071700002101088700001901109700002901128700001801157700002201175700001901197700002401216700003001240856010501270       2009                        eng d  a0897-475600aElectronic structure and catalytic study of solid solution of GaN in ZnO0 aElectronic structure and catalytic study of solid solution of Ga  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUL  a2973-29790 v213 a<p>Solid solutions of GaN in ZnO (Zn1-zGaz)(O1-xNx) (x and z &lt;= 0.15) have been prepared by simple solution combustion method, Except for minor changes in the lattice contraction, no significant change in the Wurtzite structure was observed. Raman and secondary ion mass spectrometry results show the direct Zn-N and Ga-N bonds in (Zn1-zGaz)(O1-xNx). Visible light absorption and XPS results demonstrate that N 2p states of nitride occupy the states above the O 2p valence band, and hence a change in optical band gap reduction occurs to similar to 2.5 eV from 3.37 eV for ZnO. Significant nitrogen fixation catalytic activity through NH3 formation has been observed at ambient pressure oil virgin (Zn1-zGaz)(O1-xNx) material, indicating its potential as a catalyst.</p>1 aMapa, Maitri1 aThushara, K., S.1 aSaha, Biswajit1 aChakraborty, Purushottam1 aJanet, C., M.1 aViswanath, R., P.1 aNair, Madhavan1 aMurty, K., V. G. K.1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/electronic-structure-and-catalytic-study-solid-solution-gan-zno-0