02597nas a2200229   4500008004100000022001400041245017300055210006900228260007300297300001000370490000800380520164400388653002602032653005202058653002202110653002602132653001302158100002602171700002202197700001802219856013002237       2007                        eng d  a0926-860X00aDecomposition and/or hydrogenation of hydrogen peroxide over Pd/Al2O3 catalyst in aqueous medium: factors affecting the rate of H2O2 destruction in presence of hydrogen0 aDecomposition andor hydrogenation of hydrogen peroxide over PdAl  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV  a70-780 v3323 a<p>Hydrogen peroxide destruction by its decomposition and/or hydrogenation to water in the presence of H-2 over Pd(5 wt.%)/Al2O3 catalyst in an aqueous reaction medium, similar to that used in the H-2-to-H2O2 oxidation, has been thoroughly investigated at different reaction conditions. The H2O2 destruction is strongly influenced by the oxidation state of Pd in the catalyst and also by the presence of different halide anions (viz. F-, Cl-, Br- and I-) in the acidic aqueous medium or in the catalyst, depending upon the concentration of halide anions. The cations associated with halide anions have, however, a little or no influence on the H2O2 destruction. The iodide anions strongly poisoned the catalyst, even at their very low concentration. The fluoride anions have only a small effect on the H2O2 destruction. The chloride or bromide anions drastically inhibit the rapid H2O2 decomposition, but promote the slower H2O2 hydrogenation. The H2O2 destruction reactions are strongly influenced by the halide anion and acid concentrations. The presence of acid (protons) plays a very important role in drastically reducing the H2O2 destruction, particularly in the presence of chloride anions. Both in the presence and absence of Cl- or Br- anions, the H2O2 destruction activity of the catalyst is markedly reduced because of the oxidation of Pd but it is drastically increased due to the presence of H-2. A plausible reaction mechanism for the rapid H2O2 decomposition and slower H2O2 hydrogenation reactions, prevailing under the different reaction conditions, has also been discussed. (C) 2007 Elsevier B.V. All rights reserved.</p>10adecomposition of H2O210ahalide anions as catalyst promoter or indicator10aHydrogen peroxide10ahydrogenation of H2O210aPd/Al2O31 aChoudhary, Vasant, R.1 aSamanta, Chanchal1 aJana, Prabhas  uhttps://library.ncl.res.in/content/decomposition-andor-hydrogenation-hydrogen-peroxide-over-pdal2o3-catalyst-aqueous-medium-001681nas a2200241   4500008004100000022001400041245018800055210006900243260009500312300001200407490000800419520068600427653002601113653004201139653002101181653002201202653001301224653000901237653002201246100002601268700001801294856012701312       2007                        eng d  a0021-951700aSynergetic effect of two halogen promoters present in acidic reaction medium or catalyst on the H2O2 formation (in H-2-to-H2O2 oxidation) and destruction over Pd/C (or Al2O3) catalyst0 aSynergetic effect of two halogen promoters present in acidic rea  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcMAR  a434-4390 v2463 a<p>A strong synergetic effect of two different halide anions (F- and I-, Cl- and I-, Cl- and Br-, and F- and Br-) at optimum concentration in the catalyst or in an acidic reaction medium was observed in the H-2-to-H2O2 oxidation over Pd/C, Pd/Al2O3, and halogenated Pd/Al2O3 catalysts. The synergetic effect promote, the net H2O2 formation by inhibiting the H2O2 decomposition and hydrogenation reactions. The effect is most pronounced for the combination of fluoride (or chloride) and iodide anions. The Br (1 wt%)-F (1 wt%)-Pd (5 wt%)/Al2O3 catalyst showed very high H2O2 yield (59%)/selectivity (60%) in the H-2-to-H2O2 oxidation. (c) 2006 Elsevier Inc. All rights reserved.</p>10aH-2-to-H2O2 oxidation10aH2O2 decomposition H2O2 hydrogenation10ahalogen promoter10aHydrogen peroxide10aPd/Al2O310aPd/C10asynergetic effect1 aChoudhary, Vasant, R.1 aJana, Prabhas  uhttps://library.ncl.res.in/content/synergetic-effect-two-halogen-promoters-present-acidic-reaction-medium-or-catalyst-h2o201585nas a2200217   4500008004100000022001400041245021000055210006900265260007300334300001400407490000600421520066000427653003001087653002201117653002901139653001301168653001401181100002601195700001801221856012801239       2008                        eng d  a1566-736700aDirect oxidation of H-2 to H2O2 over PdO/Al2O3 catalysts in aqueous acidic medium: influence on H2O2 formation of Pd loading, calcination temperature and reduction of catalyst and presence of halide anions0 aDirect oxidation of H2 to H2O2 over PdOAl2O3 catalysts in aqueou  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG  a2371-23750 v93 a<p>Effects of the Pd loading (0.2-10 wt%), calcination temperature (400-900 degrees C) and reduction of PdO/Al2O3 on its performance in the H-2-to-H2O2 oxidation (with H-2/O-2 = 1:1) in an aqueous 0.1 M H3PO4 medium, in the absence and presence of different halide anions, under ambient conditions have been investigated. The effect of calcination temperature on the H2O2 formation varied depending upon the Pd loading. The influence of the different halide anions was found to depend strongly on the nature of halide anion (F-, Cl-, Br- or I-) and the oxidation state of Pd and its loading in the catalyst. (C) 2008 Elsevier B.V. All rights reserved.</p>10ahalide catalyst promoters10aHydrogen peroxide10aoxidation of H-2 to H2O210aPd/Al2O310aPdO/Al2O31 aChoudhary, Vasant, R.1 aJana, Prabhas  uhttps://library.ncl.res.in/content/direct-oxidation-h-2-h2o2-over-pdoal2o3-catalysts-aqueous-acidic-medium-influence-h2o2-0