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Catalytic Effects (catalytic + effects)
Selected AbstractsCatalytic Effects of Metals on Direct Nitridation of SiliconJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2001Varong Pavarajarn Catalytic effects were investigated on the direct nitridation of silicon granules, impregnated with 0.125,2.0% by mass of calcium, yttrium, iron, copper, silver, chromium, or tungsten, in a stream of nitrogen with 10% hydrogen, using a tubular flow reactor operated at temperatures ranging from 1200° to 1390°C. Calcium and yttrium suppressed the formation of ,-silicon nitride while iron enhanced the formation of ,-silicon nitride over the temperature range investigated. An addition of 0.125% calcium resulted in about 99% overall conversion with 100%,-phase and a 2.0% yttrium addition yielded an overall conversion over 98% with an ,-phase content above 97%. Copper promoted not only the nitridation but the formation of ,-silicon nitride at 1200°C, but enhanced the ,-phase formation at higher temperatures. The role of liquid phases on the formation of ,-/,-silicon nitride was also discussed based on the nitridation of silicon impregnated with copper, calcium, silver, chromium, and tungsten. [source] Catalytic Effects of Metals on the Conversion of Methane in Gliding DischargesPLASMA PROCESSES AND POLYMERS, Issue 7-8 2007Krzysztof Schmidt-Sza, owski Abstract Plasma-catalytic methane conversion was studied under gliding-discharge conditions using a mobile (spouted) catalytic bed of fine particles. A new model of the GD reactor was tested for the non-oxidative methane coupling using alumina-supported catalysts containing Cu, Ni, Ag or Pt resistant against the plasma action. C2 hydrocarbons, besides hydrogen, were the main products, with some amounts of non-volatile substances (mainly soot). With Cu/Al2O3, Ni/Al2O3, Ag/Al2O3, and alumina beds, acetylene was mainly produced from the CH4,+,H2 mixture with none or a minor share of other C2 hydrocarbons. Using Pt/Al2O3, an increased ethylene and ethane content was found with lower acetylene content. [source] Catalytic Effects on Thermal Oxidation of Single-Walled Carbon Nanotubes by Alkali Metal ChloridesCHEMCATCHEM, Issue 4 2010Yuki Kobayashi The walled is not enough: Alkali metal chlorides lower the combustion temperature of single-walled carbon nanotubes by more than 100,K. Unlike ordinary reactions of nanotubes, the oxidation reaction in the presence of these salts is independent of the tube diameter, defects, and the degree of bundling. Furthermore, they produce no additional soot upon combustion. [source] Catalytic effects of copper oxides on the curing and degradation reactions of cyanate ester resinJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Shinn-Gwo Hong Abstract The catalytic effect of copper oxides on the curing and degradation behaviors of the cyanate ester resin is studied with infrared spectroscopy, attenuated total reflection infrared spectroscopy (ATR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The result of infrared spectroscopy and DSC analyses indicates that accelerated curing effects from different additives are in the order of zinc octoate > cuprous oxide > cupric oxide. The exothermic characteristics of the cyanate ester resin during cure are drastically affected by the presence of the copper oxides. In addition, it is obtained from TGA analyses that the thermal stability and degradation mechanism of cyanate ester resins are also significantly affected by the addition of copper oxides whereas the extent of degradation from the cupric oxide is greater than that from the cuprous oxide. These results are attributed to the differences in catalytic effects and surface areas of two copper oxides on the cyanate ester resin in contact during the thermal exposure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 442,448, 2007 [source] Catalytic Effects of Metals on Direct Nitridation of SiliconJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2001Varong Pavarajarn Catalytic effects were investigated on the direct nitridation of silicon granules, impregnated with 0.125,2.0% by mass of calcium, yttrium, iron, copper, silver, chromium, or tungsten, in a stream of nitrogen with 10% hydrogen, using a tubular flow reactor operated at temperatures ranging from 1200° to 1390°C. Calcium and yttrium suppressed the formation of ,-silicon nitride while iron enhanced the formation of ,-silicon nitride over the temperature range investigated. An addition of 0.125% calcium resulted in about 99% overall conversion with 100%,-phase and a 2.0% yttrium addition yielded an overall conversion over 98% with an ,-phase content above 97%. Copper promoted not only the nitridation but the formation of ,-silicon nitride at 1200°C, but enhanced the ,-phase formation at higher temperatures. The role of liquid phases on the formation of ,-/,-silicon nitride was also discussed based on the nitridation of silicon impregnated with copper, calcium, silver, chromium, and tungsten. [source] Catalytic effects of copper oxides on the curing and degradation reactions of cyanate ester resinJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Shinn-Gwo Hong Abstract The catalytic effect of copper oxides on the curing and degradation behaviors of the cyanate ester resin is studied with infrared spectroscopy, attenuated total reflection infrared spectroscopy (ATR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The result of infrared spectroscopy and DSC analyses indicates that accelerated curing effects from different additives are in the order of zinc octoate > cuprous oxide > cupric oxide. The exothermic characteristics of the cyanate ester resin during cure are drastically affected by the presence of the copper oxides. In addition, it is obtained from TGA analyses that the thermal stability and degradation mechanism of cyanate ester resins are also significantly affected by the addition of copper oxides whereas the extent of degradation from the cupric oxide is greater than that from the cuprous oxide. These results are attributed to the differences in catalytic effects and surface areas of two copper oxides on the cyanate ester resin in contact during the thermal exposure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 442,448, 2007 [source] Preparation and structures of a series of phosphorus-free Nickel(II) diamine complexes and their applications in hydrogenation of acetophenoneAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2010Zilu Chen Abstract To develop economical and phosphorus-free catalysts for hydrogenation of ketones, three new complexes, [Ni(1R,2R -dpen)2(H2O)Cl]2Cl2· 2Et2O (1), [Ni(1R,2R -dpen)(phen)(CH3OH)2]Cl2·2CH3OH (2) and [Ni(1,8-dan)2(DMF)Cl]2Cl2· 3H2O (3), and three reported compounds, [Ni(opda)(phen)Cl2]·CH3OH (4), [Ni(opda)2Cl2] (5) and [Ni(1,2-dach)2]Cl2 (6), were prepared and the structures of new compounds were determined by single crystal X-ray diffraction analysis, in which 1R,2R -dpen, phen, 1,8-dan, opda and 1,2-dach denote 1R,2R -1,2-diphenylethylenediamine, 1,10-phenanthroline, 1,8-diaminonaphthalene, o -phenylenediamine and 1,2-diaminocyclohexane, respectively. The catalytic effects for hydrogenation of acetophenone of these compounds were tested. This revealed very poor or no catalytic effects of these complexes in transfer hydrogenation of acetophenone using isopropanol or HCOOHNEt3 as hydrogen source. However, they presented much better catalytic effects in ionic hydrogenation of acetophenone using H2 gas as hydrogen source with a dependence of the catalytic effects on the base used in the hydrogenation reactions. The complexes represent a kind of green hydrogenation catalyst, although the conversion in the hydrogenation reactions is not as high as expected. Copyright © 2010 John Wiley & Sons, Ltd. [source] The Possible Influence of L -Histidine on the Origin of the First Peptides on the Primordial EarthCHEMISTRY & BIODIVERSITY, Issue 6 2006Hannes Reiner Abstract One of the most unsettled problems of prebiotic evolution and the origin of life is the explanation why one enantiomeric form of biomolecules prevailed. In the experiments presented in this paper, the influence of L -histidine on the peptide formation in the Salt-Induced Peptide Formation (SIPF) reaction of the enantiomeric forms of valine, proline, serine, lysine, and tryptophan, and the catalytic effects in this first step toward the first building blocks of proteins on the primordial earth were investigated. In the majority of the produced dipeptides, a remarkable increase of yields was shown, and the preference of the L - amino acids in the peptide formation in most cases cannot be denied. In summary, our data provide further experimental evidence for the plausibility of the SIPF reaction and point at a possible important role of L -histidine in the chemical evolution on the primordial earth. [source] ,-Cyclodextrin Incorporated Carbon Nanotube-coated Electrode for the Simultaneous Determination of Dopamine and EpinephrineCHINESE JOURNAL OF CHEMISTRY, Issue 3 2005Wang Ge-Yun Abstract An ,-cyclodextrin (,-CD) incorporated carbon nanotube (CNT)-coated electrode was fabricated and applied to the simultaneous determination of dopamine (DA) and epinephrine (EP). It has been found that the modified electrode shows strong catalytic effects on the electro-separation of DA and EP, and the cathodic potential difference between DA and EP is about 390 mV. The reducing peak current is proportional to DA and EP concentrations in the range of 2.0×10 -6,1.0×10 -3 and 1.0×10 -6,1.0×10 -3 mol·L -1, respectively. Their detection limits can reach 1×10 -6 and 5×10 -7 mol·L -1, respectively. Because the oxidation of ascorbic acid (AA) is an irreversible reaction in ,-CD/CNT film, the interference of AA in determination of DA and EP is eliminated. [source] | |||||||||||||