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Catalytic Reactivity (catalytic + reactivity)
Selected AbstractsA Feasibility Study of Wire-Woven Cellular Metal as Catalytic Support Material,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Byung-Chul Choi Wire-woven bulk Kagome (WBK) specimens were fabricated by wires made of Fecralloy, a Fe-Cr-Al alloy, and their feasibility as supports for an oxidation catalyst was investigated. For catalytic reactivity, the catalyst-coated WBK supports perform as well as the corresponding cordierite support, even though the WBK support has much lower flow resistance. Moreover, WBK is advantageous in terms of mass productivity, weight, durability and impact strength. The image shows a close-up view of the WBK support after heat treatment. [source] Catalytic hydrolysis of p -nitrophenyl picolinate by copper(II) and zinc(II) complexes of N-(2-deoxy-,-D-glucopyranosyl-2-salicylaldimino)INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 6 2002Xiang Yan D-glucosamine Schiff base N-(2-deoxy-,-D-glucopyranosyl-2-salicylaldimino) and its Cu(II) and Zn(II) complexes were synthesized and characterized. The hydrolysis of p -nitrophenyl picolinate (PNPP) catalyzed by ligand and complexes was investigated kinetically by observing the rates of the release of p -nitrophenol in the aqueous buffers at 25°C and different pHs. The scheme for reaction acting mode involving a ternary complex composed of ligand, metal ion, and substrate was established and the reaction mechanisms were discussed by metal,hydroxyl and Lewis acid mechanisms. The experimental results indicated that the complexes, especially the Cu(II) complex, efficiently catalyzed the hydrolysis of PNPP. The catalytic reactivity of the Zn(II) complex was much smaller than the Cu(II) complex. The rate constant kN showing the catalytic reactivity of the Cu(II) complex was determined to be 0.299 s,1 (at pH 8.02) in the buffer. The pKa of hydroxyl group of the ternary complex was determined to be 7.86 for the Cu(II) complex. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 345,350, 2002 [source] Ethylene polymerization behavior of Cr(III)-containing montmorillonite: Influence of chromium compoundsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2009Kazuhiro Yamamoto Abstract Montmorillonite was treated with Cr(NO3)3, Cr(acetate)3, and Cr(acac)3 to give three catalyst precursors, Cr-MMT-1, Cr-MMT-2, and Cr-MMT-3, respectively. Application of these catalysts to the ethylene polymerization reaction revealed Cr-MMT-1 to be much more reactive than the other two while the molecular weight distributions of the polymers were practically the same. Elemental analysis, XRD, and TEM measurements suggested that chromium occupied the interlayer section in Cr-MMT-1 and mostly the outer surface region for the other two catalysts. Aluminosilicate-supported Cr catalysts exhibited reactivity similar to that of Cr-MMT-2 and Cr-MMT-3. However, more of the low-molecular-weight polymer was formed. These data suggested that there is a relationship between the sites of the Cr ions and catalytic reactivity, and between supporting solid identity and molecular weight distribution of the polymer. The use of n -Bu2Mg and Et2Zn in the place of Et3Al led to lower activity but gave polymers of narrower molecular weight distribution, with more of the high-molecular-weight material. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2272,2280, 2009 [source] Kinetic simulation studies on the transient formation of the oxo-iron(IV) porphyrin radical cation during the reaction of iron(III) tetrakis-5,10,15,20-(N-methyl-4-pyridyl)-porphyrin with hydrogen peroxide in aqueous solutionLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 5 2003Tapan Kumar Saha Abstract High-valent oxo-iron(IV) species are commonly proposed as the key intermediates in the catalytic mechanisms of iron enzymes. Water-soluble iron(III) tetrakis-5,10,15,20-(N-methyl-4-pyridyl)porphyrin (Fe(III)TMPyP) has been used as a model of heme-enzyme to catalyse the hydrogen peroxide (H2O2) oxidation of various organic compounds. However, the mechanism of the reaction of Fe(III)TMPyP with H2O2 has not been fully established. In this study, we have explored the kinetic simulation of the reaction of Fe(III)TMPyP with H2O2 and of the catalytic reactivity of FeTMPyP in the luminescent peroxidation of luminol. According to the mechanism that has been established in this work, Fe(III)TMPyP is oxidized by H2O2 to produce (TMPyP)·+Fe(IV)=O (k1 = 4.5 × 104/mol/L/s) as a precursor of TMPyPFe(IV)=O. The intermediate, (TMPyP)·+Fe(IV)=O, represented nearly 2% of Fe(III)TMPyP but it does not accumulate in suf,cient concentration to be detected because its decay rate is too fast. Kinetic simulations showed that the proposed scheme is capable of reproducing the observed time courses of FeTMPyP in various oxidation states and the decay pro,les of the luminol chemiluminescence. It also shows that (TMPyP)·+Fe(IV)=O is 100 times more reactive than TMPyPFe(IV)=O in most of the reactions. These two species are responsible for the initial sharp and the sustained luminol emissions, respectively. 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