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81.
82.
Effects of support and additive on oxidation state and activity of Pt catalyst in propane combustion 总被引:1,自引:0,他引:1
The effects of support and additive on the oxidation state and catalytic activity of Pt catalyst in the low temperature propane combustion were systematically investigated on Pt/MgO, Pt/Al2O3 and Pt/SiO2–Al2O3. The catalytic activity varied much with both support materials and additives. The catalyst on the more acidic support showed higher activity, and the catalytic activity on every support materials increased as the electronegativity of additives increased, while some additives decreased the activity. The oxidation state of platinum, estimated by white line intensity of Pt LIII-edge XANES spectrum, also varied with the support and additives, and additives with higher electronegativity greatly prevented the platinum from its oxidation under oxidising atmosphere. Among almost all the catalysts with various supports and various additives, a clear relationship was observed between the oxidation state of platinum and the catalytic activity; the more metallic platinum showed higher activity. Thus, it was concluded that the total electrophilic/electrophobic property derived from those of the support and additive controls the oxidation state of platinum, which intensively affects the catalytic activity; i.e. higher electrophilic property provides less oxidised platinum, resulting in high catalytic activity. The mechanism of this effect was also discussed on the basis of thermochemical data, and it was proposed that the electrophobic materials promote the noble metal oxidation since the noble metal oxo-anion such as PtOδ− is more stabilised with electrophobic cation. 相似文献
83.
Summary The synthesis of poly(-thiophenediyl)benzylidene (PTB) with high molecular weight is described. Number-average degrees of polymerization reached about 74. The characterizations of the polymer was investigated by 1H-NMR, 13C-NMR, IR, and UV-VIS spectra. The polymer with well-defined structure and high molecular weight was obtained by polymerization at low temperature and in polar solvent. This polymer was thermally stable and a thermal decomposition took place at 391°C under nitrogen and at 370°C under air. The glass transformation temperature was 117°C and this PTB was nonfusible. 相似文献
84.
Masahiro Takehara Ippei Yoshimura Kouichi Takizawa Ryonosuke Yoshida 《Journal of the American Oil Chemists' Society》1972,49(3):157-161
Long chain N-acylglutamic acid was prepared in a high yield by a reaction of glutamic acid with fatty acid chloride in a mixed
solvent of water and a water miscible organic solvent such as acetone, methyl ethyl ketone, dioxane, tetrahydrofuran,t-butyl alcohol or cyclohexanone. In this reaction the composition of the mixed solvent influenced the yield of N-acylated
glutamic acid and the best yield was obtained when the reaction was carried out in the mixed solvent comprising 30–60% v/v
of the organic solvent. Long chain N-acylaspartic acid was also obtained in a high yield by the same method. As the other
method to obtain N-lauroyl-D L-glutamic acid, it was examined that N-acyl-α-aminoglutarodinitrile which was obtained by a reaction of α-aminoglutarodinitrile
with fatty acid chloride was hydrolyzed with an aqueous alkaline solution. The salts of long chain N-acylglutamic acid are
known as the surface active agents that react mildly on the human skin. 相似文献
85.
Carbon spherules were formed from a mixture of polyethylene with 5–10 wt% Polyvinylchloride under pressure of 30 MPa. The spherules were embedded in a resin and thin-sectioned with a diamond knife. Alignment of small aromatic layers in the spherules was studied by transmission electron microscopy using dark-field image and microdiffraction techniques. Based on the obtained dark-field images at various positions of the aperture on the 002 diffraction ring, a structural model for the as-prepared spherules has been proposed. In this model small aromatic layers are assumed to align approximately on circular conical surfaces with a common vertex in the spherule at or near the center of the spherule. The proposed model is supported by an electron microdiffraction study of various micro-areas of sections of the spherules. The model is also consistent with the deformation of spherules into thick disks and formation of a definite system of cracks in heat-treatment to 2800°C as revealed by scanning electron microscopy. 相似文献
86.
87.
The catalytic effects of liquid metals for low-temperature (336 °C) asphalt-cracking have been examined using a semi-batch reactor. All the liquid metals examined (Bi, Cd, Ga, In, Pb and Sn) effectively catalysed the reduction of molecular weight with minimal gasification (<1 wt%). Gasification had a positive correlation with the reduction in molecular weight in the processed asphalts. The catalytic activities of liquid metals tor these two reactions were proportional to a parameter which represents the interaction between the atoms of the catalyst metal and the radicals formed in the course of the reaction. Mass flow among four fractions (saturates, aromatics, resins and asphaltenes) had two independent paths: conversion of resins to saturates and of aromatics to asphaltenes. The former path dominated when catalytic dehydrogenation activity was relatively low, whereas the latter dominated when the catalytic activity was high. 相似文献
88.
A new Ag/Al2O3 catalyst for removing NOx in lean exhaust gas was developed. Oxidized Ag/Al2O3 catalyst is highly active for reduction of NOx with ethanol and propene, whereas reduced Ag/Al2O3 catalyst is less active for these reactions. Selectivity to N2 is also high on the oxidized Ag/Al2O3 compared to that on the reduced Ag/Al2O3. XRD and SEM studies of these two types of Ag catalysts suggest that oxidation induces an interaction between Ag and the
support, where the particles are grown in large size. In contrast, the metallic Ag particles are finely dispersed by the reduction
process. Although dispersion of Ag particles is decreased by the oxidation process, the catalytic activity is increased. This
suggests that the Ag-alumina sites created in the high temperature oxidizing environment are active in catalytic reduction
of NOx.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
89.
The hexane-soluble fractions of hydroliquefied products from three Yallourn brown coal lithotypes have been separated into five fractions by combined silica-alumina packed column chromatography. Analyses of various fractions by g.c.-m.s. permitted the identification of ≈50 components in the saturate fraction and 40 components in the diaromatic fraction, together with 30 components in the monoaromatics. The components identified were quite similar among hexane-soluble portions of all three lithotypes. A marked predominance of even carbon number alkane (C23-C29) was observed in the hydrocarbon fractions from pale lithotype over , and medium light lithotype over both pure ZnCl2 and . However, medium dark lithotype over both melt catalysts produced a saturate fraction with an odd carbon number(C22-C28) preference. Based on spectral methods, Soxhlet extracts obtained from untreated lithotypes (hexane and benzene solubles) were characterized as complex mixtures of higher molecular weight(300–1000) aliphatic hydrocarbons, which were supposed to be a precursor of the saturates produced from the corresponding lithotype in the catalytic hydroliquefaction. 相似文献
90.
Hiromi Yoshida Mikiko Tatsumi Goro Kajimoto 《Journal of the American Oil Chemists' Society》1991,68(8):566-570
Effects of microwave heating on the oxidative stability ofd-tocopherols were studied in relation to the production of fatty acids in oils. During microwave heating, the stability of
tocopherols decreased in the orderδ>β>γ>α. This order did not depend on the types of ethyl esters of fatty acids or oils present. But, the shorter the chainlength
and the lower the degree of unsaturation of the fatty acid ethyl esters, the greater was the reduction in amount of individual
tocopherols. A similar tendency was observed when tocopherol-stripped vegetable oils, with equimolar mixtures of tocopherols
added, were treated under the same conditions. The reduction in tocopherols became greater with increasing levels of free
fatty acids. 相似文献