共查询到20条相似文献,搜索用时 15 毫秒
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Vladimir N. Ignatov Francesco Pilati Corrado Berti Vittorio Tartari Claudio Carraro Giampietro Nadali Maurizio Fiorini Maurizio Toselli 《应用聚合物科学杂志》1995,58(4):771-777
Syntheses of poly(ethylene terephthalate), PET, by transesterification of dimethyl terephthalate with ethylene glycol in the presence of well-known catalysts and various lanthanide compounds were performed. Lanthanide catalysts appeared to be much more efficient in the first stage of the process (transesterification in the presence of an excess of ethylene glycol), and less active in polycondensation. PET produced with lanthanides was found to possess enhanced thermal and hydrolytic stability as compared to PET synthesized with well-known catalysts and commercial PET. © 1995 John Wiley & Sons, Inc. 相似文献
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本文采用不同的制备方法制备铜基甲醇合成催化剂,利用XRD、TPR、BET、SEM、TEM等技术手段对所制备催化剂的物相组成、物相结构、活性比表面、表面形貌、粒子大小进行了研究;并进行了活性评价。研究结果表明,用硝酸盐共沉淀法制备的催化剂,其性能和结构均优于用蒸氨法制备的催化剂。 相似文献
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J. Barrault S. Brunet N. Suppo-Essayem A. Piccirilli C. Guimon 《Journal of the American Oil Chemists' Society》1994,71(11):1231-1238
Copper chromite-type catalysts, supported by alumina or graphite and promoted with barium, were used for the onestep synthesis
of tertiary fatty amines [R2NCH3 or RN(CH3)2] from ester, acid or nitrile and ammonia, methanol and hydrogen. The surface composition of the catalysts, studied by X-ray
photoelectron spectroscopy and by adsorption experiments, showed that there was a correlation between selectivity and the
presence of a well-dispersed CuCrO2 phase, stabilized with barium. Moreover, the elements influencing the stability of the copper catalysts were also studied,
and the promoter or/and the support increased the copper surface area and the stability of the catalyst in the presence of
water or ammonia. 相似文献
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M. V. Bykova O. A. Bulavchenko D. Yu. Ermakov M. Yu. Lebedev V. A. Yakovlev V. N. Parmon 《Catalysis in Industry》2011,3(1):15-22
A series of Ni-containing catalysts supported on different materials has been tested in the hydrodeoxygenation of guaiacol,
a compound modeling the products of biomass fast pyrolysis. The reaction has been carried out in an autoclave at 320°C and
a hydrogen pressure of 17 MPa. The main guaiacol hydrodeoxygenation products are cyclohexane, 1-methylcyclohexane-1,2-diol,
and cyclohexanone (which result from aromatic ring reduction). A guaiacol conversion scheme explaining the formation of the
main products is suggested. The highest activity is shown by the Ni-containing catalysts on SiO2 and SiO2-ZrO2 supports prepared by the sol-gel method. According to X-ray diffraction and electron microscopic data, the high activity
of these catalysts is due to the high concentration of dispersed nickel as reduced films on the surface of the silicate structures.
The catalysts offer promise for refining the biomass fast pyrolysis products (bio-oil) into hydrocarbon fuel. 相似文献
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The development of new processes for the production of gaseous fuels from carbon-containing solids is essential in meeting the energy needs of the nation. In this paper, catalysed carbon gasification is examined. The change in the reactivity of the interface between gaseous reactant (hydrogen or steam) and solid carbon has been measured in the presence of various metal catalysts. With platinum it is found that over a range of temperatures the specific rate of methane production is of the same magnitude as the rate of hydrogen atomization. The catalytic effect is interpretable in terms of an enhanced rate of hydrogen dissociation on the metal surface, followed by surface diffusion across the metal/carbon interface and reaction with carbon. The gas formation rate during the interaction of water vapour with catalyst-activated carbons has been increased by more than an order of magnitude by depositing small weight fractions of active metal catalyst on the carbon surface. At the temperatures employed in this study (975–1175 K), carbon monoxide and hydrogen are the products of the catalysed reaction for each of the catalysts examined. 相似文献
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We have hydrothermally prepared and characterized a catalytically active tetrahedral aluminum species in faujasite distinct from the normal framework aluminum. The new tetrahedral species is formed after a severe steam dealummation at 830°C and is characterized by a27A1 MASNMR shift of about 53 ppm compared to the 60 ppm shift observed for framework tetrahedral aluminum. DRIFTS experiments show that the 53 ppm species is associated with a Lewis rather than a protonic site. This species is associated with strong acidity and poor cracking selectivity compared to a conventional dealuminated faujasite at the same unit cell size. This site is very active and makes large amounts of gas and coke with poor gasoline selectivity compared to typical commercial FCC catalysts. After an appropriate sequence of hydrothermal dealumination and controlled pH washing steps, the 53 ppm species is the only species observed by NMR. 相似文献
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M. Wejchan-Judek 《Polymer Bulletin》1986,15(2):141-145
Summary In the present work the synthesis of poly-/p-phenylene sulphide/ from thiophenol in the presence of various acidic catalysts has been investigated. Structural similarity of the obtained polymers to the polymer produced by Phillips Petroleum Co. was studied. 相似文献
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The condensation reaction of N-phenylhydroxylamine in the presence of clay catalysts was studied. The main products of this
reaction are azoxybenzene, aniline and nitrosobenzene. In contrast with the previously published results, p-nitrosodiphenylamine is not formed during the condensation reaction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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M. G. Meiramov 《Solid Fuel Chemistry》2014,48(2):123-128
A method for the preparation of a composite iron oxide catalyst on a carbon support is described in this work. The hydrogenation of model polyaromatic compounds in the presence of iron-containing catalysts was studied. 相似文献
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T. A. Khabas O. V. Nevvonen V. I. Vereshchagin 《Refractories and Industrial Ceramics》2005,46(1):71-75
Synthesis of mullite from a mixture of -Al2O3 + -SiO2 and native kaolin-based materials in the presence of nanodisperse aluminum is reported. In both cases, addition of nanodisperse Al increases the yield of mullite and stabilizes its structure.__________Translated from Novye Ogneupory, No. 11, pp. 28 – 33, November, 2004.For previous communications, see Novye Ogneupory, Nos. 7 – 10, 2004. 相似文献
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环己基苯经过氧化反应可生产苯酚和环己酮,还可以用作锂离子电池电解液的添加剂,也可用作柴油的十六烷值调和组分,是一种高附加值、有市场潜力的精细化学品。本文介绍了国内外通过苯与环己烯烷基化合成环己基苯及所用催化剂的研究进展,总结了苯加氢烷基化反应机理和反应路径的研究成果,包括加氢烷基化活性的来源、中间产物和碳正离子中间体的推断以及各反应产物的形成。通过对加氢烷基化机理的认识,回顾了加氢烷基化催化剂的设计思路和发展历程。最后指出可开发用于苯与环己烯烷基化的B酸型、B-L酸型以及固载化离子液体等新型催化剂。提出可借助最新的碳正离子研究手段对加氢烷基化机理进行补充完善,并认为可利用多级孔沸石作为加氢烷基化催化剂的酸性载体。 相似文献
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C. Okkerse A. de Jonge J. W. E. Coenen A. Rozendaal 《Journal of the American Oil Chemists' Society》1967,44(2):152-156
Many investigators associate the poor keeping properties of soybean oil with its linolenic acid content. On the other hand
the high linoleic acid content is a desired property from a nutritional point of view. We have therefore developed a process
for the preferential reduction of the linolenic acid content by selective hydrogenation. Conventional catalysts for the hydrogenation
of fats have a rather low selectivity in this respect. When linolenic acid in soybean oil is hardened (e.g., with a nickel
catalyst), most of the linoleic acid is converted into less unsaturated acids.
It was found that linolenic acid is hydrogenated much more preferentially in the presence of copper catalysts than in that
of nickel and other hydrogenation catalysts. At a linolenic acid content of 2%, soybean oil hardened with nickel catalyst
contained about 28% linoleic acid, whereas with copper catalyst the hardened soybean oil contained 49% linoleic acid.
By means of our process it is possible to manufacture a good keepable oil of, e.g., I.V. 115 and containing 1% linolenic acid
and 46% linoleic acid. The storage stability of this product is comparable with that of sunflower-seed oil. A liquid phase
yield of 86% is obtained after winterization at 5C for 18 hr.
The high selectivity for linolenate reduction of copper catalysts must be ascribed to the copper part of the catalyst. Investigations
into the structure of the catalyst indicate that the active center consists of copper metal crystallites; whether these centers
are promoted by the carrier or traces of other substances is under investigation. 相似文献
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