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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 27 (1994), S. 323-336 
    ISSN: 1572-879X
    Keywords: Ni/Al2O3 catalysts ; surface saturation ; chemisorption ; ALE ; hydrogenation of toluene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ni/Al2O3 catalysts were prepared by saturating gas-solid reactions as an atomic layer epitaxy (ALE) process. Vaporized Ni(acac)2 was chemisorbed on a porous alumina support, and the produced surface complex was then air treated to remove the ligand residues. The nickel content could be precisely controlled by repeating this reactor cycle. On alumina preheated at 800°C, the nickel content varied from 3 to 21 wt%, when the number of reaction cycles was increased from one to ten. The performance of the Ni-catalysts was evaluated in the gas-phase hydrogenation of toluene. The preheat temperature of alumina influenced the activity of the catalyst, and a maximum in the activity was observed for catalysts prepared from alumina preheated at 875°C. Catalysts prepared by four reaction cycles, containing about 10 wt% nickel, gave the highest utilization of nickel.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 35 (1989), S. 471-481 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An interaction range analysis of electronic structures has been developed with density matrix approximation techniques. A successive error analysis of electronic interaction of differing ranges reveals clear pattrns. Aromatic hydrocarbons and heterocycles are used as examples. The developed technique is proposed to be used as an illustrative tool for the description of delocalization and as a guide for studies where delocalized systems are modeled by small subsystems.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 29 (1986), S. 1789-1797 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An approximate method for the calculation of the electronic structure of molecules has been developed. The principal approximations involve freezing of the atomic core orbitals, description of the core-valence interactions by density matrix expansion techniques, and the enforcement of the core-valence orthogonality by auxiliary bases and projection operator techniques. The general principle in the approximations is their stepwise execution. Each approximation can be separately relaxed and tested for reliability. The developed computational techniques have been described. A detailed analysis for the approximations is given for LiH. Other molecular test calculations include HCl, H2S, H2Se, and H2S2 molecules. The results demonstrate the suitability of the method for molecular studies.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 9 (1988), S. 581-590 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Hartree-Fock valence calculations have been used to study small ZnxSy, (x,y = 1-13), clusters. The aim was to develop surface models for chemisorption processes on zinc sulfide. The calculations show that proper models should have closed ring systems with x = y. The description of the adsorption site is not very critical to the size of the cluster. The coordination to the nearest neighbors is more critical and must be described accurately. The electronic structure was shown to be localized and a minimal basis set treatment gives a qualitative picture of energy and electronic structure trends. Zinc chloride is calculated to chemisorb to a surface sulfur atom with an adsorption energy of 395 to 570 kJ/mol depending on the size of the surface model and on the basis set of the valence orbitals. The adsorption geometry is found bent and virtually independent on the modelling parameters. The calculations predict free rotation of the adsorbate. The study suggests that calculations even at the simplest level are sufficient to give a qualitative picture of the zinc chloride adsorption on zinc sulfide.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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