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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 16 (1992), S. 211-215 
    ISSN: 1572-879X
    Keywords: Lanthanum oxide ; oxidative coupling of methane ; oscillations ; unsteady reaction ; C2-hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Unsteady reaction behaviour with periodic fluctuations in reaction temperature and concentration indicating symmetric oscillations in the oxidative coupling of methane over La2O3 (obtained from lanthanum acetate by thermal decomposition in air at 600 °C and subsequently calcined in N2 at 750 °C) above 550 °C but below 700 °C has been observed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-879X
    Keywords: Propane ; aromatics ; acid catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The activity and selectivity of a mechanical Ga2O3/HZSM5 mixture in four model reactions (propane aromatization at 803 K,n-heptane cracking and meta-xylene isomerization at 623 K, methylcyclohexane transformation at 773 K) were compared after pretreatment at 873 K under nitrogen and under hydrogen flow. It was thus demonstrated that the hydrogen treatment provoked a significant increase in the dehydrogenating activity of the gallium species but only a small decrease in the protonic acidity. Moreover this hydrogen treatment created a significant hydrogenolysis activity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 22 (1993), S. 289-297 
    ISSN: 1572-879X
    Keywords: Methane oxidation ; NiO-rare earth oxide catalysts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract NiO-LnO x (Ln = lanthanide) catalysts (with Ni∶Ln=1∶1) without prereduction show high activity/selectivity and very high productivity in the oxidative conversion of methane to CO and H2. The catalysts are first activated in the initial reaction, which is started at 535–560°C, by the reduction of NiO and creation of active sites. The carbon deposition on the catalysts in the reaction, particularly for the NiO-Gd2O3, NiO-Tb4O7 and NiO-Dy2O3 catalysts, is quite fast but it has caused a little or no influence on the catalytic activity/selectivity. Pulse reaction of pure methane on NiO-Nd2O3 (at 600°C) shows involvement of lattice oxygen in the initial reaction and also reveals formation of carbon from CO on the catalyst reduced in the reaction.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 16 (1992), S. 269-272 
    ISSN: 1572-879X
    Keywords: Methane ; carbon monoxide ; hydrogen ; synthesis gas ; Co/rare earth oxide catalysts ; oxidation of methane to CO and H2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract CoO-rare earth oxide catalysts (particularly CoO-Yb2O3) show high activity and selectivity in the oxidative conversion of methane to CO and H2 with very high productivity at low temperatures (⩽ 700 °C as low as 300 °C).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 4 (1990), S. 101-106 
    ISSN: 1572-879X
    Keywords: Basicity ; base strength distribution ; solid catalysts ; step-wise thermal desorption of CO2 ; chemisorption of CO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Stepwise thermal desorption (STD) of CO2 with gravimetric analysis of the desorbed CO2 from 50–900 °C provides a simple and faster method for measuring total basicity and base strength distribution on basic solid catalysts under their operating conditions.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 15 (1992), S. 363-370 
    ISSN: 1572-879X
    Keywords: Methane conversion ; synthesis gas ; nickel-calcium oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Catalytic partial oxidation of methane over NiO-CaO (with or without its prereduction by H2) at low temperatures (⩽ 973 K) under non-equilibrium conditions yields syngas (H2/CO ratio ≈ 2.0) with high conversion/selectivity and extremely high productivity. If required, the H2/CO ratio can be increased by adding water vapour to the feed. Product selectivity is controlled by the process kinetics and also the reaction path is different from that observed for the high-temperature non-catalytic and catalytic processes operating at equilibrium.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-879X
    Keywords: Oxidative coupling of methane ; C2-hydrocarbons ; surface basicity ; promoted MgO catalysts ; Li-MgO ; Na-MgO ; PbO-MgO ; MgCl2-MgO ; CaCl2-MgO ; La-MgO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Addition of promoters, such as Li2O, Na2O, PbO, La2O3, MgCl2 and CaCl2, to MgO causes a large increase in its surface basicity (particularly strong basic sites) and catalytic activity/selectivity in oxidative coupling of methane, but the correlation between the basicity and C2-yield is poor, indicating that factors other than basicity are also important in deciding catalytic performance.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 36 (1990), S. 617-628 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung In einer Massepolymerisation bei 70°C wurden unter Anwendung von 0.2% Benzoylperoxid als Initiator fünf Kopolymerproben mit jeweils unterschiedlichen Molenbrüchen von Methylmethacrylat (MMA) bzw. 2-Ethylhexylmethacrylat (EHMA) hergestellt. Die Zusammensetzung der Kopolymere wurde mittels1H-NMR Spektroskopie ermittelt. Das Molekülgewicht der Kopolymere wurde durch Gel-Permeations-Chromatographic und Viskositätsmessungen bestimmt. Zur Ermittlung der Aktivierungsenergie für die Degradation der Kopolymere wurden thermogravimetrische Untersuchungen angestellt. Für den Masseverlust der Kopolymere wurden je 2 bis 4 Reaktionsschritte beobachtet. Bei steigendem EHMA-Gehalt konnte ein Abnehmen der thermischen Stabilität festgestellt werden.
    Notes: Abstract Five copolymer samples containing different mole fractions of methyl methacrylate (MMA) and 2-ethylhexyl methacrylate (EHMA) were prepared by bulk polymerisation at 70°C using 0.2% benzoyl peroxide as an initiator. The copolymer composition was determined by1H NMR spectroscopy. Molecular weight of copolymers was determined by gel permeation chromatography and viscosity measurements. Thermogravimetric experiments were conducted to evaluate activation energy for the degradation of copolymers. Two to four reaction stages for the weight loss were observed in the copolymers. A decrease in thermal stability was observed by an increase in EHMA content.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A simple and easy affinity purification of antibodies raised against a highly hydrophobic protein is described. This method employs silicalite zeolite, a solid matrix, to which prolamin is adsorbed. A rapid and sensitive immunoradiometric assay was developed to quantitate prolamin. Maximum prolamin in rice is present between 10 to 14 days post-anthesis.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 47-58 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Methylmethacrylat (MMA) mit einem Prepolymergehalt von 6-8% wurde mit unterschiedlichen Anteilen (1-20%) 2-Ethylhexylmethacrylat (EMMA), n-Hexylmethacrylat (HMA), 2-Ethylhexylacrylat (EHA) oder n-Hexylacrylat (HA) copolymerisiert. Aus den erhaltenen Copolymeren wurden Folien hergestellt, an denen der Einfluß der Copolymerstruktur auf Lichtdurchlässigkeit, Dichte und mechanische Eigenschaften ermittelt wurde. zugsfestigkeit and Speichermodul nahmen mit zunehmendem Comonomergehalt ab. Die Dehnung stieg im Fall von MMA/EHA- und MMA/HA-Copolymerfolien mit 15 und 20 Gew.-% Comonomeranteil merklich an. Mittels DMTA wurde die Erweichungstemperatur der Copolymeren bestimmt. Die HDT und die Erweichungstemperatur nahmen unter Biegebelastung mit steigendem Comonomergehalt de Copolymeren ab.
    Notes: The paper describes the fabrication of cast acrylic sheets by copolymerizing a prepolymer syrup of methyl methacrylate (MMA) with varying amounts (1-20 wt.-%) of 2-ethylhexyl methacrylate (EHMA), n-hexyl methacrylate (HMA), 2-ethylhexyl acrylate (EHA) and n-hexyl acrylate (HA). The effect of structure of copolymer on light transmittance, density and mechanical properties was evaluated. Tensile strength and storage modulus decreased with increasing comonomer content. Strain increased significantly in the case of MMA/EHA and MMA/HA copolymer sheets having 15 and 20 wt.-% of comonomer. Softening temperature of copolymer samples was determined using dynamic mechanical thermal analysis. Heat deflection temperature under flexural load and softening temperature decreased with increasing comonomer content in copolymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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