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  • 1
    Digitale Medien
    Digitale Medien
    Kinetic study and modeling of the hetero-homogeneous pyrolysis and oxidation of isobutane around 800 K. Part I. Pyrolysis in an unpacked pyrex reactor (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 30 (1998), S. 425-437 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Isobutane pyrolysis is studied in an unpacked Pyrex reactor at 20-100 torr initial pressures and 750-793 K. Results are interpreted in terms of a long chain radical mechanism and the reaction is modeled. The reaction selectivity or ratio of the initial production rate of isobutene (or hydrogen) to that of propene (or methane) is practically given by the ratio of the rate constant of abstraction of a tertiary hydrogen atom of isobutane to that of a primary one. A sensitivity analysis clearly shows that self-inhibition is essentially due to methylallyl radicals produced by hydrogen abstraction from isobutene. The model has been manually adjusted to experimental results and most of the adjusted rate constants are in agreement with literature data. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 425-437, 1998
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Hetero-homogeneous pyrolysis of isobutane and platinum wall-effects in conditioned or unconditioned reactorsSpecial issue dedicated to Dr. R.A. Back. The Laboratory was honored to receive Bob and his wife Margaret during a sabbatical year in 1976. Since that time, numerous and fruitful exchanges were set up between Nancy and Ottawa and many strong and friendly ties were built which will last. (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 26 (1994), S. 141-146 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrolysis of isobutane has been studied at 500°C in a “Pyrex” static reactor packed with platinum. It is shown that both dehydrogenation and demethanat on rates are strongly depressed by the metal packing. The reaction rates are very sensitive to the amount of cabonaceous coating which is deposited on the walls. As this amount increases, both rates first increase, go through a maximum and decrease. These observations are compared with those previously made on propane pyrolysis in a “Pyrex” reactor packed with stainless steel. The present results are interpreted on the basis of a hetero-homogeneous chain mechanism in which the selectivity of the free-radical reaction is not altered referring to the unpacked reactor. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550260114
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Kinetic study and modeling of the hetero-homogeneous pyrolysis and oxidation of isobutane around 800 K. Part II. Pyrolysis in pyrex reactors packed with platinum foils or PbO-treated pyrex rods (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 30 (1998), S. 439-450 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Isobutane pyrolysis has been studied at 20-200 torr initial pressures and 773-793 K, in a packed reactor treated with PbO and in a reactor packed with platinum foils. These packings strongly inhibit product formation and this effect is explained by the occurrence of the heterogeneous termination step:\documentclass{article}\pagestyle{empty}\begin{document}$ \rm H\cdot\mathrel{\mathop{\relbar\joinrel\longrightarrow}^{walls}} product $\end{document}at the reactor walls. The reaction has been modeled in the temperature and pressure range on the basis of a kinetic scheme which has been proposed for the homogeneous reaction and step (w) with the following values of kw:$$\eqalign{(k_{_{w}})_{_{\rm{PbO}}}&=3.7\ 10^{8}\ \rm{exp} \left[-{9000\over \rm{T}}\right]\rm{S}^{-1}\cr(k_{_{w}})_{_{\rm{Pt}}}&=15000\ \rm{S}^{-1}\ \rm{at\ any\ temperature}\cr}$$for both types of packing. The corresponding sticking coefficients of hydrogen atoms are:$$\eqalign{\gamma _{_{\rm{PbO}}} &=160\ \rm{exp} \left[-{9000\over \rm{T}}\right]\cr\gamma _{_{\rm{Pt}}} &=0.03\cr}$$© 1998 John Wiley & Sons, Inc. Int J Chem. Kinet 30: 439-450,1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Kinetic study and modeling of the hetero-homo-geneous pyrolysis and oxidation of isobutane around 800 K. Part III. Pyrolysis-oxidation in unpacked and in pbO-coated packed Pyrex reactors (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 30 (1998), S. 657-671 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Isobutane pyrolysis has been studied in the presence of oxygen at about 773 K in unpacked and in PbO-coated packed Pyrex reactors. The reaction is shown to be accelerated by oxygen in reactors of low surface-to-volume ratio and strongly inhibited in packed PbO-coated reactors. These oxygen effects are explained in terms of interaction between two radical chain systems, one of pyrolysis, the other of oxidation. Oxygen introduces additional chain initiations and a degenerate chain branching step due to H2O2 while oxygenated radicals are efficiently removed at the reactor wall. All experimental results have been modeled and many rate constants of elementary steps were evaluated. The collision efficiency of HO2 radicals on a PbO-coated Pyrex surface has been determined in the temperature range of this study. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 657-671, 1998
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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