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24. Formation of carbon-copper complexes and their behaviours
294
Abstracts
24. Eiiagerungs- und oxydationsreaktionenals Hilfsmittel znr Charakter&rung des Ordnnngstandes von Graph&n H. P. 3oehm und D. Horn (Ins&& fiir anorganische Chemie der Unioersitiit,D-8000 Miinchen 2, Meiserstr. 1). Das Verhalten mehrerer Natur- und Konstgraphite unterschiedlichen Ordnungsgrades des Kristallgitters wurde bei der elektrochemischen Oxydation zum G~phits~z sowie bei der Tot~oxydation mit C~omschwefels~ure und mit Simons Reagens untersucht. Deutliche Unterschiede in der Reaktivitit lieSen sich feststellen. 21. Diibsiouskinetik van Metalien in Pyre- und Elektrographit W. Weisweiler (Ins~ifui fiir Chem~sche Technic der UniversitlitKarisruhe, D-7.500 Karlsruhe). Analogous to previously reported experiments on a typical electrograph&e, apparent diffusion coefficients for Ti, V, Cr, Nb, MO,and Hf as carbides and for elementary Fe, Ni, and Cu in highly ordered pyrolytic graphite have been determined as a function of heat ~eatment and crys~llo~aphic~ orientation. The concentration profiles of the elements penetration into the graphite were measured by an electron microprobe analyzer. For the evaluation of the diffusion coefficients a new method basing on probability graphs was employed. The product of diffusion coefficients and temper time DtU3 is found to be invariant and follows the Arrhenius equation. For all species investigated, the diffusion is twice as hiih in the direction of the graphite layers than perpendicular to them; the activation energy being Q, : Qc = 20.3 : 22.1 kcal/mole in comparison to Q = 18.6kcallmole for electro graphite. The fact that the frequency factors can be correlated with the heat of formation of the corresponding carbides as well as with atomic radii according to Pauling, allows an extrapolation to the apparent diffusion coefficients of other species in different types of carbon. 22. Untersuehungen zur C~sium~~~tion von Bre~element~~p~t A 3 E. Hoi&is und D. Stritzke (Hun-Meitner-Institut fiir Kemforschung Berlin GmbH,, Bereich Kemchemie und Reaktor, D-1000 Berlin-39). Cs-137 was applied to the
polished surface of specimens made from graphite type A 3 by flashing the tracer from a heated Pt-lament. The rates of desorption into vacuum have been measured as functions of heating rate and surface concentrations. The desorption process could be described using first order kinetics. The desorption curves showed two distinct peaks. One peak represents Cs-desorption from sites of uniform desorption energy (1SeV). The other peak contains a ~nt~uum of desorption energies (2.2-3.2 eV). 23. Untersuchungen zur Ciisium-ditbsion in BrennelementgraphitA3 W. Hensel und E. Hoi&is (Han-Meitner-Instifut fiir Kemforschung Berlin GmbH., Bereich Kemchemie und Rea~for, I&loo0 Berljn-39). Diffusion coe&ients for
Cs-137 in graphite type A3 have been determined in the temperature range 800-1150°C. Initially the specimens
were outgassed at 1450°C.A thin film (~0.1 monolayers) of Cs-137 containing a small amount of carrier was evaporated onto one of the end surfaces of each of two cyliidrical specimens. The specimens were placed, their radioactive faces in contact, within a resistance furnace and annealed at a known time and temperature. Outgassing of the specimens, the application of the tracer and the diffusion anneal were carried out in the same apparatus at a pressure
compiexes and t&ii
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C. Yokokawa, S. Wasaka and H. Oda (Department of Chemical Engineering, Faculty of Engineering, Kansai University, Suita, Osaka, 564, Japan). Hard carbon obtained from divinylbenzene-acrylic acid co-polymer (Amberlite IRCdO) was heated with an addition of cupric oxide at temperatures above 1500°C.In X-ray diffraction profiles obtained by use of CUKCY radiation two unknown diffractions at Bragg angle 20 of 45.3” and 46.6” appeared bseides the diffractions at 43.5” and 50.3”which originate from metallic copper. With an advance of heat-treatment of 45.3”d~raction increased in its intensity and the other three diffractions diminished. The carbon-copper complexes which had diffractions at 45.3” and 46.6” showed a mild catalytic activity for the hydrogenation reaction of acetone to 2-propanol at 200°C. The complex species which had only one diffraction at 45.3“seemed to be most reactive but after the hydrogenation reaction the 45.3“ diffraction decreased in its intensity and the other three appeared again. In the course of the heat-treatment, where the unknown diffractions are forming, the (002) diffraction of carbon increased in its intensity. In the case of the other type of hard carbon, i.e. activated carbon produced from woody material, similar phenomena were observed but there were no indication of growth of (002) of carbon. mt. ADSORPTION, SURFACE AND CHEMICAL REACTIONS 25. Auisotropie van synthetischen Graphiten F. Fischer (LONZA AG, CIAT-Labor, CH-5643 SINS). Vers~~edene Kohlenstoff-Mate~aliern wurden bei 1000°C verkokt und bei 2700°C graphitiert. Die erhaltenen Kokse und Graphite wurden gemahlen und zur weiteren Untersuchung wurde die Kornfraktion 40-80pm herangezogen. Die Anisotropie der Kokse wurde r&tgenographisch, die der Graphite mit Hilfe eines M~ok~o~eters bestimmt. Der Zusammenhang zwisthen Auisotropie, Dichte, spezifische Ober%che und Oxyreaktivitit wird diskutiert.
Abstracts
24. Eiiagerungs- und oxydationsreaktionenals Hilfsmittel znr Charakter&rung des Ordnnngstandes von Graph&n H. P. 3oehm und D. Horn (Ins&& fiir anorganische Chemie der Unioersitiit,D-8000 Miinchen 2, Meiserstr. 1). Das Verhalten mehrerer Natur- und Konstgraphite unterschiedlichen Ordnungsgrades des Kristallgitters wurde bei der elektrochemischen Oxydation zum G~phits~z sowie bei der Tot~oxydation mit C~omschwefels~ure und mit Simons Reagens untersucht. Deutliche Unterschiede in der Reaktivitit lieSen sich feststellen. 21. Diibsiouskinetik van Metalien in Pyre- und Elektrographit W. Weisweiler (Ins~ifui fiir Chem~sche Technic der UniversitlitKarisruhe, D-7.500 Karlsruhe). Analogous to previously reported experiments on a typical electrograph&e, apparent diffusion coefficients for Ti, V, Cr, Nb, MO,and Hf as carbides and for elementary Fe, Ni, and Cu in highly ordered pyrolytic graphite have been determined as a function of heat ~eatment and crys~llo~aphic~ orientation. The concentration profiles of the elements penetration into the graphite were measured by an electron microprobe analyzer. For the evaluation of the diffusion coefficients a new method basing on probability graphs was employed. The product of diffusion coefficients and temper time DtU3 is found to be invariant and follows the Arrhenius equation. For all species investigated, the diffusion is twice as hiih in the direction of the graphite layers than perpendicular to them; the activation energy being Q, : Qc = 20.3 : 22.1 kcal/mole in comparison to Q = 18.6kcallmole for electro graphite. The fact that the frequency factors can be correlated with the heat of formation of the corresponding carbides as well as with atomic radii according to Pauling, allows an extrapolation to the apparent diffusion coefficients of other species in different types of carbon. 22. Untersuehungen zur C~sium~~~tion von Bre~element~~p~t A 3 E. Hoi&is und D. Stritzke (Hun-Meitner-Institut fiir Kemforschung Berlin GmbH,, Bereich Kemchemie und Reaktor, D-1000 Berlin-39). Cs-137 was applied to the
polished surface of specimens made from graphite type A 3 by flashing the tracer from a heated Pt-lament. The rates of desorption into vacuum have been measured as functions of heating rate and surface concentrations. The desorption process could be described using first order kinetics. The desorption curves showed two distinct peaks. One peak represents Cs-desorption from sites of uniform desorption energy (1SeV). The other peak contains a ~nt~uum of desorption energies (2.2-3.2 eV). 23. Untersuchungen zur Ciisium-ditbsion in BrennelementgraphitA3 W. Hensel und E. Hoi&is (Han-Meitner-Instifut fiir Kemforschung Berlin GmbH., Bereich Kemchemie und Rea~for, I&loo0 Berljn-39). Diffusion coe&ients for
Cs-137 in graphite type A3 have been determined in the temperature range 800-1150°C. Initially the specimens
were outgassed at 1450°C.A thin film (~0.1 monolayers) of Cs-137 containing a small amount of carrier was evaporated onto one of the end surfaces of each of two cyliidrical specimens. The specimens were placed, their radioactive faces in contact, within a resistance furnace and annealed at a known time and temperature. Outgassing of the specimens, the application of the tracer and the diffusion anneal were carried out in the same apparatus at a pressure
compiexes and t&ii
bt!hdOlWS
C. Yokokawa, S. Wasaka and H. Oda (Department of Chemical Engineering, Faculty of Engineering, Kansai University, Suita, Osaka, 564, Japan). Hard carbon obtained from divinylbenzene-acrylic acid co-polymer (Amberlite IRCdO) was heated with an addition of cupric oxide at temperatures above 1500°C.In X-ray diffraction profiles obtained by use of CUKCY radiation two unknown diffractions at Bragg angle 20 of 45.3” and 46.6” appeared bseides the diffractions at 43.5” and 50.3”which originate from metallic copper. With an advance of heat-treatment of 45.3”d~raction increased in its intensity and the other three diffractions diminished. The carbon-copper complexes which had diffractions at 45.3” and 46.6” showed a mild catalytic activity for the hydrogenation reaction of acetone to 2-propanol at 200°C. The complex species which had only one diffraction at 45.3“seemed to be most reactive but after the hydrogenation reaction the 45.3“ diffraction decreased in its intensity and the other three appeared again. In the course of the heat-treatment, where the unknown diffractions are forming, the (002) diffraction of carbon increased in its intensity. In the case of the other type of hard carbon, i.e. activated carbon produced from woody material, similar phenomena were observed but there were no indication of growth of (002) of carbon. mt. ADSORPTION, SURFACE AND CHEMICAL REACTIONS 25. Auisotropie van synthetischen Graphiten F. Fischer (LONZA AG, CIAT-Labor, CH-5643 SINS). Vers~~edene Kohlenstoff-Mate~aliern wurden bei 1000°C verkokt und bei 2700°C graphitiert. Die erhaltenen Kokse und Graphite wurden gemahlen und zur weiteren Untersuchung wurde die Kornfraktion 40-80pm herangezogen. Die Anisotropie der Kokse wurde r&tgenographisch, die der Graphite mit Hilfe eines M~ok~o~eters bestimmt. Der Zusammenhang zwisthen Auisotropie, Dichte, spezifische Ober%che und Oxyreaktivitit wird diskutiert.