Browsing by Author "Kuhn, A. T."

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Electro-catalytic Reduction of Acetylene on Platinum
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (4), 1973) Byrne, M.; Kuhn, A. T.; Whittle, V. J.
The kinetics of the cathodic reduction of acetylene on platinized platinum in aqueous acid solutions are reported. The products are both ethylene and ethane. Tafel slopes, the reaction order in hydrogen ion and the enthalpy of activation have been determined by steady-state potentiostatic techniques combined with chromatographic analysis. The observed parameters in the reduction are compared and constrastcd with those of ethylene reduction reported previously. Tafel slopes, the potential dependence of the products, a limiting current and the pH effects are interpreted in terms of a r.d.s. between a strongly adsorbed organic species and adsorbed hydrogen.
Electro-catalytic Reduction of Ethylene on Gold and other Substrates
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Byrne, M.; Kuhn, A. T.
The kinetics and mechanism of the cathodic reduction of ethylene on gold, tungsten and a number of other materials is reported. Tafel slopes, reaction orders and isotope effects indicate a rate determining step (r.d.s.) between adsorbed ethylene and adsorbed hydrogen. Contrasts between the catalytic behaviour of platinum (reported previously) and gold are discussed and attributed to the different pH dependencies of the potential of zero charge values (p.z.c.) of these metals. Catalytic efficiencies of the several materials are reviewed in the light of theories of catalysis.
Electro-Catalytic Reduction of Ethylene on Platinum and Ruthenium
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (2), 1972) Byrne, M.; Kuhn, A. T.
The kinetics of the cathodic reduction of ethylene on platinum and ruthenium in aqueous acid and alkali solutions are reported. The reduction proceeds according to the stoichiometric equations C2H4+ 2H++ 2e → C2H6(acid), or C2H4+ 2H2O + 2e → C2H6+ 2OH–(alkali). Tafel slopes, reaction orders in hydrogen ion and ethylene together with temperature effects have been determined by steady state potentiostatic techniques combined with chromatographic analysis. Two types of limiting current were observed under different conditions (i) a limiting diffusion current and (ii) a reaction limiting current associated with ethylene desorption from the electrode which leads to a maximum in the (potential-current) plots. Steady state parameters taken in conjunction with coverage measurements obtained from linear anodic sweeps indicate that the overall rate of reaction is controlled by the step C2H4(ads)+ H(ads)→ C2H5(ads)