Pulse Microcatalytic Investment of Model Hydrogenation and Dehydrogenation on Platinum. Rhenium/ Aluminium Oxide Catalyst.
No Thumbnail Available
Ayo, Daniel. Babatunde.
University of Lagos
The hydrogenation and dehydrogenation of benzene, cyclohexene and cyclohexane were investigated on a 0.3% Pt- 0.3% Re on A1203 catalyst (catalyst (A)) using the pulse microcatalytic technique. Reactions were carried out in hydrogen and in nitrogen containing 0.66% oxygen (labelled N2/02) under the following conditions: 4 atmospheres total pressure, 500c to 4000c and 120 cm3 min -1. Kinetic data were obtained on clean, coked and CS2-poisoned catalysts. The theory of Sica et al (1) was applied to extract kinetic parameters. The activation energies were found to be identical for reactions carried out on coked, CS2-poisoned (at 3730c) and clean catalysts, thus suggesting that deactivation of catalysts by cs2 and coke occur predominantly by geometrical blockage of active sites. A slight enhancement of the selectively for hydrogenation of cyclohexene to cyclohexane over dehydrogenation to benzene by CS2 poisoning suggested that the poison also exerted some electronic effect on the reactions. The II-σ bond shift mechanism of Ruiz – Vizcaya et al (2) for the dehydrogenation of cyclohexane on Pt/Pd catalyst was found to account for most of the observed kinetic phenomena. The kinetic parameters determined by the pulse experiments were largely confirmed by continuous (plug) flow microreactor experiments. The order of reaction was found to be zero and the activation energy was found to be about 8 kcal / mole for benzene and cyclohexene hydrogenation to cyclohexane. For cyclohexane dehydrogenation, the order of reaction ranged between 0.7 to 0.9 while the activation energy varied more significantly.
Hydrogenation , Hydrogenation Reaction , Dehydrogenation , Hydrogen , Benzene , Cyclohexene , Cyclohexane
Ayo, D. B. ( 1985). Pulse Microcatalytic Investment of Model Hydrogenation and Dehydrogenation on Platinum. Rhenium/ Aluminium Oxide Catalyst. A Thesis presented to the University of Lagos in Partial Fulfilment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering.