Interaction of saturated hydrocarbons with rhenium powder catalyst

Abstract

Hydrogen–deuterium exchange in methane, ethane and propane, hydrogenolysis of ethane, n-butane and isobutane and chemisorption of methane and ethane have been studied on rhenium powder catalysts.

The kinetic isotope effect and the rate sequences of the exchange reactions mentioned above show that the rate limiting step is C—H bond dissociation.

Ethane hydrogenolysis overlaps ethane exchange at 523 K. The hydrogenolysis reaction order with respect to hydrogen is slightly positive for ethane and greater than unity for butane. Methane is the main product of butane hydrogenolysis. Hydrogen assisted thermal desorption of methane produced from chemisorbed ethane evolves a peak with a maximum at 560–570 K, similar to the thermal desorption peak of methane. Therefore a strong, multiple metal–carbon bond is involved in rhenium–saturated hydrocarbon interaction, C—C bond breaking takes place easily but desorption of the reaction products is hindered.