Hydrocarbon reactions on Pd-Re/Al2O3 catalysts

The reactions of n-hexane, 2,2-dimethylbutane and methylcyclopentane in exc ess hydrogen were studied on alumina-supported Pd-Re catalysts characterize d by medium metal dispersion. Palladium is much less active than rhenium in catalyzing alkane conversions, Even very small amounts of added rhenium to palladium cause big catalytic consequences. All Re-containing samples beha ve similarly, i.e. exhibit comparable activation energies (much lower than in the case of Pd/Al2O3) and a radical loss of isomerization capability. Ac cordingly, examination of these variables cannot effectively serve in probi ng Pd-Re surfaces. However, other useful 'fingerprints' have been recognize d, among which the fragmentation factor in alkane conversions and the 2MP/3 MP product ratio in methylcyclopentane reaction are the most valuable. Thei r profound specific variations with Pd-Re composition clearly suggest that rhenium interacts with surface palladium atoms. (C) 2001 Elsevier Science B .V. All rights reserved.