Cycloalkene hydrogenation over palladium catalysts

We have studied the hydrogenation of cyclopentene, cyclohexene, cyclohepten e, and cis-cyclooctene over Pd/alumina, Pd/carbon, Pd/silica, and Pd/zircon ia catalysts. The hydrogenation reaction and the carbon deposition reaction both showed evidence for particle size sensitivity. The trend in activity with particle size was not the same for all the cycloalkenes, with cyclohep tene hydrogenation increasing with particle size, whereas for the other cyc loalkenes tested, the activity maximised at approximately 3.5 nm. The origi n of these effects is suggested to be related to the mode and strength of a dsorption of the cycloalkene. (C) 1999 Elsevier Science B.V. All rights res erved.