| Abstract: | Big variations in overall activity and product selectivity in the cyclopentane/deuterium exchange reaction were found in effect
of various pretreatments of two chlorine‐free Pd/γ‐Al2O3 catalysts. The most important changes are observed when severely prereduced (at 600 °C) Pd/Al2O3 catalysts have been reoxidised and mildly rereduced: the multiple type of exchange, typical of mildly pretreated Pd catalysts,
is replaced by a stepwise mode, and a big increase in catalytic activity occurs. At this state, the Pd/γ‐Al2O3 catalysts retain some water (as surface hydroxyls) generated by reoxidation and mild reduction. Deuterium spillover from
Pd onto alumina and changes in acidity of alumina are invoked to rationalize the kinetic results. Changes in the state of
Pd after various pretreatments, as probed by temperature‐programmed hydride decomposition, can hardly be correlated with changes
in the catalytic behaviour in the exchange reaction.
This revised version was published online in August 2006 with corrections to the Cover Date. |
