The stability of these catalysts was analysed in three consecutive runs. An increase in the catalytic activity was observed from the first to the second reaction cycle. A possible explanation for this phenomenon could be the beneficial restructuring of the catalyst after the first run, as it has been pointed out by other authors. After that a gradual loss of activity was observed in successive runs. Pd leaching was negligible so that it can be excluded as a cause of deactivation. The formation of carboneous deposits seams to be most reliable explanation for the loss of activity. Elemental analyses of the used catalysts together with the C balances from the identified species support this conclusion. Research in course is addressed to elucidate the reaction mechanism and the phenomena causing catalyst deactivation.