Hydrogenation of 1,3-butadiene on Pd/SiO2 in the presence of H2S -: Deactivation and reactivation of the catalyst

The deactivation of a Pd/SiO2 catalyst by H2S during the hydrogenation of 1,3-butadiene and its subsequent reactivation have been studied. The poisoning effect of H2S on Pd catalysts during C4H6 hydrogenation strongly decreased when the temperature of reaction was increased from 373 K to 508 K, due to the competition of butadiene for H2S chemisorption sites. The presence of H2S on the Pd sites causes an important decrease in the selectivity of the catalyst for a given conversion level. On the other hand, the irreversible adsorption of butadiene on Pd gives rise to an additional deactivation, and also to an increase in the observed selectivity. Reactivation of pre-poisoned catalysts can be performed at temperatures starting from around 400 K. The rate of sulfur desorption leading to catalyst reactivation strongly depends on the reaction atmosphere during the reactivation period, as well as on the temperature. During the reactivation stage, a high selectivity to butenes was observed, in spite of the presence of sulfur. (C) 1997 Elsevier Science B.V.