Comparing Separation vs. Fresh Start to Assess Reusability of Pd/C Catalyst in Liquid‐Phase Hydrogenation

The reusability of metal catalysts is a key issue for the potential application of new catalysts in research and industrial practice. The most common procedure for testing catalyst reusability in liquid‐phase heterogeneous reactions is based on separating a catalyst from a reaction mixture followed by the next run. An alternative procedure called “fresh start” consists of the addition of a new portion of reagents to the reaction mixture without any isolation operation. In this work, we compare both procedures in a model Pd/C‐catalyzed hydrogenation with different heteroatoms, e. g ., O‐, S‐, and N‐vinyl derivatives. It was shown that regardless of whether the catalyst is stable or potentially poisoned during the reaction, both procedures lead to comparable results. It appears that a much easier implementation of a fresh start procedure may be an option of choice. The possibilities of using both procedures to rationalize the experimental protocol for assessing Pd/C catalyst reusability in liquid‐phase hydrogenations are discussed.