Semihydrogenation of Phenylacetylene Catalyzed by Palladium Nanoparticles Supported on Carbon Materials

Palladium catalysts were prepared supporting palladium colloids on three types of carbon supports:  multiwall carbon nanotubes (NTs), carbon black (CB), and an activated carbon (AC). These catalysts were tested in a reaction of great industrial interest such as the partial hydrogenation of phenylacetylene. The liquid-phase hydrogenation reaction of phenylacetylene was performed under very mild conditions (323 K, flow of H2 of 30 mL/min, 1 bar of pressure). The catalytic activities are very close to that of the homogeneous catalyst. A total conversion was achieved in all the Pd/C catalysts and also with very high selectivity toward styrene (higher than 95%). The carbon support produces differences between the catalysts. The AC provokes a Pd particle agglomeration, and the catalyst has the lowest activity and selectivity. The highest selectivity is obtained for the Pd/NT sample. The ease of manipulation of the Pd/NT catalysts is noteworthy, facilitating its recovery by filtration and its subsequent reutiliz...