Sulfur-doped porous carbon supported palladium catalyst for high selective o-chloro-nitrobenzene hydrogenation

Sulfur-modified carbon support can effectively modulate the performance of the metal catalyst. Here we prepared a sulfur-doped mesoporous carbon material (CSx) through carbonization of poly(sodium p-styrenesulfonate or p-styrenesulfonate co-maleate), which was supported with Pd and employed for the selective hydrogenation of o-chloro-nitrobenzene (o-CNB) to o-chloro-aniline (o-CAN). Such catalyst shows almost 100% selectivity of o-CAN at 100% o-CNB conversion (performed in a batch reactor: t = 210 min, No-CNB,0/mcat =0.63 mol/gcat). The stability (recyclability) study of the optimal catalyst shows that the catalyst can be reused for at least six times without decreasing the selectivity (100% conversion can be achieved with slightly prolonged reaction time). We suggest that the electronic effect between the S and Pd, which reduces the hydrogen adsorption and dissociation ability of Pd, to be responsible for the excellent selectivity, and the formation of C–S covalent bond to be responsible for the good stability.