Size control of Pt nanoparticle catalysts for high-selectivity hydrogenation of nitrobenzene to p-aminophenol

Liquid-phase hydrogenation reaction of nitrobenzene to p-aminophenol (PAP) is investigated using a series of Pt-based catalysts, where activated carbon served as support and ethylene glycol (EG) as the reducing agent and solvent. Different platinum sources are employed to obtain Pt/C catalysts with different Pt metal particle sizes, as determined by transmission electron microscopy. The underlying mechanism of nitrobenzene selective hydrogenation on different size of Pt clusters have been systematically investigated. Characterization and catalytic tests show that the catalytic performance of the Pt-based catalyst is deeply influenced by particle size, where the size around 2.5 nm exhibits a suitable hydrogen absorption and activation ability, leading to the best catalytic performance. Under the optimal reaction conditions, the PAP selectivity reached 76.4 % and the conversion of NB reached 100 %. Moreover, the catalyst displayed strong recyclability with the PAP selectivity remaining above 70 % after five cycles of the catalyst, which would enable promising industrial applications.