Ni-Silicides nanoparticles as substitute for noble metals for hydrogenation of nitrobenzene to p-Aminophenol in sulfuric acid

Abstract

The hydrogenation of nitrobenzene (NB) in acid medium is regarded as the most promising route to prepare p-aminophenol (PAP). The noble metals such as Pt have been reported as commercial catalysts but base metals are inactive due to strong acids needed in the reaction medium. Therefore, Ni-based catalyst has been attempted using solid acids, however, the results are not attractive. In this work, in order to improve the acid-resistance of Ni in sulfuric acid, we insert Si into the Ni crystal structure to form Ni-silicides. The as-prepared supported Ni-silicides nanoparticles exhibit excellent acid-resistance and perform high activity and selectivity of the entitled reaction. NiSi2 nanoparticles supported on acid-treated active carbon are highly active and selective to convert NB to PAP in sulfuric acid. The XPS measurements show that the Ni in the Ni-silicides donates electrons to silicon, but the Ni valence is still far lower than nickel oxide, which causes its stability in acids and the activity to hydrogen activation is partially reserved. Thus, the catalysts exhibit excellent stability in alloy structure, morphology, and catalytic performance in reuses, suggesting the Ni-silicides nanoparticles as the promising substitute for precious metal for PAP manufactures.