MgAPO-5-supported Pt-Pb-based novel catalyst for the hydrogenation of nitrobenzene to p-aminophenol

摘要

A series of MgAPO-5-supported Pt or bimetallic Pt-Pb catalysts of various Pt loadings were prepared for the hydrogenation of nitrobenzene (NB) to p-aminophenol (PAP). The structural modification and changes in the electronic properties of the catalysts were analyzed using temperature-programmed desorption of hydrogen, high-resolution transmission electron microscopy, and diffuse reflectance infrared Fourier transformation spectroscopy of the adsorbed carbon monoxide. Results show that Pb doping in Pt/MgAPO-5 catalyst decreases the hydrogenation rate of NB and phenylhydroxylamine simultaneously and increases PAP selectivity greatly. A possible reason for the improvement in the PAP selectivity of the Pb-Pt/MgAPO-5 is the increase in electron density of the Pt sites caused by the interaction of Pb and Pt. The decreased rate of NB hydrogenation over the modified Pb-Pt/MgAPO-5 catalyst can be improved considerably by increasing the reaction temperature or hydrogen pressure while maintaining a high PAP selectivity.