Synthesis of bifunctional Pt/MgAPO-5 catalysts and their catalytic performance in the hydrogenation of nitrobenzene to p-aminophenol

MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al₂O₃ ratio. The samples were characterized by XRD, SEM, solid state NMR, FT-IR and NH₃-TPD. Using MgAPO-5 as acidic supports, bifunctional Pt/MgAPO-5 catalysts were prepared for hydrogenation of nitrobenzene to p-aminophenol (PAP). The results showed that the MgO/Al₂O₃ ratios influenced the Mg content and the acidity of MgAPO-5 samples, thereby greatly affecting the catalytic performance of Pt/MgAPO-5 catalysts. The selectivity to PAP over Pt/MgAPO-5 was dependent on the amount of strong acid sites of MgAPO-5. When the MgO/Al₂O₃ molar ratio was 0.5, the synthesized MgAPO-5 sample exhibited the largest amount of strong acid and a highest PAP yield of 41.1% was achieved over Pt/MgAPO-5 catalyst.