Effect of Ge and CeO2 on Pt–Ge/Al2O3–CeO2 reforming catalysts

The preparation, characterization and catalytic properties of Pt/Al2O3, PtGe/Al2O3, Pt/Al2O3–CeO and PtGe/Al2O3–CeO2 catalysts are reported. Supports were prepared by impregnating commercial boehmite with cerium nitrate. The solids were calcined at 650 °C to obtain Al2O3–CeO2 mixed oxide supports. The catalysts were characterized by means of H2 and NH3 thermodesorption (TPD) measurements, FITR-pyridine and FTIR-CO adsorption spectroscopy. Cyclohexane dehydrogenation and n-heptane reforming reactions were used to evaluate the catalytic activity. It was found that the role of Ge in the bimetallic PtGe catalysts was to dilute the platinum conglomerates, diminishing the number of Pt total surface atoms and inhibiting the Pt hydrogenolytic properties. On the other hand, cerium oxide significantly modified the acidity of the cerium-containing supports. The PtGe/Al2O3–CeO2 catalyst showed a high selectivity towards isomerized olefins in the n-heptane reforming and a high resistance to self-deactivation. It is demonstrated that by inducing modifications to the alumina support, improved catalysts for n-heptane reforming can be obtained.