Enhancement of Pd–Pt/Al2O3 catalyst performance in naphthalene hydrogenation by mixing different molecular sieves in the support

The hydrogenation of naphthalene in hexane was carried out over the catalyst Pd–Pt supported on alumina mixed with different molecular sieves including ZSM-5, Beta, USY and SAPO-11. The catalyst was characterized by N2 sorption, NH3–TPD, TPR, and H2–O2 titration. The results indicated that the catalyst performance for naphthalene hydrogenation is related to its acid property, pore structure, Pd–Pt dispersion, and metal-support interaction, which may be well regulated by mixing proper molecular sieves in the alumina support. The catalyst Pd–Pt supported on a two-component support of Al2O3–SAPO-11 is provided with proper acidity, large pores and moderate metal dispersion; it exhibits excellent performance in the saturated hydrogenation of naphthalene to decalin (over it a complete conversion of naphthalene is observed and the selectivity to decalin exceeds 90% at 260–300 °C).