Hydrocarbon fuel synthesis from sorbitol over bifunctional catalysts: Association of tungstated titania with platinum, palladium or iridium

International audienceTo selectively transform sorbitol into hydrocarbons in aqueous phase, new bifunctional catalytic systems are designed by associating a hydrogenating metallic catalyst (M/ZrO2, M = Pt, Ir or Pd) and a dehydratingacidic catalyst (TiO2–WOx) in a mechanical mixture. Zirconium oxide was chosen as support because ithas virtually no dehydration activity and gives a good stability to the metal in water. This stability isevaluated through several characterizations before and after contact with the aqueous reaction medium.It is proposed that stability in water is driven by two parameters. The support stability is a key parameterfor the overall catalyst stability, and the metal–support interaction determines the sintering extent. Thenature of the metal has also an important influence on the activity and selectivity of the bifunctionalM/ZrO2+ TiO2–WOxsystem for sorbitol transformation. Pd and Ir are slightly active and mainly trans-form sorbitol into isosorbide, whereas Pt is selective for long-chain alkane production. The mass ratiobetween metallic and acidic catalysts in the mechanical mixture also modifies the yield structure, witha Pt/ZrO2:TiO2–WOx20:80 ratio for optimal liquid hydrocarbons production