Influence of noble metals (Pd, Pt) on the performance of Ru/Al2O3 based catalysts for toluene hydrogenation in liquid phase

• Published in: Applied catalysis. A, General Vol. 525; pp. 41 - 49
• Main Authors: Suppino, Raphael Soeiro, Landers, Richard, Cobo, Antonio José Gomez
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.09.2016
• Subjects: Alumina; Catalyst activation; Formaldehyde; Noble metal; Toluene hydrogenation; Catalyst activation; Noble metal; Toluene hydrogenation; Alumina; Formaldehyde
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2016.06.038

[Display omitted] •Synergistic effects can be induced by adding Pt to Ru/Al2O3 catalysts prepared by wet impregnation and reduced by H2CO3.•Reduction by H2CO3 led to metallic species, whereas oxides were formed after H2 activation, notably on monometallic solids.•The addition of Pd or Pt seems to have promoted the reduction of Ru also inhibiting its oxidation on bimetallic catalysts.•The preparation method under mild conditions led to catalysts with small metallic particles and narrow size distribution. Catalytic hydrogenation of aromatic compounds is of great interest due to environmental aspects and the wide range of industrial processes involving such reaction. In this context, the present work aims to study the influence of Pd or Pt addition on the performance of Ru/Al2O3 based catalysts for toluene hydrogenation in liquid phase. For this, catalysts were prepared by wet impregnation from chlorinated precursors and reduced in liquid phase by formaldehyde (H2CO). After impregnation, a part of the catalysts were activated ex situ at 573K or in situ at 523K under H2. The studied solids were characterized by N2 physisorption, SEM+EDX, TEM, XPS and TPR techniques. Catalytic tests were conducted in a slurry Parr reactor at 373K under constant H2 pressure of 5MPa. Results show that solids reduction by H2CO led to metallic species, while the activation treatments form oxides and decrease the catalytic activity. The initial reaction rate of non-activated monometallic catalysts follows the order: Ru/Al2O3≫Pd/Al2O3≈Pt/Al2O3. A synergistic effect on the activity of Ru/Al2O3 based catalysts is induced by the Pt addition.