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

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 573 K or in situ at 523 K under H-2. The studied solids were characterized by N-2 physisorption, SEM + EDX, TEM, XPS and TPR techniques. Catalytic tests were conducted in a slurry Parr reactor at 373 K under constant H-2 pressure of 5 MPa. 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 approximate to Pt/Al2O3. A synergistic effect on the activity of RU/Al2O3 based catalysts is induced by the Pt addition. (C) 2016 Elsevier B.V. All rights reserved.