*3.2. Catalyst Preparation*

The supported catalysts were prepared by wet impregnation where the appropriate amount of the metal precursor (Ru, Mn, Fe, Cu or Ag) was dissolved in water, the corresponding support (alumina, silica, zirconia, spinel or HY zeolite) slowly added and the resulting suspension stirred for 3 h. Then the mixture was dried overnight at 80 ◦C followed by calcination at 450 ◦C for 6 h in static air to obtain the corresponding supported catalyst with a metal content of 1–5 wt.% corresponding to the amount of added metal precursor. All catalysts were stored in a desiccator and used without further activation.
