II International Symposium on Carbon for Catalysis ABSTRACTS

OP-I-6
CARBON SUPPORTED PLATINUM CATALYSTS: INFLUENCE OF ACTIVATION
TREATMENT OF A SYNTHETIC CARBON SUPPORT AND OF METAL
DEPOSITION IN THE SELECTIVE LIQUID PHASE OXIDATION OF ALCOHOLS
Korovchenko P., Donze C., Gallezot P., Besson M.
Institut de Recherches sur la Catalyse-CNRS 2 Avenue Albert Einstein 69626 Villeurbanne
Cedex France
e-mail: michele.besson@catalyse.cnrs.fr
Oxidations of alcohols into carbonyl functionalities are key reactions in the synthesis of
fine chemicals. The need to substitute stoichiometric oxidations (using mineral oxidants) with
“green” oxidations using benign oxidizing agents like molecular oxygen or hydrogen
peroxide has been often emphasized [1]. Supported noble metal catalysts, e.g. Pd/C or Pt/C
are known to catalyse the oxidation of alcohols in the presence of molecular oxygen.
It was previously reported that benzylalcohol (Bzol) can be very selectively oxidized to
benzylalcohol (Bzal) in dioxane, while the use of a 50/50 mixture of dioxane and alkaline
aqueous solution yielded benzoic acid (Bzoic) by further oxidation of Bzal [2]. In this work,
we examined the effect of the activation treatment of the synthetic carbon and of the method
of deposition of the metal on the characteristics of the supported metallic catalyst and its
activity in thi reaction.
Experimental
Synthetic carbon samples were activated carbons with controlled pore size. They were
prepared by carbonisation at 800°C of a porous polymeric resin precursor prepared from
Novolac resin and hexamethylenetetramine in polyethyleneglycol. The carbon particles thus
produced were spherical particles (50-90 µm). Then, they were activated by a “burn off”
technique using either CO 2 at 850°C (carbon noted xC) or air at 450°C (carbon noted xA),
with x = burn-off percentage (MAST). In some cases, the carbons activated under CO 2 were
oxidized with NaOCl before the cationic exchange (carbon note xC ox ).
Platinum deposition (nominal 3 wt. %) was performed by liquid phase impregnation
using H 2 PtCl 6 and in situ formaldehyde reduction in basic medium (noted imp) or by cationic
exchange with Pt(NH 3 ) 4 Cl 2 (noted ex) and reduction under hydrogen at 300°C.
Carbons were characterized by standard BET method, Boehm titration, TPD-MS.
Catalysts were characterized by Transmission Electron Microscopy (TEM) and by CO
chemisorption at 35°C. The catalytic activity of prepared catalysts was estimated using
oxidation of benzylalcohol to benzaldehyde or benzoic acid with air in a 250 ml batch reactor.
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