II International Symposium on Carbon for Catalysis ABSTRACTS

OP-I-4
PREPARATION AND CHARACTERISATION OF DISPERSED PALLADIUM
CATALYSTS SUPPORTED ON CARBON PREVIOUSLY TREATED WITH
DIFFERENT STRONG OXIDANTS
Santacesaria E., Cozzolino M., Balato V., Tesser R., Di Serio M.
University of Naples “Federico <strong>II</strong>” – Dept. of Chemistry – Laboratory of Industrial
Chemistry Via Cintia – Complesso M.te S. Angelo – 80126 Napoli (Italy)
e-mail: santacesaria@chemistry.unina.it
It is well known that carbon is a useful support to obtain dispersed palladium catalysts. The
interaction of palladium precursors with the carbon surface is mainly given by the oxygenated
groups existing on the surface such as: lactones, carboxylic, carbonilic and phenolic groups.
These oxygenated groups can strongly be increased by oxidation [1, 2] with oxygen but also
by contacting the carbon surface with a solution of strong oxidant such as: permanganate,
hydrogen peroxide or nitric acid [3]. It is possible, by using titration methods [1] to evaluate
the distribution of the different sites on the surface.
Different catalysts have been prepared by supporting palladium acetate on carbon treated with
four different oxidants dissolved in water, that is: potassium permanganate 0.1 M and 1 M,
nitric acid 0.1 M, sodium hypochlorite 8% by weight, hydrogen peroxide 12 and
120 volumes. Prepared supports have been characterised, first of all, for what concerns the
determination of the concentration (mmols/g) of respectively the carboxylic and of the
hydroxyls group on the surface. The obtained values have then been compared with the initial
concentrations for the untreated carbon. The obtained results are reported in Tab. 1.
Carbon support pretreatments Conc. of
-COOH groups
Conc. of
-OH groups
Dispersion %
for 1% Pd
catalysts
Reaction rate
(ml/h g of
Pd)
Untreated carbon 0.16 0.05 56 12.24
Carbon + KMnO 4 (0.1 M) 0.83 0.39 56 19.24
Carbon + KMnO 4 (1.0 M) 1.21 0.88 54 (3% Pd) 13.71
Carbon + HNO 3 (0.1 M) 0.27 0.15 69 19.24
Carbon + NaClO (8% b.w.) 0.16 0.05 60 15.75
Carbon + H 2 O 2 (12 vol.) 0.16 0.05 72 20.12
Carbon + H 2 O 2 (120 vol.) 0.27 0.26 48 5.90
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