II International Symposium on Carbon for Catalysis ABSTRACTS

OP-I-12
The carbon matrix avoids the formation of large Al 2 O 3 or TiO 2 crystallite in the
composite, as shown by XRD. XPS show that both organic and inorganic phases were nearly
independent, no significant interactions between them were observed. The carbon matrix, as
well Al 2 O 3 or TiO 2 oxides present similar XPS patterns than their pure phases. Their acidity,
determined by isopropanol decomposition depended on the nature of the metal oxide present
(TiO 2 ≥Al 2 O 3 ) while the organic fraction was not active.
Regarding to the hydrophilic character of the samples, two types of active sites were
determined by water adsorption at room temperature. The strong primary centres correspond
to the micropore filling or water adsorption on acidic centres and weak secondary centres
correspond to adsorption on hydrophilic (C=O) groups (2). Primary centres were more
abundant and stronger on composites than in carbon aerogels according with their more acid
character and smaller microporosity.
The activity order in toluene combustion was C1000Pt > TiC1000Pt > AlC1000Pt
(Figure 1). In previous works (1) we found that catalyst activity increase with Pt-particle size,
thus combustion is a structure sensitive reaction. In this sense, Al/C-Pt catalyst must be the
most active of this series. The large concentration and strength of primary water adsorption
sites on composite surface could be related with their smaller combustion activity.
Table 1. Textural characteristics and dispersion.
Figure 1. Catalysts activity
C1000Pt TiC100Pt AlC1000Pt
Sample Oxide SCO 2 V 2 V 3 d H2
% wt m 2 g -1 cm 3 g -1 nm
C-Pt 0 857 0.62 0.00 5.7
AlC-Pt 47 421 0.27 0.80 13.1
TiC-Pt 41 415 0.31 0.40 1.9
CCO2 (%)
100
80
60
40
20
0
150 170 190 210 230
T (ºC)
References
1 F.J. Maldonado-Hódar, C. Moreno-Castilla, A.F. Pérez-Cadenas; Appl. Catal. B. 54, 209
(2004)
2 F. Kraehenbuehl, C. Quellet, B. Schmitter, F. Stoeckly. J. Chem. Soc. Faraday Trans., 82,
3439 (1986)
61