II International Symposium on Carbon for Catalysis ABSTRACTS

OP-I-12
INFLUENCE OF THE SUPPORT HYDROFOBICITY ON THE PERFORMANCE OF
COMBUSTION Pt –CATALYSTS
Maldonado-Hódar F.J., Carrasco-Marín F., Pérez-Cadenas A., Fairén-Jiménez D.,
Moreno-Castilla C.
Grupo de Investigación en Materiales de Carbón. Dpto. Química Inorgánica.
Facultad de Ciencias. Universidad de Granada. 18071. Granada. Spain
e-mail: fjmaldon@ugr.es
The catalytic combustion of volatile organic compounds from dilute stream is one of the most
interesting technological solutions to avoid air pollution. Noble metals, mainly Pt catalysts,
are the most active and selective, and both organic and inorganic materials have been used as
supports. Because the catalytic combustion must be developed at low temperature as possible,
saving energy and avoiding the by-products formation, hydrophilic inorganic supports can
adsorb the water generated by combustion blocking the catalyst active sites. Thus, we have
previously shown that hydrophobic Pt/C catalysts totally mineralize toluene and xylenes at
reaction temperatures sensibly lower than Pt/inorganic supports (1). However, increasing
reaction temperature this effect decreases, and carbonaceous supports become unstable in air
flow.
Therefore it is important to clarify the influence of support hydrophobicity on the catalysts
activity, which permits the development of the most adequate supports. The use of organicinorganic
composite materials prepared by sol – gel method can offer the advantages of large
porosity and surface areas but mainly guarantee the purity of the support, avoiding the
interferences of inorganic matter present in classical activated carbons. In this work we have
prepared, by impregnation, a series of Pt catalysts supported on carbon aerogel and on carbon-
TiO 2 , Al 2 O 3 composites. The combination of Pt (the most active catalysts) with the different
types of supports will permit to optimize the catalyst characteristics. Supported catalysts were
physically and chemically characterized, taking special attention to their porous, acidic and
hydrophilic character. They were used in the toluene combustion reaction and the results
related with the physical properties of the supports.
Carbon aerogel was mainly mesoporous, while composite aerogels were macroporous
(Table 1). The surface area of composite aerogels decreased about 50% regarding carbon
aerogel, indicating the low surface area of inorganic phase.
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