Characterization hydrogen-oxygen titration

As for all catalysts, well-characterized samples are necessary to be able to relate the catalytic performance to physico-chemical properties. Transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAFS) were used in this study to characterize the stabilized metal colloid. The necessity of such extensive characterization of particle size has been outlined by Harada et al. [6,7] showing that the formation of aggregates may be overlooked and misinterpreted as large metal particles when using TEM alone. The actual availability of the polymer stabilized surface has been probed by hydrogen/oxygen titration adopted from the description of Bernard et al. [8]. 

In this paper we describe the preparation, characterization and the catalytic properties of polymer stabilized Rh particles for hydrogenation of 4-fert-butylphenol. The combination of TEM, XAFS and a newly developed liquid phase hydrogen/oxygen titration technique is applied to characterize particle size and availability for the reactants. 

The catalysts were characterized using the following techniques BET siuface area measmement, gas porosimetry, hydrogen-oxygen titration, carbon monoxide chemisorption, scanning electron microscopy, and X-ray diffiaction. Prior to characterization, the entire monoliths were crushed and sieved to a particle size less than 250 pm (60 mesh). 

Characterization of Supported Metal Catalysts. - Chemisorption of different probe molecules and Temperature Programmed Reduction (TPR) studies are frequently used to study the metal dispersion, surface composition and oxidation state of metals in mono- and bimetallic supported catalysts. Combined use of CO, hydrogen and oxygen chemisorption as well as oxygen-hydrogen titration can provide information about the dispersion and surface composition of metal nanoclusters. TPR studies of bimetallic catalysts can give information about the type, the reducibility, and the oxidation state of metal components. In addition, the position of TPR peaks can be used to characterize the type of interactions of the metal species in the catalysts. - ... 

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