Hydrogen-oxygen titration

The surface and size of the metal particles after reduction were determined by gas chromatographic impulse titration in a flow system—for the platinum samples hydrogen-oxygen titration in nitrogen (7) was used, whereas chemisorption of oxygen in helium flow (8) was used for the nickel samples. Some samples were analyzed by electron microscopic examinations described in Ref. 9. 

Various research groups have used the hydrogen-oxygen titration method to determine dispersion (and possibly surface composition) although oxygen and chemisorption have also been used. Menon and... 

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. 

Tournayan, L. Charcosset, H. Frety, R. Leclercq, C. Turlier, P. Barbier, J. and Leclercq, G. "Hydrogen-oxygen titrations over platinum-rhenium and plati-... 

The uncertainty involving ascribing a specific value to the O Rh stoichiometry, at least for poorer dispersed catalysts, has implications when employing the hydrogen-oxygen titration method63 to determine dispersion where a value of x is required in determining the overall reaction stoichiometry ... 

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). 

Benson, J.E. and Boudart, M. (1965). Hydrogen-oxygen titration method for the measurement of supported platinum surface areas. J. Catal. 4, 704-710. Chui, G.K., Anderson, R.D., and Baker, R.E. (1979). Brazilian vehicle calibration for ethanol fliels. Proc. Ill Int. Symp. Alcohol Fuels Teclmol., Asilomar, California, May 28-31, Vol. II. 

Prasad, J., Murthy, K.R., and Menon, P.G. (1978). The stoichiometry of hydrogen-oxygen titrations on supported platinum catalysts. J. Catal. 52, 515-520... 

Sample Oxygen-hydrogen titration Hydrogen-oxygen titration ... 

The results of catalytic activity correlate very well with the free metal surface area (dispersion) obtained by hydrogen-oxygen titration cycles HOTC method. 

One valuable chemisorption technique is the hydrogen-oxygen titration reaction. First proposed by Benson and Boudart for Pt catalysts [59], it represents the titration of an oxygen monolayer by hydrogen near 300 K and its stoichiometry for Pt was predicted based on equations 3.1 and... 

Benson JE, Boudart M. Hydrogen-oxygen titration method for the measurement of supported platinum surface areas. J Catal. 1965 4 704. 

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