G. Cerrato, C. Morterra

Department of Chemistry IFM, University of Turin, via P. Giuria 7,1-10125 Turin, Italy 

Aim of the present contribution is the investigation of the surface chemical role played by the presence of Ce02 in some Pt catalysts supported on alumina, i.e., some model catalysts fairly similar to those actually working in three-way converters. 

Also the ambient temperature adsorption of H2 will be used for the characterization of the surface chemical features of Pt-containing systems in fact it has been long known that, of the various forms of adsorbed hydrogen, the strongly held one (i.e., the species irreversible at RT) corresponds to a dissociative adsorption, in which there is an H/Pt ratio of 1 1 [10]. The irreversible H2 uptake is thus a suitable tool for the evaluation of the noble metal dispersion. 

Physical, structural, and morphological characteristics of the various supports have been reported previously [6]. The corresponding features of the Pt-containing catalysts were determined by the usual means (i) BET areas with a conventional all-glass gas-volumetric appartus, using N2 uptake at 77 K and the t-plot method [11] (ii) crystal phases with XRD 

H2 and CO adsorption quantitative data were obtained in the form of adsorption isotherms (at 298 K) with an all-glass gas-volumetric apparatus the amounts of irreversibly adsorbed H2 and CO species were calculated as the difference between primary isotherms (overall uptake) and secondary isotherms (reversible uptake). 

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M. -Trung Tran, N. S. Gnep, G. Szabo, and M. Guisnet, Influence of the calcination temperature on the acidic and catalytic properties of sulphated zirconia, Appl. Catal. A 171, 207-217 (1998). P. Canton, R. Olindo, F. Pinna, G. Strukul, P. Rieflo, M. Meneghetti, G. Cerrato, C. Morterra, and A. Benedetti, Alumina-promoted sulfated zirconia system Structure and microstructure characterization, Chem. Mater. 13, 1634-1641 (2001). 

V. Bolis, G. Cerrato, G. Magnacca, C. Morterra, Surface acidity of metal oxides. Combined microcalorimetric and IR-spectroscopic studies of variously dehydrated systems. Ther-mochim. Acta312(1-2), 63-77 (1998). doi 10.1016/S0040-6031(97)00440-l Fubini B, Bolis V, Bailes M, Stone FS (1989) The reactivity of oxides with water vapor. Solid State Ionics 32-33, (Part 1 (0))258-272. doi 10.1016/0167-2738(89)90230-0 J.M. Newsam, M.M.J. Treacy, W.T. Koetsier, C.B.D. Gruyter, Structural characterization of zeolite beta. Proc. R. Soc. Lond. Math. Phys. Sci. 420(1859), 375 05 (1988). doi 10.1098/ rspa.1988.0131... 

V. Bolis, G. Cerrato, G. Magnacca, C. Morterra, Surface acidity of metal oxides. Combined microcalorimetric and IR-spectroscopic studies of variously dehydrated systems. Thermochim Acta 312, 63-77 (1998)... 

C. Morterra, G. Cerrato, andF. Pinna, Preparation and characterization of sulfated zirconia catalysts obtained via various procedures, Appl. Catal. A 176(1), 27 3 (1999). 

M. Signoretto, F. Pinna, G. Strukul, P. Chies, G. Cerrato, S. Di Ciero, and C. Morterra, Platinum - Promoted and Unpromoted Sulfated Zirconia Catalysts Prepared by a One - Step Aerogel Procedure, J. Catal. 167, 522-532 (1997). 

C. Morterra, G. Magnacca, V. Bolis, G. Cerrato, M. Baricco, A. Giachello and MFucale, in Catalysis and Automotive Pollution Control 111, Studies in Surface Science and Catalysis, vol. 96, A. Frennet and J.-M. Bastin Eds., Elsevier (Amsterdam) 1995, p. 361. 

Pinna F, Signoretto M, Struknl G, Cerrato G, Morterra C, Catal Lett 26 3-4, 1994. 

Morterra, C., Cerrato, G., Emanuel, C., Bolis, V. (1993). On the Surface Addity of Some Sulfate-Doped ZrCh Catalysts. Journal of Catalysis, Vol.142, No.2, (August 1993), pp. 349-367, ISSN 0021-9517... 

SIgnoreito M, Pinna F, Strukul G, Cerrato G, Morterra C PlaUnum promoted zirconia sulfate catalysts one pol Preparation, physical properties and catalytic activity. CaMfLerrl996,... 

Bolis, V., Magnacca, G., Cerrato, G., and Morterra, C. Effect of snlfation on the acid-base properties of teragonal zirconia. A calorimetric and IR spectroscopic study. Top. Catal 2002,19, 259-269. 

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