THERMODYNAMIC PROPERTIES OF SURFACE CARBON ON Ir-Ni CATALYST.

The thermodynamic properties of surface carbon on alumina-supported Ir-Ni have been determined from measurements of the Boudouard equilibrium in the temperature range from 525 to 675 K. The experimental data indicated the presence of carbon monoxide and carbon coadsorbed on the metal surface. The enthalpy of surface-carbon formation on Ir-Ni catalyst is slightly negative to graphite and insensitive to the fractional coverage with carbon. Surface composition measurements by means of Auger electron spectroscopy demonstrate considerable Ir enrichment on the surface of the Ir-Ni/Al//2O//3 catalyst.