TPR, TPD and pulse adsorption methods may be employed in the character
ization of unsupported bimetallic catalysts. Correlation of the result
s obtained by the three methods affords the determination of ''real''
TPR profiles i.e. the hydrogen consumption assigned to the reduction o
f oxides or the lowering of the oxidation degree of the cations lying
on the surface (modification of their valence). The results are applie
d to Ni-Cr unsupported catalysts.