On the catalytic properties and structure of small platinum particles supported on graphite

The crystallographic structure of small platinum particles was studied and correlated with their catalytic activity. The platinum particles are found to be fcc cubo-octahedra with either a (111) or a (110) face in contact with the basal graphite plane. Particles appear in well-defined azimuthal orientations on the surface which indicates the strong nature of their interaction with the substrate. The catalytic properties are studied using the conversion of neopentane as a test reaction. An interesting correlation between the number of B₃ sites on (111) faces of the cubooctahedral particles and the selectivity for neopentane conversion is reported. The findings are in agreement with an early model of isomerization proposed by M. Boudart, A. W. Aldag, L. D. Ptak, and J. E. Benson (J. Catal. 11, 35-45, (1986).