EFFECT OF THE SIZE OF PLATINUM PARTICLES ON THE CHEMISORPTION OF OXYGEN

An unambiguous particle-size effect has been observed in the desorption of oxygen from a faujasite-embedded platinum dispersion with distinctly different and narrow particle-size distributions. A kinetic analysis of the desorption spectra revealed a relative increase in the activation energy for desorption by about 60 kJ mol-1 as the Pt particle size decreased from 5 to 1 nm. A coverage-dependent activation energy has to be assumed for a consistent interpretation of the experimental results.