STABILITY OF PT-CO BIMETALLIC PARTICLES - EFFECT OF THE SUPPORT INDUCED MORPHOLOGY ON REACTIVITY IN CO HYDROGENATION

The structure and the stability of bimetallic particles are controlled by their interaction with surface oxide species on support or by supp ort geometry. Location and size of the bimetallic particles estimated by XRD and XPS, depends on the environment and treatment. Thus, the Pt -Co bimetallic particles entrapped in NaY zeolite cages become unstabl e upon mild oxidation by O2 and/or reaction with surface protons causi ng the Co2+ ions formed to migrate irreversibly from the supercages in to the sodalite cages as determined by TPR and TPD. Differences in the selectivity pattern observed for the CO hydrogenation over alumina an d NaY zeolite supported Pt-Co catalysts, can be interpreted by the int eraction between bimetallic particles with surface cobalt oxide specie s and the zeolite cage wall, respectively.