TRANSFORMATION OF CARBON-COMPOUNDS ON GRAPHIMET CATALYSTS .5. THE EFFECT OF PRETREATMENT ON THE STRUCTURE AND ACTIVITY OF PT-GRAPHIMET CATALYST

The effect of medium-temperature reduction (MTR, 573 K) on the structu re and catalytic activity of Pt-graphimet was studied by transmission electron microscopy, small angle X-ray scattering, O-2-H-2 titration a nd sorption microcalorimetry. The test reaction was the hydrogenation of cyclohexene, MTR resulted in the migration of interlayer platinum a toms to the catalyst surface, leading to metal aggregation and the for mation of additional inserted active sites responsible for increased O -2 and H-2 adsorption. The decrease in catalytic activity observed upo n MTR is attributed to the encapsulation of small surface particles in side the graphite 'host'.