COKING OF PT-IR/AL2O3 AND PT-RE/AL2O3 CATALYSTS IN DIFFERENT PRESSURES OF CYCLOPENTANE

The coking reaction with cyclopentane was investigated at various pressures on bimetallic PtRe/Al203 and PtIr/Al2O3 catalysts. At atmospheric pressure addition of iridium or rhenium to platinum acts in the same way on the amount of deposited coke as an increasing working pressure on pure Pt/Al2O3 catalysts. Such modification induces a lowering of coke content and yields more dehydrogenated carbonaceous deposits. Nevertheless, the toxicity of coke defined by its fouling effect on the pure metallic reaction of benzene hydrogenation depends on the nature of the metallic phase and the overall pressure. These toxicities are linked to the presence of light polyaromatic compounds which are precursors of graphitic coke. © 1990.