Differential effect of coke burning with oxygen or ozone on Pt-Re interaction in Pt-Re/Al2O3

Pt-Re/Al2O3 catalysts were prepared by different methods (coimpregnation, successive impregnations and catalytic reduction). The degree of Pt-Re interaction on the catalysts was indirectly determined by the hydrogenolysis of cyclopentane. The deposition of coke was performed at 500 degrees C and atmospheric pressure. The modifications in the metallic phase when eliminating coke by combustion with oxygen at high temperature (450 degrees C) and with ozone at low temperature (125 degrees C) were studied. The regeneration with ozone enabled the elimination of coke without modifying the metal phase of the catalyst, keeping the degree of interaction between Pt and Re and maintaining Pt dispersion nearly constant. The regeneration with oxygen produced the elimination of Pt-Re interaction and an increase in the dispersion of Pt.