SULFUR ADSORPTION, DESORPTION AND EXCHANGE ON PLATINUM ALUMINA, RHENIUM ALUMINA AND PLATINUM RHENIUM ALUMINA CATALYSTS

Sulphidation of a partially coked Pt-Re/Al2O3 catalyst results in a catalytic behaviour similar to that of a presulphided catalyst. Sulphur is able to displace coke from the metal surface. The amount of irreversibly chemisorbed sulphur - as determined by using (H2S)-S-35 for catalyst sulphidation - increases in the order: Pt/Al2O3 < Pt-Re/Al2O3 < Re/Al2O3. The reverse order was found for the exchange of S-35 with (H2S)-S-32. In Pt-Re-S/Al2O3, the dilution of platinum ensembles occurs to a greater extent and in a more rigid structure than in Pt-S/Al2O3.