Poisoning of a platinum catalyst with thiophene under reforming conditions

Summary

• 1. An investigation was made of the poisoning of a platinized alumina catalyst (5% Pt) with thiophene labeled with radiosulfur under the conditions for the dehydrogenation of cyclohexane in a flow system at 450° and 20 atm.

• 2. The general laws relating the poisoning of this catalyst to time and to the thiophene content of the mixture are similar to those found earlier for a catalyst containing 1% of platinum.

• 3. The use of radiosulfur made it possible for the first time to determine the sulfur content of the catalyst; this varied from 0.063% to 0.14% accord ing to the thiophene content of the original mixture, which corresponds to a change in the Pt: S atomic ratio from 13 to 5.6.

• 4. The relation of the sulfur content of the catalyst to its activity is linear.

• 5. Regeneration is accompanied by the removal of sulfur from the catalyst, but the activity is already completely regained at a point at which the catalyst still contains about 40%, of the sulfur present before regeneration.