摘要：

Previously we showed that because of the high susceptibility of iridium to oxidative agglomeration, direct application of the Pt/γ-Al 2 O 3 regeneration procedure to Pt-Ir/γ-Al 2 O 3 reforming catalysts is ineffective [1] . Special considerations are needed to ensure that the agglomerated Ir particles are in their metallic state in order to facilitate iridium redispersion. Further advances in our understanding of the redispersion chemistry resulted in an iridium redispersion technology replacing elemental chlorine with chlorine containing compounds. However, iron contamination of the catalyst extrudates was observed when iron scale were present in the catalyst bed. The iron scale formed in the furnace tubes because of exposure to sulfur and the oxidation and reduction environment encountered during catalyst regeneration. The critical sequence of steps leading to iron transfer in the regeneration of iridium containing catalysts has been identified. These involve the reduction of Fe 2 O 3 to Fe 3 O 4 and metallic iron and their reactions with HCl during the HCl saturation step forming mobile divalent iron chloride species, which transfer to the catalyst extrudates through physical contacts. Successful modifications to the regeneration procedure result in high iridium redispersion and essentially no iron transfer.

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