Process for reactivation of iridium-containing catalysts
AssigneeExxon Research & Engineering Co.
InventorJohn D. Paynter
Life of this patent
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Abstract
In a process for redispersion of the iridium agglomerates (irridium and/or iridium oxide) of a deactivated iridium-containing catalyst, especially a platinum-iridium catalyst, in ferrous metal equipment, wherein the agglomerated iridium, or agglomerated platinum and iridium, is redispersed and the catalyst reactivated by sequential prereduction-halogen treatments, the improvement comprising adding and maintaining small amounts of water with the halogen to suppress ferrous metal corrosion and catalyst contamination during the required treatment with halogen.
Claims23
In a process for reactivating a reforming catalyst, which includes an iridium component composited with a refractory porous inorganic oxide, previously inactivated by coke deposition thereon during contact with a hydrocarbon feed at hydrocarbon conversion conditions and subsequently regenerated by burning at elevated temperatures in the presence of oxygen containing gases to remove accumulated coke deposits therefrom, the improved combination which comprises:
- contacting, without interim contact with a substantially halogen-free, oxygen-containing gas at temperatures in excess of about 775.degree.F., a bed of the coke-depleted catalyst in a cycle which includes, in sequence, the steps of
- i. contacting the coke-depleted catalyst with hydrogen or a hydrogen-containing gas at a temperature sufficient to reduce the said iridium component and then
- ii. contacting said reduced catalyst at an elevated temperature from about 550.degree.F to about 1150.degree.F in a reaction zone provided with exposed ferrous metal surfaces with a gas comprising elemental halogen or halogen precursor and water in amount ranging from about 0.1:1 to 15:1 molar ratio of water:halogen, in a non-oxygen containing atmosphere, sufficient to suppress corrosion of the ferrous metal surfaces of the reaction zone and to effect redispersion of the iridium.
In a process for reactivating reforming catalyst, comprised of halogen and iridium composited with a refractory porous inorganic oxide, previously inactivated by coke deposition thereon during contact with a hydrocarbon feed at reforming conditions, and subsequently contacted with oxygen at an elevated temperature to burn accumulated coke deposits therefrom, a method for reactivating said coke depleted catalyst by
- contacting a bed of the said coke-depleted catalyst without intermediate contact with a substantially halogen-free, oxygencontaining gas at temperatures in excess of about 775.degree.F., which includes the sequence of steps comprising
- i. contacting said coke-depleted catalyst in a reaction zone with hydrogen or a hydrogen-containing gas at an elevated temperature for a time sufficient to reduce at least a portion of the iridium of said catalyst to its metallic state;
- ii. contacting said reduced catalyst at an elevated temperature from about 550.degree.F to about 1150.degree.F in a reaction zone, in a non-oxygen atmosphere, with a gas comprising elemental halogen or elemental halogen precursor and water in concentration ranging from about 0.1:1 to 15:1 molar ratio of water:halogen to effect redispersion of the iridium;
- iii. contacting said treated catalyst from step (ii) in said reaction zone, with hydrogen or a hydrogen-containing gas at an elevated temperature for a time sufficient to further reduce at least a portion of said iridium to its metallic state;
- and
- iv. contacting said treated catalyst from step (iii) in said reaction zone, in a non-oxygen-atmosphere with a gas comprising elemental halogen or elemental halogen precursor and water at an elevated temperature from about 550.degree.F to about 1150.degree.F in concentration ranging from about 0.1:1 to 15:1 molar ratio of water:halogen to effect redispersion of the iridium.
In a process for reactivating a reforming catalyst, comprised of halogen and iridium composited with a refractory porous inorganic oxide, previously inactivated by coke deposition thereon during contact with a hydrocarbon feed at reforming conditions, and subsequently contacted with oxygen at an elevated temperature to burn accumulated coke deposits therefrom, a method for reactivating said coke-depleted catalysts by
- contacting a bed of the said coke-depleted catalyst in a plurality of cycles without intermediate contact with a substantially halogen-free, oxygen-containing gas at temperatures in excess of about 775.degree.F., a cycle of which includes the sequence of steps comprising
- i. contacting said coke-depleted catalyst in a reaction zone with hydrogen or a hydrogen-containing gas at an elevated temperature for a time sufficient to reduce at least a portion of the iridium of said catalyst to its metallic state;
- and then
- ii. contacting said reduced catalyst at an elevated temperature from about 550.degree.F to about 1150.degree.F in a reaction zone, in a non-oxygen containing atmosphere, with a gas comprising elemental halogen or elemental halogen precursor and water in concentration ranging from about 0.1:1 to 15:1 molar ratio of water:halogen up to, but not substantially beyond, the point of halogen breakthrough to effect redispersion of the iridium.
Dependencies are inferred from the claim text.