Abstract: A method for regenerating a Group VIII noble metal catalyst which has been contaminated with coke during a reforming process. The method comprises (a) burning off the coke from the catalyst, (b) redispersing the noble metal on the surface of the catalyst support by contacting the catalyst with halogen gas and carbon dioxide, and (c) chemically reducing the catalyst. The presence of carbon dioxide in the redispersing step improves the activity of the regenerated catalyst.

Abstract: A reforming process using a Supported Group VIII noble metal reforming catalyst which has been pretreated with an unsaturated aliphatic hydrocarbon at elevated temperatures, thereby lowering activity during initial reforming operations and reducing gas production during the initial operation.

Abstract: A method for regenerating a Group VIII noble metal catalyst which has been contaminated with coke during a reforming process. The method comprises (a) burning off the coke from the catalyst, (b) redispersing the noble metal on the surface of the catalyst support by contacting the catalyst with halogen gas and carbon dioxide, and (c) chemically reducing the catalyst. The presence of carbon dioxide in the redispersing step improves the activity of the regenerated catalyst.

Abstract: Supported Group VIII noble metal reforming catalysts are pretreated with an unsaturated aliphatic hydrocarbon at elevated temperatures, thereby lower activity during initial reforming operation and reducing gas production during the initial operation.

Abstract: A deactivated reforming catalyst comprising a type L zeolite containing a Group VIII noble metal may be regenerated and have enhanced dispersion by a method involving contacting the catalyst with oxygen and water at elevated temperatures, contacting the catalyst at elevated temperatures with a source of chlorine such as HCl or Cl.sub.2, and preferably oxygen and water, contacting the catalyst at elevated temperatures with oxygen and optionally water, and contacting the catalyst at elevated temperatures with hydrogen and optionally water to reduce the catalyst.Preferably the noble metal is platinum.

Abstract: This invention relates to a method for treating zeolite-containing catalysts. It is particularly suitable for making catalytic compositions made up of large pore zeolites of which a large percentage of the cationic substitution sites therein contain an alkali or alkaline earth metal and further containing one or more other Group VIII noble metals and a binder. The binder preferably is formed of a particular ratio of alumina from both a sol and boehmite. The step of impregnating the zeolite with a catalytic metal may be carried out at a particular pH range so as to promote aromatics yield after later regeneration. The formed catalyst is treated with a solution of a particular pH at one or more instances either in the catalyst production procedure or after its use to stabilize the catalyst after regeneration. This catalyst is suitable for use as a reforming catalyst or in the production of benzene. The catalyst has quite high activity, selectivity, and excellent physical characteristics.

Abstract: This invention relates to a method for producing zeolite-containing catalysts. It is particularly suitable for making catalytic compositions made up of large pore zeolites of which a large percentage of the cationic substitution sites therein contain an alkali or alkaline earth metal and further containing one or more other Group VIII noble metals and a binder. The binder preferably is formed of a particular ratio of alumina from both a sol and boehmite. The step of impregnating the zeolite with a catalytic metal is carried out at a particular pH range so as to promote aromatics yield after later regeneration. This catalyst is suitable for use as a reforming catalyst or in the production of benzene. The catalyst has quite high activity, selectivity, and excellent physical characteristics.

Abstract: A class of bound catalysts which exhibit superior activity maintenance in dehydrocyclization reactions are defined as a type L zeolite having exchangeable cations of which at least 75% are selected from Group IA and calcium and barium cations and containing well dispersed particles of at least one Group VIII noble metal where at least 90% of the noble metal thereof is dispersed in the form of particles having a diameter less than 7 .ANG.. The catalysts may also be identified as type L zeolites loaded with at least one Group VIII noble metal which have a terminal cracking index (as a measure of production of pentanes versus butanes from hexane) of at least 1.5.

Abstract: A class of catalysts which exhibit superior activity maintenance in dehydrocyclization reactions are defined as a type L zeolite having exchangeable cations of which at least 75% are selected from Group IA and calcium and barium cations and containing well dispersed particles of at least one Group VIII noble metal where at least 90% of the noble metal prior to reduction thereof is dispersed in the form of particles having a diameter less than 7 .ANG.. The catalysts may also be identified as type L zeolites loaded with at least one Group VIII noble metal which have a terminal cracking index (as a measure of production of pentanes versus butanes from hexane) of at least 1.5.

Abstract: A class of catalysts which exhibit superior activity maintenance in dehydrocyclization reactions are defined as a type L zeolite having exchangeable cations of which at least 75% are selected from Group IA and calcium and barium cations and containing well dispersed particles of at least one Group VIII noble metal where at least 90% of the noble metal prior to reduction thereof is dispersed in the form of particles having a diameter less than 7 .ANG.. The catalysts may also be identified as type L zeolites loaded with at least one Group VIII noble metal which have a terminal cracking index (as a measure of production of pentanes versus butanes from hexane) of at least 1.5.

Abstract: A class of bound catalysts which exhibit superior activity maintenance in dehydrocyclization reactions are defined as a type L zeolite having exchangeable cations of which at least 75% are selected from Group IA and calcium and barium cations and containing well dispersed particles of at least one Group VIII noble metal where at least 90% of the noble metal thereof is dispersed in the form of particles having a diameter less than 7 .ANG.. The catalysts may also be identified as type L zeolites loaded with at least one Group VIII noble metal which have a terminal cracking index (as a measure of production of pentanes versus butanes from hexane) of at least 1.5.

Abstract: A reforming catalyst comprising a type L zeolite containing at least one Group VIII noble metal may be prepared by a method involving contacting the freshly prepared catalyst with oxygen, hydrogen or an inert gas and optionally water at elevated temperatures, contacting the catalyst at elevated temperatures with a source of chlorine such as HCl or Cl.sub.2 and preferably oxygen and water, and contacting the catalyst at elevated temperatures with oxygen and optionally water. Prior to use the catalyst is reduced by contact at elevated temperatures with hydrogen and optionally water. This process enhances the dispersion of the noble metal particles.

Abstract: A process is disclosed for reactivating a coked and agglomerated iridium and selenium containing catalyst and particularly platinum-iridium-selenium on alumina reforming catalysts. The process includes a low temperature decoking step to achieve partial decoking while minimizing agglomeration, a reducing step involving contacting the decoked agglomerated catalyst with a reducing gas such as hydrogen to reduce agglomerated iridium oxides to the free metal, a halide pretreatment step to increase the chloride level of the catalyst to about 1.3 weight percent and above, and a halogen redispersion step. The redispersion step is performed with a mixture of elemental halogen and water vapor.

Abstract: A process is disclosed for reactivating an agglomerated iridium and selenium containing catalyst and particularly platinum-iridium-selenium on alumina reforming catalysts. The process includes a reducing step involving contacting a decoked agglomerated catalyst with a reducing gas such as hydrogen to reduce agglomerated iridium oxides to the free metal, a hydrogen halide pretreatment step to provide a halide level to the catalyst of about 1.3 weight percent, and an elemental halogen/oxygen or wet oxygen redispersion step. The hydrogen halide pretreatment step is performed under elemental oxygen-free conditions prior to redispersion and allows high iridium redispersion values to be obtained. If no iridium oxides are initially present, the hydrogen step is optional.

Abstract: A process is disclosed for reactivating an agglomerated iridium and selenium containing catalyst and particularly platinum-iridium-selenium on alumina reforming catalysts. The process includes contacting a substantially decoked agglomerated catalyst with a reducing gas such as hydrogen to reduce agglomerated iridium oxides present to the free metal, a hydrogen halide pretreatment step to increase the halogen level of the catalyst to about 1.3 weight percent and above, and a redispersion step involving hydrogen halide and elemental oxygen. Use of hydrogen halide and elemental oxygen in the redispersion treatment eliminates the need for use of elemental chlorine gas. If no iridium oxides are initially present, the hydrogen reduction step is optional.

Abstract: A process is described for reactivating agglomerated iridium-containing catalysts such as Pt-Ir on Al.sub.2 O.sub.3 reforming catalyst. The agglomerated catalyst is decoked to remove carbon deposits; treated with hydrogen to reduce metal oxides to the free metals; pretreated with hydrogen halide to provide at least about a 1.3 weight percent halide content; and treated with a low mass flow rate of chlorine of about one gram chlorine per 100 grams catalyst per hour. Use of a low mass halogen flow rate significantly retards ferrous metal corrosion and significantly reduces the quantity of chlorine normally used in achieving high redispersion values.

Abstract: A process is disclosed for reactivating an agglomerated iridium-containing catalyst and particularly platinum-iridium on alumina reforming catalysts. The process includes a reducing step involving contacting a decoked agglomerated catalyst with a reducing gas such as hydrogen to reduce agglomerated iridium oxides to the free metal, a hydrogen halide pretreatment step to provide a halide level to the catalyst of about 1.3 weight percent, and an elemental halogen redispersion step. The hydrogen halide pretreatment step is performed under elemental oxygen-free conditions prior to redispersion and allows high iridium redispersion values to be obtained. If no iridium oxides are initially present, the hydrogen step is optional.

Abstract: A process is disclosed for reactivating agglomerated iridium-containing catalysts, in series, and particularly platinum-iridium on alumina reforming catalysts. The process includes a reducing step, involving contacting a decoked agglomerated catalyst with a reducing gas, such as hydrogen, to reduce agglomerated iridium oxides to the free metal, a halide pretreatment step to increase the halide level of the catalyst to about 1.3 weight percent and above, a halogen/water vapor redispersion step at elevated temperature and a contacting of a second catalyst, in series, with the halogen/water vapor effluent at elevated temperature to partially burn-off the carbon deposits on the catalyst surface. Utilizing the effluent halogen stream, rather than subjecting to a scrubbing operation represents a savings in process costs, minimizes pollution problems and provides additional halogen protection to subsequent catalyst reactors in the process scheme.

Abstract: A process is disclosed for reactivating a coked and agglomerated iridium-containing catalyst and particularly platinum-iridium on alumina reforming catalysts. The process includes a low temperature decoking step to achieve partial decoking while minimizing agglomeration, a reducing step involving contacting the decoked agglomerated catalyst with a reducing gas such as hydrogen to reduce agglomerated iridium oxides to the free metal, a halide pretreatment step to increase the chloride level of the catalyst to about 1.3 weight percent and above, and a halogen redispersion step. The redispersion step is performed with a mixture of elemental halogen and water vapor.

Abstract: A process is described for the redispersion of iridium-containing catalysts involving a low temperature hydrogen reduction step, i.e., from 190.degree. C. up to about 250.degree. C. after a coke burn-off. The low temperature reduction step allows milder conditions during subsequent halogen redispersion.