Abstract: Disclosed is a method for producing aromatic hydrocarbons, which comprises contacting a light hydrocarbon feedstock comprising olefins and/or paraffins with a zeolite catalyst in a fixed-bed, adiabatic reactor containing a fixed catalyst bed comprised of the zeolite catalyst, to thereby effect a catalytic cyclization reaction of the light hydrocarbon feedstock, wherein the catalytic cyclization reaction is performed under conditions which satisfy the following requirements: (1) the zeolite catalyst has an initial stage-catalytic activity of 0.2 (sec.sup.-1) or more in terms of the initial stage, first-order reaction rate constant of the decomposition of n-hexane catalyzed by the zeolite catalyst; (2) the catalyst bed has a temperature of from 450.degree. C. to 650.degree. C.

Abstract: An adsorption arrangement in combination with a catalytic hydrocarbon conversion process suspends non-hydrocarbon materials that act to enhance the operation of the conversion zone by using an adsorption zone arrangement to keep the compounds in recirculation about the reaction zone and integrates the adsorption zone arrangement with a chiller to increase the recovery of C.sub.4 hydrocarbons. The process of this invention is particularly useful for the isomerization of hydrocarbons wherein the adsorption zone arrangement operates to maintain chloride compounds in the reaction zone and to prevent contamination of product streams with the chloride compounds while increasing the recovery of C.sub.4 hydrocarbons. This invention can be used in combination with traditional adsorptive methods of removing contaminant from feedstreams that enter reaction zones.

Abstract: The invention is directed a process for regenerating deactivated reforming catalysts comprising at least one Group VIII metal on zeolite L, preferably wherein the catalysts are extruded using a binder material such as alumina or silica. The process includes: a) coke burn at severe conditions to improve the accessibility of the Group VIII catalytic metal particles by transporting them to the outside of the zeolite microchannels; b) catalytic metal redispersion by wet oxychlorination with elemental chlorine and oxygen; c) stripping with a gas stream comprising oxygen and water at low pressure to remove as much residual chlorine as possible; and d) reduction of catalytic metals with hydrogen at low pressure. The process is particularly effective for recovering activity of catalysts which have been severely deactivated.

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: The present invention is a process for regenerating deactivated catalyst or redispersing catalytic metal in a fresh catalyst comprising at least one Group VIII catalytic metal, zeolite, an inert binder. The process comprises coke burn, hydrogen reduction, catalyst conditioning, oxychlorination, low pressure stripping, and low pressure final hydrogen reduction.

Abstract: A low-pressure, high-temperature, wet post-treatment after oxyhalogenation during regeneration to improve activity and selectivity recovery of a regenerated catalyst involves exposing a halogenated catalyst to a gaseous stream including water having a partial pressure of up to about 1.5 psia, oxygen having a partial pressure of less than about 4.5 psia, and an inert gas at a temperature within the range of about 450.degree. C. to about 530.degree. C. at a pressure within the range of about 14.7 psia to about 65 psia for a time sufficient to effect a hydrogen halide partial pressure in offgas from the halogenated catalyst of less than about 0.004 psia to effectively remove excess halide from the halogenated catalyst.

Abstract: The present invention concerns a regeneration process for a catalyst containing at least one metallic element selected from the group formed by platinum, palladium, ruthenium, rhodium, osmium, iridium and nickel, preferably platinum, on a refractory oxide based support, which has been deactivated by coke deposition. The regeneration process is characterised in that said regeneration consists of treatment with a gas containing at least chlorine and molecular oxygen, at a temperature between 20.degree. C. and 800.degree. C. and a total gas flow rate, expressed in litres of gas per hour and per gram of catalyst, of between 0.05 and 20. The process at least restores the initial catalytic properties of the catalyst.

Abstract: This invention relates to a process for improving the effectiveness of a refinery process catalyst. The process comprises treating the refinery process catalyst with an effective amount of reducing agent selected from the group consisting of hydrazine, oximes, hydroxylamines, carbohydrazide, erythorbic acid, and mixtures thereof.

Abstract: Acidic halides, especially chlorides, are removed from dry process vapor and liquid hydrocarbon streams by contact with solid caustic, such as a bed of NaOH. Salt deposits from form on the solid caustic, which are periodically removed by passing a liquid hydrocarbon continuous phase containing a minor amount of dissolved or entrained water over the solid caustic. Salts may be removed from the liquid hydrocarbon by extraction with water, which also saturates the liquid hydrocarbon so that it may be used to remove additional salt deposits.

Abstract: Provided is a process for catalytic reforming a hydrocarbon feedstock containing at least 20 ppbw sulfur. The process comprises passing the hydrocarbon feedstock through at least two serialy connected reforming zones, with each zone containing a highly sulfur sensitive reforming catalyst. The catalyst in the first reforming zone is more frequently regenerated than the catalyst in the second reforming zone. The result is a highly efficient and simplified process for reforming a sulfur contaminated hydrocarbon feedstock. The process basically employs a minor portion of the highly sulfur sensitive reforming catalyst as both the reforming catalyst and a sulfur removal agent.

Abstract: A catalytic reforming process uses a riser reactor with multiple catalyst injection points to obtain high aromatics yields from a naphtha feedstock. Product from the riser reactor typically is discharged into a fluidized-reforming reactor, in which the reforming reaction is completed and catalyst is separated from hydrogen and hydrocarbons. Hydrocarbons from the reactor are separated to recover an aromatized product. Catalyst is regenerated to remove coke and reduced for reuse in the reforming process.

Abstract: Provided is a process for catalytically reforming a hydrocarbon feedstock using a highly sulfur sensitive catalyst. The process comprises contacting the hydrocarbon in a reaction zone, with the hydrocarbon feed and catalyst flowing in opposite directions. Once the catalyst has passed through the reaction zone, it is then passed to a regeneration zone for regeneration. The process eliminates the need of passing the hydrocarbon feed through a sulfur sorber prior to entry into the reaction zone, as the spent catalyst which is leaving the reaction zone for regeneration acts as a sulfur sorber and removes the sulfur from the feed entering the reaction zone.

Abstract: A process for reducing the amount of down time or yield loss associated with a sulfur upset when using a sulfur-sensitive catalyst. The process comprises applying a metallic coat, cladding, plating or paint to a reactor system which comprises a base metal, so as to form an adherent metallic layer on the base metal and thereby produce a metal-coated reactor system; loading a sulfur-sensitive catalyst into the system; and, after a sulfur upset, using a process comprising sulfur stripping to remove sulfur contaminants from the metal-coated reactor system.

Abstract: A regeneration process for reconditioning catalyst particles containing platinum by transferring the catalyst particles through a combustion zone and a reconditioning zone is disclosed. Drying of the catalyst particles and redispersion of the platinum occur simultaneously in a single reconditioning zone. Catalyst that enters the reconditioning zone is contacted countercurrently with a heated gas stream containing chlorine and oxygen. A low moisture content of the gas stream aids drying and allows the equilibrium reaction between hydrogen chloride and oxygen on the one hand, and water and chlorine on the other hand to be shifted to chlorine. This shift of the equilibrium reaction can be further improved by maintaining an oxygen-enriched environment within the reconditioning zone. By eliminating the need for separate drying and redispersion zones used previously, the regeneration apparatus is less expensive to build and the regeneration process is less expensive to operate.

Abstract: A regeneration process and apparatus eliminates the need for an external chlorination recycle loop. The method and apparatus uses two-pass internal mixing of a chlorine compound input stream and drying gas to both mix and heat the chlorination gas before entering the chlorination zone. The only heat required for the process is a small amount for vaporizing the chlorine containing input stream to prevent the formation of chloride droplets. All other heat for the chlorination zone is supplied internally in the regeneration vessel.

Abstract: There is provided a process for regenerating a coked catalyst comprising a zeolite and a noble metal such as platinum. The process involves treating the coked catalyst under somewhat mild oxidation conditions, whereby a sufficient portion of the coke is removed from the catalyst to restore the hydrocarbon sorption properties of the zeolite component to the level observed in the non-coked form. Surprisingly, the original activity of the catalyst is substantially restored, even though a substantial amount of coke remains on the regenerated catalyst.

Abstract: Disclosed is a method for starting up a cyclic or semi-cyclic reforming reactor after catalyst regeneration. The method mitigates disruptions to the reforming unit after catalyst regeneration, such as excessive light gas make and a decrease in recycle hydrogen purity.

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, 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 semi-continuous process for combusting coke from catalyst particles in a fixed bed is improved by rejecting from the combustion process a high moisture content flue gas stream which is produced by the combustion of a relatively large proportion of the hydrogen in the coke that enters the combustion section during an early stage of combustion. By operating the early stage of combustion at conditions to increase the rate of combustion of the hydrogen in the coke relative to that of the carbon in the coke, the overall equilibrium level of water in a flue gas/recycle gas that circulates through the process is lowered. The high moisture content flue gas stream from the early stage of combustion is rejected separately from the process.

Abstract: Apparatus for regenerating spent hydrocarbon conversion catalyst. Catalyst particles in a vertically-elongated movable tapered bed are contacted with a hot oxygen-containing gas stream in order to remove, by means of combustion, coke which accumulated on the catalyst particles while they were used in a hydrocarbon conversion zone. Catalyst moves downward under the influence of gravity. The catalyst bed is tapered such that the thickness of the bed, in a dimension which is transverse to the direction of catalyst movement, varies from a minimum at the top of the tapered bed to a maximum at the bottom of the tapered bed. Gas passes through the tapered bed in a direction which is substantially transverse to the direction of catalyst movement. Substantially, all of the catalyst in the bed is in contact with the flowing gas.

Abstract: A sulfur-sensitive catalyst which has been deactivated by accumulating sulfur on the catalyst is desulfurized by contact with ammonia at high temperature. The technique is particularly effective for reforming catalysts containing a large-pore zeolite which are selective for dehydrocyclization of paraffins. The desulfurization may be combined with regeneration for coke removal from the catalyst.

Abstract: There is disclosed a process for regenerating a deactivated catalyst containing a zeolite and a noble metal of group VIII of the Periodic Table supported thereon which comprises subjecting the deactivated catalyst to decoking treatment under reductive or oxidative condition and subsequently to contact treatment with a solution containing a halogen or a halogen-containing compound and thereafter calcining the deactivated catalyst. According to the above process, the catalytic activity of a deactivated catalyst is restored to the level comparable to that of a fresh catalyst by the use of an inexpensive regenerating agent and simplified steps. Thus, the regeneration process is expected to find effective use in petroleum refinery, petrochemical industry, etc.

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: The present invention provides a method and apparatus for reforming a hydrocarbon feedstock in the presence of steam using a steam-active reforming catalyst The present invention can generally be used in conjunction with any steam-active reforming processes wherein the hydrocarbon reforming and catalyst regeneration operations are conducted simultaneously and the catalyst is regenerated using a steam-diluted oxygen (or air) regeneration medium. In the present invention, catalyst regeneration effluent gas is advantageously reused in the reforming operation to provide at least a portion of the steam environment required for reforming the hydrocarbon feedstock. Free oxygen is preferably removed from the regeneration effluent gas before the regeneration effluent gas is brought into contact with the hydrocarbon feedstock.

Abstract: The invention presented involves a method for regenerating, replacing or treating the catalyst in a hydroprocessing reactor, the method comprising admixing with the feedstock, recycle stream or hydrogen stream of the reactor an additive which comprises a nonionic, organometallic platinum group metal coordination composition which is a) resistant to breakdown under ambient temperatures; b) capable of breakdown at temperatures existing in the vicinity of the catalyst; and c) does not contain a disadvantageous amount of phosphorus, arsenic, sulfur, antimony or halides.

Abstract: A reactivated catalyst having optimum activity for hydrocracking and other acid catalyzed chemical conversion processes is prepared by contacting its deactivated counterpart, which contains a crystalline molecular sieve, a Group VIII noble metal hydrogenation component and carbonaceous deposits, with a gas containing molecular oxygen, preferably air, at a temperature between 950.degree. and 1200.degree. F., preferably between about 1050.degree. and 1150.degree. F., for a time sufficient to remove at least a portion of the carbonaceous deposits. When the reactivated catalyst contains a dealuminated Y zeolite that has been ion-exchanged with both noble metal and rare earth metal cations, its activity for hydrocracking in an ammonia-deficient atmosphere can be further increased by a rejuvenation procedure in which the reactivated catalyst is contacted with an aqueous ammonia solution in which an ammonium salt has been dissolved.

Abstract: The process is a hydrogen regeneration of spent Group VIII metal modified non-acidic microporous crystalline materials employed as catalysts in dehydrogenation and dehydrocyclization.

Abstract: A process is described for redispersing agglomerated metal on a catalyst. The catalyst comprises noble metal on a low acidity oxide support, and the process comprises contacting the catalyst with a gas stream containing about 3 to about 6 Torr chlorine and about 250 to about 750 Torr oxygen under conditions sufficient to achieve redispersion.

Abstract: A process for the regeneration of a coked platinum, or polymetallic platinum reforming catalyst with ozone. The coked catalyst is contacted, and carbon burned from the catalyst at temperatures ranging from about 20.degree. C. to 200.degree. C., preferably about 60.degree. C. to 150.degree. C., with a gaseous stream containing ozone in concentration ranging from about 1 to 50 volume percent ozone sufficient to substantially deplete said catalyst of sufficient carbon to restore the activity of the catalyst to that of the corresponding fresh catalyst.

Abstract: A process for regenerating a coke contaminated reforming catalyst comprising platinum on a molecular sieve, said process consisting essentially of contacting said catalyst with a halogen-free oxygen-containing gas at a temperature of less than 780.degree. F. for a sufficient period of time such that the aromatization activity is restored to within 20.degree. F. of the activity said catalyst possessed at the start of the previous run cycle.

Abstract: The present invention is a process for regenerating a large-pore zeolitic catalyst that has been deactivated by the formation of Group VIII metal agglomerates on the catalyst surface. In the process, the Group VIII metal agglomerates are redispersed to produce agglomerates of small size. It comprises an oxychlorination step, a nitrogen purge step and a reduction step.

Abstract: A process for reforming hydrocarbons has a regeneration process for reconditioning catalyst particles containing platinum that improves the process by transferring the catalyst particles through a combustion zone, a drying zone, a redispersion zone and a chloride uptake zone. Drying of the catalyst particles immediately after the combustion of coke improves the operation of a platinum redispersion zone and a chloride uptake zone. Separate platinum redispersion zones and chloride uptake zones are provided so that the dried catalyst that enters the platinum redispersion zone can be contacted with a high concentration of chlorine with a lower overall concentration of chloride compounds in the redispersion zone. The lower moisture content allows the equilibrium reaction between hydrogen chloride and oxygen on the one hand, and water and chlorine on the other hand to be shifted to the production of chlorine.

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 process for the reforming of hydrocarbons is improved by the use of an enhanced nucleate boiling surface in a selected portion of the feed effluent heat exchanger. In a vertical type heat exchanger where the reforming feedstream enters at a lower end of the heat exchanger and is at least partially vaporized in the heat exchanger by contact with a reforming effluent stream that enters an upper end of the heat exchanger and is at least partially condensed therein, an enhanced nucleate boiling surface is formed on the heat exchange surface that is in contact with the entering liquid phase portion of the stream feed. The enhanced nucleate boiling surface increases the amount of condensing that takes place on the opposite side of the heat exchange surface in a boiling-condensing zone.

Abstract: A deactivated catalyst comprising a nonacidic zeolite and a Group VIII metal is regenerated by a two-step carbon burn process. The first oxidation step contacts the nonacidic zeolite catalyst with a halogen-free gaseous stream comprising oxygen and an inert gas at a first temperature sufficient to combust carbonaceous material while maintaining a substantial portion of the active Group VIII metal surface area withn the micropores of the nonacidic zeolite for a first period of time sufficient to substantially complete combustion of at least a portion the carbonaceous material at the first temperature. The second step contacts this nonacidic zeolite catalyst with a gaseous stream comprising oxygen and an inert gas at a second temperature sufficient to combust any remaining carbonaceous material for a second period of time sufficient to maintain a substantial portion of the active Group VIII metal surface area in the micropores of the nonacidic zeolite catalyst.

Abstract: A semi-continuous process for combusting coke from catalyst particles in a fixed bed is improved by injecting combustion air for the regeneration section to the three places, upper air to the burn zone, middle air to the chlorination zone and lower air to the burn zone. By this method combustion gas is added the halogenation gas loop which circulates chlorination gas around the chlorination zone in substantially closed system. Any gas that leaves the chlorination zone flows into the burn zone from the chlorination zone. Thus, passing additional air to the chlorination zone increases the oxygen concentration of the chloriation gas to that additional oxygen-containing chlorination gas and chlorination gas with a higher oxygen concentration passes into the burn zone from the chlorination zone. This method adds air for coke combustion and improves platinum dispersion in the halogenation zone.

Abstract: A catalytic reforming process in which sulfur moieties are removed from a gaseous product stream by use of a sulfur trap comprised of about 10 to about 70 wt. % nickel dispersed on a support. The sulfur which is removed is both sulfur which is inherent in the feed as well as sulfur which results from presulfiding the catalyst.

Abstract: A process for regeneration of a deactivated hydroprocessing catalyst is provided. The process comprises exposing the catalyst to laser radiation in the presence of an oxidizing gas. The process may be used to regenerate supported or unsupported metal catalysts which have been fouled by coking.

Abstract: A process and apparatus are disclosed for the catalytic conversion of hydrocarbons in a transport or sub-transport fluidized bed reaction zone. Inert particles are used to transfer heat to the reaction zone. The particles may be heated separately from the catalyst in a combustion zone or together with the catalyst in a regenerator. Fuel is fired to heat the inert particles or a mixture of catalyst and inert particles. Hydrogen deficient fuels such as charcoal or coke are preferred.

Abstract: A semi-continuous process for combusting coke from catalyst particles in a fixed bed is improved by segregating flue gas from the combustion process into a high moisture content flue gas stream which is withdrawn from the process and a relatively low moisture content flue gas stream which is combined with an oxygen-containing make-up gas and recycled to the process. When coke is combusted in a fixed bed to which catalyst is added at an inlet and withdrawn from an outlet on a semi-continuous basis, hydrogen from the coke is quickly combusted whereas less volatile coke components are more slowly combusted. As a result, flue gas passing through the catalyst that has just entered the bed will have the highest water concentration. By separately recovering the flue gas stream having this high moisture content, the overall equilibrium level of water in a flue gas/recycle gas that circulates through the process is lowered.

Abstract: A process for producing a dehydrogenated hydrocarbon product stream by catalytically dehydrogenating a feed stream is disclosed. The process utilizes a plurality of dehydrogenation catalyst-filled tubes in a furnace with all of the tubes connected in parallel to a common product outlet conduit, so that the effluent of all of the tubes is contained in a common product stream. Essentially continuous regeneration of the dehydrogenation catalyst, is achieved by cyclically contacting a portion of the catalyst with an admixture of oxygen-containing regeneration gas and diluent while contacting the remaining portion of the catalyst with an admixture of hydrocarbon feed material and diluent, and wherein free hydrogen is added to react with the oxygen-containing regeneration effluent gas before the oxygen-containing effluent gas enters the product stream.

Abstract: The invention concerns a method of catalytic reforming in a plurality of fluidized bed type reaction zones located side by side, the catalyst circulating from zone to zone with the aid of elevating means and a carrier gas in the form of hydrogen. According to the invention, nitrogen is used as the elevating gas to raise the exhausted catalyst drawn off from the bottom of the last catalytic zone (through which the feedstock passes) to the top of the catalyst regenerating zone, and also to raise the regenerated catalyst to the top of the first catalytic zone through which the feedstock passes.

Abstract: A method for continuously or semi-continuously regenerating reforming catalyst by the recirculation of a gas stream advantageously controls the water content by using an oxygen-deficient makeup gas stream to supply the oxygen for combustion of coke. The volume of makeup gas entering the process is increased by reducing its oxygen concentration so that additional waste gases from the combustion of coke on the catalyst can be vented. The venting of additional gas from the circulating gas stream lowers the overall water concentration during the combustion of coke. The oxygen-deficient makeup gas stream can be supplied by oxygen and nitrogen separation from air. Where the production of the oxygen-deficient makeup gas stream also produces an oxygen-enriched stream, the oxygen-enriched stream is advantageously added to a catalyst reconditioning step for an increased dispersion of metals in the catalyst.

Abstract: Method and apparatus for effecting treatment needed to regenerate spent hydrocarbon conversion catalyst. The invention may be termed a variable gas flow catalyst bed. Catalyst particles in a vertically-elongated movable bed are contacted with a hot oxygen-containing gas stream in order to remove, by means of combustion, coke which accumulated on the catalyst particles while they were used in a hydrocarbon conversion zone. The catalyst particles are confined in the bed by means of catalyst retention screens. The catalyst retention screens are configured such that gas flow through the bed varies from a maximum at the top of the bed to a minimum at the bottom of the bed. The variation in gas flow is accomplished by varying the size of gas flow apertures in the retention screens from a maximum at the top of the bed to a minimum at the bottom of the bed.

Abstract: A reactor system contained in a fired heater and a hydrocarbon upgrading process are discosed for the concurrent conversion of a hydrocarbon feedstock and the regeneration of a deactivated catalyst. An effluent product slipstream from a set of operating reactors is used to hydrogen-regenerate deactivated catalyst in another set of reactors. Flue gas withdrawn from the fired heater stack is used as a purge and/or carrier gas during oxygen-regeneration of the catalyst.

Abstract: Valuable product yield and catalyst useful life are improved by regenerating spent catalyst at temperatures below those maintained in the reaction zone. Relatively cold regenerated catalyst is then preheated and reactor effluent product is quenched by directly contacting the regenerated catalyst with hot reactor effluent product. The quenching step minimizes undesirable thermal cracking of valuable product to C.sub.2 -light gas. The process and apparatus are useful both in aromatization and dehydrogenation of aliphatic hydrocarbons.

Abstract: A process for dispersing or dispersing relatively large crystallites of an agglomerated Group VIII noble metal species present on a porous inorganic support is disclosed. The process includes contacting the agglomerated noble metal species, e.g., palladium or platinum, present on the support, e.g., alumina, silica or a zeolite such as ZSM-5 from which at least a major portion of any extraneous matter such as coke or other residue has previously been removed, with nitric oxide (NO) alone or in admixture with a source of halogen such as Cl.sub.2 and thereafter removing sorbed nitrogen oxide(s) and halogen, if present. The thus treated metal-loaded catalyst demonstrates substantially increased benzene hydrogenation activity (BHA) compared to the same catalyst prior to treatment indicating significant dispersion/redispersion of the metal crystallites as smaller crystallites.

Abstract: A process for restoring deactivated catalysts containing zeolite with a noble metal of Group VIII of the Periodic Table and to be used in the production of aromatic compounds, wherein decoking of the deactivated catalysts is carried out in the presence of halogen or a halogen-containing compound. This restoration process permits effective restoration of deactivated catalysts and thus is expected to be employed in the fields of petroleum purification, petrochemistry and so forth.

Abstract: An improved fluid-bed reaction process and apparatus are disclosed in which feedstock is preheated and may be at least partially converted by contacting the feedstock with spent catalyst in a preheat zone. Additional benefits include a reduction in catalyst poisons and coke production in the reaction zone. By contacting the fresh feed with hot spent catalyst, at least a portion of the coke which would otherwise form in the reactor is deposited on the spent catalyst. Temporary catalyst poisons are also sorbed onto the spent catalyst. The spent catalyst is then withdrawn from the preheat zone, stripped of entrained hydrocarbon and regenerated.

Abstract: The present invention is a process for regenerating a sulfur-contaminated, highly selective, large-pore zeolite catalyst. It comprises a multistep process involving exposure of the catalyst to a combination of oxidizing conditions, reducing conditions and treatment with a halogen acid gas. These conditions are effective to agglomerate a Group VIII metal and remove sulfur. Thereafter, the catalyst is oxychlorinated to redisperse the Group VIII metal over the catalyst surface. A carbon removal step is optionally included.