Abstract: A catalyst, a process for making the catalyst and a process for using the catalyst in aromatization of alkanes to aromatics, specifically, aromatization of alkanes having two to six carbon atoms per molecule, such as propane, to aromatics, such as benzene, toluene and xylene. The catalyst is an aluminum-silicon-germanium zeolite on which platinum has been deposited. Germanium is in the framework of the crystalline zeolite. Platinum is deposited on the zeolite. The catalyst may be supported on magnesia, alumina, titania, zirconia, thoria, silica, boria or mixtures thereof. The catalyst may contain a sulfur compound on the surface of the catalyst. The sulfur compound may be added to the catalyst in a pretreatment process or introduced with the hydrocarbon feed to contact the catalyst during the aromatization process.

Abstract: A chromium catalyst is disclosed for use in dehydrogenation and dehydrocyclization processes.

Abstract: There is provided a catalyst containing porous macrostructures comprised of: (a) a three-dimensional network of particles of porous inorganic material (e.g., zeolites); and, (b) at least one metal (e.g., a catalytically active metal). The particles of the at least one macrostructure occupy less than 75% of the total volume of the at least one macrostructure and are jointed together to form a three-dimensional interconnected network. The three-dimensional interconnected network will usually be comprised of pores having diameters greater than about 20 Å. The macrostructures can be made by forming an admixture containing a porous organic ion exchanger (e.g., a polymer-based ion exchange resin) and a synthesis mixture (e.g., for zeolite formation) capable of forming the porous inorganic material and the at least one metal; converting the synthesis mixture to the porous inorganic material; and removing the porous organic ion exchanger from the inorganic material.

Abstract: A catalyst, a process for making the catalyst and a process for using the catalyst in aromatization of alkanes to aromatics, specifically, aromatization of alkanes having two to six carbon atoms per molecule, such as propane, to aromatics, such as benzene, toluene and xylene. The catalyst is an aluminum-silicon-germanium zeolite on which platinum has been deposited. Germanium is in the framework of the crystalline zeolite. Platinum is deposited on the zeolite. The catalyst may be supported on magnesia, alumina, titania, zirconia, thoria, silica, boria or mixtures thereof. The catalyst may contain a sulfur compound on the surface of the catalyst. The sulfur compound may be added to the catalyst in a pretreatment process or introduced with the hydrocarbon feed to contact the catalyst during the aromatization process.

Abstract: A hydrocarbon conversion process comprising contacting a hydrocarbon stream such as, for example, gasoline, with a catalyst composition to effect the conversion of the hydrocarbon to olefins and C6 to C8 aromatic hydrocarbons such as toluene and xylenes. The catalyst composition comprises a zeolite, a promoter and optionally a binder.

Abstract: A process for recovering cumene, characterized by subjecting 2,3-dimethyl-2,3-diphenylbutane produced in a process in which cumene is used, to hydrogenolysis in the presence of a catalyst thereby to convert it into cumene, and recovering the cumene.

Abstract: There is provided macrostructures of porous inorganic material which can have controlled size, shape, and/or porosity and a process for preparing the macrostructures. The macrostructures comprise a three-dimension network of particles of porous inorganic materials. The process for preparing the macrostructures involves forming an admixture containing a porous organic ion exchanger and a synthesis mixture capable of forming a porous inorganic material and then converting the synthesis mixture to a solid porous inorganic material. After formation of the composite material, the porous organic ion exchanger can be removed from the composite material to obtain the macrostructures, either before or after the porous inorganic material is hydrothermally treated with a structure directing agent to convert at least a portion of such porous inorganic material to a crystalline molecular sieve composition. The resulting macrostructure is composed of particles of the crystalline molecular sieve composition.

Abstract: A process for selectively producing para-xylene from a feedstock enriched in C8 isoalkanes and/or isoalkenes is disclosed. The feed is contacted with Group VIII metal loaded molecular sieve catalyst of low acidity under dehydrocyclization conditions wherein the molecular sieve has a channel size ranging from about 5-8 Angstroms and a 10 to 12 membered ring structure containing at least two elements selected from the group consisting of Si, Al, P, Ge, Ga and Ti.

Abstract: The present invention relates to a process for the preparation of para-xylene from trimethylpentane.

Abstract: The present invention relates to new crystalline zeolite SSZ-54 prepared using a templating agent comprising N-isopropyl ethylenediamine, or a mixture of 1-N-isopropyl diethylenetriamine and isobutylamine, and processes employing SSZ-54 in a catalyst.

Abstract: A process is disclosed for the conversion of lower molecular weight hydrocarbons, such as methane, into higher molecular weight hydrocarbon products, such as hydrocarbons having between 4 and 29 carbons. The process includes forming hydrated electrons, such as by mixing the lower molecular weight hydrocarbons with water and contacting the mixture with an energy source to form hydrated electrons. The hydrated electrons react with the methane to form hydrogen and higher molecular weight hydrocarbon products. Also disclosed is a related process for converting higher molecular weight hydrocarbons to lower molecular weight hydrocarbons by forming a mixture of higher molecular weight hydrocarbons and water and contacting the mixture with an energy source to form hydrated electrons that react with the higher molecular weight hydrocarbons to form hydrogen and lower molecular weight hydrocarbon products.

Abstract: This invention relates to a process for reactivating a dehydrocyclodimerization catalyst. Dehydrocyclodimerization catalysts which contain an aluminum phosphate binder can be deactivated when they are exposed to hydrogen at temperatures above 500° C. The instant process restores substantially all of the catalyst's lost activity. The process involves treating the catalyst with a fluid comprising water and drying the catalyst. The process is employed particularly advantageously in combination with coke removal for reactivating catalysts that contain coke deposits and that have also been hydrogen deactivated. This invention also relates to a method of producing a dehydrocyclodimerization catalyst that is resistant to hydrogen deactivation.

Abstract: A process for selectively producing para-xylene from a feedstock enriched in C8 isoalkanes and/or isoalkenes is disclosed. The feed is contacted with Group VIII metal loaded molecular sieve catalyst of low acidity under dehydrocyclization conditions wherein the molecular sieve has a channel size ranging from about 5-8 Angstroms and a 10 to 12 membered ring structure containing at least two elements selected from the group consisting of Si, Al, P, Ge, Ga and Ti.

Abstract: A catalyst composition and a process for converting a hydrocarbon stream such as, for example, gasoline to C6 to C8 aromatic hydrocarbons such as toluene and xylenes are disclosed. The catalyst composition comprises an alumina, a silica, and a metal wherein the weight ratio of aluminum to silicon is in the range of from about 0.002:1 to about 0.6:1. The process comprises contacting a hydrocarbon stream with the catalyst composition under a condition sufficient to effect the conversion of a hydrocarbon to a C6 to C8 aromatic hydrocarbon. Also disclosed is a process for producing the catalyst composition which comprises: (1) contacting a zeolite with an effective amount of an acid under a condition sufficient to effect a reduction in aluminum content of the zeolite to produce an acid-leached zeolite; and (2) impregnating the acid-leached zeolite with an effective amount of a metal compound under a condition sufficient to effect the production of a metal-promoted zeolite.

Abstract: he present invention provides a process for natural gas in the form, e.g., of stranded gas or associated gas to transportable liquids. More particularly, the present invention provides a process in which the gas is non-oxidatively converted to aromatic liquid, preferably in proximity to the wellhead, which may be onshore or offshore. In one aspect, the present invention provides integration of separation of wellhead fluids into associated gas and crude with blending of the aromatic liquid derived from the gas with the crude. Alternatively, or in combination, in another aspect, the present invention provides integration of conversion of byproduct hydrogen to power with non-oxidative conversion of gas to aromatic liquid.

Abstract: The present invention relates to a process for the preparation of para-xylene from trimethylpentane.

Abstract: A catalyst composition and a process for converting a hydrocarbon stream such as, for example, gasoline to C6 to C8 aromatic hydrocarbons such as toluene and xylenes are disclosed. The catalyst composition includes an alumina, a silica, and a metal wherein the weight ratio of aluminum to silicon is in the range of from about 0.002:1 to about 0.6:1. The process includes contacting a hydrocarbon stream with the catalyst composition under a condition sufficient to effect the conversion of a hydrocarbon to a C6 to C8 aromatic hydrocarbon. Also disclosed is a process for producing the catalyst composition which includes: (1) contacting a zeolite with an effective amount of an acid under a condition sufficient to effect a reduction in aluminum content of the zeolite to produce an acid-leached zeolite; and (2) impregnating the acid-leached zeolite with an effective amount of a metal compound under a condition sufficient to effect the production of a metal-promoted zeolite.

Abstract: A process is disclosed for selectively producing one or more aromatic compounds selected from benzene, toluene, para-xylene, meta-xylene, ortho-xylene, ethylbenzene and mixtures thereof from a feed containing C6-C20 hydrocarbons and/or C6-C8 alcohols. The feed is initially subjected to a chemical conversion step to increase the concentration of C6-C8 paraffin and/or olefin precursors of said one or more aromatic compounds and then resulting precursor-enriched feed is then contacted with a dehydrocyclization catalyst under conditions of temperature and hydrogen partial pressure sufficient to effect dehydrocyclization of said paraffin and/or olefin precursors. A product rich in the desired aromatic compound(s) can then be recovered from the dehydrocyclization effluent.

Abstract: A molybdenum-loaded crystalline aluminosilicate molecular sieve that exhibits the MFI crystal structure and has a silica-to-alumina ratio of about 50:1 is useful for aromatizing a hydrocarbon feed stream. The crystalline aluminosilicate preferably has an external surface acidity selectively passivated by means of an amorphous silica layer. A process for the aromatization of methane comprises a one- or multi-step process that contacts a feed stream comprising at least methane with a catalyst composition comprising the preferred molecular sieve, at hydrocarbon conversion conditions that include a temperature of 600-800° C., a pressure of less than 5 atmospheres absolute and a Weight Hourly Space Velocity (WHSV) of 0.1-10 h−1, with the external surface acidity of the crystalline aluminosilicate preferably selectively passivated by an amorphous silica layer. C6-plus aromatic hydrocarbons are preferably recovered from the process by means of an intermediate separation step.

Abstract: A catalyst and an improved process for producing olefins by catalytic naphtha cracking are described. The process provides relatively higher yields over a commercially important range of naphtha conversion, while providing about the same or lower yields of aromatics and methane over the range. In the process, a hydrocarbon naphtha feedstock including a hydrocarbon having about three to about twenty carbon atoms per molecule is passed into a reactor containing a pentasil zeolite catalyst. The catalyst includes about 0.1 to about 10 weight percent phosphorus and about 0.1 to about 10 weight percent of a promoter metal selected from the group consisting of gallium, germanium, tin and mixtures thereof. The hydrocarbon may be passed into the reactor together with a diluent selected from the group consisting of steam, nitrogen, methane, and ethane and mixtures thereof. Alternatively, the hydrocarbon may be passed into the reactor together with additional propane.

Abstract: A process for the removal of hydrocarbon contaminants, such as dienes and olefins, from an aromatics reformate by contacting an aromatics reformate stream with a hydrotreating catalyst and/or a molecular sieve. The hydrotreating catalyst substantially converts all dienes to oligomers and partially converts olefins to alkylaromatics. The molecular sieve converts the olefins to alkylaromatics. The process provides an olefin depleted product which can be passed through a clay treater to substantially convert the remaining olefins to alkylaromatics. The hydrotreating catalyst has a metal component of nickel, cobalt, chromium, vanadium, molybdenum, tungsten, nickel-molybdenum, cobalt-nickel-molybdenum, nickel-tungsten, cobalt-molybdenum or nickel-tungsten-titanium, with a nickel molybdenum/alumina catalyst being preferred. The molecular sieve is an intermediate pore size zeolite, preferably MCM-22. The clay treatment can be carried out with any clay suitable for treating hydrocarbons.

Abstract: The present invention is directed to a halogen-containing catalyst which contains one or more halogen components and in which the halogen amount distribution in the catalyst is uniform, and a process for preparing a halogen-containing catalyst which comprises the steps of supporting one or more halogen components on an L type zeolite, and then drying it at a water evaporation rate of 15% by weight/hour or less. According to the present invention, there can be provided the catalyst in which the halogen amount distribution in the catalyst is uniform, so that a cracking activity can be reduced, and the process for preparing the catalyst.

Abstract: A process for selectively producing para-xylene from a feedstock enriched in C8 isoalkanes and/or isoalkenes is disclosed. The feed is contacted with Group VIII metal loaded molecular sieve catalyst of low acidity under dehydrocyclization conditions wherein the molecular sieve has a channel size ranging from about 5-8 Angstroms and a 10 to 12 membered ring structure containing at least two elements selected from the group consisting of Si, Al, P, Ge, Ga and Ti.

Abstract: There is provided a process for converting hydrocarbons using a catalyst comprising macrostructures having a three-dimensional network of particles comprised of porous inorganic material. The particles of the macrostructures occupy less than 75% of the total volume of the macrostructures and are joined together to form a three-dimensional interconnected network comprised of pores having diameters greater than about 20 Å. The macrostructures can be made by forming an admixture containing a porous organic ion exchanger and a synthesis mixture capable of forming the porous inorganic material; converting the synthesis mixture to the porous inorganic material; and removing the porous organic ion exchanger from the inorganic material.

Abstract: A catalyst composition, a process for producing the composition, and a hydrotreating process for converting a hydrocarbon stream such as, for example, gasoline, to olefins and C6 to C8 aromatic hydrocarbons such as toluene and xylenes are disclosed. The catalyst composition comprises a zeolite and a promoter. The process for producing the composition comprises the steps: (1) combining a zeolite with a promoter under a condition sufficient to incorporate the zeolite with the promoter to produce a first promoted zeolite; (2) incorporating the first promoted zeolite with a second promoter to produce a second promoted zeolite; and (3) heating the second promoted zeolite. The hydrotreating process comprises contacting a hydrocarbon stream with the catalyst composition under a condition sufficient to effect the conversion of a hydrocarbon to an olefin and a C6 to C8 aromatic hydrocarbon.

Abstract: A molybdenum-loaded crystalline aluminosilicate molecular sieve that exhibits the MFI crystal structure and has a silica-to-alumina ratio of about 50:1 is useful for aromatizing a hydrocarbon feed stream. The crystalline aluminosilicate preferably has an external surface acidity selectively passivated by means of an amorphous silica layer. A process for the aromatization of methane comprises a one- or multi-step process that contacts a feed stream comprising at least methane with a catalyst composition comprising the preferred molecular sieve, at hydrocarbon conversion conditions that include a temperature of 600-800° C., a pressure of less than 5 atmospheres absolute and a Weight Hourly Space Velocity (WHSV) of 0.1-10 h−1, with the external surface acidity of the crystalline aluminosilicate preferably selectively passivated by an amorphous silica layer. C6-plus aromatic hydrocarbons are preferably recovered from the process by means of an intermediate separation step.

Abstract: The present invention relates to a process for the preparation of para-xylene from trimethylpentane.

Abstract: A hydrocarbon conversion process in which the rate of coke formation is reduced and aromatics and light olefins yield is increased by the use of an improved zeolite catalyst that comprises a silylated, zeolite material preferably treated with steam. Another embodiment includes the use of an improved zeolite catalyst that comprises silylated, acid treated zeolite material.

Abstract: Low temperature hydrothermal treatment of an LTL zeolite-producing mixture produces a colloidal suspension of the zeolite; the suspension may be used as seeds in Al— and Ga—LTL zeolite manufacture.

Abstract: A process in which a hydrocarbon feedstock containing non-aromatics is passed consecutively through a catalyst arrangement of two catalyst compositions, (1) a steam treated zinc-promoted zeolite and (2) a zeolite that has been subjected to a heat treatment, under hydrocarbon conversion conditions to yield a product containing lower olefins and BTX. An arrangement of two catalyst compositions, (1) a steam treated zinc-promoted zeolite and (2) a zeolite that has been subjected to a heat treatment, for consecutive contact with a hydrocarbon feedstock.

Abstract: A composition, a process for producing the composition, and a hydrocarbon conversion process for converting a hydrocarbon stream such as, for example, gasoline, to olefins and C6 to C8 aromatic hydrocarbons such as toluene and xylenes are disclosed. The composition comprises a silylated catalyst which comprises a zeolite, a clay or silica, and a promoter. The process for producing the composition comprises the steps: (1) combining a zeolite with a clay or silica and a promoter under a condition sufficient to bind the clay to the zeolite to produce a clay-bound zeolite; (2) heating the clay-bound zeolite to produce a modified zeolite; and (3) silylating the modified zeolite with a silylating agent. The hydrocarbon conversion process comprises contacting a hydrocarbon stream with the catalyst composition under a condition sufficient to effect the conversion of a hydrocarbon to an olefin and a C6 to C8 aromatic hydrocarbon.

Abstract: A novel high stability catalyst composition comprising a mixture of zeolite and zinc spinel that has been treated with a reducing gas under high temperature conditions, a method of making such high stability catalyst, and the use thereof for converting paraffin hydrocarbons to olefins and aromatics.

Abstract: A catalytic reforming process comprising the catalytic conversion of hydrocarbons to aromatics, said process comprising treating a halided zeolite catalyst (hiz-cat) containing a Group VIII metal at commercial startup conditions and then reforming hydrocarbons, wherein said catalyst is prepared by washing a bound zeolite catalyst base or a bound zeolite catalyst before halide addition. A preferred hiz-cat is a non-acidic Pt K L-zeolite catalyst prepared by a process that includes the steps of preparing a calcined silica-bound K L-zeolite catalyst base; washing said bound zeolite catalyst base with a liquid comprising water; and incorporating Pt and halogen-containing compound(s) comprising chlorine and fluorine into said washed catalyst base. Ammonium chloride and ammonium fluoride are preferred halide sources.

Abstract: A catalyst composition suitable for the conversion of n-butane to butenes. The same catalyst composition that with chlorination is further suitable, when used in the conversion of n-butane, for the production of an increased amount of BTX (benzene-toluene-xylene) and greater selectivity to the production of isobutylenes than attained with the unchlorinated catalyst. A process for the preparation of catalyst compositions suitable for the conversion of n-butane. Use of the catalyst compositions in processes for the conversion of n-butane.

Abstract: A catalytic reforming process comprising the catalytic conversion of hydrocarbons to aromatics, said process comprising treating a halided zeolite catalyst (hiz-cat) containing a Group VIII metal at commercial startup conditions and then reforming hydrocarbons, wherein said catalyst is prepared by washing a bound zeolite catalyst base or a bound zeolite catalyst before halide addition. A preferred hiz-cat is a non-acidic Pt K L-zeolite catalyst prepared by a process that includes the steps of preparing a calcined silica-bound K L-zeolite catalyst base; washing said bound zeolite catalyst base with a liquid comprising water; and incorporating Pt and halogen-containing compound(s) comprising chlorine and fluorine into said washed catalyst base. Ammonium chloride and ammonium fluoride are preferred halide sources.

Abstract: A process useful in steam cracking is disclosed for selectively converting a feed comprising C4+ dienes and oxygenate to a product comprising increased C2+ monoolefins and para-xylene levels by contacting said feed under diolefin conversion conditions with a catalyst comprising a porous crystalline material having a Diffusion Parameter for 2,2-dimethylbutane of about 0.1-100 sec−1 when measured at a temperature of 120° C. and a 2,2-dimethylbutane pressure of 60 torr (8 kPa), a temperature of 430° C. and 0.5 WHSV.

Abstract: An aromatization process, selective for the dehydrocyclization of paraffins to aromatics, is effected using a large-pore molecular-sieve catalyst containing a uniformly distributed platinum-group metal component, and a tin component incorporated into the large-pore molecular sieve by secondary synthesis. The use of this catalyst results in greater selectivity of conversion of paraffins to aromatics and in improved catalyst stability.

Abstract: A composition is prepared by a method which comprises mixing a first solid material comprising a platinum group metal, a rhenium component, a porous carrier material and, optionally, a halogen component and a second solid material comprising silica and bismuth. The thus-obtained composition is employed as a catalyst in the conversion of hydrocarbons to aromatics. In an alternate embodiment, hydrocarbons are converted to aromatics by sequentially contacting the hydrocarbons with the first solid material and then the second solid material.

Abstract: A process for catalytic reforming and for producing aromatics is carried out in the presence of a catalyst comprising at least one support, at least one metal from group VIII of the periodic table and at least one additional element M selected from the group formed by germanium, tin, lead, rhenium, gallium, indium, and thallium. The process is characterized in that the catalyst is prepared using a process in which said metal M is introduced in an aqueous solvent in the form of at least one organometallic compound comprising at least one carbon-M bond.

Abstract: A method for optimizing the yield of aromatics and light olefins in a process for the conversion of cracked gasoline to aromatics and light olefins by separating the cracked gasoline into a light fraction and a heavy fraction and contacting the light fraction with a zeolite catalyst.

Abstract: A catalyst composition, a process for producing the catalyst composition, and a hydroconversion process for converting a fluid stream comprising at least one saturated hydrocarbon to C.sub.6 to C.sub.8 aromatic hydrocarbons such as benzene, toluene, and xylenes are disclosed. The catalyst composition comprises a zeolite and a promoter. The process for producing the composition comprises the steps of: (1) combining a zeolite with a complexing ligand and a promoter compound under a condition sufficient to produce a modified zeolite; and (2) heating the modified zeolite to produce a promoted zeolite. The hydroconversion process comprises contacting a fluid stream with the catalyst composition under a condition sufficient to effect the conversion of a saturated hydrocarbon to a C.sub.6 to C.sub.8 aromatic hydrocarbon.

Abstract: An improved zeolite catalyst containing an acid-treated zeolite, a boron component and a zinc component manufactured by a novel method having certain process steps necessary for providing the improved zeolite catalyst. The process steps include a first steam treatment of an acid-treated zeolite, followed by incorporation of such zeolite with a boron component and a zinc component, followed by a second steam treatment. Processes are also disclosed for using the improved zeolite catalyst in the conversion of hydrocarbons, preferably non-aromatic hydrocarbons, to lower olefins (such as ethylene and propylene) and aromatic hydrocarbons (such as benzene, toluene, and xylene).

Abstract: There are herein disclosed an L-type zeolite catalyst which is obtainable by supporting a platinum component, one or more halogen components and one or more metal components selected from the group Ib of the periodic table on an L-type zeolite, the support amount of one or more metal components selected from the group Ib being in the range of 0.001 to 3% by weight based on the total weight of the catalyst in terms of the metal, a molar ratio of one or more metal components selected from the group Ib/platinum being in the range of 0.01 to 1; and a method for producing aromatic hydrocarbons or a gasoline having a high octane number which comprises the step of bringing one or more fractions selected from a C6 fraction, a C7 fraction, and a C8.sup.+ fraction into contact with this catalyst.

Abstract: A catalytic material is provided which effectuates the aromatization, reformation, and dehydrogenation of aliphatic, cycloaliphatic, and mixtures of aliphatic and cycloaliphatic hydrocarbons. The catalyst comprises an L-zeolite associated with a Group VIII metal such as platinum and having a rare earth metal ion incorporated therein. A method of using the catalytic material is also provided.

Abstract: A process for producing catalyst compositions for converting a cracked gasoline feedstock to a product comprising incremental aromatics and lower olefins. The catalyst compositions produced thereby. A process for converting a cracked gasoline feedstock to a product comprising incremental aromatics and lower olefins.

Abstract: An improved zeolite based catalyst comprising a mixture of a zeolite and a binder treated with boron trichloride and prepared by a novel method including exposing a mixture of a zeolite material and a binder to gaseous boron trichloride under suitable process conditions.

Abstract: A process for desulfurizing and enhancing the octane of cracked gasoline by first aromatizing the cracked gasoline and, second, hydrodesulfurizing the resulting intermediate product stream.

Abstract: A novel zeolite catalyst composition comprising a mixture of a zeolite, a binder, and a zinc borate compound wherein such mixture is calcined or treated with steam. Preferably, the zeolite has not been treated with an acid. Also provided is a process of making such composition, a product by such process, and the use thereof in the conversion of a hydrocarbon-containing fluid such as a gasoline-boiling range fluid or coker naphtha. Use of such zeolite in the conversion of a hydrocarbon-containing fluid also includes pre-treating such hydrocarbon-containing fluid with a nitrogen removal medium such as ion-exchange resin.

Abstract: A catalyst for the oxidative condensation of a lower aliphatic hydrocarbon ncluding a carrier of a solid, oxide superacid, and at least one transition metal compound and at least one alkali metal compound supported on the carrier. By contacting a lower aliphatic hydrocarbon with oxygen in the presence of the above catalyst, a hydrocarbon with an increased carbon number can be obtained.

Abstract: A hydrocarbon conversion process in which the rate of coke formation is reduced without a significant sacrifice in light olefin and BTX yield by the use of a silylated, stabilized metal promoted zeolite catalyst. Another embodiment includes a novel silylated spinel/zeolite catalyst. Another embodiment includes a process for producing a zinc or gallium promoted zeolite in which the promoter is stabilized by a high temperature water vapor treatment in the presence of a metal oxide such as alumina and thereafter the stabilized catalyst precursor is calcined and silylated.