Abstract: A hydroconversion catalyst for hydrodesulfurizing feedstock while preserving octane number of the feedstock includes a support having a mixture of zeolite and alumina, the zeolite having an Si/Al ratio of between about 1 and about 20, and an active phase on the support and including a first metal selected from group 6 of the periodic table of elements, a second metal selected from the group consisting of group 8, group 9 and group 10 of the period table of elements and a third element selected from group 15 of the periodic table of elements. A hydroconversion process is also disclosed.

Abstract: There is provided a coated zeolite catalyst in which the accessibility of the acid sites on the external surfaces of the zeolite is controlled and a process for converting hydrocarbons utilizing the coated zeolite catalyst. The zeolite catalyst comprises core crystals of a first zeolite and a discontinuous layer of smaller size second crystals of a second zeolite which cover at least a portion of the external surface of the first crystals The coated zeolite catalyst finds particular application in hydrocarbon conversion processes where catalyst activity in combination with zeolite structure are important for reaction selectivity, e.g., catalytic cracking, alkylation, disproportional of toluene, isomerization, and transalkylation reactions.

Abstract: The invention, in one embodiment, is a method for preparing crystalline zeolites by (a) contacting a calcined essentially aluminum free borosilicate zeolite with an aqueous acid solution, thereby producing an at least partially deboronated zeolite; (b) contacting said at least partially deboronated zeolite with a solution selected from the group consisting of an aqueous aluminum salt solution, thereby producing an aluminosilicate zeolite; an aqueous gallium salt solution, thereby producing a gallosilicate zeolite; an aqueous iron salt solution, thereby producing a ferrosilicate zeolite; and mixtures thereof; and (c) where the contacting in step (b) occurs at a pH of not greater than about 3.5.

Abstract: A hydroconversion catalyst for hydrodesulfurizing feedstock while preserving octane number of the feedstock includes a support having a mixture of zeolite and alumina, the zeolite having an Si/Al ratio of between about 1 and about 20, and an active phase on the support and including a first metal selected from group 6 of the periodic table of elements, a second metal selected from the group consisting of group 8, group 9 and group 10 of the period table of elements and a third element selected from group 15 of the periodic table of elements. A hydroconversion process is also disclosed.

Abstract: There is provided a zeolite bound zeolite catalyst which does not contain significant amount of non-zeolitic binder and can be tailored to optimize its performance and a process for converting hydrocarbons utilizing the zeolite bound zeolite catalyst. The zeolite bound zeolite catalyst comprises core crystals containing first crystals of a first zeolite and optionally second crystals of a second zeolite having a composition, structure type, or both that is different from said first zeolite and binder crystals containing third crystals of a third zeolite and optionally fourth crystals of a fourth zeolite having a composition, structure type, or both that is different from said third zeolite. If the core crystals do not contain the second crystals of the second zeolite, then the binder crystals must contain the fourth crystals of the fourth zeolite. The zeolite bound zeolite finds application in hydrocarbon conversion processes, e.g.

Abstract: A catalyst and process for converting carbon dioxide into oxygenates. The catalyst comprises copper, zinc, aluminum, gallium, and a solid acid.

Abstract: The present invention is directed to certain catalyst compositions and processes that are capable of reducing sulfur compounds normally found as part of the gasoline fraction streams of fluid catalytic cracking processes. The present invention requires an equilibrium cracking catalyst composition comprises at least one Y-type zeolite having kinetic conversion activity of at least about 3 in combination with a Lewis acid containing alumina composite present in at least 50 weight percent of the composition. The resultant equilibrium catalyst composition has a kinetic conversion activity of at least about 2.

Abstract: The current invention describes organoclay compositions and methods of using them for removing impurities from contaminated liquids. The compositions are formed by contacting an attapulgite, sepiolite, or zeolite clay mineral with an alkylamine base. The method of use involves contacting the organoclay composition with a contaminated liquid, such as oil in water, allowing the organoclay to absorb the contaminants. The organoclay can be in the form of a granular solid for inline filter applications, or it can be a finely divided powder for other applications.

Abstract: A novel process for converting C2 to C6 aliphatic hydrocarbons to aromatics and catalyst for use in this process are disclosed. The catalyst that contains a zeolite having a silica to alumina molar ratio greater than about 20 and a pore diameter from about 5 Å to about 6 Å, an essentially non-acidic binder, and a gallium component. The binder is selected from silica, zirconia, titania, and mixtures thereof and results in a catalyst formulation having both enhanced selectivity to desired C6-C9 aromatic products and improved stability compared to prior art compositions. Preferred zeolites that can be used include those of the MFI structure type, with ZSM-5 being a specific example.

Abstract: An exhaust system comprising a heat-resistant HC adsorbent comprising an MFI metallo-silicate including at least one of gallium (Ga) and indium (In) as a skeleton forming element, and a metal component ME including at least one of an alkali metal and an alkali earth metal in a content of ME≦0.05% by weight. Such an HC adsorbent has an excellent heat resistance.

Abstract: There is provided a coated zeolite catalyst in which the accessibility of the acid sites on the external surfaces of the zeolite is controlled and a process for converting hydrocarbons utilizing the coated zeolite catalyst. The zeolite catalyst comprises core crystals of a first zeolite and a discontinuous layer of smaller size second crystals of a second zeolite which cover at least a portion of the external surface of the first crystals The coated zeolite catalyst finds particular application in hydrocarbon conversion processes where catalyst activity in combination with zeolite structure are important for reaction selectivity, e.g., catalytic cracking, alkylation, disproportional of toluene, isomerization, and transalkylation reactions.

Abstract: A catalyst and process for converting carbon dioxide into oxygenates. The catalyst comprises copper, zinc, aluminum, gallium, and a solid acid.

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: The present invention provides a method for preparing a zeolite having lattice substituted heteroatoms. The method includes: (a) contacting a calcined borosilicate zeolite with an acid, thereby producing an at least partially deboronated zeolite; and (b) contacting the at least partially deboronated zeolite with a salt-containing aqueous solution comprising one or more salts selected from the group consisting of aluminum salt, gallium salt, and iron salt, thereby producing a silicate or borosilicate zeolite having a lattice comprising aluminum atoms; gallium atoms, iron atoms or a combination thereof. Step (b) is conducted at a pH of about 3.5 or less. Preferably, step (a), step (b) or both are conducted at a temperature of from about ambient temperature to about 300° C., preferably, under stirring/tumbling.

Abstract: This invention relates to a process for producing zeolite-bound high silica zeolites and the use of the zeolite-bound high silica zeolite produced by the process for hydrocarbon conversion. The process is carried out by forming an extrudable paste comprising a mixture of high silica zeolite in the hydrogen form, water, silica, and optionally an extrusion aid, extruding the extrudable paste to form silica-bound high silica zeolite extrudates, and then converting the silica of the binder to a zeolite binder. The zeolite-bound high silica zeolite produced by the process comprises high silica zeolite crystals that are bound together by zeolite binder crystals. The zeolite-bound high silica zeolite finds particular application in hydrocarbon conversion processes, e.g., catalytic cracking, alkylation, disproportionation of toluene, isomerization, and transalkylation reactions.

Abstract: Disclosed is a catalytic promoter for fluid catalytic cracking of hydrocarbons, comprising a HZSM-5 zeolite in an amount of 5-65 wt % based on the total weight of the catalytic promoter, said zeolite being modified with Zn and at least one element selected from the group consisting of P, Ga, Al, Ni and rare earth elements, the combined amount of said modifying elements being 0.01-10.37 wt % based on total weight of said modified HZSM-5 zeolite. A reduced olefin content in gasoline from catalytic cracking process, an increased gasoline octane number and an increased lower olefin yield can be obtained using said catalytic promoter.

Abstract: A zeolitic catalyst useful in the selective disproportionation and transalkylation of toluene comprises a molecular sieve having a pore diameter of about 5 to 8 Å, a refractory inorganic oxide and a reduced weak non-framework metal which is believed to provide Lewis acidity.

Abstract: A process for the preparation of nanostructured materials in high phase purities using cavitation is disclosed. The method comprises mixing a metal containing solution with a precipitating agent and passing the mixture into a cavitation chamber. The chamber consists of a first element to produce cavitation bubbles, and a second element that creates a pressure zone sufficient to collapse the bubbles. The process is useful for the preparation of mixed metal oxide catalysts and materials for piezoelectrics and superconductors.

Abstract: A catalyst for purifying exhaust gas is disclosed which can attain a high percentage of NO purification in an oxygen-excess atmosphere even after exposure to a hydrothermal environment. The catalyst for purifying exhaust gas comprises a combination of a carrier having platinum deposited thereon and CeO2 having an average crystallite diameter D satisfying D≧13.0 nm. The carrier is made of a gallosilicate having an SiO2/Ga2O3 molar ratio M satisfying 100≦M≦1,230.

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 method and a catalyst are described for selective oxidation of aromatic compounds (e.g., benzene and its derivatives) into hydroxylated aromatic compounds (e.g., corresponding phenols). For example, benzene can be converted into phenol with a yield of at least 30-40%, and a selectivity on the basis of benzene of at least 95-97%. The selectivity for this reaction based on N2O is at least 90-95%. Therefore, no substantial N2O decomposition or consumption for complete benzene oxidation to CO+CO2 or other side products occurs. Similar results are obtained with benzene derivatives (e.g., fluorobenzene, difluorobenzene, phenol), although the selectivity is somewhat lower in the case of derivatives (e.g., about 80-85% in the case of fluorosubstituted benzenes). A preferred catalyst for this process is a composition containing a high-silica pentasil-type zeolite (e.g., an HZSM-5 type zeolite) which contains no purposefully introduced additives such as transition or noble metals.

Abstract: The present invention is a process for converting a hydrocarbon feedstream by a catalytic reaction in a catalytic cracking process comprising contacting said feedstream with a demetallated molecular sieve catalyst prepared by first synthesizing the molecular sieve in a metal aluminosilicate form, wherein the metal is Fe, Ga, Zn, B, Cr, Ni or Co and mixtures thereof, removal of the template, if present, by calcination, extracting the metal, with partial extraction of Al, cation exchange to reduce the residual base cation level to less than 1% wt; and catalyst fabrication by mixing the exchanged molecular sieve, optionally adding a secondary promoter, with a binder and forming.

Abstract: The present invention relates to zeolites X, most of the exchangeable sites of which are occupied by lithium and di- and/or trivalent cations, having an improved thermal stability and an improved crystallinity with respect to zeolites of the prior art with the same degree of exchange of lithium and of di- and/or trivalent cations.

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 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.

Abstract: The invention concerns a process for selective hydroisomerization of compounds with an n-alkane chain containing more than 10 carbon atoms, in which the compound to be treated is brought into contact with a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve having a one- or two-dimensional pore network, the accessible pore openings of which are delimited by 10 oxygen atoms, and a distance termed the bridging distance between the pores of less then 0.70 nm, and the zeolite is such that a catalyst which undergoes a standard n-heptadecane isomerization test has, for a conversion of 95%, a selectivity of at least 70% for isomerized products, and the catalyst contains at least 5% by weight of at least one hydro-dehydrogenating element selected from the group formed by non noble GVIII metals, GVIB metals, and niobium, and the catalyst preferably contains phosphorous. The sieve is preferably a NU-10, NU-23, NU-87, EU-13 or Theta-1 zeolite.

Abstract: An HC emission control member includes an HC adsorbing layer on a carrier and an HC oxidizing layer on the HC adsorbing layer. The hydrophobic property of the HC adsorbing layer is enhanced, so that satisfactory adsorption and desorption of HC could be obtained.

Abstract: An HC adsorbent has an MFI-type metallo-silicate including at least one of gallium and indium as a framework forming element, and aluminum (Al) in the MFI-type metallo-silicate in a content of Al.ltoreq.0.05% by weight. Such an HC adsorbent has an excellent heat-resistance.

Abstract: A synthetic, crystalline, porous material is disclosed, together with the related preparation process. Such material of zeolitic nature containing oxides of silicon, titanium and gallium corresponds, in the calcined and anhydrous state, to the following empyrical formula:pHGaO.sub.2 .multidot.qTiO.sub.2 .multidot.SiO.sub.2,wherein p has a value greater than zero and smaller than or equal to 0.050, and q has a value greater than zero and smaller than or equal to 0.025, and the H.sup.+ of HGaO.sub.2 can be at least partially replaceable or replaced by cations.

Abstract: A process for producing a cyclic alcohol by a catalytic hydration reaction of a starting cyclic olefin represented by the following formula (1) and water:C.sub.s H.sub.2s-2-t R.sub.t (1)wherein R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group or a cyclohexyl group; s is an integer of 5 to 12; and t is an integer of 1 to 4, which comprises supplying a part or the whole of a residue left after separation of said cyclic alcohol from an oil phase containing said cyclic alcohol, unreacted cyclic olefin and impurities having a boiling point between the boiling point of said starting cyclic olefin and that of said cyclic alcohol to a distillation column(s), and recycling the unreacted cyclic olefin obtained after removal of said impurities.

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: The invention concerns a process for the selective hydroisomerisation of compounds containing at least one n-alkane chain containing more than 10 carbon atoms, in which the compound to be treated is brought into contact with a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve with a mono- or bidimensional pore network in which the openings of the accessible pores are delimited by 10 oxygen atoms, and the distance termed the bridge width between the pores is less than 0.70 nm, and in which the catalyst, when subjected to a standard n-heptadecane isomerization test, has a selectivity of at least 70% towards isomerized products for a conversion of 95%.The sieve is preferably a NU-10, NU-23, NU-87, EU-13 or Theta-1 zeolite.

Abstract: Disclosed is a process for the preparation of pyridine bases by a reaction of an aliphatic aldehyde and/or ketone with ammonia under gaseous phase using a specified catalyst in which a specified metal or combined metals are carried in or onto specified zeolites, for example, such as zeolites having a specified specific density range.

Abstract: This invention relates to the preparation of novel titanium silicate molecular sieves with modified properties such as adsorption, ion-exchange and catalytic behavior by selective extraction of framework titanium atoms after synthesis of the sieves.

Abstract: A catalyst system and a process for converting a hydrocarbon stream such as, for example, a C.sub.9 +aromatic compound to C.sub.6 to C.sub.8 aromatic hydrocarbons such as xylenes are disclosed. The catalyst system comprises a first catalyst composition and a second catalyst composition wherein said catalyst system is not a physical mixture of said first catalyst composition and said second catalyst composition, said first catalyst is a metal-promoted, alumina- or silica-bound beta zeolite, and said second catalyst composition is a ZSM-5 zeolite having incorporated therein an activity promoter selected from the group consisting of silicon, phosphorus, sulfur, and combinations of two or more thereof. The process comprises contacting a hydrocarbon stream with the catalyst system under a condition sufficient to effect the conversion of a the hydrocarbon to a C.sub.6 to C.sub.8 aromatic hydrocarbon.

Abstract: Catalyst for controlling emissions of the present invention is comprised of at least one kind of transition metal atoms and at least one of Al or Si, wherein said transition metal atoms form a part of the surface of the catalyst for purifying exhaust gas. Accordingly, the catalyst for purifying exhaust gas has both high performance for purifying NO.sub.x and high heat resistance, because monoatomic active metal disperses in the catalyst structure, active metal is taken firmly in the structure, and said transition metal forms a part of the surface of the surface.

Abstract: A composition which comprises a platinum-promoted zeolite and a gallium-promoted zeolite is disclosed. The composition can be used for converting a C.sub.9 + aromatic compound to a C.sub.6 to C.sub.8 aromatic hydrocarbon. Also disclosed is a process for converting a C.sub.9 + aromatic compound to a C.sub.6 to C.sub.8 aromatic hydrocarbons employing the composition.

Abstract: A catalyst is disclosed which comprises a clay belonging to the family of smectites, containing multi-metal pillars, together with a process which uses such a catalyst for the alkylation of aromatic hydrocarbons by means of long chain linear olefins. The resulting alkyl-aromatic compounds are useful for preparing biodegradable synthetic detergents.

Abstract: A crystalline zeolite high-silica SSZ-37 is prepared using a N,N-dimethyl-4-azoniatricyclo [5.2.2.0.sup.(2,6) ] undec-8-ene cation as a template wherein said zeolite is used in hydrocarbon conversion processes.

Abstract: A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl.sub.2, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

Abstract: A hydroconversion catalyst composition includes a catalytically active matrix having a surface area of between about 50 m.sup.2 /g to about 290 m.sup.2 /g, a silicious molecular sieve support medium distributed through the matrix and having a surface area of between about 250 m.sup.2 /g to about 1200 m.sup.2 /g and a catalytically active phase supported on the support medium and including a first metal selected from group IIIA of the periodic table of elements and a second metal selected from group VIB of the periodic table of elements. The matrix preferably further includes aluminum, gallium, cobalt, molybdenum, and phosphorus.

Abstract: A process for producing an olefin oxide comprising oxidizing a corresponding lower olefin with molecular oxygen in the gas phase in the presence of a crystalline metallosilicate having supported thereon at least one salt selected from the group consisting of alkali metal salts of nitric acid, alkaline earth metal salts of nitric acid, silver salts of nitric acid and silver salts of nitrous acid. Said process can produce an olefin oxide at a high selectivity.

Abstract: A porous material composed of many SiO.sub.4 tetrahedra sheets having interlayer bridges of SiO.sub.2. It has pores having a diameter of 10 .ANG. or above, and possesses the properties of a solid acid formed by the isomorphous substitution of metal atoms for Si of SiO.sub.4 frameworks. It is made by a process including introducing an organic substance into interlayer space of crystals of layered silicates to expand the spacing between crystal layers, as well as forming bridges of SiO.sub.2 therebetween, bringing the intercalated compounds into contact with a metal salt to link metal atoms to the SiO.sub.4 frameworks, and firing the products. The material can withstand a temperature of 800.degree. C., has a pore diameter larger than that of zeolites, etc., and is useful in making an adsorbent or catalyst for molecules having a high molecular weight, such as a catalyst for the catalytic cracking of petroleum.

Abstract: Novel fluoride containing substituted smectite clays are disclosed as well as their preparation and uses. The clay has the formulaA.sub.x (M.sub.y M'.sub.4--y)(Si.sub.8--x M.sub.t M'.sub.v)O.sub.20 (OH).sub.4--u F.sub.uwhere A is a cation, M and M' are metals having a +3 oxidation state, each selected from the group consisting of aluminum, gallium, iron and chromium, x is the moles of A, y is the moles of M, t and v are the moles of M and M' in the tetrahedral layer and t+v=x and u is the moles of F. The clay composition may be used as is or after pillaring to catalyze hydrocarbon conversion processes such as alkylation.

Abstract: The invention relates to a crystalline zeolite-like gallosilicate having an atomic ratio of Si/Ga in the outer crystalline surface that is not larger than the average Si/Ga ratio for the whole of the crystal. The invention also relates to a method of making such a gallosilicate comprising the hydrothermal crystallization of a strictly inorganic reaction mixture having the following molar ratios: SiO.sub.2 /Ga.sub.2 O.sub.3 .gtoreq.5; OH.sup.- /SiO.sub.2 =0.05-1.0; and H.sub.2 O/SiO.sub.2 =10-1,000. The invention further relates to the above-described method wherein said reaction mixture is prepared by adding an aged gel to a first mixture, the first mixture preferably having a composition with the following molar ratios: SiO.sub.2 /Ga.sub.2 O.sub.3 .gtoreq.5; OH.sup.- /SiO.sub.2 =0.05 to 1.0; and H.sub.2 O/SiO.sub.2 =20 to 100.

Abstract: Gallosilicates can be formed in the absence of structure-guiding organic hydrocarbons or amines by(a) combining water, a base, a gallium material selected from the group consisting of alkali metal gallates, Ga.sub.2 O.sub.3 and hydrated derivatives of Ga.sub.2 O.sub.3, and gallium salts optionally in aqueous solution, with a powder consisting essentially of particles of silicon dioxide or a hydrated derivative thereof having a diameter of 0.1 to 5 microns and a specific surface area of 20-22 m.sup.2 /g in amounts such that the atomic ratio of silicon to gallium is at least 10 to form an alkaline aqueous reaction mixture; and(b) heating the reaction mixture to produce zeolite-like gallosilicates. These materials are advantageously recovered from the reaction mixture and subjected to ion exchange to replace any alkali metal or alkaline-earth metal ions present with protons.

Abstract: Zeolite catalytic cracking catalyst compositions and additives that contain a Lewis acid supported upon alumina are useful for to process hydrocarbon feedstocks. The compositions are especially useful for the production of reduced sulfur gasoline.

Abstract: An anlytical equipment and method for the selective detection of individual oxygenated compounds in complex organic mixtures, in particular fuels, comprising, downstream an equipment of chromatographic separation, a cracking reactor, a catalytic hydrogenation microreactor and a FID detector. The cracking reactor is provided with a catalyst under the form of metal elements, made of palladium, inserted inside the capillary tube though which flows the gas under test. Thanks to the present equipment, the analytical process, based on the specific response of oxygenates to the method of flame ionization detection (O-FID), foresees that the cracking reaction takes place at temperatures below 1000 degrees C. and, consequently allows to keep the cracking reactor at stand-by temperatures below 700 degrees C.

Abstract: The invention relates to a crystalline zeolite-like gallosilicate having an atomic ratio of Si/Ga in the outer crystalline surface that is not larger than the average Si/Ga ratio for the whole of the crystal. The invention also relates to a method of making such a gallosilicate comprising the hydrothermal crystallization of a strictly inorganic reaction mixture having the following molar ratios: SiO.sub.2 /Ga.sub.2 O.sub.3 .gtoreq.5; OH.sup.- /SiO.sub.2 =0.05-1.0; and H.sub.2 O/SiO.sub.2 =10-1,000. The invention further relates to the above-described method wherein said reaction mixture is prepared by adding an aged gel to a first mixture, the first mixture preferably having a composition with the following molar ratios: SiO.sub.2 /Ga.sub.2 O.sub.3 .gtoreq.5; OH.sup.- /SiO.sub.2 =0.05 to 1.0; and H.sub.2 O/SiO.sub.2 =20 to 100.

Abstract: The present invention is directed to a novel catalyst composition and its use in the dehydrogenation of paraffins to olefins. The catalyst comprises an alloy of a Group VIII noble metal and a metal selected from the group consisting of zinc and gallium on a support selected from the group consisting of silica, zinc oxide modified silica and zinc oxide modified silica-pillared clays when said alloy is a zinc alloy, and silica, gallium oxide modified silica and gallium oxide modified silica-pillared clays when said alloy is a gallium alloy. The instant catalyst is an active and selective catalyst for the catalytic dehydrogenation of paraffins to olefins, especially gaseous paraffins, having the added benefit of retaining high activity and selectivity even following repeated regeneration by calcination in oxygen containing gas at temperatures of 450.degree. C. to 650.degree. C., preferably 450.degree. C. to 500.degree. C.