WO2005032713A1 - Procede pour preparer un catalyseur avec un liant non acide et procede pour utiliser ce catalyseur pour produire des substrat aromatiques - Google Patents

Procede pour preparer un catalyseur avec un liant non acide et procede pour utiliser ce catalyseur pour produire des substrat aromatiques Download PDF

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WO2005032713A1
WO2005032713A1 PCT/US2003/028029 US0328029W WO2005032713A1 WO 2005032713 A1 WO2005032713 A1 WO 2005032713A1 US 0328029 W US0328029 W US 0328029W WO 2005032713 A1 WO2005032713 A1 WO 2005032713A1
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catalyst
gallium
zeolite
composite
binder
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PCT/US2003/028029
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English (en)
Inventor
Sanjay B. Sharma
John E. Kulach
Aaron J. Imrie
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Uop Llc
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Priority to PCT/US2003/028029 priority Critical patent/WO2005032713A1/fr
Priority to AU2003278771A priority patent/AU2003278771A1/en
Publication of WO2005032713A1 publication Critical patent/WO2005032713A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G50/00—Production of liquid hydrocarbon mixtures from lower carbon number hydrocarbons, e.g. by oligomerisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/061—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing metallic elements added to the zeolite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/405—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing rare earth elements, titanium, zirconium, hafnium, zinc, cadmium, mercury, gallium, indium, thallium, tin or lead
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/76—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G35/00—Reforming naphtha
    • C10G35/04—Catalytic reforming
    • C10G35/06—Catalytic reforming characterised by the catalyst used
    • C10G35/065—Catalytic reforming characterised by the catalyst used containing crystalline zeolitic molecular sieves, other than aluminosilicates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/20—After treatment, characterised by the effect to be obtained to introduce other elements in the catalyst composition comprising the molecular sieve, but not specially in or on the molecular sieve itself
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/36—Steaming
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/42—Addition of matrix or binder particles

Definitions

  • Dehydrocyclodimenzation is a process in which aliphatic hydrocarbons containing from 2 to 6 carbon atoms per molecule are reacted over a catalyst to produce an aromatic product and hydrogen. Normal downstream separations will typically yield, in addition to the major C 6 -C 9 aromatic product stream, a light ends byproduct containing hydrogen for purge and recycle, an unconverted C 2 -C 4 product for recycle, and a trace C 4 + non-aromatic byproduct.
  • This process is well known and the associated background and details are given in US-A-4654455 and US-A-4746763, hereby incorporated by reference.
  • the dehydrocyclodimerization reaction is carried out at temperatures in excess of 500°C using dual functional catalysts containing acidic and dehydrogenation components.
  • the acidic function is provided by a surface active oxide such as hydrated silica or hydrated alumina having hydroxyl groups that may be ion-exchanged with a metal having the requisite dehydrogenation function (e.g. gallium).
  • a metal having the requisite dehydrogenation function e.g. gallium
  • the metal may be impregnated onto the acidic support as a metal oxide.
  • ion exchange capacity of the support is not needed, so that various forms of alumina (e.g. eta-alumina) may be used.
  • Silica is also mentioned as a suitable support, although this material alone lacks the appreciable acidity required for the dehydrocyclodimerization reaction.
  • silica is again referenced as a preferred catalyst support, either with or without surface hydroxyl groups, depending upon whether metal loading is to be achieved via ion-exchange (former case) or metal oxide impregnation (latter case).
  • the silica support here is characterized as having a surface area of greater than 500 m 2 /g and a pore volume of less than 0.8 ml/g.
  • a zeolitic catalyst composition for the production of aromatics from C 2 , C 3 , and C 4 paraffinic hydrocarbons is disclosed.
  • the catalyst comprises a crystalline aluminosilicate having a molar SiO /Al 2 O ratio of at least 5: 1 and is loaded with both a gallium compound and at least one rare earth metal
  • zeolite e.g. lanthanum
  • the novelty of this formulation lies in the rare earth additive, which is - l - taught to improve aromatic selectivity compared to that achieved using conventional gallium zeolitic catalysts. It is further mentioned that the zeolite may be bound with silica or alumina.
  • a second example of a zeolite and gallium containing catalyst that may be bound with silica is provided in US-A-4350835 for converting gaseous feed stocks containing ethane to liquid aromatics.
  • the acidity of the zeolite component of the catalyst may be reduced during synthesis through a steaming procedure to cause a desired amount of zeolite dealumination.
  • the substantial improvement in selectivity to aromatics obtained in the dehydrocyclodimerization process of the present invention has important commercial implications in terms of product yields and catalyst life.
  • the catalyst disclosed in US-A-4636483 comprising a crystalline aluminosilicate, gallium, and phosphorus containing alumina as a binder.
  • the binder material which increases aromatic selectivity and also significantly improves catalyst life through a reduction in detrimental carbonaceous byproduct (i.e. coke) formation.
  • the aluminum phosphate binder is conveniently prepared by combining an alumina hydrosol with a phosphorous compound to modify the sol prior to gellation. Details of this procedure are provided in US-A- 4629717. [0006]
  • One particular drawback associated with the use of this phosphorous containing alumina binder is described in US-5212127 where catalysts incorporating this material are subject to deactivation through extended exposure to hydrogen at temperatures exceeding 500°C.
  • the gallium containing zeolite catalyst having an essentially non-acidic binder provides a significantly reduced deactivation rate under dehydrocyclodimerization conditions, which is a principal object of this invention.
  • This stability enhancement results from both a decreased production of coke-forming byproducts as well as high tolerance to the deleterious effects of high temperature hydrogen exposure.
  • regeneration cycles are extended significantly, allowing for the potential use of a simple, fixed bed operation, in contrast to the current standard reactor technology employing more complex continuous catalyst regeneration.
  • the present invention is a process for the dehydrocyclodimerization of C 2 -C 6 aliphatic hydrocarbons comprising contacting a feed stream with a catalyst comprising a gallium component, a zeolite support having a silica to alumina molar ratio greater than 20 and a pore diameter from 5A to 6A, and an essentially non-acidic binder at dehydrocyclodimerization conditions to yield a hydrogen gas stream and a product stream containing C 6 -C 9 aromatic compounds.
  • the present invention is a process for preparing a catalyst for the dehydrocyclodimerization of C 2 -C 6 aliphatic hydrocarbons, the process comprising forming a bound zeolite comprising a zeolite having a silica to alumina molar ratio greater than 20 and a pore diameter from 5 A to 6A, and an essentially non-acidic binder; calcining the bound zeolite at a temperature from 450°C to 700°C for a period from 1 to 20 hours to yield a calcined composite; contacting the calcined composite with an aqueous solution of a gallium metal salt selected from the group consisting of gallium nitrate, gallium chloride, gallium bromide, gallium hydroxide, and gallium acetate to yield a gallium-impregnated composite; reducing the gallium-impregnated composite at a temperature from 400°C to 700°C for a period from 1 to 10 hours in
  • the figure illustrates graphically the unexpected improvements in dehydrocyclodimerization catalyst stability obtainable using a 1% gallium-impregnated composite of 2: 1 MFI structure type zeolite : silica binder catalyst of the present invention.
  • the figure shows catalyst activity as measured by propane conversion, predominantly to aromatics, over time in an accelerated stability test.
  • this invention relates to a dehydrocyclodimerization process.
  • the catalyst used in this process comprises a zeolite, an essentially non-acidic binder, and a gallium metal component.
  • the zeolites that may be used are any of those having a silica to alumina molar ratio greater than 20 and preferably greater than 40 and a pore diameter of 5 to 6 Angstroms (A).
  • the silica to alumina molar ratio refers to the composition of the fundamental three dimensional network structure that characterizes the zeolite.
  • silica to alumina ratio or SiO /Al 2 O 3 ratio
  • Si/Al ratio which is exactly half of the silica to alumina molar ratio.
  • zeolites that can be used are those having known structure types, as classified according to their three-letter designation by the Structure Commission of the International Zeolite Association ("Atlas of Zeolite Structure Types", by Meier, W.M.; Olsen, D.H; and Baerlocher, Ch., 1996) of
  • MFI, MEL, MTW, MOR, and BEA MFI structure type zeolites are preferred, with ZSM-5 being an especially preferred specific type of MFI zeolite.
  • Other zeolites within the aforementioned structure types that are useful in the catalyst described herein include ZSM-8, ZSM-11, ZSM-12 and ZSM-35, mordenite, beta, and MCM-22.
  • the preparation of zeolites is well known in the art and involves forming a reaction mixture of an aluminum source, a silicon source, a structure directing agent, e.g. an alkali metal or templating agent, e.g., an organic ammonium cation and water.
  • zeolites can be synthesized using solution media containing fluoride ions or other "non-conventional" media
  • the zeolites which can be used in the present invention are those that have been synthesized using conventional procedures.
  • the conventional method of preparing ZSM-5 is that disclosed in US-A- 3,702,886 which is incorporated in its entirety by reference.
  • Zeolites prepared using fluoride ions are expressly excluded from those zeolites which can be used in the present invention. Accordingly, the zeolites usuable in the present process will be referred to as conventional zeolites meaning that they have been synthesized using conventional procedures.
  • the zeolites as synthesized will contain some of the structure directing agent and/or the templating agent in its pores. These ions can be exchanged for other ions such as hydrogen ions by means well known in the art. Usually this involves contacting the zeolite with a solution containing an excess amount of a compound of the desired ion at a temperature of 15°C to 100°C for a time of 20 minutes to 50 hours. In the case where hydrogen is the ion to be exchanged, the zeolite can be contacted with an aqueous solution of a mineral acid. Alternately, the zeolite can be contacted with an ammonium salt solution, e.g., ammonium nitrate which can optionally contain a mineral acid followed by calcination.
  • an ammonium salt solution e.g., ammonium nitrate which can optionally contain a mineral acid followed by calcination.
  • the zeolite content of the catalyst can vary considerably, it is usually present in an amount from 30 to 90 weight percent and preferably from 50 to 70 weight percent of the catalyst.
  • a second constituent of the catalyst of this invention is an essentially non-acidic binder for the zeolite.
  • Suitable binders having the characteristic of being non-acidic and thus acting as an inert material that is essentially refractory in the dehydrocyclodimerization conditions of the present invention are silica, zirconia, titania, and mixtures thereof.
  • refractory binder or matrix materials also have favorable properties in terms of facilitating fabrication of the dehydrocyclodimerization catalyst, providing strength, and reducing fabrication costs.
  • amorphous silica is preferred in practice due to its ready availability and low cost.
  • An especially preferred amorphous silica is a synthetic, white, amorphous silica (silicon dioxide) powder that is classified as wet-process, hydrated silica.
  • This type of silica is produced by a chemical reaction in a water solution, from which it is precipitated as ultra-fine, spherical particles. It is preferred that the BET surface area of the silica is in the range from 300-800 m /g.
  • binder acidity is an objective, the acidity of the binder cannot be completely eliminated, due to binder impurities that provide acid sites.
  • commercially available sources of silica typically contain 500-700 ppm of alumina that imparts acidity.
  • the binder materials used in preparing the various embodiments of the catalyst of the present invention are characterized as being essentially non-acidic.
  • binders should be first mixed with the zeolite to provide a homogeneous mixture.
  • various additives may be optimally incorporated into the zeolite/binder mixture to improve the characteristics of the mixture for forming purposes.
  • a suitable peptizing agent can optimally be added to the mixture of zeolite and binder.
  • the zeolite at this point may or may not be already impregnated with a catalytically active metallic component (e.g. gallium).
  • the mixing of zeolite, binder, and additives is carried out to form a homogeneous dough or thick paste having the correct moisture content to allow for the formation of extrudates with acceptable integrity to withstand direct calcination. Extrudability is determined from an analysis of the moisture content of the dough or mixture, with a moisture content in the range of 30-50% by weight being preferred.
  • a moisture content in the range of 30-50% by weight being preferred.
  • the extrusion procedure is in fact a preferred method of forming a bound zeolite with physical properties (e.g. shape, strength) suitable for use in the dehydrocyclodimerization process.
  • physical properties e.g. shape, strength
  • the dough is extruded through a die pierced with multiple holes and the spaghetti-shaped extrudate of zeolite and binder is cut to form particles in accordance with techniques well known in the art.
  • Multitudes of different extrudate shapes are possible, including, but not limited to, cylinders, cloverleaf, dumbbell and symmetrical and asymmetrical polylobates.
  • the preferred method of forming a bound zeolite is according to the well-known "oil-dropping" technique for combining the zeolite and essentially non-acidic binder.
  • the initial mixing of zeolite and binder involves the synthesis of an appropriate sol, or carrier material, of the binder used for suspending the zeolite. Details of this technique are provided in US-A-2620314, incorporated herein by reference.
  • temperature-activated gelling agents are hexamethylene tetraamine (HMT), urea, and mixtures thereof.
  • the formation of spherical bound zeolite particles involves dispersing the zeolite/hydrosol/gelling agent mixture into an oil bath or tower that has been heated such that gellation occurs.
  • the combined mixture preferably is dispersed into the oil bath as droplets from a nozzle, orifice, or rotating disk.
  • the gelling agents release ammonia that sets or converts the hydrosol spheres into hydrogel spheres.
  • the spheres are then continuously withdrawn from the oil bath and typically subjected to specific aging and washing treatments in oil and ammoniacal solutions, respectively, to further improve their physical characteristics.
  • the catalyst preferably should have an average diameter of less than 1.0 mm, preferably from 0.2 to 0.8 mm.
  • silica sols may gel without a gelling agent or even a substantial change in temperature. This type of sphere formation can also be applied to the catalyst preparation.
  • Types of silica sols used to form a silica bound zeolite are commercially available as aquasols or organosols containing dispersed colloidal silica particles.
  • an inverted silica sol produced by an acid addition technique and a basic gelling agent such as a mixture of urea and HMT, is preferred.
  • the preferred starting acidic sol is an aqueous zirconium acetate solution, which is preferably combined with a urea gelling agent.
  • the acidic sol is preferably a solution of titanyl oxychloride, which is preferably combined with a urea gelling agent.
  • an inert diluent typically of somewhat smaller size than the zeolite powder
  • This diluent can act as a bridging material for the essentially non-acidic binder and zeolite, thus preserving the zeolite pore system.
  • Typical inert diluents used to prevent binder blinding are non-colloidal silica and some types of clays resistant to low pH conditions.
  • An essential feature of the present invention is that the chemical characteristics of the essentially non-acidic binder are properly matched with those of the zeolite.
  • bound zeolite particles may be formed by spray-drying the zeolite and binder mixture at a temperature of from 425° to 760°C. In any event, conditions and equipment should be selected to obtain appropriately sized particles.
  • the resulting particles should be dried at 80°C to 150°C for several hours and then calcined in dry air.
  • the initial forming stage in the production of extrudates, beads, pellets, or other shapes yields "green" particles of the bound zeolite which posses sufficient strength for the subsequent calcination step.
  • Calcination of the bound zeolite, for the purpose of setting the binder and activating the zeolite yields a calcined composite.
  • the temperatures most commonly used for this calcination or firing step range from 450°C to 700°C, preferably from 600°C to 650°C. The calcination temperatures are maintained for a period from 1 to 20 hours.
  • the calcined composite is optimally subjected to steaming to tailor or adjust its acid activity.
  • the steaming may be effected at any stage of the catalyst preparation process but usually is carried out on the calcined composite of zeolite and binder prior to incorporation of the catalytic metal (gallium) component.
  • Steaming comprises subjecting the calcined composite to a steaming atmosphere comprising steam present in an amount from 5 to 100% of the saturation level.
  • Other conditions for steaming include an absolute pressure from 1 to 20 atmospheres, and a temperature from 600°C to 1200°C.
  • the steaming temperature is preferably from 650° to 1000°C and more preferably from 750°C to 850°C.
  • the steaming should be carried out for a period of at least one hour, preferably from 6 to 48 hours.
  • the calcined composite may be washed with one or more of a wash solution of ammonium nitrate, a mineral acid, and/or water.
  • the catalyst may be washed with a solution containing from 5 to 30% by weight of ammonium nitrate.
  • a mineral acid such as HC1 or HNO 3 is preferred; sufficient acid is added to maintain a pH from 1 to 6, preferably from 1.5 to 4.
  • the catalyst is maintained in a bed over which the solution and/or water is circulated for a period from 0.5 to 48 hours, and preferably from 1 to 24 hours.
  • the washing may be effected at any step in the catalyst preparation, and two or more stages of washing may be employed.
  • the calcined composite Prior to addition of the catalytic metal component the calcined composite preferably is ion-exchanged with an ion-exchange solution of a salt containing at least one hydrogen-forming cation such as NH ⁇ + or a quaternary ammonium ion.
  • the hydrogen- forming cation replaces principally alkali-metal cations to provide, after calcination, the hydrogen form of the zeolite component.
  • the binder is typically present in the calcined composite in an amount of less than 70% by weight, preferably between 10% and 70% by weight of the binder and zeolite combined.
  • the zeolite should comprise more than 30%, and usually from 30% to 90%, of the catalyst weight, not considering the weight of the active gallium metal (metal-free basis).
  • gallium component Another necessary constituent of the instant catalyst is a gallium component.
  • the gallium component may be deposited onto the calcined composite of zeolite and binder in any suitable manner known in the art that results in a uniform dispersion of the gallium.
  • the gallium is deposited onto the calcined composite by contacting (i.e. impregnating) it with an aqueous solution of a gallium metal salt, where the salt is selected from the group consisting of gallium nitrate, gallium chloride, gallium bromide, gallium hydroxide, gallium acetate, etc.
  • the amount of gallium deposited onto the calcined composite normally varies from 0.1 to 5 percent by weight, expressed as gallium metal, of the finished catalyst.
  • Those skilled in the art are cognizant of the contacting conditions (e.g. time, temperature, and solution concentration) required to achieve a desired loading of gallium on the finished catalyst.
  • the gallium compound may be impregnated onto the calcined composite by any technique known in the art such as by dipping the composite into a solution of the metal compound or by spraying such solution onto the composite.
  • a preferred method of preparation involves the use of a steam-jacketed rotary dryer to achieve evaporative impregnation.
  • the calcined composite particles are immersed in an impregnating solution of any of the previously mentioned gallium metal salts, where the composite and solution are contained in the dryer.
  • the calcined composite is tumbled therein by rotation of the dryer, and evaporation of the impregnation solution in contact with the tumbling composite is expedited through the application of steam to the dryer jacket.
  • the gallium component may also be impregnated directly onto the zeolite prior to binding it with the essentially non-acidic binder. This type of metal loading procedure confines the gallium component to the zeolite alone without incorporating any gallium into the binder.
  • the resulting gallium-impregnated composite particles are then heated in the presence of hydrogen- containing gas to a temperature from 500°C to 700°C for a time from 1 to 15 hours.
  • hydrogen-containing gas may be diluted with nitrogen or other inert diluent to provide the necessary hydrogen- containing gas.
  • the reduction and dispersion can be performed in the actual reactor vessel (in situ) used for dehydrocyclodimerization using either pure hydrogen or a mixture of hydrogen and hydrocarbons.
  • the reduced gallium-impregnated composite resulting from the high temperature hydrogen treatment, is oxidized in an oxidizing atmosphere comprising air and steam at a temperature from 400°C to 700°C for a time from 1 to 10 hours.
  • the amount of steam present in the air can vary from 1 to 100 percent of the saturation level.
  • the zeolitic finished catalyst particles, bound with an essentially inert binder now contain well-dispersed gallium in the form of gallium oxide.
  • other metals referred to as catalyst promoter metals, may also be simultaneously or sequentially impregnated onto either the calcined composite or the zeolite component.
  • promoter metal is accomplished in substantially the same manner as the procedure described above for incorporating the gallium component onto the calcined composite or zeolite.
  • the technique similarly comprises contacting the composite or zeolite with an aqueous solution containing the desired promoter metal in the form of a salt and subjecting the resulting promoter metal impregnated composite to hydrogen and air/steam environments.
  • Promoter metals that may be used to enhance dehydrocyclodimerization activity and/or selectivity include indium, molybdenum, zinc, tin, and mixtures thereof.
  • the dehydrocyclodimerization conditions for use with the final finished catalyst will, of course, vary depending on such factors as feed stock composition and desired conversion.
  • a normal set of conditions for the dehydrocyclodimerization of C 2 - C 6 aliphatic hydrocarbons to aromatics includes a temperature from 350°C to 650°C, an absolute pressure from 1 to 20 atmospheres, and a liquid hourly space velocity (LHSV) from 0.2 hr "1 to 5 hr "1 .
  • LHSV is the hourly volumetric liquid feed flow rate divided by the catalyst volume.
  • Preferred process conditions are a temperature from 400°C to 550°C, an absolute pressure from 2 to 10 atmospheres, and a LHSV from 0.5 hr "1 to 2.0 hr "1 .
  • one of requisite skill in the art will be able to adjust reaction conditions to suit the particular feed stock. It is understood, for example, that the temperature required for optimal dehydrocyclodimerization performance decreases with increasing average carbon number of the feed stream.
  • the feed stream to the dehydrocyclodimerization process is defined herein as all streams introduced into the dehydrocyclodimerization reaction zone. Included in such feed streams are C 2 -C 6 aliphatic hydrocarbons.
  • C -C 6 aliphatic hydrocarbons is meant one or more non-aromatic ringed, straight, or branched chain isomers having from two to six carbon atoms per molecule. Furthermore, these hydrocarbons may be saturated or unsaturated.
  • the hydrocarbons C 3 and/or C 4 are selected from isobutane, normal butane, isobutene, normal butene, propane, and propylene.
  • Diluents including hydrogen, nitrogen, helium, argon, and neon may also be included in the feed stream.
  • a recycle gas stream containing hydrogen is mixed with the feed stream before entering the reaction zone.
  • hydrogen although negatively impacting the equilibrium conversion of aliphatic hydrocarbons to aromatics, significantly benefits the catalyst stability.
  • normal practice in the dehydrocyclodimerization process mandates a separation of the hydrogen gas stream, which may contain gaseous reaction byproducts or potentially any of the aforementioned gaseous diluents, from the hydrocarbon product after reaction in the presence of the catalyst. This separation is accomplished through cooling of the reactor effluent to yield a liquid product stream containing C 6 -C 9 aromatic compounds.
  • the primary product streams from the process described herein are a hydrogen gas stream and a liquid product stream. While the bulk of the hydrogen gas stream is recycled to the reactor, the net hydrogen production resulting from the dehydrocyclodimerization reaction is purged from this recycle loop along with some gaseous hydrocarbon byproduct impurities (e.g. methane).
  • gaseous hydrocarbon byproduct impurities e.g. methane
  • the feed stream is contacted with the instant catalyst in a dehydrocyclodimerization reaction zone maintained at dehydrocyclodimerization conditions.
  • This contacting may be accomplished by using the catalyst in a fixed bed system, a moving bed system, a fluidized bed system, or a batch type operation.
  • a fixed bed of catalyst may be desired rather than a somewhat more complicated moving bed, such as the dense-phase moving bed system described in US-A-3725249.
  • the fixed bed has the additional benefit of minimizing losses of valuable catalyst through attrition or breakage.
  • the feed stream is preheated by any suitable means to the desired reaction temperature and then passed into a dehydrocyclodimerization zone containing a bed of the catalyst of the present invention.
  • the dehydrocyclodimerization catalyst may be retained in one or more separate reactors with suitable means therebetween to assure that the desired conversion temperature is maintained at the entrance to each reactor.
  • the C 2 -C 6 aliphatic hydrocarbon reactants may be contacted with the catalyst bed in either upward, downward, or radial flow fashion with the latter being preferred. In addition, these reactants are essentially in the vapor phase when they contact the catalyst.
  • the dehydrocyclodimerization system then preferably comprises a dehydrocyclodimerization zone containing one or more fixed or dense phase moving beds of the instant catalyst.
  • a dehydrocyclodimerization zone containing one or more fixed or dense phase moving beds of the instant catalyst.
  • This dehydrocyclodimerization zone may be one or more separate reactors with suitable heating means therebetween to compensate for any heat loss encountered in each catalyst bed.
  • the dense-phase moving bed system it is common practice to remove catalyst from the bottom of the reaction zone, regenerate it by conventional means known in the art, and then return it to the top of the reaction zone.
  • the catalyst of the present invention preferably provides 50% selectivity to C 6 -C 9 aromatic products. That is, of the C 2 -C 6 aliphatic hydrocarbons in the feed that are converted in the dehydrocyclodimerization process of the present invention, preferably 50% by weight are present as C 6 -C 9 aromatic products in the product stream.
  • a sample of currently used (i.e. prior art) catalyst was tested in a pilot plant to establish a baseline for dehydrocyclodimerization activity and stability.
  • the catalyst composition was a 1% gallium formulation, where the active metal was loaded onto an MFI structure type zeolite bound with aluminum phosphate. The ratio of zeolite to binder was approximately 2:1.
  • the catalyst was prepared according to the procedure described in US-A-4629717 where an alumina hydrosol was initially mixed with a phosphorous-containing compound to yield a phosphorous modified sol. The sol was then gelled (in this case according to the aforementioned "oil dropping" technique described US-A-2620314) to form a phosphorous modified alumina composite used as the catalyst support material.
  • the experiment was performed using dehydrocyclodimerization conditions within the preferred commercial operating ranges as defined previously. These parameters were designed so that the catalyst activity decline could be measured over a relatively short time frame.
  • the feed used was pure propane.
  • the reactor effluent was analyzed by gas chromatography to determine its composition after 24 hours on stream and every 12 hours thereafter, up to 72 hours on stream. For each reactor effluent sample, the corresponding propane conversion and selectivity to desired aromatics was determined and plotted against the operating time on stream. Using linear regression to estimate relative activity decline, the catalyst tested in this example showed an average loss of 0.55% in conversion per hour of operation. From statistical analysis of the regression data the 95% confidence interval for this activity decay (i.e.

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Abstract

L'invention concerne un procédé pour convertir des hydrocarbures aliphatiques C2-C6 en substances aromatiques, et un procédé pour préparer un catalyseur à utiliser dans ce procédé. Le catalyseur contient une zéolite présentant un rapport moléculaire silice/alumine supérieur à 20 et un diamètre de pore compris entre 5Å et 6Å, un liant essentiellement non acide, et un composant de gallium. Le liant est sélectionné dans: silice, zirconium, titanium, et des mélanges de ceux-ci et permet d'obtenir une formulation de catalyseur présentant à la fois la sélectivité améliorée pour des produits aromatiques C6-C9 voulus et une stabilité améliorée pour des compositions de l'état de la technique. Des zéolites préférées peuvent être utilisées, notamment celles de type de structure MFI, ZSM-5 constituant un exemple spécifique de ces zéolites.
PCT/US2003/028029 2003-09-08 2003-09-08 Procede pour preparer un catalyseur avec un liant non acide et procede pour utiliser ce catalyseur pour produire des substrat aromatiques WO2005032713A1 (fr)

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AU2003278771A AU2003278771A1 (en) 2003-09-08 2003-09-08 A process for preparing a catalyst with a non-acidic binder and a process for using the catalyst to produce aromatics

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WO2009097067A2 (fr) * 2008-01-28 2009-08-06 Exxonmobil Chemical Patents Inc. Production de produits aromatiques à partir de méthane
WO2009124902A1 (fr) * 2008-04-08 2009-10-15 Basf Se Catalyseur de déhydroaromatisation d'hydrocarbures aliphatiques, contenant un liant à teneur en silicium
WO2009124960A1 (fr) * 2008-04-08 2009-10-15 Basf Se Catalyseur de déshydroaromatisation de méthane et de mélanges contenant du méthane
WO2011042451A1 (fr) 2009-10-08 2011-04-14 Basf Se Procédé de fabrication d'un catalyseur en lit fluidisé relié à si
US20140163281A1 (en) * 2012-12-12 2014-06-12 Uop Llc Conversion of methane to aromatic compounds using a catalytic composite
WO2024002750A1 (fr) * 2022-06-29 2024-01-04 IFP Energies Nouvelles Procede de traitement d'un catalyseur comprenant une zeolithe
FR3137311A1 (fr) * 2022-06-29 2024-01-05 IFP Energies Nouvelles Procédé de traitement d’un catalyseur comprenant une zéolithe

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Cited By (15)

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Publication number Priority date Publication date Assignee Title
US8841227B2 (en) 2008-01-28 2014-09-23 Exxonmobil Chemical Patents Inc. Production of aromatics from methane
WO2009097067A3 (fr) * 2008-01-28 2009-12-10 Exxonmobil Chemical Patents Inc. Production de produits aromatiques à partir de méthane
JP2011509827A (ja) * 2008-01-28 2011-03-31 エクソンモービル・ケミカル・パテンツ・インク メタンからの芳香族化合物の製造
WO2009097067A2 (fr) * 2008-01-28 2009-08-06 Exxonmobil Chemical Patents Inc. Production de produits aromatiques à partir de méthane
JP2011518660A (ja) * 2008-04-08 2011-06-30 ビーエーエスエフ ソシエタス・ヨーロピア メタン及びメタン含有混合物を脱水素芳香族化するための触媒
WO2009124960A1 (fr) * 2008-04-08 2009-10-15 Basf Se Catalyseur de déshydroaromatisation de méthane et de mélanges contenant du méthane
US8742189B2 (en) 2008-04-08 2014-06-03 Basf Se Catalyst for the dehydroaromatisation of methane and mixtures containing methane
WO2009124902A1 (fr) * 2008-04-08 2009-10-15 Basf Se Catalyseur de déhydroaromatisation d'hydrocarbures aliphatiques, contenant un liant à teneur en silicium
US9486796B2 (en) 2009-10-08 2016-11-08 Basf Se Process for producing an si-bonded fluidized-bed catalyst
WO2011042451A1 (fr) 2009-10-08 2011-04-14 Basf Se Procédé de fabrication d'un catalyseur en lit fluidisé relié à si
US9821300B2 (en) 2009-10-08 2017-11-21 Basf Se Process for producing an Si-bonded fluidized-bed catalyst
US20140163281A1 (en) * 2012-12-12 2014-06-12 Uop Llc Conversion of methane to aromatic compounds using a catalytic composite
WO2024002750A1 (fr) * 2022-06-29 2024-01-04 IFP Energies Nouvelles Procede de traitement d'un catalyseur comprenant une zeolithe
FR3137312A1 (fr) * 2022-06-29 2024-01-05 IFP Energies Nouvelles Procédé de traitement d’un catalyseur comprenant une zéolithe
FR3137311A1 (fr) * 2022-06-29 2024-01-05 IFP Energies Nouvelles Procédé de traitement d’un catalyseur comprenant une zéolithe

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