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WO2009116995A1 - Procédés de conversion de l'éthylbenzène et d'isomérisation du xylène et catalyseurs pour ces procédés - Google Patents

Procédés de conversion de l'éthylbenzène et d'isomérisation du xylène et catalyseurs pour ces procédés Download PDF

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Publication number
WO2009116995A1
WO2009116995A1 PCT/US2008/057361 US2008057361W WO2009116995A1 WO 2009116995 A1 WO2009116995 A1 WO 2009116995A1 US 2008057361 W US2008057361 W US 2008057361W WO 2009116995 A1 WO2009116995 A1 WO 2009116995A1
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catalyst
xylene
mass
isomerization
ethylbenzene
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PCT/US2008/057361
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English (en)
Inventor
Paula L. Bogdan
Patrick C. Whitchurch
Robert B. Larson
James E. Rekoske
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Uop Llc
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Priority to PCT/US2008/057361 priority Critical patent/WO2009116995A1/fr
Publication of WO2009116995A1 publication Critical patent/WO2009116995A1/fr

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    • 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
    • B01J29/48—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 arsenic, antimony, bismuth, vanadium, niobium tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • 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
    • B01J29/076—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
    • C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
    • C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
    • C07C5/2708—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with crystalline alumino-silicates, e.g. molecular sieves
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
    • C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
    • C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
    • C07C5/2724—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with metals
    • 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
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2529/00—Catalysts comprising molecular sieves
    • C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
    • C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • C07C2529/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65
    • C07C2529/78—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • This invention relates to catalysts and catalytic processes for the isomerization of xylenes and for the conversion of ethylbenzene by dealkylation in the presence of hydrogen, particularly such catalysts using a combination of molecular sieve, platinum group metal and molybdenum and their use to enhance isomerization activity while retaining ethylbenzene dealkylation activity, low transalkylation activity and low aromatic ring loss to naphthenes.
  • Numerous processes have been proposed for the isomerization of one or more of xylenes (meta-xylene, ortho-xylene and para-xylene) to form other isomers of xylene.
  • the sought xylene isomer is para-xylene due to the demand for terephthalic acid for the manufacture of polyester.
  • these xylene isomerization processes comprise contacting the xylene isomer sought to be isomerized with an isomerization catalyst under isomerization conditions.
  • Various catalysts have been proposed for xylene isomerization. These catalysts include molecular sieves, especially molecular sieves contained in a refractory, inorganic oxide matrix. The catalysts also contain a hydrogenation metal component.
  • the dealkylation should be selective to the ethylbenzene and not cause undue loss of xylene.
  • the isomerization and ethylbenzene conversion should not result in undue production of transalkylated products such as toluene and trimethylbenzene.
  • the dealkylation should not cause the production of naphthenes that would contaminate any benzene stream separated from the product of the isomerization and ethylbenzene conversion, and thus reduce the value of the benzene.
  • Catalysts containing molybdenum provide advantageously low production of naphthenes. However, they do not exhibit a good balance between xylene isomerization and ethylbenzene dealkylation, and they are capable of generating toluene and C 9+ aromatics, especially at lower partial pressures of hydrogen.
  • a catalyst exhibiting good ethylbenzene conversion provides a low ratio of para-xylene to total xylenes. If the concentration of molybdenum is increased, some improvement can be obtained in xylene isomerization, but at a cost in ethylbenzene conversion activity.
  • US 4,362,653 discloses a hydrocarbon conversion catalyst which could be used in the isomerization of isomerizable alkylaromatics that comprises silicalite (having an MFI-type structure) and a silica polymorph.
  • the catalyst may contain optional ingredients. Molybdenum is listed as one of the many optional ingredients.
  • US 4,899,012 discloses catalyst for isomerization and conversion of ethylbenzene containing a Group VIII metal, lead, a pentasil zeolite and an inorganic oxide binder.
  • US 6,573,418 discloses a pressure swing adsorption process to separate para-xylene and ethylbenzene from C 8 aromatics.
  • catalysts disclosed for ethylbenzene isomerization include those containing ZSM-5 type of molecular sieve (AI-MFI) dispersed on silica.
  • the catalysts contain a hydrogenation metal and listed among the hydrogenation metals are molybdenum.
  • Suitable matrix materials are said to be alumina and silica. See example 12 which uses a molybdenum-containing catalyst for xylene isomerization.
  • US 4,331 ,822 discloses a process for the isomerization of xylenes using a catalyst comprising a crystalline aluminosilicate and at least two metals, one of which is platinum and the other is at least one metal selected from the group consisting of titanium, chromium, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, palladium, tin, barium, cesium, cerium, tungsten, osmium, lead, cadmium, mercury, indium, lanthanum, beryllium, lithium, and rubidium.
  • a catalyst comprising a crystalline aluminosilicate and at least two metals, one of which is platinum and the other is at least one metal selected from the group consisting of titanium, chromium, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, palladium, tin, barium, ces
  • Catalyst A-5 is the only specific disclosure of a platinum and molybdenum-containing catalyst and comprises 0.24 wt-% platinum and an atomic ratio of platinum to molybdenum of 0.7:1 , i.e., 0.17 wt-% molybdenum. Examples 5 and 6 summarize some of the results using catalyst A-5.
  • a catalyst using molybdenum tends to generate less naphthenes than a platinum-containing catalyst.
  • the molybdenum-containing catalysts have been inferior to platinum- containing catalysts in isomerization activity, i.e., yields a xylene product distribution not as close to equilibrium as are the products using a platinum-containing catalyst.
  • platinum-containing catalysts have been preferred for commercial use even though they typically co-produce greater amounts of naphthenes than do molybdenum catalysts.
  • Catalysts are sought that provide the combination of the low naphthene generation achievable with molybdenum catalysts good ethylbenzene conversion and isomerization activity. Moreover, catalysts are sought that can be used in a xylene isomerization facility regardless of whether it operates at lower pressures, e.g., 700 kPa, or higher pressures, e.g., 1500 kPa.
  • molybdenum-containing catalysts and processes for using the catalysts are provided for the isomerization of xylene and the dealkylation of ethylbenzene that exhibit not only desirable ethylbenzene conversion activity but also desirable isomerization activity, i.e., approach to xylene equilibrium distribution, while retaining low naphthene generation activity.
  • the advantages provided by the catalysts of the invention can render them viable alternatives to conventional platinum-containing catalysts.
  • the improvement in molybdenum-containing catalysts provided by this invention resides in providing a sufficient amount of platinum group metal to enhance the xylene isomerization activity of the catalyst but below that amount that results in an undue increase in naphthene co-production.
  • the catalysts in accordance with this invention have a combination of a catalytically-effective amount of molecular sieve having a pore diameter of from 4 to 8 angstroms, preferably a pentasil structure zeolite, e.g., MFI-type zeolite, and a catalytically-effective amount of molybdenum hydrogenation component in combination with an isomerization-enhancing amount of at least one platinum group metal.
  • the catalyst comprises at least 0.2, often between 0.5 and 5, and most preferably between 0.5 and 3, mass-% molybdenum.
  • the total platinum group metal is often in an amount of at least 10, say, between 20 to 500, and preferably between 25 and 400, parts per million-mass (ppm-mass).
  • the preferred platinum group metal is platinum.
  • the broad aspects of the processes of this invention comprise contacting a feed stream containing a non-equilibrium admixture of at least one xylene isomer and ethylbenzene, wherein preferably between 1 and 60, and more frequently between 5 and 35, mass-% of the feed stream is ethylbenzene, with a catalyst comprising a catalytically-effective amount of amount of molecular sieve having a pore diameter of from 4 to 8 angstroms, preferably a pentasil structure zeolite, e.g., MFI-type zeolite, and a catalytically-effective amount of molybdenum hydrogenation component in combination with an isomerization-enhancing amount of at least one platinum group metal wherein the total amount of platinum group metal is below that which results under the isomerization conditions in undue co-production of naphthenes, to provide an isomerization product having a reduced ethylbenzene concentration and an isomer
  • the isomerization conditions include the presence of hydrogen in a mole ratio to hydrocarbon of between 0.5:1 to 6:1 , preferably 1 :1 or 2:1 to 5:1.
  • the isomerization is conducted under at least partially vapor phase conditions.
  • the ethylbenzene conversion is at least 60 mass-% and the xylene distribution is at least 90, preferably at least 95, percent of equilibrium.
  • para-xylene preferably comprises at least 23, and more preferably at least 23.4, mass-%.
  • the naphthene net make is less than 0.15, preferably less than 0.1 , mass-% based on the xylenes and ethylbenzene in the feed.
  • the catalysts used in the processes of this invention comprise a molecular sieve having a pore diameter of from 4 to 8 angstroms, and a molybdenum hydrogenation component in an amorphous aluminum phosphate binder.
  • molecular sieves include those having ShAI 2 ratios greater than 10, and often greater than 20, such as the MFI, MEL, EUO, FER, MFS, MTT, MTW, TON, MOR, UZM-8 and FAU types of zeolites.
  • Pentasil zeolites such as MFI, MEL, MTW and TON are preferred, and MFI-type zeolites, such as ZSM-5, silicalite, Borolite C, TS-1 , TSZ, ZSM-12, SSZ-25, PSH-3, and ITQ-1 are especially preferred.
  • MFI-type zeolites such as ZSM-5, silicalite, Borolite C, TS-1 , TSZ, ZSM-12, SSZ-25, PSH-3, and ITQ-1 are especially preferred.
  • the zeolite is combined with binder for convenient formation of catalyst particles.
  • the relative proportion of zeolite in the catalyst may range from 1 to 99 mass-%, with 2 to 90 mass-% being preferred.
  • the binder should be uniform in composition and relatively refractory to the conditions used in the process.
  • Suitable binders include inorganic oxides such as one or more of alumina, aluminum phosphate, magnesia, zirconia, chromia, titania, boria and silica.
  • the catalyst also may contain, without so limiting the composite, one or more of (1) other inorganic oxides including, but not limited to, beryllia, germania, vanadia, tin oxide, zinc oxide, iron oxide and cobalt oxide; (2) non-zeolitic molecular sieves, such as the aluminophosphates of US 4,310,440, the silicoaluminophosphates of US 4,440,871 and ELAPSOs of US 4,793,984; and (3) spinels such as MgAI 2 O 4 , FeAI 2 O 4 , ZnAI 2 O 4 , CaAI 2 O 4 , and other like compounds having the formula MO — AI 2 O 3 where M is a metal having a valence of 2; which components can be added to the composite at any suitable point.
  • other inorganic oxides including, but not limited to, beryllia, germania, vanadia, tin oxide, zinc oxide, iron oxide and cobalt oxide
  • a preferred binder or matrix component comprises an amorphous phosphorous-containing alumina (hereinafter referred to as aluminum phosphate) component.
  • the atomic ratios of aluminum to phosphorus in the aluminum phosphate binder/matrix generally range from 1 :10 to 100:1 , and more typically from 1 :5 to 20:1.
  • the aluminum phosphate has a surface area of up to 450 m 2 /g, and preferably the surface area is up to 250 m 2 /g. See, for instance, US 6,143,941.
  • Aluminum phosphate binders tend to reduce the transalkylation activity of the catalyst, e.g., co-production of toluene and trimethylbenzene.
  • the aluminum phosphate may be prepared in any suitable manner.
  • One suitable technique for preparing aluminum phosphate is the oil-drop method of preparing the aluminum phosphate which is described in US 4,629,717. This technique involves the gellation of a hydrosol of alumina which contains a phosphorus compound using the well-known oil-drop method. Generally this technique involves preparing a hydrosol by digesting aluminum in aqueous hydrochloric acid at reflux temperatures of 80° to 105 0 C. The mass ratio of aluminum to chloride in the sol often ranges from 0.7:1 to 1.5:1. A phosphorus compound is added to the sol.
  • Preferred phosphorus compounds are phosphoric acid, phosphorous acid and ammonium phosphate. The relative amount of phosphorus and aluminum expressed in atomic ratios ranges from 10:1 to 1 :100, and often 10:1 to 1 :10.
  • the molecular sieve can be added to the hydrosol prior to gelling the mixture.
  • One method of gelling involves combining a gelling agent with the mixture and then dispersing the resultant combined mixture into an oil bath or tower which has been heated to elevated temperatures such that gellation occurs with the formation of spheroidal particles.
  • the gelling agents which may be used in this process are hexamethylene tetraamine, urea or mixtures thereof.
  • the gelling agents release ammonia at the elevated temperatures which 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 drying treatments in oil and in ammoniacal solution to further improve their physical characteristics.
  • the resulting aged and gelled particles are then washed and dried at a relatively low temperature of 100° to 150 0 C and subjected to a calcination procedure at a temperature of 450° to 700 0 C for a period of 1 to 20 hours.
  • the combined mixture preferably is dispersed into the oil bath in the form of droplets from a nozzle, orifice or rotating disk.
  • the particles may be formed by spray-drying of the mixture at a temperature of from 425° to 760 0 C.
  • conditions and equipment should be selected to obtain small spherical particles; the particles preferably should have an average diameter of less than 5.0 mm, more preferably from 0.2 to 3 mm, and optimally from 0.3 to 2 mm.
  • the catalyst may be an extrudate.
  • the well-known extrusion method initially involves mixing of the molecular sieve with optionally the binder and a suitable peptizing agent 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, with moisture content in the range of from 30 to 50 mass-% being preferred.
  • the dough is then extruded through a die pierced with multiple holes and the spaghetti-shaped extrudate is cut to form particles in accordance with techniques well known in the art.
  • a multitude of different extrudate shapes is possible, including, but not limited to, cylinders, cloverleaf, dumbbell and symmetrical and asymmetrical polylobates.
  • the extrudates may be further shaped to any desired form, such as spheres, by marumerization or any other means known in the art.
  • a composite structure having a core and an outer layer containing molecular sieve and binder such as gamma alumina, aluminum phosphate, and the like.
  • the thickness of the molecular sieve layer is less than 250 microns, e.g., 20 to 200, microns.
  • the core may be composed of any suitable support material such as alumina or silica, and is preferably relatively inert towards dealkylation.
  • at least 75, and preferably at least 90, mass-% of the molybdenum in the catalyst is contained in the outer layer.
  • the catalyst may be in any suitable configuration including spheres and monolithic structures.
  • the catalyst may contain other components provided that they do not unduly adversely affect the performance of the finished catalyst. These components are preferably in a minor amount, e.g., less than 40, and most preferably less than 15, mass-% based upon the mass of the catalyst.
  • hydrocarbon conversion catalysts such as: (1) refractory inorganic oxides such as alumina, titania, zirconia, chromia, zinc oxide, magnesia, thoria, boria, silica-alumina, silica-magnesia, chromia-alumina, alumina- boria, silica-zirconia, phosphorus-alumina, etc.; (2) ceramics, porcelain, bauxite; (3) silica or silica gel, silicon carbide, clays and silicates including those synthetically prepared and naturally occurring, which may or may not be acid treated, for example, attapulgite clay, diatomaceous earth, fuller's earth, kaolin, kieselguhr, etc.; and (4) combinations of materials from one or more of these groups.
  • refractory inorganic oxides such as alumina, titania, zirconia, chromia, zinc oxide, magnesia, thoria,
  • Catalysts of the invention comprise molybdenum and at least one platinum group metal as a hydrogenation metal catalyst components.
  • Platinum-group metals include one or more of platinum, palladium, rhodium, ruthenium osmium, and iridium, preferably platinum.
  • the molybdenum comprises at least 60 atomic- percent, preferably at least 80 atomic-percent to essentially all, of the hydrogenation metal (elemental basis) of the hydrogenation component.
  • the platinum group metal present is in an amount of 20 to 500 ppm-mass.
  • Molybdenum (calculated on an elemental basis) generally comprises from 0.2 to 5 mass-% of the final catalyst.
  • the relative amounts of molybdenum and the at least one platinum group metal are such that the isomerization activity is enhanced as compared to a substantially identical catalyst but having no platinum group metal thereon.
  • the proximity of the hydrogenation metals to the active molecular sieve sites can play a role in the performance of the catalyst.
  • the binder and molecular sieve components can, in addition to the method of catalyst preparation, influence the absolute and relative amounts of the hydrogenation metal components in proximity to the active molecular sieve sites. Consequently, more or less hydrogenation component may be desirable depending upon these other factors affecting the catalyst.
  • the relative portions of each of the components that resides proximate the active molecular sieve sites may vary depending upon the above factors.
  • An additional factor affecting the absolute and relative amounts of molybdenum and platinum group metal is the type of platinum group metal used as platinum, for instance, may be suitable in a lesser amount than, say, ruthenium.
  • the Evaluation Conditions for this characterization comprise using feed stream containing 15 mass-% ethylbenzene, 25 mass-% ortho-xylene and 60 mass-% meta-xylene; a hydrogen to hydrocarbon ratio of 4:1 ; a pressure of 700 kPa gauge; a weight hourly space velocity of 10 hr "1 , and a temperature sufficient to convert 75 mass-% of the ethylbenzene with the data taken at 50 hours of operation.
  • These specified conditions are for the purpose of providing common conditions for catalyst evaluation and are not limiting as to the xylene isomerization conditions that may be used in the processes of this invention.
  • the preferred catalysts of this invention exhibit, under Evaluation Conditions, sufficient isomerization activity to provide a xylene-containing isomerization product stream in which of the xylenes, para-xylene comprises at least 23 mass-%, ortho-xylene at least 21 mass-%, and meta-xylene at least 48 mass-%.
  • para-xylene preferably comprises at least 23, and more preferably at least 23.4, mass-%.
  • the xylene distribution is at least 90, preferably at least 95, percent of equilibrium.
  • the naphthene net make is less than an isomerization catalyst comprising platinum group metal as the only hydrogenation metal component. Often, the naphthene net make is less than 0.15, preferably less than 0.1 , mass-% based on the xylenes and ethylbenzene in the feed at Evaluation Conditions.
  • the molybdenum and platinum group metal components are in amounts suitable to provide less total toluene and trimethylbenzene make as compared to catalyst containing only the molybdenum component and a catalyst containing only the platinum group metal component at Evaluation Conditions.
  • the preferred catalysts of this invention can be characterized as having under specified conditions, a net make of toluene and trimethylbenzene of less than 3, preferably less than 2, mass-% based on the mass of C 8 aromatics (xylenes and ethylbenzene) in the feed.
  • the hydrogenation metal may exist within the final catalyst composite as a compound such as an oxide, sulfide, halide, oxysulfide, etc., or as an elemental metal or in combination with one or more other ingredients of the catalyst composite. It is within the scope of the present invention that the catalyst composites may contain other metal components. Such metal modifiers may include rhenium, tin, germanium, lead, cobalt, nickel, indium, gallium, zinc, uranium, dysprosium, thallium, and mixtures thereof. Catalytically effective amounts of such metal modifiers may be incorporated into the catalysts by any means known in the art to effect a homogeneous or stratified distribution.
  • the catalysts of the present invention may contain a halogen component, comprising fluorine, chlorine, bromine or iodine or mixtures thereof, with chlorine being preferred. Preferably, however, the catalyst contains no added halogen other than that associated with other catalyst components.
  • the hydrogenation metal component may be incorporated into the catalyst composite in any suitable manner. One method of preparing the catalyst involves the utilization of a water-soluble, decomposable compound of the hydrogenation metal to impregnate the calcined sieve/binder composite. Alternatively, a hydrogenation metal compound may be added at the time of compositing the sieve component and binder.
  • One useful process for making the catalysts comprises forming the catalyst composite without the molybdenum component and then impregnating or otherwise depositing on the composite with a molybdenum compound such as ammonium heptamolybdate, molybdenum trioxide, ammonium dimolybdate, molybdenum oxychloride, molybdenum halides, e.g., molybdenum chloride and molybdenum bromide, molybdenum carbonyl, phosphomolybdates, and heteromolybdic acids.
  • a molybdenum compound such as ammonium heptamolybdate, molybdenum trioxide, ammonium dimolybdate, molybdenum oxychloride, molybdenum halides, e.g., molybdenum chloride and molybdenum bromide, molybdenum carbonyl, phosphomolybdates, and heteromolybdic acids.
  • the catalyst composites are dried at a temperature of from 100° to 320 0 C for a period of from 2 to 24 or more hours.
  • the catalyst may be calcined at a temperature of from 400° to 650 0 C in an air atmosphere for a period of from 0.1 to 10 hours. Steam may also be present during the calcination, e.g., from 0.5 to 20, say, 1 to 10, mol-% steam based on the air.
  • the resultant calcined composites often are subjected to a substantially water-free reduction step to ensure a uniform and finely divided dispersion of the optional metallic components.
  • the reducing agent contacts the catalyst at conditions, including a temperature of from 200° to 650 0 C and for a period of from 0.5 to 10 hours, effective to reduce substantially all of the platinum group metal component to the metallic state.
  • sulfiding can enhance isomerization activity.
  • Sulfiding conditions are those in which the sulfiding agent is incorporated into the catalyst without forming sulfur dioxide.
  • the sulfiding may be done during the catalyst preparation or thereafter, including as a pretreatment at catalyst start-up or during use of the catalyst.
  • the sulfiding may be conducted in any convenient manner. For instance, a solid or sorbed sulfur-containing component, i.e., sulfiding agent, may be incorporated into the catalyst composite which decomposes during the catalyst preparation or during start-up or use of the catalyst.
  • the formed catalyst may be contacted with a liquid or gaseous sulfiding agent under sulfiding conditions.
  • sulfiding agents include hydrogen sulfide, carbonyl sulfide, carbon disulfide, salts, especially ammonium and organo salts, of sulfates, bisulfates, sulfites, and bisulfites, sulfur dioxide, sulfur trioxide, organosulfides, e.g., dimethyl sulfide, diethyl sulfide, and methyl ethyl sulfide; mercaptans, e.g., methyl mercaptan, ethyl mercaptan, and t-butyl mercaptan; thiophenes, e.g., tetrahydrothiophene.
  • the sulfiding conditions can vary widely and will depend upon the nature to the sulfiding agent and the extent of sulfiding desired. For instance, with oxygen- containing sulfur compounds, the sulfiding conditions should be sufficient to reduce the sulfur moiety to sulfide. The selection of the sulfiding conditions will also be influenced limits of feasibility at the location of the catalyst undergoing sulfiding. Thus, different conditions may be preferred where the sulfiding is being conducted after the catalyst has been installed in a reactor for the isomerization as would be preferred where the catalyst is at a facility for the manufacture of catalyst.
  • the sulfiding may be conducted over a temperature range of 0° to 600 0 C, preferably 10° to 500 0 C and a pressure of from 10 to 5000 or more kPa absolute.
  • the duration of the sulfiding will depend upon the other conditions of the sulfiding, e.g., the sulfiding agent, the concentration of the sulfiding agent, and sulfiding temperature, as well as the amount of sulfur to be incorporated into the catalyst.
  • the sulfiding is conducted for a period of time of at least 10 minutes, and may, in the case of in situ sulfiding in an isomerization reactor, be continuous.
  • the sulfiding is usually done over a period of at least 10 minutes, e.g., 10 minutes to 24 hours. Often, the sulfiding is done in the presence of hydrogen, e.g., at a partial pressure of 10 to 5 MPa.
  • the sulfiding may be accomplished as a pretreatment or during the isomerization process itself. In the latter case, the sulfiding agent is usually provided in a low concentration, e.g., less than 50, say 0.001 to 20, ppm-mass of the feedstock.
  • Catalysts may be regenerated. Where the loss of catalytic activity is due to coking of the catalyst, conventional regeneration processes such as high temperature oxidation of the carbonaceous material on the catalyst may be employed.
  • the catalyst suffering from the loss of isomerization activity may be regenerated by sulfiding to regain at least a portion of the isomerization activity.
  • the regeneration may also reduce the naphthene make of the catalyst.
  • the regeneration can occur while the catalyst is in the isomerization reactor, either by intermittently supplying sulfiding agent during the isomerization process at times that regeneration is sought, or by terminating the isomerization process and conducting a dedicated sulfiding.
  • the sulfiding agent is usually provided in an amount between 0.1 and 20 ppm-mass based upon the feed stream, for a time sufficient to introduce between 0.5 and 3 atoms of sulfur per atom of molybdenum.
  • the feedstocks to the aromatics isomerization process of this invention comprise non-equilibrium xylene and ethylbenzene. These aromatic compounds are in a non-equilibrium mixture, i.e., at least one C 8 aromatic isomer is present in a concentration that differs substantially from the equilibrium concentration at isomerization conditions.
  • a non-equilibrium xylene composition exists where one or two of the xylene isomers are in less than equilibrium proportion with respect to the other xylene isomer or isomers.
  • the xylene in less than equilibrium proportion may be any of the para-, meta- and ortho-isomers.
  • the feedstocks will contain meta-xylene.
  • the mixture will have an ethylbenzene content of 1 to 60 mass-%, an ortho-xylene content of 0 to 35 mass-%, a meta-xylene content of 20 to 95 mass-% and a para-xylene content of 0 to 30 mass-%.
  • the non- equilibrium mixture is prepared by removal of para-, ortho- and/or meta-xylene from a fresh C 8 aromatic mixture obtained from an aromatics-production process.
  • the feedstocks may contain other components, including, but not limited to naphthenes and acyclic paraffins, as well as higher and lower molecular weight aromatics.
  • the alkylaromatic hydrocarbons may be used in the present invention as found in appropriate fractions from various refinery petroleum streams, e.g., as individual components or as certain boiling-range fractions obtained by the selective fractionation and distillation of catalytically cracked or reformed hydrocarbons.
  • Concentration of the isomerizable aromatic hydrocarbons is optional; the process of the present invention allows the isomerization of alkylaromatic-containing streams such as catalytic reformate with or without subsequent aromatics extraction to produce specified xylene isomers and particularly to produce para-xylene.
  • the feedstock in the presence of hydrogen, is contacted with the catalyst described above. Contacting may be effected using the catalyst system in a fixed-bed system, a moving-bed system, a fluidized-bed system, and an ebullated-bed system or in a batch-type operation. In view of the danger of attrition loss of valuable catalysts and of the simpler operation, it is preferred to use a fixed-bed system.
  • the feed mixture is preheated by suitable heating means to the desired reaction temperature, such as by heat exchange with another stream if necessary, and then passed into an isomerization zone containing catalyst.
  • the isomerization zone may be one or more separate reactors with suitable means therebetween to ensure that the desired isomerization temperature is maintained at the entrance to each zone.
  • the reactants may be contacted with the catalyst bed in upward-, downward-, or radial-flow fashion.
  • the isomerization is conducted under isomerization conditions including isomerization temperatures generally within the range of 100° to 550 0 C or more, and preferably in the range from 150° to 500 0 C.
  • the pressure generally is from 10 kPa to 5 MPa absolute, preferably from 100 kPa to 3 MPa absolute.
  • the isomerization conditions comprise the presence of hydrogen in a hydrogen to hydrocarbon mole ratio of between 0.5:1 to 6:1 , preferably 1 :1 or 2:1 to 5:1.
  • One of the advantages of the processes of this invention is that relatively low partial pressures of hydrogen are still able to provide the sought selectivity and activity of the isomerization and ethylbenzene conversion.
  • a sufficient mass of catalyst comprising the catalyst is contained in the isomerization zone to provide a weight hourly space velocity with respect to the liquid feed stream (those components that are normally liquid at STP) of from 0.1 to 50 hr " ⁇ and preferably 0.5 to 25 hr "1 .
  • the isomerization conditions may be such that the isomerization is conducted in the liquid, vapor or at least partially vaporous phase. For convenience in hydrogen distribution, the isomerization is preferably conducted in at least partially in the vapor phase.
  • the partial pressure of C 8 aromatics in the reaction zone is preferably such that at least 50 mass-% of the C 8 aromatics would be expected to be in the vapor phase.
  • the isomerization is conducted with essentially all the C 8 aromatics being in the vapor phase.
  • the isomerization conditions are sufficient that at least 50, preferably between 60 and 80 or 90, percent of the ethylbenzene in the feed stream is converted. Generally the isomerization conditions do not result in a xylene equilibrium being reached.
  • the isomerization process is to generate para- xylene, e.g., from meta-xylene
  • the feed stream contains less than 5 mass-% para- xylene and the isomerization product comprises a para-xylene to xylenes mole ratio of between 0.233:1 to 0.25:1 preferably at least 0.235:1.
  • the isomerization product is fractionated to remove light by-products such as alkanes, naphthenes, benzene and toluene, and heavy byproducts to obtain a Ca isomer product.
  • Heavy byproducts include dimethylethylbenzene and trimethylbenzene.
  • certain product species such as ortho-xylene or dimethylethylbenzene may be recovered from the isomerized product by selective fractionation.
  • the product from isomerization of C 8 aromatics usually is processed to selectively recover the para-xylene isomer, optionally by crystallization.
  • Selective adsorption is preferred using crystalline aluminosilicates according to US 3,201 ,491. Improvements and alternatives within the preferred adsorption recovery process are described in US 3,626,020, US 3,696,107, US 4,039,599, US 4,184,943, US 4,381 ,419 and US 4,402,832, incorporated herein by reference.
  • Catalyst A (comparative): Steamed and calcined aluminum-phosphate- bound MFI zeolite spheres are prepared using the method of Example I in US 6,143,941. The pellets are impregnated with an aqueous solution of ammonium heptamolybdate, dried and calcined in dry air for 2 hours at 538°C to give 1.0 mass- % molybdenum on the catalyst. The calcined catalyst is reduced in hydrogen at 425°C.
  • Catalyst B (comparative): Steamed and calcined aluminum-phosphate- bound MFI zeolite spheres are prepared using the method of Example I in US 6,143,941. The pellets are impregnated with an aqueous solution of tetra-ammine platinum chloride to give 0.037 mass-% platinum after drying and calcination at 538°C. The calcined catalyst is reduced in hydrogen at 425°C.
  • Catalyst C Steamed and calcined aluminum-phosphate-bound MFI zeolite spheres are prepared using the method of Example I in US 6,143,941.
  • the pellets are impregnated with 1.0 mass-% Mo from an aqueous solution of ammonium heptamolybdate, dried and calcined in dry air at 538°C.
  • the calcined catalyst is impregnated with an aqueous solution of tetra-ammine platinum chloride to give 0.009 mass-% platinum. After drying and calcination at 538°C, the catalyst is reduced in hydrogen at 425°C.
  • Catalyst D Steamed and calcined aluminum-phosphate-bound MFI zeolite spheres are prepared using the method of Example I in US 6,143,941. The pellets are impregnated with 0.5 mass-% Mo from an aqueous solution of ammonium heptamolybdate, dried and calcined in dry air at 538°C. The calcined catalyst is impregnated with an aqueous solution of tetra-ammine platinum chloride to give 0.0094 mass-% platinum. After drying and calcination at 538°C, the catalyst is reduced in hydrogen at 425°C.
  • Catalysts A to D are evaluated in a pilot plant for the isomerization of a feed stream containing 15 mass-% ethylbenzene, 25 mass-% ortho-xylene and 60 mass-% meta-xylene.
  • the pilot plant runs are at a hydrogen to hydrocarbon ratio of 4:1.
  • the pilot plant runs are summarized in Table 1.
  • the product data are taken at 50 hours of operation.
  • the weight hourly space velocities are based upon grams of zeolite loaded. Table 1
  • Catalyst E (Comparative): Steamed and calcined aluminum-phosphate- bound MFI zeolite spheres are prepared using the method of Example I in US 6,143,941. The pellets are impregnated with an aqueous solution of ammonium heptamolybdate, dried and calcined in dry air for 2 hours at 538 0 C to give 0.9 mass- % molybdenum on the catalyst.
  • Catalyst F A portion of calcined catalyst E is impregnated with an aqueous solution of tetra-ammine platinum chloride to give 0.005 mass-% platinum.
  • Catalyst G A second portion of calcined catalyst E is impregnated with an aqueous solution of tetra-ammine platinum chloride to give 0.039 mass-% platinum. After drying and calcination at 538°C, the catalyst is reduced in hydrogen at 425°C.
  • Catalyst H (Comparative): Steamed and calcined aluminum-phosphate- bound MFI zeolite spheres are prepared using the method of Example I in US 6,143,941.
  • Catalysts E, F, G, H, B and C are evaluated in a laboratory reactor for the isomerization of a feed stream containing 15 mass-% ethylbenzene, 25 mass-% ortho-xylene and 60 mass-% meta-xylene. The tests are conducted at a hydrogen to hydrocarbon ratio of 4:1. The data are summarized in Table 2. The product data are taken at 20 hours of operation. The weight hourly space velocities are based upon grams of zeolite loaded.
  • the reactor configuration, especially its smaller reactor size in comparison to the pilot plant, and reactor variable controls of the laboratory reactor are such that the performance data may not be directly comparable to the data from the pilot plant. Nevertheless, the performance data from the laboratory reactor are believed to be indicative of the relative performances of the catalysts.

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Abstract

L'invention porte sur des catalyseurs qui comprennent une combinaison d'un tamis moléculaire ayant un diamètre de pore de 4 à 8 angströms et une quantité catalytiquement efficace de composant d'hydrogénation molybdène et une quantité suffisante d'au moins un composant d'hydrogénation métal du groupe du platine pour améliorer l'isomérisation.
PCT/US2008/057361 2008-03-18 2008-03-18 Procédés de conversion de l'éthylbenzène et d'isomérisation du xylène et catalyseurs pour ces procédés WO2009116995A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112570005A (zh) * 2019-09-30 2021-03-30 中国石油化工股份有限公司 一种调控反应体系中金属加氢活性的方法及其应用
CN116408139A (zh) * 2021-12-31 2023-07-11 中国石油天然气股份有限公司 一种二甲苯异构化催化剂及其制备方法与应用

Citations (2)

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Publication number Priority date Publication date Assignee Title
US5689027A (en) * 1994-11-18 1997-11-18 Mobil Oil Corporation Selective ethylbenzene conversion
US20050020435A1 (en) * 2003-07-23 2005-01-27 Beck Jeffrey S. High temperature calcination of selectivated molecular sieve catalysts for activity and diffusional modification

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5689027A (en) * 1994-11-18 1997-11-18 Mobil Oil Corporation Selective ethylbenzene conversion
US20050020435A1 (en) * 2003-07-23 2005-01-27 Beck Jeffrey S. High temperature calcination of selectivated molecular sieve catalysts for activity and diffusional modification

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112570005A (zh) * 2019-09-30 2021-03-30 中国石油化工股份有限公司 一种调控反应体系中金属加氢活性的方法及其应用
CN112570005B (zh) * 2019-09-30 2023-08-04 中国石油化工股份有限公司 一种调控反应体系中金属加氢活性的方法及其应用
CN116408139A (zh) * 2021-12-31 2023-07-11 中国石油天然气股份有限公司 一种二甲苯异构化催化剂及其制备方法与应用

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