KR100543270B1 - Aromatic conversion processes and zeolite catalyst useful therein - Google Patents

Abstract

The present invention relates to alkylation, transalkylation or isomerization of aromatic hydrocarbons. The process involves contacting an aromatic hydrocarbon with a zeolite-bound zeolite catalyst under conversion conditions. Zeolite-bonded zeolite catalysts comprise a first crystal of a first macroporous zeolite bound by a second crystal of a second zeolite.

Description

AROMATIC CONVERSION PROCESSES AND ZEOLITE CATALYST USEFUL THEREIN}

The present invention relates to the isomerization, alkylation and / or transalkylation of aromatic hydrocarbons using zeolite-bonded zeolite catalysts.

As a method of producing ethylbenzene or monoalkylaromatic products such as isopropylbenzene, also known as cumene, in high yield, various methods are known including alkylation and / or alkyl exchange. However, this method has problems such as generating unintended by-products. Examples of such byproducts produced with cumene include alkylating agent oligomers, higher polyaromatic compounds and unwanted monoalkylated and dialkylated compounds such as n-propylbenzene, butylbenzene and ethylbenzene. In particular, the production of unwanted xylenes is a problem in the production of ethylbenzene. Another problem associated with this process involves the use of Friedel Craft catalysts such as solid phosphoric acid or ammonium chloride. When using a phosphate catalyst, water must generally be supplied simultaneously, which produces corrosive sludge by-products. The use of certain crystalline microporous molecular sieves, such as catalysts, avoids the problems associated with sludge byproducts. However, the major disadvantages associated with the use of zeolite catalysts are that undesired by-products can be produced and that catalyst deactivation is relatively fast, requiring time-consuming and expensive replacement or reactivation of the catalyst.

Crystalline microporous molecular sieve is an ordered, porous, crystalline material with a number of small cavities that can be interconnected by many small channels or pores, with a finite crystal structure as determined by x-ray diffraction. These pores are sized to absorb molecules of a certain size but not to absorb larger molecules. Molecular sieves, such as crystalline silicates, crystalline aluminosilicates, crystalline silicoalumino phosphates and crystalline aluminophosphates, by means of the spaces or channels of the gaps formed by the crystalline network, are used as catalysts in the separation process and in various hydrocarbon conversion processes. It can be used as a catalyst support.

In the pores of crystalline molecular sieves, hydrocarbon conversion reactions such as alkylation and alkylation of aromatics are governed by conditions imposed by the size of the molecular sieve. Reactant selectivity occurs when a particular fraction of the feed is too large to react through the pores, whereas product selectivity occurs when the product fails to pass through the channel or subsequently reacts. The product distribution can be altered by the transition state selectivity in which a particular reaction cannot occur because the reaction transition state is so large that it cannot form in the pores. Selectivity can be derived from steric confinement upon diffusion, where the size of the molecule is similar to the size of the pore system. Non-selective reactions on the surface of the molecular sieve are generally undesirable because these reactions do not apply to the form-selective limitations imposed on the reactions occurring in the channels of the molecular sieve.

Zeolites consist of a silica lattice and optionally alumina incorporating exchangeable cations such as alkali or alkaline earth metal ions. The term "zeolite" includes materials containing silica and optionally alumina, but it should be understood that the silica and alumina portions may be replaced in whole or in part by other oxides. For example, the silica portion may be replaced by germanium oxide, tin oxide, phosphorus oxide and mixtures thereof. The aluminum part can be replaced by boron oxide, iron oxide, titanium oxide, gallium oxide, indium oxide and mixtures thereof. Thus, the terms "zeolite" and "zeolitic material" as used herein refer to materials containing silicon and optionally aluminum atoms in their crystalline lattice structure, as well as gallosilicates, silicoaluminophosphates (SAPO) and alumines It may also mean a material containing an atom suitable for replacing silicon and aluminum, such as nophosphate (ALPO). As used herein, “aluminosilicate zeolite” shall mean a zeolite material consisting essentially of silicon and aluminum atoms in a crystalline lattice structure.

Numerous methods have been proposed for isomerization, alkylation or alkyl exchange of aromatic hydrocarbons. For example, US Pat. No. 4,312,790 includes a xylene isomerization process using an alumina-bonded zeolite catalyst. U. S. Patent No. 5,227, 558 includes a process for aromatic alkylation using a zeolite beta catalyst bound by a binder such as alumina. European Patent Application No. 0 109 962 discloses the use of xylene isomerization and ethylbenzene with a catalyst comprising mordenite in acid form and another specific acid form of zeolite such as ZSM-5, ZSM-8 or ZSM-11. Deethylation to benzene is initiated. "Chemical Abstracts", 101: 72405n (1984) and 85: 95018s (1976) describe the use of xylene isomerization and ethylbenzene with a catalyst comprising mordenite in acid form and another specific acid form of zeolite. Deethylation is initiated.

Synthetic zeolites are typically prepared by crystallizing zeolites from supersaturated synthetic mixtures. The crystalline product thus obtained is then dried and calcined to form a zeolite powder. Although zeolite powder has excellent adsorption property, its practicality is severely limited because it is difficult to operate a fixed bed with zeolite powder. Thus, zeolite crystals are generally combined before the powder is used for commercial use.

Zeolite powders are typically joined by the formation of zeolite aggregates such as rings, spheres or extrudates. The extrudate is usually formed by extrusion of the zeolite in the presence of a non-zeolitic binder and drying and calcination of the resulting extrudate. The binder materials used are resistant to temperatures that can occur in various hydrocarbon conversion processes and other conditions such as, for example, mechanical wear. Examples of binder materials include amorphous materials such as alumina, silica, titania and various types of clays. In general, zeolites need to be resistant to mechanical abrasion (ie, the production of fines, small particles having a size of less than 20 μm).

Although these bonded zeolite aggregates have much better mechanical strength than zeolite powders, when these bonded zeolites are used in aromatic conversion, the performance of the zeolite catalysts, such as activity, selectivity, activity retention or combinations thereof, are combined. Can be reduced due to zero. For example, the binder is typically present in an amount up to about 50% by weight of the zeolite, so that the binder can degrade the adsorbability of the zeolite aggregates. In addition, since the bound zeolite is prepared by extruding or otherwise producing the zeolite with a binder and drying and calcining the resulting extrudate, the amorphous binder can penetrate the pores of the zeolite or otherwise block the pores of the zeolite, or By slowing down the mass transport to the pores of the can reduce the efficacy of the zeolite used in the aromatic conversion process. Moreover, when bound zeolites are used in aromatic conversion processes, the binders may not only affect the chemical reactions occurring in the zeolites but may also promote undesired reactions which may produce undesired products by themselves.

Summary of the Invention

In one embodiment, the present invention is directed to aromatic conversion processes such as isomerization, alkylation and / or transalkylation of aromatic hydrocarbons using zeolite-bonded zeolite catalysts. Zeolite-bonded zeolite catalysts include a binder comprising a first crystal of the macroporous first zeolite and a second crystal of the second zeolite. Isomerization, alkylation or transalkylation of the aromatic stream according to the invention gives the desired product in high yield.

In another embodiment, the present invention includes a binder comprising a first crystal of a first zeolite having a MOR, EMT or MAZ structure, and a second crystal of a second zeolite, found to have special use in an aromatic conversion process. To a zeolite-bound zeolite catalyst.

1 is an SEM micrograph of the catalyst of Example 1. FIG.

2 is an SEM micrograph of the catalyst of Example 2. FIG.

The zeolite-bonded zeolite catalyst comprises a binder comprising a first crystal of the macroporous acidic zeolite, and a second crystal of the second zeolite, preferably having an average particle diameter smaller than the average particle diameter of the first particle. Using the second zeolite crystals as binders provides a means for controlling unintended reactions occurring in or near the outer surface of the first zeolite crystals, improving mass transport of the reactants and from the pores of the first zeolite And catalysts with better access to the pores. In addition, the second zeolite binding crystal may optionally have catalytic activity, act as a catalyst carrier, and / or selectively prevent unwanted molecules from entering or exiting the pores of the first zeolite. .

Unlike typical zeolite catalysts used in hydrocarbon conversion processes, which are commonly combined with silica or alumina or other amorphous binders commonly used to improve the mechanical strength of zeolites, the zeolite catalysts of the present invention utilize non-zeolitic binders. It does not contain a considerable amount. Preferably, the zeolite catalyst comprises less than 10% by weight, more preferably less than 5% by weight of the non-zeolitic binder, based on the total weight of the first and second zeolites, most preferably the non-zeolitic It is substantially free of binders. Preferably, the second zeolite crystal is bonded to the first zeolite crystal by adhering to the surface of the first zeolite crystal to form a matrix or bridge structure that holds the first crystal grains together. More preferably, the second zeolite particles are intergrown to bind with the first zeolite by forming a coating or partial coating on the larger first zeolite crystal, most preferably the second zeolite crystal is crystallized. The liver grows and binds to the first zeolite crystal by forming an over-growth that is wear resistant on the first zeolite crystal.

Although the present invention is not limited in theory, it is believed that one of the advantages of the zeolite catalyst system of the present invention is obtained by a second zeolite which can control the accessibility of the acid sites on the outer surface of the first zeolite to the reactants. Since the acid sites present on the outer surface of the zeolite catalyst are not form-selective, these acid sites can negatively affect the reactants entering the pores of the zeolite and the products exiting the pores of the zeolite. In this sense, since the acidity of the second zeolite can be carefully selected, unlike the conventional bonded zeolite catalyst, the second zeolite has no negative effect on the reactants exiting the pores of the first zeolite, It can also have a positive effect on the reactants exiting the pore. In addition, since the second zeolite is not an amorphous but instead a molecular sieve, the hydrocarbon may have increased access to the pores of the first zeolite during the hydrocarbon conversion process. Regardless of this theory, zeolite-bonded zeolite catalysts have improved properties as disclosed herein when used in catalytic processes.

The terms "acidic", "weakly acidic" and "strongly acidic" as used herein for zeolites are well known to those skilled in the art. The acidity of zeolites is well known. However, in connection with the present invention the terms acid strength and acid site density should be distinguished. The acid site of the zeolite can be Bronsted acid or Lewis acid. The density of the acid sites and the number of acid sites are important for determining the acidity of the zeolite. Factors directly affecting acid strength include (i) the chemical composition of the zeolite framework, i.e. the relative concentration and type of tetrahedral atoms, (ii) the concentration of exogenous-skeletal cations and the resulting exogenous-skeletal species, ( iii) the local structure of the zeolite, for example the pore size and position in the crystal at or near the surface of the zeolite, and (iv) the pretreatment conditions and the presence of co-adsorbed molecules. Although the amount of acidity is associated with isomorphic substitution, this acidity is limited to the loss of acid sites in pure SiO ₂ compositions. As used herein, the terms “acidic”, “weakly acidic” and “strongly acidic” refer to the concentration of acid sites, regardless of the strength of these acid sites, which can be measured by ammonia adsorption.

As used herein, the term "average particle diameter" refers to the arithmetic mean of the diameter distribution of crystals based on volume.

Examples of macroporous zeolites suitable for use in zeolite-bonded zeolite catalysts include zeolites having a pore size of about 7.0 GPa or greater. Such zeolites are described in "Atlas of Zeolite Structure Types", eds. W.H.Meier and D.H.Olson, Buttersworth-Heineman, Third Edition, 1992. Examples of macroporous zeolites include VFI, AFI, MAZ, MEI, FAU, EMT, OFF, BEA, and MOR structured zeolites (IUPAC Zeolite Naming Commission). Examples of macroporous zeolites are, for example, mazzite, offretite, zeolite L, VPI-5, zeolite Y, zeolite X, omega, beta, ZSM-3, ZSM-4, ZSM-18, ZSM-20 and SAPO-37. The structural forms of the first and second zeolites can be the same or different. Zeolites are typically at least partially in hydrogen form. Preferred first zeolites are zeolites having a BEA or MOR structure.

As is known to those skilled in the art, the acidity of the zeolite can be reduced using many methods, such as venting steam. The acidity of the zeolite also depends on the form of the zeolite, which is most acidic when in the hydrogen form, and less acidic than the acid form for other forms of zeolite, such as the sodium form. Thus, zeolites having a molar ratio of silica to alumina disclosed herein include zeolites having a molar ratio disclosed as well as zeolites having no molar ratio disclosed but having equivalent catalytic activity.

Large pore size zeolites suitable for use in zeolite-bonded zeolite catalysts are X ₂ O ₃ : (n) YO ₂ (X is a trivalent element such as aluminum, boron and / or gallium, and Y is silicon, tin and / Or a tetravalent element such as germanium, and n is a value greater than 2 depending on the zeolite and the particular type of trivalent element present in the zeolite.

When the first zeolite is an aluminosilicate zeolite, the ratio of silica to alumina of the first zeolite is usually not limited to any particular ratio since it depends on the structural type of the first zeolite. Generally, however, depending on the structure of the zeolite, the first zeolite will have a silica to alumina mole ratio of at least about 2: 1 and may have a silica to alumina mole ratio of about 300: 1. Preferably the aluminosilicate zeolite is in hydrogen form.

The crystal size of the first crystals will preferably be in the range of about 0.1 μm to 15 μm. More preferably, the first crystal will have an average particle diameter of 1-6 μm. The use of macrocrystals reduces the specific external surface area of the crystals and thereby increases the ratio of acid sites to surface acid sites in the crystals, so it is desirable to use macrocrystals.

Methods of determining the crystal size are well known to those skilled in the art. For example, the crystal size can be determined directly by taking a suitable scanning electron microscope (SEM) picture.

The outer surface acidity of the large first crystal of the first zeolite is preferably lower than the acidity in the channel of the zeolite. The outer surface acidity is preferably at least 40% lower, more preferably at least 50% lower, even more preferably at least 60% lower than the acidity in the channel. Most preferably the first crystals are substantially free of surface acidity.

Methods for reducing the surface acidity of the first crystals include removing alumina from the zeolite surface by hydrothermal, acid or chemical treatment. For example, the surface acidity of the first crystal can be reduced by treating the surface of the first crystal with basic compounds such as amines, phosphines, phenols, multinuclear hydrocarbons, cationic dyes and the like. In addition, the surface acidity of the crystals can be reduced by depositing on the crystal surface a material such as a porous crystalline silicate that coats the zeolite crystals and forms a layer or shell that inactivates the crystal surface on the surface of the first crystal. . A method of depositing an outer porous non-acidic shell on a zeolite crystal surface is disclosed in US Pat. No. 4,088,605, which is incorporated herein by reference.

Another method of depositing a porous crystalline silicate layer or shell on the zeolite crystal surface is an organic directing agent (e.g. tetrapropylammonium bromide, colloidal silica), and an alkali or alkaline earth metal base (e.g. Sodium hydroxide) is preferably mixed in this order to form an alkaline aqueous solution, a first crystal is added to the alkaline aqueous solution, and the aqueous mixture is reacted under low alkaline crystalline conditions to produce a non-acidic porous crystalline silicate layer. Forming a compound.

Preferred first zeolite is zeolite beta. Methods of making them are disclosed in US Pat. No. 3,308,069 and Reissue Pat. No. 28,341, incorporated herein by reference.

The most useful type of zeolite beta as the first macroporous zeolite is the following empirical formula (X / n) M. (1-X) Q.AlO ₂ .Y SiO ₂ .WH ₂ O, where X is less than 1, preferably Less than 0.75, Y is greater than 5 and less than 100, W is about 4 or less, M is a metal ion, n is a valence of M, Q is a hydrogen ion, ammonium ion or organic cation, or a mixture thereof) Crystalline aluminosilicate having. For the purposes of the present invention, Y is preferably greater than 5 and less than about 50. As a result, the atomic ratio of silica to aluminum in the above formula is greater than 5: 1 and less than 100: 1, preferably greater than 5: 1 and less than about 50: 1.

In the above formula, other elements such as gallium, boron and iron may be variously substituted for aluminum. Similarly, elements such as germanium and phosphorus can be variously substituted for silicon.

Suitable organic cations are tetraethylammonium bromide or hydroxide, dibenzyl-1, 4-diazabicyclo [2.2.2] octane chloride, dimethyldibenzyl ammonium chloride, 1,4-di (1-azonium) in aqueous solution. Cations derived from bicyclo [2.2.2] octane) butane dibromide or dihydroxide and the like.

M is typically an organic synthesized sodium ion, but may also be a metal added by techniques such as ion exchange or pore filling. Suitable metal cations include those of the periodic table IA, IIA or IIIA or hydrogenation components. Examples of such cations include ions of lithium, potassium, calcium, magnesium, barium, lanthanum, cerium, nickel, platinum, palladium and the like.

The second zeolite used in the zeolite-bonded zeolite catalyst is preferably a macroporous zeolite of the type as described above for the first zeolite. In some applications, the second zeolite is reduced in acid or substantially free of acid, and the aluminosilicate zeolite can be prepared with a high silica to alumina molar ratio. When the second zeolite is an aluminosilicate zeolite, the ratio of silica to alumina of the second zeolite depends on the structure type of the zeolite and is not limited to any particular ratio. Generally, however, depending on the structure of the zeolite, the second zeolite will have a silica to alumina molar ratio of at least about 2: 1, and for some aluminosilicate zeolites, the higher silica to alumina molar ratios of 10: 1, 500: 1, 1000: 1, and in some applications may contain even less traces of alumina. The second zeolite is preferably present in the range of about 10 to about 60 weight percent based on the weight of the first zeolite. More preferably, the amount of second zeolite is about 20 to about 50 weight percent.

The second zeolite crystals preferably have a smaller size than the first zeolite particles. The second zeolite crystals preferably have an average particle diameter of less than 1 μm, more preferably from about 0.1 to about 0.5 μm. The second zeolite crystals are bonded to the first zeolite particles to maximize the performance of the catalyst as well as preferably form inter-growth layers that grow between the crystals to coat or partially coat the first zeolite. Preferably the coating is wear resistant.

Zeolite-bonded zeolites may also contain hydrogenation components such as metals that are catalytically active. By catalytically active metal (s) is meant an elemental state such as oxides, sulfides, halides, carboxylates or the like or some other catalytically active form of metal (s). Such catalytically active metals are known to those skilled in the art and include, for example, one or more metals of groups IB, IIB, IIIA, IVA, VA, VIA, IVB, VB, VIB, VIIB and VIII of the Periodic Table. . Examples of suitable metals include platinum, palladium, rhodium, iridium, iron, molybdenum, cobalt, tungsten, nickel, manganese, titanium, zirconium, vanadium, hafnium, zinc, tin, lead, chromium and the like. The amount of catalytically active metal is generally from about 0.001 to about 10 weight percent, preferably from about 0.05 to about 3.0 weight percent, based on the weight of the catalyst. Methods of incorporating hydrogenation components into zeolite-bonded zeolite catalysts are well known to those skilled in the art.

Zeolite-bonded zeolite catalysts in which the second zeolite is aluminosilicate may be prepared by a three step process as described below (but not limited to this method). The first step involves the synthesis of the first zeolite. Methods of making the first zeolite are well known to those skilled in the art. For example, for zeolite beta, the method is disclosed in US Pat. No. 3,308,069.

After preparing the first zeolite, silica-bonded zeolites can be prepared by mixing a mixture comprising zeolite crystals, silica gel or sol, water and optionally extrusion aids, until a homogeneous composition of extrudable paste is produced. Can be. Optionally, alumina may be added to silica. Silica binders used to prepare silica-bonded zeolite aggregates are typically silica sol and may contain, for example, only small amounts (eg less than 2% by weight) of alumina. The amount of zeolite in the extrudate upon drying is about 40 to 90 weight percent, more preferably about 50 to 80 weight percent and the remainder is primarily silica, for example about 20 to 50 weight percent silica.

The paste thus obtained is molded (eg extruded), cut into small strands (eg 2 mm diameter extrudate), dried at 100-150 ° C. for 4-12 hours and then about 400-550 Calculate for about 1 to 10 hours in air at < RTI ID = 0.0 >

Optionally, the silica-bonded aggregates can be made into very small particles useful in fluid bed processes such as catalytic cracking. This preferably comprises mixing the silica solution with the zeolite and the zeolite to form an aqueous solution of the zeolite and silica binder, which is then spray dried to form small flowable silica-bonded aggregate particles. Methods of making such aggregate particles are known to those skilled in the art. Examples of such methods are described in Scherzer, "Octane-Enhancing Zeolite FCC Catalysts", Julius Scherzer, Marcel Dekker, Inc. New York, 1990. As with the silica-bonded extrudate as described above, the flowable silica-bonded agglomerate particles undergo a final step, described below, which converts the silica binder into a second zeolite.

The final step in the three-step catalyst preparation process is the conversion of the silica present in the silica-bonded zeolite to a second zeolite. The first zeolite crystals are bonded to each other without using a significant amount of non-zeolitic binders.

To prepare the zeolite catalysts, the silica-bonded aggregates can first be aged in a suitable aqueous solution at elevated temperature. The aging temperature of the contents and agglomerates of the solution should then be chosen so that the amorphous silica binder is converted to the desired second zeolite. The newly formed second zeolite is produced as crystals. These crystals can be grown on and / or adhered to the first zeolite crystals and can be prepared in the form of new inter-crystal grown crystals, which are generally much smaller than the first crystal (eg sub-micron size). . These newly formed crystals grow together and are interconnected.

The nature of the zeolite produced in the secondary synthesis conversion of the silica into the zeolite can vary as a function of the composition of the secondary synthesis solution and the synthetic aging conditions. The secondary synthesis solution is preferably an aqueous ionic solution containing a sufficient source of hydroxy ions to convert the silica to the desired zeolite. Templates such as organic amines can be added to assist in the conversion process. After aging the zeolite-bound zeolite is separated from the solution, washed, dried and calcined.

The catalyst is further ion exchanged as is known in the art to replace the original alkali metal present in the zeolite at least partially with a different cation (e.g. groups IB to VIII of the periodic table), or the alkali metal as an intermediate After replacement with ammonium, this ammonium form can be calcined to provide an acidic hydrogen form to provide a more acidic zeolite. Acidic forms can be readily prepared by ion exchange using a suitable acidic reagent such as ammonium nitrate. The zeolite catalyst may then be calcined at a temperature of 400-550 ° C. for 10-45 hours to remove ammonia and form an acidic hydrogen form. Ion exchange is preferably carried out after the formation of the zeolite catalyst.

Zeolite-bonded zeolite catalysts are particularly useful as catalysts in hydrocarbon conversion processes, including isomerization, alkylation and transalkylation of aromatic hydrocarbons. Processes associated with alkylation and transalkylation of aromatic hydrocarbons are disclosed in US Pat. No. 4,891,458, which is incorporated herein by reference.

When alkylation is carried out, the reaction conditions are as follows. Aromatic hydrocarbon feeds should be present in stoichiometric excess. The molar ratio of aromatic to olefins should preferably be at least about 4: 1 to prevent the catalyst from fouling rapidly. The reaction temperature may be between 100 ° F and 600 ° F, preferably between 250 ° F and 450 ° F. When cumene is produced, the temperature range is most preferably 250 ° F. to 375 ° F. in order to lower the impurity content of the product. To slow catalyst contamination, the reaction pressure must be sufficient to maintain the liquid phase, at least in part. It is typically 50 to 1000 psig depending on the feed and the reaction temperature. The contact time may be 10 seconds to 10 hours, but typically 5 minutes to 1 hour. Weight hourly space velocity (WHSV), which is g (pounds) of aromatic hydrocarbons and olefins per gram (lb) of catalyst per hour, is generally in the range of about 0.5 to 50.

When the transalkylation is carried out according to the invention, the molar ratio of aromatic hydrocarbons to alkylaromatic hydrocarbons is generally from about 0.5 to about 50: 1, preferably from about 1: 1 to about 20: 1. The reaction temperature is about 100 ° F to 1000 ° F, but is preferably about 250 ° F to 900 ° F. The reaction pressure is typically about 50 psig to 1000 psig, preferably 200 psig to 600 psig. The weight space velocity per hour is about 0.1 to 10.

Examples of suitable aromatic hydrocarbon feeds that can be alkylated or transalkylated include aromatic compounds such as benzene, toluene, xylene, trimethylbenzene or mixtures thereof.

Suitable olefins for the alkylation of aromatic hydrocarbons are ethylene, propylene, butene-1, transalkyl-butene-2 and cis-butene-2, pentene, hexene, octene, nonene, decene, undecene, dodecene, and tridecene or their It contains from 2 to 30 carbon atoms, such as mixtures. Preferred olefins are ethylene and propylene. These olefins may be present as a mixture with the corresponding C ₂ -C ₃₀ paraffins, but are typically dienes, acetylene, water, sulfur compounds or nitrogen compounds which may be present in the olefin feedstream to prevent rapid deactivation of the catalyst. It is desirable to remove. However, in some cases, it may be desirable to adjust and add small amounts of water or nitrogen compounds to optimize the catalytic properties.

When the transalkylation is carried out, the transalkylator is an alkyl-aromatic hydrocarbon containing at least one (eg 1 to 6) alkyl group. Each group of alkylaromatic hydrocarbons will contain from 1 to about 14 carbon atoms, and preferably from 1 to about 6 carbon atoms. For example, suitable alkylaromatic hydrocarbons include methylbenzene, ethylbenzene, dimethylbenzene, trimethylbenzene, diethylbenzene, triethylbenzene, diethylmethylbenzene (diethyltoluene), diisopropylbenzene, triisopropylbenzene Mono-, di-, tri- and tetra-alkyl aromatic hydrocarbons such as diisopropyltoluene, dibutylbenzene and the like. The aromatic hydrocarbons alkylated by the transalkylator and the transalkylator may be the same, for example both may be ethylbenzene and react to produce diethylbenzene and benzene.

The reaction products obtainable using the process of the present invention are reactions of cumene, toluene and ethylene or polyethyltoluene obtained from the reaction of ethylbenzene, benzene and propylene or polyisopropylbenzene obtained from the reaction of benzene and ethylene or polyethylbenzene. Ethyl toluene obtained from, toluene and cymen obtained from the reaction of propylene or polyisopropyltoluene, xylene obtained from the reaction of trimethylbenzene and toluene, and secondary-butylbenzene obtained from the reaction of benzene and n-butene or polybutylbenzene It includes.

When performing alkylation or transalkylation, various types of reactors can be used in the process of the present invention. For example, the process can be carried out batchwise by adding the catalyst and the aromatic feed to the stirred autoclave, heating to the reaction temperature, and then slowly adding the olefin or alkylaromatic feed. Coolers may be used to circulate the heat transfer fluid through the autoclave jacket or to remove heat of reaction and maintain a constant temperature. Large scale industrial processes may use either fixed bed reactors operated in a bottom-up or top-down manner or moving bed reactors operated by catalysts and hydrocarbons flowing in the same or opposite directions. Such a reactor may contain a single catalyst bed or multiple beds and may have a device for adding or cooling olefins between stages. Addition of olefins between stages and a more thorough isothermal process improves product quality and catalyst life. The mobile bed reactor continuously removes the spent catalyst to regenerate it so that it can be replaced with fresh or recycled catalyst. Catalytic distillation reactors can also be used, which is particularly advantageous for alkylation reactions.

The olefin may be added in two or more stages to carry out the alkylation process. Preferably, two or more catalyst beds or reactors will be in series, with at least a portion of the olefins added between the catalyst beds or reactors. Cooling between the stages can be performed using a cooling coil or a heat exchanger. On the one hand, cooling between the stages can be carried out by the stepwise addition of the aromatic feed, ie by adding the aromatic feed to two or more stages. In this case, at least a portion of the aromatic feed is added between the catalyst beds or reactors in a manner similar to the staged addition of olefins described above. By adding the aromatic feed in stages, further cooling takes place to offset the heat of reaction.

In fixed bed reactors or mobile bed reactors, alkylation is completed in a relatively short reaction zone followed by the introduction of olefins. 10-30% of the reacting aromatic molecules may be alkylated one or more times. The transalkylation is a slower reaction that occurs in the alkylation zone and also occurs in the rest of the catalyst bed. When the transalkylation reaction is equilibrated, the selectivity to the monoalkylated product may be at least 90% by weight.

The alkylation reactor effluent contains excess aromatic feed, monoalkylation products, alkylation products and various impurities. The aromatic feed is recovered by distillation and recycled to the alkylation reactor. Typically a small purging stream is taken from the recycle stream to remove unreacted impurities from the loop. The bottoms material taken from the benzene distillate is further distilled to allow the monoalkylated product to be removed from the alkylated product and other heavy materials. In most cases, the recovered monoalkylated product should be very pure. For example, at present, the purity of cumene having less than 500 ppm of ethylbenzene and butylbenzene is required to be 99.9%. Since only a small fraction of the by-products ethylbenzene and n-propylbenzene are economically removed by distillation, it is important to use a catalyst that produces little feed of ethylene and very few impurities.

Additional monoalkylated products can be prepared by transalkylation. The alkylated products can be recycled to the alkylation reactor for alkylation or they can be treated with additional aromatic feed in a separate reactor. Typically, it is desirable to blend the bottoms material resulting from the distillation of the monoalkylation product with a stoichiometric excess of aromatic feed and to react the mixture in separate reactors on a suitable transalkylation catalyst. The effluent from the transalkylation reactor is mixed with the mixture of the alkylation reactor effluent and the distilled stream. The purge stream can be taken from the alkylation product stream to remove unreactive heavy materials from the loop, or the alkylation product stream can be distilled off to remove the heavy materials prior to transalkylation.

When isomerization is carried out, the aromatic hydrocarbon feed used is an isomerizable monocyclic alkylaromatic hydrocarbon containing preferably 2 to 3 alkyl group substituents on the ring, and preferably 2 to 4 carbon atoms on the ring. And isomerizable bicyclic alkylaromatic hydrocarbons containing alkyl group substituents. Such hydrocarbons include (A) a monocyclic alkylaromatic hydrocarbon of formula (I), and (B) a bicyclic alkylaromatic hydrocarbon of formula (II):

Where

R ¹ is an alkyl group having 1 to about 4 carbon atoms;

X is an integer from 2 to 3 and equal to the number of alkyl groups;

R ² and R ³ are independently selected from alkyl groups having 1 to about 4 carbon atoms;

Y is an integer from 0 to 2;

Z is an integer from 0 to 2;

The sum of Y and Z is an integer from 1 to 4 and is equal to the total number of alkyl groups.

R ¹ , R ² and R ³ may be straight or branched chain alkyl groups. Examples of suitable alkyl groups include methyl, ethyl, n-propyl, n-butyl, isopropyl, isobutyl, or combinations thereof. Preferred group is methyl.

Suitable monocyclic alkylaromatic hydrocarbons include xylenes (eg para-xylene, ortho-xylene and meta-xylene), diethylbenzenes (eg 1,4-diethylbenzene, 1,2-di Ethylbenzene and 1,3-diethylbenzene), trimethylbenzene (e.g. mesitylene (1,3,5-trimethylbenzene), hemimelitene (1,2,3-trimethylbenzene), sudoku Men (1,2,4-trimethylbenzene)), ethyltoluene, triethylbenzene (e.g. 1,3,5-triethylbenzene), methylpropylbenzene, ethylpropylbenzene, dipropylbenzene, diisopropyl Benzene, triisopropylbenzene and the like. Suitable bicyclic alkylaromatic hydrocarbons include monoalkylnaphthalenes (eg 1-methylnaphthalene and 3-ethylnaphthalene), dialkylnaphthalenes (eg 1,2-dimethylnaphthalene, 1,2-diethylnaphthalene, 2 , 3-dimethylnaphthalene, 2,3-dipropylnaphthalene, 2,6-dimethylnaphthalene, 2,6-dibutyl-naphthalene) and the like.

The alkylaromatic hydrocarbon feed may consist solely of monocyclic alkylaromatic hydrocarbons and / or bicyclic alkylaromatic hydrocarbons having 2 to 3 alkyl groups on the ring or may include other aromatic hydrocarbons such as ethylbenzene and toluene.

The process of the invention is particularly useful for isomerizing one or more xylene isomers in a C ₈ aromatic feed to obtain ortho-, meta- and para-xylene in approximately equilibrium ratios. In particular, xylene isomerization can be used in conjunction with a separation process to produce para-xylene. For example, part of the para-xylene in the mixed C ₈ aromatic stream can be recovered using methods known in the art, such as crystallization, adsorption and the like. The stream thus obtained can be reacted under xylene isomerization conditions to recover ortho-, meta- and paraxylene at near equilibrium ratios. At the same time, it is desirable to convert ethylbenzene in the feed with little total loss of xylene. The zeolite-bonded zeolite catalyst herein will contain a hydrogenation / dehydrogenation component, such as platinum, which hydrogenates ethene formed during deethylation of ethylbenzene to reduce the formation of ethylation products. The acidity of the first zeolite and the second zeolite of the zeolite-bonded zeolite catalyst can be chosen to balance xylene isomerization and ethylbenzene dealkylation while minimizing undesired side reactions. The isomerization process is performed by contacting a C ₈ aromatic stream containing one or more xylene isomers or ethylbenzene or mixtures thereof with a zeolite-bound zeolite catalyst under isomerization conditions.

In the vapor phase, suitable isomerization conditions have a temperature range of 250 ° C. to 600 ° C., preferably 300 ° C. to 550 ° C., a pressure range of 0.5 to 50 atm abs, preferably 10 to 25 atm abs, and the hourly weight space velocity is 0.1 to 100, preferably 0.5 to 50. Optionally isomerization in the vapor phase is carried out in the presence of 0.1 to 10.0 moles of hydrogen per mole of alkylbenzene. When using hydrogen, the catalyst comprises from 0.01 to 2.0% by weight of hydrogenated / dehydrogenated components, in particular platinum, palladium or nickel, selected from group VIII of the periodic table. Group VIII metal components refer to metals and their compounds such as oxides and sulfides.

The following examples illustrate the invention.

Example 1 Preparation of Catalyst A-mordenite-bonded Mordenite

Mordenite was formed into silica-bound particles as shown in Table 1 below:

The components were mixed in a domestic mixer in the order listed above. After addition of methocel, thickened dough was obtained. Total mixing time was about 24 minutes.

The dough was broken into 2 cm pieces, dried at 120 ° C., crushed and sieved through a fraction of 1-2 mm. The sifted fractions were calcined in air at 510 ° C. for 8 hours.

The composition of the silica-bonded calcined particles was 69.95 wt% mordenite and 30.05 wt% SiO ₂ . Silica-bonded mordenite particles were converted to bonded mordenite by mordenite as shown in Table 2 below.

Components 1 and 2 were dissolved in a beaker containing component 3 to make a solution and to correct for moisture loss. The solution was poured into 300 ml stainless steel autoclave. The beaker was rinsed using component 4 and poured into the autoclave. Component 5 was then added to the contents of the autoclave and the contents were stirred. Finally 80 g of silica-bound particles were added to the contents of the autoclave. The particles were covered with liquid. Molar composition of the synthesis mixture was _{0.79 Na 2 O / 0.48 (TEA} ) was _{2 O / 0.33 Al 2 O 3} /10 SiO 2/169 H 2 O. The autoclave was placed in an oven and heated to 150 ° C. or lower for 2 hours and held at this temperature for 96 hours. After the aging time, the autoclave was opened and the product collected.

The product was washed 7 times with 1400 mL of water at 60 ° C. The conductivity of the final wash water was 75 μm S / cm. The product was dried overnight at 120 ° C. and then calcined in air at 500 ° C. for 20 hours. The amount of product recovered was 75.8 g.

The resulting extrudate was characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) as shown in Table 3 below.

Example 2 Preparation of Catalyst B— Zeolite Beta Bound by Zeolite Beta

Zeolite beta (sodium form and silica to alumina molar ratio 26) was formed from silica-bonded extrudate as shown in Table 4 below:

The ingredients were mixed in the order listed. Total mixing time was about 28 minutes. Plastic extrudeable dough was obtained. The dough was extruded into about 2 mm extrudate. The extrudate was dried overnight at 120 ° C. and calcined at 510 ° C. for 8 hours.

The composition of the calcined silica-bonded extrudate was 69.90 wt% beta, 30.05 wt% SiO ₂ .

Silica-bonded extrudate was converted to bound zeolite beta by zeolite beta as shown in Table 5 below.

At room temperature, components 1 and 2 were dissolved in component 3 and the beaker to form a solution. The solution was poured into 300 ml stainless steel autoclave. The beaker was rinsed using component 4 and then added to the contents of the autoclave. The contents of the autoclave were stirred and finally 50.00 g (anhydrous weight) beta crystals were added to the contents of the autoclave. Molar composition of the synthesis mixture was _{0.37 Na 2 O / 3.63 TEAOH /} 0.32 Al 2 O 3/10 SiO 2/223 H 2 O.

The autoclave was placed in an oven at room temperature. The oven was heated to 150 ° C. for 2 hours and then held at 150 ° C. for 72 hours. The product thus obtained was washed eight times at 60 ° C. with 150 ml of water. The conductivity of the final wash water was 48 μm S / cm. The product was dried overnight at 120 ° C. and then calcined in air at 500 ° C. for 20 hours. The amount of product recovered was 55.26 g.

The product was analyzed by XRD and SEM to give the results in Table 6 below.

Example 3

Catalyst B was tested for alkylation of benzene using 1-dodecene as alkylating agent. Prior to use, Catalyst B was treated three times with 1.0 N aqueous ammonium nitrate in excess of 5 times its weight at 70 ° C. The catalyst B was then washed with deionized water and dried at 70 ° C. overnight until the conductivity of the final wash water was less than 75 μm SCM. Finally, catalyst B was heated from 35 ° C. to 435 ° C. for about 3 to 30 minutes, held at 435 ° C. for 2 hours, and then at 510 ° C. for 5 hours. ICPES analysis showed that the sodium content of the catalyst was 83 ppm.

The test was carried out by drying 1.12 g of catalyst B at 200 ° C. for 1 hour. Catalyst B was then cooled to 65 ° C. with a nitrogen feed. After cooling, 10.6 g of decane, 5.89 g of benzene and 2.12 g of 1-dodecene were added to the feed under nitrogen with stirring. Samples were taken at various intervals and analyzed by gas chromatography.

The test was carried out using commercially available alumina-bonded H-beta zeolite catalyst (30 wt% alumina and SiO ₂ / Al ₂ O ₃ = 11: 1). The same test was conducted for catalyst B. The reaction product was dodecylbenzene in which phenyl groups were bonded at different positions along the C ₁₂ chain. Product selectivity (based on total alkylation product) and 1-dodecene conversion are described in Table I below:

Example 4

5.5 g of catalyst B was tested for alkylation of benzene using ethylene. The test was carried out using the following method: 5.5 g of catalyst was placed in the center of a catalyst basket consisting of two concentric cylinders of steel mesh. The rest of the basket was filled with an inert 3A zeolite 1/16 "extrudate. The basket was then placed in a 300 cc stirred (750 rpm) autoclave reactor. Benzene (54.6 g / h), ethylene (68.9 std ml / min) and A feed containing hydrogen (73.3 std ml / min) was placed in the reactor The temperature of the reactor was 180 ° C. and the run time was 16 hours The liquid and gas streams were regularly analyzed by gas chromatography.

The test was also performed using commercially available alumina-linked beta zeolites analyzed in Example 3. The test is carried out in the same manner as for catalyst B, except that the aluminum-bonded catalyst has higher activity since the SiO ₂ / Al ₂ O ₃ ratio is higher, so that ethylene is added at 86.6 std ml / min to compare the two catalysts. It was fed and hydrogen was supplied at 46.7 std ml / min.

The results of this test are listed in Table II below:

The data shows that catalyst B has good ethylene selectivity.

Example 5

Catalyst A and commercially available alumina-bonded mordenite catalysts were prepared by mixing 34% by weight of toluene, 17% by weight of 1,3,5-trimethylbenzene, 41% by weight of 1,2,4-trimethylbenzene, and 1 A feed containing 2,3-trimethylbenzene was tested for alkylalkyl exchange.

4.5 g of catalyst were mixed with 4.5 g of quartz and then placed in a stainless steel reactor 0.5 inches in diameter. The total length of the reactor was 5 inches. The reactor is equipped with an axial thermo-well for measuring the actual temperature of the bed. De-edging of the catalyst was performed for 12.5 minutes at a temperature of 716 ° F., a pressure of 72.5 psig, a hydrogen flow rate of 705 cc / min and a model feed flow rate of 8.5 g / hr. After de-aging, the catalyst was hydrogen stripped for 1 hour at a temperature of 716 ° F., a hydrogen flow rate of 335 cc / min and a pressure of 72.5 psig. After the hydrogen stripping, the model feed was introduced into the hydrogen stream. Initial run was performed at 716 ° F. for 1 hour and after 3 hours on the stream the temperature was increased to 892 ° F. Test conditions and results are listed in Table III below.

These data show that Catalyst A has higher activity and higher xylene selectivity than the alumina-bonded mordenite catalyst.

Claims (38)

(i) under alkylation conversion conditions, a feedstream containing aromatic hydrocarbons and at least one olefin is contacted with a zeolite-bonded zeolite catalyst, or (ii) under transalkylation conversion conditions, each independently 2 to 4 An aromatic hydrocarbon feedstream containing a polyalkyl aromatic hydrocarbon having at least two alkyl groups having 2 carbon atoms is contacted with a zeolite-bonded zeolite catalyst, or (iii) isomerizable monocyclic alkyl under isomerization conversion conditions Contacting a feedstream containing an aromatic hydrocarbon, an isomerizable bicyclic alkylaromatic hydrocarbon, or a mixture thereof with a zeolite-bound zeolite catalyst, wherein the catalyst is based on the total weight of the first zeolite and the second zeolite Less than 10% by weight of non-zeolitic binder Oil, and, (a) first crystals of an acidic first zeolite of pore size greater than 7.0Å, and (b) comprising a binder comprising second crystals of non-acidic second zeolite, Process for carrying out alkylation, transalkylation or isomerization of aromatic hydrocarbons. The method of claim 1, And the second crystal intergrows to form at least a partial coating on the first crystal. The method according to claim 1 or 2, Wherein the catalyst contains less than 5% by weight of a non-zeolitic binder based on the total weight of the first zeolite and the second zeolite. The method according to claim 1 or 2, The first crystal has an average particle diameter larger than 0.1 mu m and the second crystal has an average particle diameter smaller than the first crystal. The method according to claim 1 or 2, The average particle diameter of the first crystal is 1 to 6 mu m and / or the average particle diameter of the second crystal is 0.1 to 0.5 mu m. The method according to claim 1 or 2, The first zeolite and / or the second zeolite are each independently X ₂ O ₃ : (n) YO ₂ , wherein X is aluminum, boron, titanium and / or gallium, Y is silicon, tin and / or germanium, n is a value of greater than 2). The method according to claim 1 or 2, Wherein the first zeolite is an aluminosilicate zeolite and the silica to alumina molar ratio is from 2: 1 to 150: 1. The method according to claim 1 or 2, Wherein the first zeolite and the second zeolite are each independently selected from the group of structures consisting of MAZ, MEI, AFI, EMT, OFF, BEA and MOR. The method according to claim 1 or 2, And wherein the second zeolite has the same structure as the first zeolite. The method of claim 1, Wherein the conversion comprises alkylation (i). The method of claim 10, The aromatic hydrocarbon is benzene, toluene, xylene or mixtures of two or more thereof. The method of claim 10 or 11, Olefin is ethylene, propylene, butene-1, trans-butene-2, cis-butene-2, pentene-1, hexene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene- 1, tridecene-1 or a mixture of two or more thereof. The method of claim 10 or 11, Wherein the feedstream has a molar ratio of aromatic hydrocarbons to olefins of at least 4: 1. The method of claim 10 or 11, The conversion conditions include a temperature of 37 to 316 ° C. (100 to 600 ° F.) and / or a pressure of 0.34 to 6.90 MPag (50 to 1000 psig) and / or a weight hourly space velocity of 0.5 to 50. . The method of claim 1, Wherein the conversion comprises an alkyl exchange (ii). The method of claim 15, The first zeolite and / or the second zeolite is BEA or MAZ. The method according to claim 15 or 16, Polyalkyl aromatic hydrocarbons are dimethylbenzene, trimethylbenzene, diethylbenzene, triethylbenzene, diethylmethylbenzene, diisopropylbenzene, triisopropylbenzene, diisopropyltoluene, dibutylbenzene or mixtures of two or more thereof How to be. The method according to claim 15 or 16, Wherein the molar ratio of aromatic hydrocarbons to polyalkyl aromatic hydrocarbons in the feedstream is from 1: 1 to 50: 1. The method according to claim 15 or 16, Wherein the conversion conditions comprise a temperature of 37 to 316 ° C. (100 to 600 ° F.) and / or a pressure of 0.34 to 6.90 MPag (50 to 1000 psig) and / or a weight hourly space velocity of 0.1 to 100. The method of claim 1, Wherein the conversion comprises isomerization (iii). The method of claim 20, Wherein the first zeolite is MOR structured and / or the second zeolite is BEA type. The method of claim 20 or 21, Wherein the second crystal is present in an amount of 10 to 60 weight percent based on the weight of the first crystal. The method of claim 20 or 21, Wherein the first zeolite is at least partially in hydrogen form. The method of claim 20 or 21, The zeolite-bonded zeolite catalyst further comprises at least one metal hydride. The method of claim 20 or 21, Isomerization conditions include a temperature of 250 to 600 ° C. and / or a pressure of 20 kPa to 5.07 MPa (0.2 to 50 atm abs) and / or a weight hourly space velocity of 0.1 to 100 and / or a hydrogen / hydrocarbon mole ratio of 0.1 to 10 Way. The method of claim 20 or 21, Wherein the alkylaromatic hydrocarbon is selected from the group consisting of (a) a monocyclic alkylaromatic hydrocarbon of formula (I), and (b) a bicyclic alkylaromatic hydrocarbon of formula (II): Formula I Formula II Where Each R ¹ is independently an alkyl group having 1 to 4 carbon atoms; x is 2 or 3; R ² and R ³ are each independently an alkyl group having 1 to 4 carbon atoms; y and z are each independently 0, 1 or 2, provided that the sum of y and z is 2, 3 or 4. The method of claim 26, The feed comprises a monocyclic alkylaromatic hydrocarbon of formula I wherein R ¹ is methyl or ethyl and x is 2. The method of claim 26, Wherein the feed comprises a bicyclic alkylaromatic hydrocarbon of formula II wherein R ² and R ³ are each methyl, y is 1 and z is 1. The method of claim 20 or 21, Wherein the feed is an aromatic C ₈ mixture of ethylbenzene and xylene, wherein the concentration of paraxylene is lower than the thermodynamic equilibrium concentration. Less than 10% by weight of non-zeolitic binder based on the total weight of the first zeolite and the second zeolite, and (a) an acidic first zeolite having a pore size of at least 7.0 mm3 selected from the group consisting of MAZ, EMT and MOR A zeolite-bonded zeolite catalyst comprising a first crystal of, and (b) a binder comprising a second crystal of a non-acidic second zeolite. The method of claim 30, A catalyst in which a second crystal grows between crystals to form a film at least partially over the first crystal. 32. The method of claim 30 or 31, A catalyst wherein the second crystal is wear resistant. 32. The method of claim 30 or 31 wherein A catalyst containing less than 5% by weight of a non-zeolitic binder based on the total weight of the first zeolite and the second zeolite. 32. The method of claim 30 or 31 wherein A catalyst wherein the first crystal has an average particle diameter greater than 0.1 μm and the second crystal has an average particle diameter smaller than the first crystal. The method of claim 34, wherein A catalyst having an average particle diameter of the first crystals of 1 to 6 mu m and an average particle diameter of the second crystals of 0.1 to 0.5 mu m. 32. The method of claim 30 or 31 wherein Catalyst having the same structural type as the first zeolite and the second zeolite, preferably MOR. 32. The method of claim 30 or 31 wherein A catalyst wherein the first zeolite and / or the second zeolite is an aluminosilicate zeolite or a gallium silicate zeolite. 32. The method of claim 30 or 31 wherein A catalyst that can be prepared by converting silica to a second zeolite in a silica-bonded extrudate comprising a first crystal of the first zeolite.