JPH0244582B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in the isomerization of xylene, and more particularly to an aromatic hydrocarbon feedstock containing mainly a mixture of xylene isomers that has not reached a thermodynamic equilibrium composition, in particular containing ethylbenzene and p
- A method for isomerizing a xylene isomer mixture in which xylene is present at a concentration below the thermodynamic equilibrium composition of the xylene isomer mixture to obtain an aromatic hydrocarbon composition having a high p-xylene concentration, and for use in the method , relates to an improved process in which the ability to hydrogenate benzene rings and undesirable side reactions are suppressed. Industrially, the isomerization of xylenes is an isomerization reaction process of an aromatic hydrocarbon raw material mainly containing a mixture of xylene isomers and a specific xylene isomer, usually p-xylene, from the resulting isomerization reaction mixture. The isolation step and the recycling step of the residual composition mixture after separation are carried out in an appropriate combination. At that time, the xylene isomer mixture composition in the isomerization reaction product should be as close as possible to the thermodynamic equilibrium composition; decomposition of xylenes (especially hydrogenation of benzene rings);
Suppression of side reactions such as disproportionation reactions increases the efficiency of the isomerization reaction and reduces costs, which has a great impact on industrial value. Many methods have been proposed for the isomerization of xylenes, and most of these methods use catalysts containing crystalline aluminosilicate zeolites. Research has been focused on this and many proposals have been made. In particular, methods for changing the shape and structure of the zeolite catalyst; methods for modifying the zeolite catalyst by subjecting it to physical treatment, such as heat treatment; and methods for chemically modifying the zeolite catalyst by adding various components to it. Many studies have been conducted. For example, treating Y-type zeolite with heated steam to improve catalyst activity and stabilization (see US Pat. No. 3,887,630), and supporting M ₀ O ₃ on Offretite to improve ethylbenzene decomposition activity. Method (U.S. Patent No.
3848009). However, some of the xylene isomerization catalysts proposed so far have (a) excellent activity for xylene isomerization reactions and (b) undesirable side reactions (e.g. nuclear hydrogenation of benzene rings, hydrogenolysis). ,
It is rare to find a catalyst that fully satisfies the two conflicting conditions (a) and (b): extremely low levels of demethylation (especially disproportionation, transalkylation, etc.). Can not. In particular, when isomerizing a xylene isomer mixture containing ethylbenzene, it is desirable to de-ethylate ethylbenzene together with the isomerization reaction of xylenes, and several methods have been proposed for this purpose. For example, the method described above is described in US Pat.
It is described in specifications such as No. 4098836, No. 4163028, and No. 4152363. However, in the conventionally proposed method, in addition to the main reactions of isomerization of xylene and deethylation of ethylbenzene, hydrogenation of benzene rings, disproportionation of xylene, transalkylation of xylenes and ethylbenzene, etc. Undesirable side reactions occur,
Loss of xylenes is inevitable. For example, the three US patents described above disclose methods for isomerizing xylene isomer mixtures containing ethylbenzene using ZSM series zeolites modified with platinum group metals such as nickel or platinum. However, ZSM-type zeolite catalysts modified with nickel (Ni content of 2% by weight or more)
In this case, under so-called severe reaction conditions where the conversion rate of ethylbenzene is high, the demethylation reaction of xylene is promoted and xylene loss increases. Therefore, it has been considered advantageous industrially to use ZSM-type zeolite catalysts modified with platinum group metals, which cause less demethylation reactions. However, for example, ZSM-type zeolite modified with platinum has excellent isomerization properties for xylenes and also has an excellent ability to selectively deethylate the ethyl group of ethylbenzene. The hydrogenation activity of the benzene ring itself is high, and the hydrogenation reaction occurs more markedly as the temperature decreases from thermodynamic equilibrium, thereby increasing the production of naphthenes. the result,
Due to the increased xylene loss, ZSM-type zeolite catalysts modified with platinum had to be used industrially at high temperatures of 800°C (427°C) or higher. Furthermore, the temperature required for the isomerization reaction depends on the space velocity, but generally a temperature of about 300 to 320°C is sufficient; higher temperatures do not improve isomerization, but rather cause disproportionation and trans-alkylation. This will promote undesirable reactions such as, and increase xylene loss. In order to avoid such undesirable reactions as much as possible, the space velocity based on the zeolite catalyst is increased, the optimum temperature for isomerization is made higher than in conventional methods, and xylene loss due to disproportionation etc. is suppressed. A method has also been proposed for promoting deethylation at the same time (see US Pat. No. 4,152,363). However, in this method, it is difficult to maintain the isomerization rate at a high level, and the high temperature and high space velocity cause a large deterioration in the activity of the catalyst, which is a major drawback from an industrial perspective. Therefore, the main object of the present invention is to develop a new and improved xylene isomerization method that does not have the above-mentioned drawbacks that occur when xylenes are isomerized using a ZSM-based zeolite catalyst containing platinum. The objective is to provide a method for Other objects and advantages of the invention will become apparent from the following detailed description. According to the present invention, an aromatic hydrocarbon feedstock containing mainly a mixture of xylene isomers with ethylbenzene, which has not reached a thermodynamic equilibrium composition, is prepared in the gas phase in the presence of hydrogen at elevated temperatures to form a crystalline A method of isomerizing xylene by contacting it with an aluminosilicate-containing catalyst composition, wherein the crystalline aluminosilicate-containing catalyst composition comprises (a) platinum and (b) titanium, chromium, zinc, gallium, germanium, strontium. , yttrium, zirconium, molybdenum, palladium,
Zeolite ZSM-5, zeolite ZSM containing at least two metals selected from the group consisting of tin, barium, cerium, tungsten, osmium, lead, cadmium, mercury, indium, lanthanum, and beryllium.
−11, Zeolite ZSM−12, Zeolite ZSM−
35 and the zeolite ZSM-38, the crystalline aluminosilicate having a silica-alumina ratio of at least 10 is provided. The method of the present invention is characterized in that the zeolite contains at least two metals, platinum and another specific metal as described above, as a catalyst for the isomerization of xylenes. silica/
The point is to use a catalyst composition consisting of a crystalline aluminosilicate with an alumina molar ratio of at least 10. The crystalline aluminosilicate (hereinafter sometimes referred to as zeolite) that is the base of the catalyst used in the present invention mainly contains hydrogen ions or hydrogen ion precursors such as ammonium ions at the cation site, and Silica/alumina molar ratio ranges from 20 to 200, preferably from 30 to 150
, more preferably from 40 to 100. That is, in the present invention, the content of silica is relatively large compared to alumina.
So-called high-silica-containing zeolites are used as catalyst base. Many zeolites with a relatively high silica content compared to alumina have been proposed in the past, and high silica-containing zeolites with an extremely high silica content of as high as 2000 silica/alumina molar ratio are also known. The silica/alumina ratio is relatively low among high-silica-containing zeolites,
Therefore, the feature is that an alumina component having relatively high acid activity is used. However, in the case of conventional high-silica-containing zeolite catalysts, the acid activity is weakened and alkylbenzene
In particular, in order to promote hydrogenation-dealkylation of monoalkylbenzenes and suppress side reactions such as disproportionation and/or transalkylation, basic substances such as amines are used together, and the zeolite is treated with steam. Measures are taken to destroy some of the acid sites, shorten the contact time, and treat at high temperatures (e.g., 426.7°C or higher) (e.g.,
(See US Pat. No. 4,101,595) However, in the present invention, zeolite having a relatively high acid activity can be used as it is without such treatment. The zeolite used in the present invention is
ZSM-5 (see US Pat. No. 3,702,886),
ZSM-11 (see US Pat. No. 3,709,979),
ZSM-12 (see US Pat. No. 3,832,449),
ZSM-35 (see US Pat. No. 4,016,245),
ZSM-38 (see US Pat. No. 4,046,859). These zeolites are generally obtained in a form containing an alkali metal at the cation site. In the present invention,
By ion-exchanging such zeolite by a conventional method, it is used instead of so-called H-type zeolite, which mainly contains hydrogen or hydrogen precursors at the cation sites. It should be understood that unless otherwise specified, it refers to type H zeolite. It has been found that the most excellent effect is achieved when ZSM-5 type zeolite is used as the catalyst base in the present invention among the above-mentioned zeolites. According to a preferred embodiment of the method of the present invention, therefore, a method is provided in which ZSM-5 type zeolite is used as the base of the isomerization catalyst. In the method of the present invention, a zeolite having a silica/alumina molar ratio as described above is used, comprising (a) platinum (hereinafter sometimes referred to as "metal (a)"); (b) titanium, chromium, Zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, palladium, tin, barium, cerium, tungsten, osmium,
At least one metal selected from the group consisting of lead, cadmium, mercury, indium, lanthanum, and beryllium (hereinafter this metal may be referred to as "metal (b)") modified with at least two metals. Used as the main catalyst component. According to the research of the present inventors, a zeolite catalyst modified only with the metal (a), that is, only platinum, is excellent in the isomerization reaction of xylenes as described above, but at the same time, it is difficult to hydrogenate the benzene ring. , also has a catalytic effect on reactions such as demethylation of xylenes, and such catalytic action causes undesirable side reactions during the isomerization of xylenes, resulting in the loss of xylenes. When a) and metal (b) are used together, and these two different metals are simultaneously contained in zeolite, the benzene ring is It has surprisingly been found that the catalytic action of undesirable reactions such as hydrogenation and demethylation of xylenes can be effectively suppressed. Further, as the metal (b) which is the other metal component used for modifying the zeolite according to the present invention, among the above-mentioned metals, tin, barium, titanium, indium and cadmium are particularly suitable for suppressing side reactions. is highly suitable. Here, "modified with metals (a) and (b)" refers to a state in which metals (a) and (b) are ion-exchanged to the cation sites of zeolite and/or a state in which metals (a) and (b) are ion-exchanged to cation sites of zeolite. b) means that metals (a) and (b) are contained in either or both of the states in which metals (a) and (b) are physically adhered and maintained on the zeolite surface. Zeolite modified with metal (a) and metal (b) in this way can be prepared by a generally known method for modifying zeolite with metal.
Modification with metal (a) and metal (b) may be performed either first or at the same time, but the preferred preparation method is to modify with metal (a) and then modify with metal (b).
This is a method of denaturing according to (b). To facilitate understanding, typical methods will be explained in more detail. Industrially useful zeolites generally have their cation sites replaced by ions of alkali metals or alkaline earth metals such as Na, K, Ca, etc. Or exchanged with ammonium ion. This exchange may be performed simultaneously with the modification with metal (a), or it can be performed prior to the modification. According to one method, a zeolite in which cation sites are substituted with alkali metal or alkaline earth metal ions is immersed in an aqueous solution containing metal (a) ions and ammonium ions. This yields a zeolite in which at least most of the cation sites are of the ammonium ion type and modified with metal (a). The ammonium ion type zeolite modified with the metal (a) thus obtained can then be converted into a hydrogen ion type zeolite modified with the metal (a) by calcining at a temperature of about 200 to 600°C. The other method is to treat zeolite whose cation sites have been replaced with alkali metal or alkaline earth metal ions with an inorganic or organic acid such as hydrochloric acid, sulfuric acid, acetic acid, or oxalic acid to remove most of the cation sites. This is a method in which the metal (a) is ion-exchanged or supported in the hydrogen ion type. Still another method is to treat zeolite whose cation sites have been replaced with alkali metal or alkaline earth metal ions with an aqueous solution of a water-soluble ammonium compound, and to prepare a zeolite whose cation sites have been mostly replaced with ammonium ions. For example, about 250 ~
After baking at a temperature of 650℃ to form H-type zeolite,
This is a method in which metal (a) is ion-exchanged or supported. In this case, the ammonium ion replacement treatment involves replacing the zeolite with 5 to 20% of water-soluble ammonium compounds such as ammonium chloride and ammonium nitrate.
This can be easily carried out by contacting with an aqueous solution of % by weight. Ion exchange of zeolite with metal (a) and/or
Or the support is metal(a) for normal zeolite.
This can be carried out by a method known as an ion exchange method or a supporting method. For example, the various zeolites to be treated may be contacted with a water-soluble or water-insoluble medium containing the desired metal (a) compound dissolved therein. Such compounds of metal (a) include halides, oxides, sulfides, oxyacids, complex compounds, and the like. For example, water-soluble platinum compounds [e.g. H ₂ PtCl ₆ ,
Platinum may be supported on the zeolite by impregnating the zeolite with an aqueous solution of PtCl ₂ ] and then evaporating the water, or by ion exchange such as a platinum amine complex [for example, Pt(NH ₃ ) ₄ Cl ₂ ]. The zeolite may be ion-exchanged by immersing the zeolite in an aqueous solution of a platinum compound having the above-mentioned properties and thoroughly washing the zeolite by passing through the solution. In addition, before carrying out the modification treatment with the metal (a) mentioned above, the zeolite is heated in advance at a temperature of 100 to 700°C, preferably 200 to 600°C, in an oxygen atmosphere such as air, or an inert gas atmosphere such as nitrogen. 1 below
Heat treatment for ˜50 hours can also yield superior catalysts, which is generally preferred. The zeolite modified with the metal (a) in this way is heated at a temperature of 100 to 700°C, preferably 200 to 600°C, in an oxygen-containing atmosphere such as air, or in an inert gas atmosphere such as nitrogen, for about 1 to Heat treatment for about 5 hours is possible and preferred. The metal (a) modified zeolite prepared as described above is then modified with metal (b). metal(b)
The modification method can be carried out in the same manner and under the same conditions as for the modification of metal (a) described above. Therefore, the modification with metal (b) is not particularly different from the commonly known preparation methods of zeolite modified with various metals. Next, various metal compounds used in the modification with metal (b) are illustrated, but these are merely examples, and compounds not exemplified may be used as long as they are water-soluble or solvent-soluble compounds. Needless to say, it can be used even if (1) Titanium compounds Titanium fluoride, chloride, bromide, iodide,
Sulfates and nitrates, ammonium hexafluorotitanate, ammonium pentafluoroperoxotitanate, ammonium hexachlorotitanate, diethylammonium hexachlorotitanate, diethylammonium hexabromotitanate, bis(acetonitrile)tetrachlorotitanium(2) chromium compounds OrCl ₂ , OrSO ₄ , Cr( _CH3COO ) _{2H2O ,}
CrCl ₃ , Cr(NO ₃ ) ₂・9H ₂ O, Cr(SO ₄ ) ₂ , Cr
(NH ₃ ) ₆ X ₆ (hexaamminechromium compound),
H ₂ Cr ₂ O ₇ , (NH ₄ ) ₂ Cr ₂ O ₇ (3) Germanium compound GeCl ₄ , GeCl ₂ , GeR ₄ (R=alkyl) (4) Molybdenum compound H ₂ MoO ₄ , (NH ₄ ) ₆ Mo ₉ C ₂₄ , MoCl ₅ (5) Palladium compounds PdCl ₂ , PdSO ₄・2H ₂ O, Pd(NO ₃ ) ₂ , [Pd
(NH ₃ ) ₄ ]Cl ₂ (6) Tin compounds SnCl ₂ , SnCl ₄ , H ₂ SnCl ₆ , SnR ₄ (R=alkyl), (NH ₄ ) ₂ SnCl ₆ , (C ₂ H ₅ ) ₄ NSnCl ₃ ( 7) Barium compounds Barium fluoride, chloride, perchloride, bromide, iodide, thiosulfate, hyposulfite, sulfate, nitrate, phosphate, carbonate, thiocyanate, metasilicate, acetate, water oxide,
Acetate, formate (8) Tungsten compound Tungstic acid, (NH ₄ ) ₁₀ W ₁₂ O ₄・5H ₂ O (9) Osmium compound OsO ₄ , OsCl ₄ (10) Lead compound Pd (CH ₃ COO) ₂ , Pd ( _NO3 ) ₂ , _PdCl4 , _PdR4
(R=alkyl) (11) Cadmium compounds Cadmium chloride, perchlorate, bromide,
Iodides, sulfates, nitrates, cyanates, thiocyanates, carbonates, acetates, hydroxides and sulfites, tris(ethylenediamine) cadmium nitrate, dichloro(ethylenediamine)
Cadmium (12) Indium compounds Indium fluorides, chlorides, bromides, iodides, perchlorates, nitrates and sulfates, ammonium hexafluoroindium, ammonium aquapentachloroindium (13) Other metal compounds Strontium, perylium, Gallium, yttrium, zirconium, cerium, zinc,
Lanthanum and mercury are used in the form of the following compounds. Fluoride, chloride, bromide, iodide, perchloride, cyanide, sulfate, nitrate, nitrite, sulfite, acetate, oxalate, formate, carbonate, phosphate, thiocyanate, thiosulfate, hydroxide , oxides, and various complexes. The noble metal-modified zeolite thus obtained can be in the form of a fine powder or, if necessary, molded into various desired shapes, such as pellets or tablets, as is customary. After that, it can be subjected to the reaction of the present invention. When molding the modified zeolite, the modified zeolite is processed using a synthetic or natural refractory inorganic oxide, which is usually used as a binder for zeolite catalysts, according to a conventional method.
For example, it can be mixed with silica, alumina, silica-alumina, kaolin, silica-magnesia, etc., then molded into a desired shape, and then baked and hardened. The amount of the catalytically active component or modified zeolite in such a molded article is generally 1 to 99% by weight, preferably 10 to 90% by weight, based on the weight of the molded article.
Advantageously, it is expressed in % by weight. Catalysts consisting of zeolites modified with metals (a) and (b) prepared in this way are used under a reducing atmosphere such as in hydrogen gas for 200 min.
Processed at temperatures of ~600°C, preferably 250-500°C, this reduction treatment is usually carried out after charging the reactor. The respective contents of metals (a) and (b) in the zeolite modified with metals (a) and (b) according to the present invention can be varied depending on the type of metal used, etc. a) is generally from 0.001 to 2% by weight, preferably from 0.005 to 1.5% by weight, more preferably from 0.005 to 1.5% by weight, based on the weight of the crystalline aluminosilicate.
Advantageously, it is included in the crystalline aluminosilicate in the range of 0.01 to 1% by weight;
(b), in terms of the atomic ratio of the metal (a)/metal (b), generally 1/0.01 to 1/10, preferably 1/0.05 to 1/5;
More preferably, it is convenient to use within the range of 1/0.1 to 1/3. The catalyst according to the present invention prepared as described above contains the metal (a) usually in the form of a cation and/or oxide, and the metal (b) in the state before reduction before being subjected to the isomerization reaction. is contained in the form of an oxide or a cation depending on the type of metal, and when reduced during the isomerization reaction, the metal (a) becomes an elemental state, and the metal (b) becomes an elemental state, an oxide, or a cation. or a mixture thereof. The aromatic hydrocarbon raw material subjected to the isomerization reaction of xylenes according to the present invention mainly contains a xylene isomer mixture containing ethylbenzene that has not reached thermodynamic equilibrium. As is well known, xylene has three isomers: ortho, meta, and para isomers, and when a mixture of these three isomers in any ratio is subjected to an isomerization reaction, the isomerization reaction It is known that when the ratio of isomers reaches a certain value, an equilibrium state is reached, and isomerization apparently does not proceed any further. The composition of the xylene isomer mixture in this equilibrium state is called the "thermodynamic equilibrium composition," and this thermodynamic equilibrium composition differs slightly depending on the temperature. For example, the equilibrium composition of the xylene isomer mixture at the following temperature is as follows. It is as follows. [] In the case of a mixture of only three xylene isomers [427°C]; p-xylene 23.4% by weight m-xylene 52.1% by weight o-xylene 24.5% by weight [] In the case of a mixture of xylene isomers containing ethylbenzene [427 °C]; Ethylbenzene 8.3% by weight p-xylene 21.5% by weight m-xylene 47.8% by weight o-xylene 22.4% by weight Therefore, in this specification, "a xylene isomer mixture containing ethylbenzene that has not reached a thermodynamic equilibrium composition" refers to a mixture of xylene isomers in which the concentration of at least one of the three isomers of xylene deviates from the concentration in the thermodynamic equilibrium composition. The aromatic hydrocarbon feedstock used as starting material in the process of the invention may consist solely of a xylene isomer mixture containing ethylbenzene, or may consist of a xylene isomer mixture and other aromatic hydrocarbons, benzene. , toluene, ethyltoluene, trimethylbenzene, diethylbenzene, ethylxylene, tetramethylbenzene and the like. In the latter case, it is desirable that the xylene isomer mixture generally accounts for 30% by weight or more, preferably 50% by weight or more, based on the weight of the aromatic hydrocarbon feedstock. In the method of the present invention, aromatic hydrocarbon raw materials that can be used particularly advantageously include petroleum reforming,
_C8 obtained from pyrolysis, hydrocracking
It is an aromatic hydrocarbon fraction which, in addition to the xylene isomer mixture, also contains ethylbenzene with the same number of carbon atoms. In the present invention,
In particular, these xylene isomer mixtures and ethylbenzene together account for at least 80% by weight, preferably at least 90% by weight, based on the weight of the fraction.
Very advantageous results are obtained when using C ₈ aromatic hydrocarbon fractions. The isomerization of the aromatic hydrocarbon raw material described above can be carried out under xylene isomerization reaction conditions known per se, except for the use of the above-mentioned specific catalyst. However, the reaction temperature is generally 250 to 450
°C, preferably 270-400 °C, particularly preferably 280
~380°C, and the hydrogen partial pressure is generally 0 to 25 Kg/cm ² G, preferably 0 to 20
Kg/cm ² G, particularly preferably within the range of 0 to 12 Kg/cm ² G, can be freely selected. When carrying out the method of the present invention, the feed ratio of the aromatic hydrocarbon raw material can vary widely depending on the type of hydrocarbon raw material and/or catalyst used, but is generally about 1 to about 500, preferably 2 to 500. It is advantageous to feed at a weight unit hourly space velocity of 100, more preferably 3 to 50. In this specification, "weight unit hourly space velocity" is a value calculated by the following formula: weight of hydrocarbon feedstock supplied per unit time/weight of catalyst, where "weight of catalyst" is the base of the catalyst. Means the weight of crystalline aluminosilicate. Additionally, the dealkylation of the present invention is carried out in the presence of hydrogen. The hydrogen supply ratio at that time can vary widely depending on the type of hydrocarbon raw material and/or catalyst used, but it is generally 0.1 to 15, preferably 0.1 to 15, expressed as a molar ratio of hydrogen/hydrocarbon raw material. It is appropriate to supply them at a ratio within the range of 1 to 10. According to the method of the present invention described above, it is possible to achieve various excellent advantages as described below in comparison with similar conventional techniques, and the method contributes greatly to industry. The advantages of the method of the present invention are as follows. (i) Since the benzene ring hydrogenation and demethylation reactions of xylene are significantly suppressed, xylene loss is significantly reduced and the xylene isomerization yield is improved. (ii) Since it becomes possible to operate at high hydrogen partial pressures, the efficiency of xylene production facilities can be greatly increased. (iii) It becomes possible to suppress coke formation on the catalyst, and the stock utilization rate is greatly improved. The present invention will be further explained below with reference to Examples. Example 1 (a) Preparation of H-ZSM-5 Zeolite ZSM-5 was synthesized according to the method disclosed in US Pat. No. 3,965,207. During the synthesis, tri-n-propylamine and n-propyl bromide were added as organic nitrogen cation sources. The compound is determined from the X-ray diffraction pattern.
It was identified as ZSM-5. After filtering the obtained ZSM-5 and washing thoroughly with water, it was heated at 100℃ in an electric dryer.
It was dried for 8 hours at 200°C, then for 16 hours at 200°C, and further calcined at 450°C for 13 hours in an electric Matsufuru furnace under air flow. Thereafter, 250 g was subjected to ion exchange with 1.5% by weight of ammonium chloride aqueous solution at 80° C. for 24 hours. This operation was repeated two more times.
After that, wash thoroughly with water and heat in an electric dryer at 100℃ for 8 hours.
H ⁺ type ZSM-5 was obtained by drying at 200° C. for 16 hours and then calcining at 450° C. for 16 hours in an electric Matsufuru furnace with air circulation. The sodium content of this is 0.05% by weight,
The silica/alumina molar ratio was 92. (b) Preparation of Pt/ZSM-5-1 Dissolve 0.173 g of [Pt(NH ₃ ) ₄ ]Cl ₂ in 90 c.c. of water, and add the H-form obtained by the method of (a) above to this solution.
30g of ZSM-5 was added. This was immersed for 8 hours at 50°C with occasional shaking, filtered, and thoroughly washed with water at room temperature. Pt/ZSM-5 was then obtained by drying in an electric dryer at 100°C for 8 hours, then at 200°C for 16 hours, and then calcining in an electric Matsufuru furnace at 450°C for 8 hours under air flow.
The catalyst obtained contained 0.24% platinum based on the total weight. (Hereinafter, this will be referred to as catalyst A) (c) Preparation of Pt/ZSM-5-2 22.0g of H-ZSM-5 and 25% ammonia water
After adding 120 ml, a solution of 0.113 g of [Pt(NH ₃ ) ₄ ]Cl ₂ dissolved in 60 ml of 2.5% aqueous ammonia was added dropwise using a pipette while thoroughly stirring with a glass rod. After stirring at room temperature for 5 hours using a magnetic stirrer, the mixture was washed with deionized water until the electrical conductivity of the liquid became 15 μ/cm or less. After drying at 100° C. and 200° C. for 4 hours each, it was fired in an electric Matsufuru furnace in an air atmosphere for 4 hours. Platinum content is 0.28% by weight
It was [Catalyst B]. Catalysts C to H were prepared using the same procedure, and their platinum contents were as shown in Table 1. (d) Preparation of various metal-supported Pt-ZSM-5 Weigh out the various metal salts shown in Table-1 so that the metal atomic ratio is constant as shown in Table-1 with respect to the amount of supported platinum, Pt-ZSM-5 prepared by the above method was added to a solution in a suitable solvent (deionized water unless otherwise specified),
It was evaporated to dryness and impregnated with metal salts. then 100
After drying at 200°C and 200°C, it was fired in an electric Matsufuru furnace at 450°C in an air atmosphere to prepare various metal-supported Pt-ZSM-5 powders. As a specific example, indium-supported Pt-ZSM-
An example of No. 5 is shown below. 3 g of catalyst E was added to a solution of 13.5 mg of InCl ₃ 4H ₂ O (the atomic ratio of indium to platinum is equivalent to 1.2) in 50 ml of deionized water, and the mixture was heated for 4 hours with occasional shaking in a constant temperature water bath at 70°C. After heating, water was distilled off using a rotary evaporator at a water bath temperature of 45°C, and then at 100°C and 200°C.
After drying in an electric dryer for 4 hours in an air atmosphere, the catalysts were calcined in an electric Matsufuru furnace at 450°C for 4 hours in an air atmosphere to obtain catalyst E-2.

【table】

[Table] Example 2 Add 1/1 weight ratio of alumina gel for chromatography (300 meshes) to the powdered catalysts A and A-2 obtained in Example 1 and mix thoroughly to obtain a size of 10 to 20 meshes. It was molded into. The obtained molded product was fired in an electric Matsufuru furnace at 450° C. in an air atmosphere for 8 hours, and then filled into a pressurized fixed bed reactor. After that,
Reduction treatment was performed at 400° C. for 2 hours in a hydrogen stream, and then a xylene isomerization reaction was performed using mixed xylene having the composition shown in Table 2. The reaction conditions were: reaction temperature: 350℃, weight unit hourly space velocity (WHSV): 8.0Hr ^-1 (based on zeolite weight), hydrogen/aromatic hydrocarbon (molar ratio): 3/1, pressure: 120psia, and feed The product composition 50 hours after the start was as shown in Table 2. Based on these results, Pt/ZSM-5 has a second metal type.
When tin is added as (b), the equilibrium concentration of PX, which indicates the strength of isomerization activity, does not decrease at all;
It is industrially important because it greatly suppresses the hydrogenation activity of benzene nuclei and the demethylation activity of xylenes, which are unique properties of platinum metal, while maintaining the deethylation rate unique to platinum at a high level. The xylene loss rate is greatly improved.

【table】

[Table] Martens Here PX equilibrium attainment rate (%) = [PX] _P − [PX] _F / [PX] _E − [PX] _F ×100 EB decomposition rate (%) = [EB] _F − [EB ] _P / [EB] _F ×100 Xylene loss rate (%) = [X] _F − [X] _P / [X] _F ×1
00 Deethylation rate (%) = Total number of moles of EB disappeared - Number of moles of EB disappeared due to disproportionation and transalkylation / Total number of moles of EB disappeared x 10
0 Amount of demethylation = Sum of moles of toluene and C ₇ naphthenes generated - Number of moles of C ₉ aromatics generated Ring loss rate (%) = (1 - Number of moles of benzene rings in the product / benzene rings in the feed (number of moles of) x 100 The abbreviations mean the following. [PX] _F : Concentration of paraxylene in xylene 3 isomer in feed liquid (wt%) [PX] _P : Paraxylene concentration in xylene 3 isomer in product liquid (wt%) [PX] _E : At reaction temperature Equilibrium concentration of paraxylene in xylene isomers (wt%) [EB] _F : EB concentration in feed liquid (wt%) [EB] _P : EB concentration in product liquid (wt%) [X] _F : Feed liquid Concentration of xylene 3 isomer in product liquid (weight%) [X] _P : Concentration of xylene 3 isomer in product liquid (weight%) Example 3 Powdered catalysts B-5 and D- obtained in Example 1
4. Molding, calcination, and reduction of E, E-2, and F-1 were performed in exactly the same manner as catalysts A and A-2 described in Example 2, and xylene isomerization was performed using the same reaction equipment, raw materials, and reaction conditions. reaction was carried out. The reaction characteristic values 70 hours after starting the feed were as shown in Table 3. Note that the definition of the reaction characteristic value is the same as in Example 2. As in Example 2, when Ba, In, Ti, and Od are added, (1) isomerization activity and Pt deethylation activity are not impaired (2) benzene ring hydrogenation activity and xylenes demethylation It is clear that the anti-inflammatory activity is suppressed.

[Table] Example 4 In this example, the same catalysts A, A-2, B-5, D-4, E,
Regarding E-2 and F-1, a benzene hydrogenation reaction was carried out using an atmospheric fixed bed flow reactor. The reaction conditions were: reaction temperature: 200℃, weight unit hourly space velocity (WHSV): 8.0Hr ^-1 (based on zeolite weight),
Hydrogen/benzene = 1/1 (mole ratio), pressure: normal pressure, and feed is 99.98wt% benzene. Table 4 shows the benzene conversion rate 2 hours after starting the feed. In addition, Figure 1 shows the liquid non-aromatics (the
99wt% or more is the production amount of C ₆ ⁺ naphthenes) and the hydrogenation product of xylenes (C ₆ ⁺ naphthenes), and a positive correlation is observed between the two. That is, the metal (b), which suppresses the formation of naphthenes during the xylene isomerization reaction under pressure, suppresses the hydrogenation of benzene under normal pressure conditions.

【table】

[Table] Non-aromatic compounds are found only in liquid. Example 5 Table 5 from the powdered catalysts obtained in Example 1
The catalyst described in Example 2 was molded and calcined in the same manner as described in Example 2, using an atmospheric fixed bed flow reactor.
Table 5 shows the results obtained using the same benzene under the reaction conditions described in Example 4. As is clear from Table-5, metal (b) listed in Table-5
The hydrogenation activity of the benzene ring is improved by the addition of
From the relationship shown in Figure 1, it is clear that C ₆ ⁺ naphthenes in the product of the xylene isomerization reaction are reduced and xylene loss is suppressed.

【table】

[Table] Example 6 A xylene isomerization reaction was carried out using the catalyst used in Example 5 under normal pressure. Calcination and reduction treatment of the catalyst were as described in Example 5. The reaction conditions are 380℃ and WHSV6 for catalysts B and B-1, and 350℃ and WHSV8 for all catalysts other than catalysts B and B-1.The following reaction conditions are the same for all catalysts listed in Table 5. be. That is,
Pressure: normal pressure, hydrogen/hydrocarbon molar ratio 1/1,
The feedstock is the same as in Example 2. Table 6 shows the reaction characteristic values 20 hours after starting the feed.
The definitions of the characteristic values are the same as those described in Example 2. As is clear from Table 6, when the metal (b) listed in Table 6 is added to the Pt-ZSM-5 catalyst, (1) the xylenes isomerization properties are almost maintained; (2) The inherent EB deethylation activity of platinum is not impaired. (3) The demethylation activity of xylenes, which is unique to platinum, is suppressed. This is clear, and when combined with the facts described in Example 5, the metal (b) listed in Table 6 (same as Table 5) can be replaced with Pt.
It is clear that by adding ZSM-5 as a catalyst for the xylene isomerization reaction, the xylene loss rate can be greatly improved.

【table】

[Table] Example 7 Powdered catalysts H, H-1, and H-1 obtained in Example 1
Gamma alumina for chromatography (300
Add 1/1 (weight ratio) of 1:1 (Metsushi) and mix thoroughly.
It was molded to a size of ~20 pieces. After baking each of the obtained molded products in air at 450℃ for 8 hours,
Subsequently, reduction treatment was performed at 400° C. for 2 hours in a hydrogen stream. Thereafter, a benzene hydrogenation reaction was carried out using the same method and conditions as described in Example 5. The benzene conversion rate 2 hours after starting the feed was as shown in Table 7. A xylene isomerization reaction was subsequently carried out using the same method and conditions as described in Example 6. The reaction characteristic values 5 hours after starting the feed were as shown in Table 8. In addition, the definition of the reaction characteristic value is the same as that described in Example 2. As is clear from the table, Sn/Pt
It can be seen that if the atomic ratio is too small, the effect of suppressing benzene hydrogenation activity is insufficient, and on the other hand, if it is too large, isomer activation and ethylbenzene decomposition activity are also reduced.

【table】

[Table] Example 8 Catalysts I, J, K and L prepared by the method of Example 1-(b) with only the platinum concentration changed were molded and fired in the same manner as described in Example 2, and then fixed at normal pressure. The flow reactor was charged and reduced at 400°C for 2 hours, followed by measuring the hydrogenation activity of benzene under the same conditions as described in Example 4, and then using the same reaction conditions and feedstock as in Example 6. Table 9 shows the results of the isomerization reaction of xylenes under pressure. As is clear from Table 9, the benzene ring hydrogenation activity by platinum reaches almost saturation at a platinum concentration of 0.3%.
Moreover, since only the demethylation activity increases as the platinum concentration increases, the platinum concentration is preferably 1% or less.

[Table] Example 9 The catalyst described in Example 8 was packed into a pressurized fixed bed flow reactor, and WHSV was carried out at a reaction temperature of 380°C, a hydrogen/hydrocarbon molar ratio of 3/1, and a total pressure of 7.4 Kg/cm ² G. The isomerization reaction of xylenes was carried out using the feedstock described in Example 2 instead, and the data 50 hours after the start of the reaction is shown in Table 10. Table 10 shows that as WHSV increases, the xylene loss rate decreases, but the equilibrium attainment rate of PX, which is most important for xylenes isomerization, decreases.

【table】 [Brief explanation of the drawing]

Figure 1 shows the amount of liquid non-aromatics produced by hydrogenation of benzene and the hydrogenation product of xylenes (C ₆ ⁺ naphthenes) obtained by the isomerization reaction of xylenes in an example of the present invention. ) and the amount of production.

Claims (1)

[Claims] 1. An aromatic hydrocarbon feedstock mainly containing a mixture of xylene isomers including ethylbenzene, which has not reached a thermodynamic equilibrium composition, is crystallized in the gas phase in the presence of hydrogen at an elevated temperature. A method for isomerizing xylene by contacting the crystalline aluminosilicate-containing catalyst composition with (a) platinum and (b) titanium, chromium, zinc, gallium, germanium, Strontium, yttrium, zirconium, molybdenum, palladium, tin, barium, cerium, tungsten, osmium, lead,
Zeolite ZSM-5, zeolite ZSM-11, zeolite ZSM-12, zeolite ZSM-35 and Silica selected from the group consisting of zeolite ZSM-38/
An improved process characterized in that it consists of a crystalline aluminosilicate with an alumina molar ratio of at least 10. 2. The method of claim 1, wherein the metal (b) is selected from the group consisting of tin, barium, titanium, indium and cadmium. 3. The catalyst composition contains from 0.001 to 2% by weight of platinum(a) based on the weight of the crystalline aluminosilicate.
The method according to claim 1, comprising: 4. The catalyst composition contains the metal (b) within a range of 1/0.01 to 1/10 in terms of the atomic ratio of platinum (a)/the metal (b).
The method according to claim 1, comprising: 5. The method of claim 1, wherein the crystalline aluminosilicate has a silica/alumina molar ratio within the range of 20 to 10,000. 6. The method according to claim 1, wherein the isomerization is carried out at a temperature of 250 to 450°C. 7. The method according to claim 1, wherein the isomerization is carried out under a hydrogen partial pressure of 0 to 25 Kg/cm ³ G. 8. Claim 1, wherein the aromatic hydrocarbon feedstock is supplied at a hourly space velocity of about 1 to about 500 units by weight.
The method described in section. 9. The method according to claim 1, wherein hydrogen is supplied at a molar ratio of hydrogen/the aromatic hydrocarbon raw material of 0.1/1 to 15 to 1. 10 Claim 1, wherein the aromatic hydrocarbon feedstock contains at least 30% by weight, based on the weight of the hydrocarbon feedstock, of a mixture of xylene isomers.
The method described in section. 11 The xylene isomer mixture and ethylbenzene together account for at least 80% of the aromatic hydrocarbon feedstock.
% by weight.