JPS6248648B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for isomerizing xylenes. More specifically, the present invention relates to a method for isomerizing a mixture of xylene isomers in which at least one of the xylene isomers has a concentration below the thermodynamic equilibrium concentration. In particular, the present invention provides p-xylene by isomerizing a xylene isomer mixture in which the concentration composition of p-xylene is below the thermodynamic equilibrium concentration.
- Concerning a method for obtaining a composition with a high xylene concentration. Conventionally, it is a well-known method to isomerize a xylene mixture in which at least one component has a concentration below the thermodynamic equilibrium concentration by contacting it with, for example, a silica-alumina catalyst to obtain a mixture having a certain equilibrium composition. be. and p as a xylene isomer mixture
-There are three isomer mixtures of xylene, m-xylene and o-xylene, and isomer mixtures containing other alkylbenzenes, and it is known that these mixtures each form a thermodynamic equilibrium composition. There is. For example, it is known that the equilibrium composition of a mixture of three isomers at 427°C is as follows in terms of molar ratio. p-xylene m-xylene o-xylene 23.4% 52.1% 24.5% (The Chemical Thermodynamics of
Organic Compounds by STULL, WESTRUM
and SINKE John Wiley and Sons in 1969) On the other hand, isomerization of xylenes is industrially divided into a process of isomerization of xylenes, a process of separating xylene isomers from the isomerization reaction mixture, and a process of separating xylene isomers from the isomerization reaction mixture. A suitable combination of steps for recycling the composition mixture is carried out. In this case, bringing the composition in the isomerization reaction closer to the thermodynamic equilibrium composition and suppressing side reactions such as decomposition of xylenes and disproportionation reactions have a great influence on its industrial value. In most of the conventional isomerization methods for xylenes, research has focused on improving and developing catalysts, mainly silica-alumina catalysts, and improving isomerization conditions, and many proposals have been made regarding this. In particular, much research has been carried out on methods of changing the shape and structure of the silica/alumina catalyst itself, methods of processing it, and methods of adding various components to silica/alumina. However, there are very few silica-alumina catalysts that satisfy the conditions of having excellent isomerization reaction activity and suppressing undesirable side reactions as much as possible. On the other hand, the present inventors have previously proposed that crystalline aluminosilicate prepared using a certain cation source is a new zeolite. As a catalyst, it has excellent activity, with little deterioration of activity even after long-term use, and little side reactions.What is especially surprising is that the equilibrium composition of xylenes in the isomerization reaction mixture was previously unknown. It was found that the composition of p-xylene showed a much higher value than the equilibrium attainment rate mentioned above. The present invention has been achieved based on this knowledge, and has the following formula (1) M ₂ /nO・Al ₂ O ₃・XSiO ₂ ...(1) where M is at least one ion selected from the group consisting of hydrogen ions, alkaline earth metal ions, group metal ions of the periodic table, and rare earth metal ions, and n is the valence of these ions. ,X
indicates 10 or more. ] X-rays having a composition represented by the following and substantially represented by the following values: A catalyst containing a crystalline aluminosilicate zeolite having a lattice spacing is brought into contact with a raw material mixture containing xylene isomers, at least one of which has a thermodynamic equilibrium concentration or less, in a gas phase. This is an isomerization method. The isomerization of the present invention is performed using the new zeolite (hereinafter this zeolite may be referred to as TPZ-3).
The present invention is characterized in that the zeolite is used as a catalyst, but it also includes embodiments in which ion-exchanged and/or impregnated zeolites with various metals, such as group metals of the periodic table, are used as catalysts. TPZ-3 used in the method of the present invention and its manufacturing method were proposed by the present inventors in Japanese Patent Application No. 155017-1982 (filed on November 4, 1982).
Next, these will be explained. The TPZ-3 is a composition containing an alkali metal ion source, an organic nitrogen-containing cation source, a silica source, an alumina source, and water, and each component is expressed in molar ratio as follows: SiO ₂ /Al ₂ O ₃ = 10 ~ 1000 R / (Si + Al) = 1 × 10 ^-4 ~ 1 OH ^- / (Si + Al) = 1 × 10 ^-4 ~ 1.5 H ₂ O / (Si + Al) = 5 ~ 100 OH ^- /H ₂ O = 1×10 ^-5 to 1×10 ^-1 [However, in the formula, R is NNNN'N'N'-hexaalkyl-1.6-hexanediammonium ion, OH ^- is an alkali metal ion and NNNN'N'N'-hexaalkyl -1.6- Indicates a hydroxyl group based on hexanediammonium ion. ] can be prepared by maintaining the composition at a temperature of 80° C. or higher for a period sufficient to form crystals. The crystalline zeolite used in the present invention is a zeolite with a high silica content, and
Conventionally known ZSM-5, ZSM-11, ZSM-12,
It shows a completely different X-ray diffraction pattern from ZSM-based zeolites such as ZSM-38 and Zeta 3 type zeolite, and its characteristics are also different. In preparing such TPZ-3, alkali metal ions and NNNN'N'N'-hexaalkyl-1,6-hexanediammonium ions are used as cation sources. The silica source may be any one commonly used in zeolite production, such as silica powder, colloidal silica, dissolved silica, and silicic acid. To explain these specific examples in detail, as the silica powder, precipitated silica produced by a precipitation method from an alkali metal silicate group such as aerosil silica, fuming silica, and silica gel is suitable;
Colloidal silica can be used in various particle sizes, for example, from 10 to 50 microns. Examples of dissolved silica include water glass silicates, alkali metal silicates containing 1 to 5 moles, especially 2 to 4 moles of SiO ₂ per mole of Na ₂ O or K ₂ O;
Examples include silicates obtained by dissolving silica in alkali metal hydroxide, and colloidal silica or water glass silicates are particularly preferred. The alumina source may be any one commonly used in the production of zeolites, such as aluminum salts such as chlorides, nitrates, and sulfates; for example, colloidal alumina, pseudoboehmite,
Boehmite, γ-alumina, α-alumina, β-
Examples include alumina in a hydrated or hydrateable state such as alumina trihydrate; sodium aluminate, among which sodium aluminate or aluminum salts are preferred. Further, part or all of the alumina source may be used as an aluminosilicate compound as shown in the silica source described above. The ratio of silica source to alumina source in the raw material mixture is expressed as SiO ₂ and Al ₂ O ₃ , respectively.
The SiO ₂ /Al ₂ O ₃ (molar ratio) is suitably in the range of 10 to 1000, preferably in the range of 10 to 500, and particularly preferably in the range of 20 to 250. On the other hand, the alkali metal is preferably added in the form of a salt readily soluble in water or in the form of a hydroxide. As an alkali metal cation source, for example, sodium hydroxide, potassium hydroxide, sodium or potassium aluminate, sodium or potassium silicate are added, and it is especially effective that the alkali metal is sodium. And desirable. The organic nitrogen-containing cation used with the alkali metal ion is NNNN'N'N'-hexaalkyl-1,6-hexanediammonium.
The alkyl group forming such ammonium preferably has 1 to 4 carbon atoms, preferably 1 to 2 carbon atoms. Especially NNNN′N′N′-hexamethyl-1,6
-Hexanediammonium is preferred. NNNN′N′N′-hexaalkyl-1,6-hexanediammonium itself does not necessarily need to be used by mixing it into the raw material mixture;
A compound capable of forming such ammonium in the raw material mixture may be added to form the diammonium in the mixture. For example, in the raw material mixture
NNN'N'-tetraalkyl-1,6-hexamethylenediamine and an alkyl halide (e.g., an alkylating agent such as methyl iodide) are added and allowed to react with each other to produce NNNN'N'N'-hexaalkyl-1 , 6-hexanediammonium may be formed. The molar ratio of such diammonium (R) to the sum of silica and alumina (expressed as Si+Al) ranges from 1×10 ⁻⁴ to 1, preferably 5×10 ⁻⁴
~0.5, particularly preferably 1×10 ^-3 ~1×
It is appropriate to use a range of 10 ^-1 . Furthermore, in the raw material mixture during the preparation of TPZ-3, alkali metal ions and
NNNN'N'N'-hexaalkyl-1,6-hexanediammonium ion-based hydroxyl group (OH ^- ) ratio is 1 in molar ratio to (Si + Al).
A range of from 1.times.10.sup. ^-4 to 1.5, preferably from 1.times.10.sup. ^- 3 to 1, particularly preferably from 5.times.10.sup. ^-3 to 0.4 is advantageous. In addition, the molar ratio of hydroxyl groups (OH ^- ) based on alkali metal ions and NNNN'N'N'-hexaalkyl-1,6-hexanediammonium ions to water in the raw material mixture is 1 x 10 ^-5 ~ in the range of 1×10 ⁻¹ , preferably 1×
10 ⁻¹ , particularly preferably 1×10 ⁻⁴ to 1×10 ⁻²
It is desirable to control the amounts of water and cations so that they fall within the range of . Furthermore, in the raw material mixture, water is (Si+
The molar ratio to Al) is preferably in the range of 5 to 100, preferably 10 to 50, and particularly preferred in the range of 15 to 40. A raw material mixture containing the alkali metal ion source, organic nitrogen-containing cation, silica source, alumina source, and water in the proportions as described above,
The reaction is carried out by heating and maintaining the mixture at a temperature and time sufficient to form crystalline zeolite, but the preferred reaction temperature is 80°C or higher, especially
100-200°C is advantageous. The reaction time is usually 5 hours to 100 days, preferably 10 hours to 50 days, particularly preferably 1 day to 7 days, and the pressure is autogenous pressure or higher, and it is generally carried out under free pressure. It may also be carried out under an atmosphere of an inert gas such as nitrogen gas. The reaction for forming crystalline zeolite is continued by heating the raw material mixture to the desired temperature and, if used, under stirring until crystalline zeolite is formed. After crystals are thus formed, the reaction mixture is cooled to room temperature, filtered, washed with water until the ionic conductivity is, for example, 50 μ/cm or less, and the crystals are separated. Furthermore, if necessary, the crystals may be dried at room temperature or under normal pressure or reduced pressure, for example, at 50 DEG C. or higher for about 5 to 24 hours. The crystalline zeolite thus obtained has cations consisting of alkali metal ions and divalent organic nitrogen-containing ions, such as
It is also possible to perform ion exchange by using an aqueous NH ₄ Cl solution to replace cation sites with ammonium ions. The crystals thus obtained may be calcined at a temperature of 100 to 600°C, preferably 300 to 500°C, for 8 to 24 hours, preferably 8 to 16 hours, and this calcination is also included in the present invention. The crystalline zeolite used in the method of the present invention also includes a method of ion-exchanging some or all of its alkali metal ions, divalent ammonium ions, or monovalent ammonium ions with at least one other cation. Examples of ion-exchangeable cations include monovalent cations such as silver and ammonium; divalent alkaline earth metal cations such as magnesium, calcium, and barium; trivalent cations such as aluminum; and others such as manganese, cobalt, nickel, platinum, and palladium. Group metal ions such as; and cations of rare earth metals. Rare earth metals include lanthanum, cerium, praseodymium, neodymium, samarium,
These include europium, cadrinium, terbium, scandium, and yttrium. In the case of exchanging the various cations, conventional methods may be used, and the crystalline zeolite may be contacted with a water-soluble or water-insoluble medium containing an aqueous solution containing the desired cation. Such contacting can be accomplished in either a batch or continuous manner. By performing the above-mentioned ion exchange, the crystallinity of the crystalline zeolite of the present invention may be increased, and the activity may be improved. Prior to performing the above-mentioned crystalline zeolite formation reaction, if powder particles of crystalline zeolite, which is the target product, are present in the raw material mixture, not only will the zeolite formation reaction rate be increased, but also the particle size will be large. Zeolite is obtained. Therefore, incorporating powder particles of the desired crystalline zeolite into the raw material mixture often produces favorable results. The crystalline aluminosilicate zeolite thus obtained exhibits a characteristic X-ray diffraction grating, as is clear from the examples shown below. The crystalline zeolite (TPZ-3) used in the present invention obtained in this way has the following formula (1) M ₂ /nO・Al ₂ O ₃・XSiO ₂ ...(1) [However, the formula is It is expressed in the form of a substance, the definitions of M and n are the same as above, and X indicates 10 or more. ] X-rays having a composition represented by the following and substantially represented by the following values: It has a lattice spacing. The characteristic peaks of the X-ray lattice spacing of the crystalline zeolite (TPZ-3) used in the present invention are as described above, and the strengths and weaknesses of each peak are as follows. 11.2±0.5 Strong 9.9±0.5 Strong 4.67±0.1 Weak 4.33±0.1 Very Strong4.02±0.05 Strong 3.83±0.05 Weak 3.72±0.05 Weak 3.44±0.04 Weak 3.33±0.04 Strong 3.2 8±0.03 little As long as the characteristic peak of the X-ray lattice spacing is substantially observed, the zeolite falls within the scope of the zeolite used in the present invention. Of the above peaks (3.44
±0.04), (3.33±0.04) and (3.28±0.03)
It should be understood that each may independently vary between weak and strong. If we define the strength of each peak mentioned above more strictly, we can define the intensity of the strongest peak (d=4.33±0.1Å) as follows:
Relative intensity of each peak as 100 (I/I ₀
(%)) can be expressed as follows: 100-60 is very strong, 60-40 is strong, 40-20 is medium, and 20-10 is weak. d(Å) I/I ₀ 11.2±0.5 Moderate to strong 9.9±0.5 Moderate to strong 4.67±0.1 Moderate 4.33±0.1 Very strong 4.02±0.05 Strong to very strong 3.83±0.05 Moderate 3.72±0.05 Weak ～Moderate 3.44±0.04 Weak～Strong 3.33±0.04 Weak～Strong 3.28±0.03 Medium Furthermore, in addition to the above-mentioned peaks, a strong peak near 20 Å is sometimes observed in the X-ray diffraction diagram of the zeolite. The presence or absence of a peak does not essentially affect the identification of the zeolite used in the present invention. Zeolite (TPZ-3) in the method of the present invention
is chemically expressed by the following formula (1) M ₂ /nO・Al ₂ O ₃・XSiO ₂ ...(1) [However, the formula is expressed in the form of an oxide in an anhydrous state, The definition is the same as above, and X represents 10 or more. ] It has a composition expressed as follows. In the above formula (1), X is 10 or more, preferably 10 to
1000, especially 10-500 is advantageous. Among these, the range of 20 to 250 is particularly preferable because a zeolite with excellent properties can be obtained. As mentioned above, M is at least one ion selected from the group consisting of hydrogen ions, alkaline earth metal ions, group metal ions of the periodic table, and rare earth metal ions, and n is the valence of these ions. The cations include hydrogen ions, ammonium ions, the above-mentioned organic nitrogen-containing ions, alkaline earth metal ions, periodic group metal ions, rare earth metal ions, and other metal ions. That's fine. In particular, those containing at least one of hydrogen ions, group metal ions, and rare earth metal ions are preferred because they have various interesting activities.
Among these, those containing group metal ions can be advantageously used as the isomerization reaction catalyst for xylenes in the method of the present invention. To explain the ratio of cation to alumina in the above equation (1), zeolite is modeled to be a combination of silica tetrahedron and alumina tetrahedron, and the charge of the alumina tetrahedron is

[Formula] It has a neutralized structure due to the presence of cations within the crystal. Therefore, theoretically, it can be said that the amount of cations is equimolar to that of alumina, that is, M ₂ /nO/Al ₂ O ₃ (molar ratio)=1. However, in practice, synthetic forms of zeolite usually contain cation precursors that cannot be removed by normal washing, and actual analytical data for synthetic forms of zeolite are
It should be noted that it is rather rare for M ₂ /nO/Al ₂ O ₃ (molar ratio) to be exactly 1. Furthermore, the zeolite of the present invention may support other metals or metal oxides in a physically mixed state. The crystalline zeolite used in the present invention is stable and uniform; for example, even if it is heat-treated at 800°C for 12 hours or more, the above-mentioned X-ray diffraction pattern does not substantially change. It is understood that it is extremely stable. Further, this crystalline zeolite is extremely porous and has excellent shape selectivity depending on the pore size. The zeolite thus obtained is subjected to the reaction of the present invention in the form of a fine powder or, if necessary, after being shaped into various desired shapes, such as pellets or tablets, as is customary. be able to. When molding zeolite, the zeolite is mixed with synthetic or natural refractory inorganic oxides that are commonly used as binders for zeolite catalysts, such as silica, alumina, silica-alumina, kaolin, and silica. After mixing with magnesia or the like, it can be molded into a desired shape and then baked to harden. The amount of zeolite as a catalytically active component in such a molded article is
It is generally advantageous to use from 1 to 100% by weight, preferably from 10 to 90% by weight, based on the weight of the molding. The zeolite catalyst prepared in this way is heated at temperatures of 200 to 600°C, preferably 250 to 550°C, under a reducing atmosphere such as hydrogen gas.
It is also possible to process at temperatures of °C. In the method of the present invention, the zeolite (TPZ-
3) When xylenes are isomerized using a catalyst, a raw material mixture containing at least one xylene isomer having a thermodynamic equilibrium concentration or lower is used, especially when the concentration of p-xylene is lower than the thermodynamic equilibrium concentration. Those whose composition is below the thermodynamic equilibrium concentration are advantageously used.
Examples of the raw material mixture include p-xylene, m
It may be a mixture of three isomers of -xylene and o-xylene, or it may be a mixture of four isomers containing ethylbenzene. These xylene isomer mixtures are brought into contact with the zeolite (TPZ-3) catalyst in the gas phase. In the isomerization reaction of the present invention, hydrogen may or may not be present in the raw material mixture. Particularly when using a catalyst containing H-type TPZ-3, satisfactory results can be obtained without using hydrogen, but in general it is often preferable to use hydrogen. In this case, hydrogen is desirably used in an amount of 1 to 100 times the amount of hydrogen per mole of hydrocarbon. Furthermore, in the isomerization of the present invention, non-aromatic hydrocarbons, such as ethylcyclohexane, alkyl-substituted cyclopentane, paraffin, and naphthene, whose normal pressure boiling point is 50 to 150°C, particularly 120 to 150°C, are added. You can also do this by In the isomerization reaction, the weight hourly space velocity (WHSV) is
0.1~200, preferably 0.1~50, and the reaction temperature is 280~500℃, preferably 300℃.
It is appropriate to carry out the reaction at a temperature in the range of ~450°C. Further, the reaction of the present invention is desirably carried out in a pressure range of normal pressure to 30 kg/cm ² G, preferably normal pressure to 25 kg/cm ² G. As described above, according to the present invention, it is possible to obtain a xylene mixture in which the equilibrium attainment rate of p-xylene is extremely high, and the active life of the catalyst is long, so that it is industrially advantageous.
-Can produce xylene. In particular, when the zeolite catalyst is used in the method of the present invention, a unique phenomenon is observed in which a high p-xylene (PX) equilibrium attainment rate can be maintained for several days under normal pressure without using a carrier gas. Furthermore, as is clear from Example 9 described below, when the zeolite catalyst is used for a long period of time and its activity deteriorates and the PX equilibrium attainment rate decreases, it can be easily recovered by simply increasing the reaction temperature. It has the industrial advantage of being measurable. Furthermore, in carrying out the method of the present invention, if side reactions such as disproportionation reactions and trans-alkylation reactions other than the desired isomerization reactions are observed depending on the reaction conditions such as temperature, pressure, and WHSV, they may occur. In order to suppress side reactions, zeolite catalysts can be ion-exchanged or supported with various metals, steamed or amine-treated, and some amines may be added to the raw material mixture used for the reaction. . The method of the present invention will be described in detail below with reference to Examples. Example 1 50 g of methyl iodide is added to 800 ml of an ethanol solution of 25 g of NNN'N'-tetramethyl-1,6-hexanediamine. Mild fever for about 3 hours,
Although a precipitate is formed, the mixture is shielded from light and stirring is continued for another day. The white powder produced is separated, washed with acetone, and then dried under reduced pressure to yield NNNN'N'N'-hexamethyl-1,6-hexanediammonium salt almost quantitatively. 77g of water glass (manufactured by Wako Pure Chemical Industries, Ltd.) as a silica source
SiO ₂ 30.88Wt%, Na ₂ O 16.56Wt%, H ₂ O
44.56wt%), aluminum sulfate as alumina source
3.32 g of 18 hydrate (special grade, manufactured by Wako Pure Chemical Industries, Ltd.), 13.50 g of sulfuric acid (98%, special grade, manufactured by Wako Pure Chemical Industries, Ltd.) as a neutralizing agent, and organic ammonium were synthesized as described above.
Add 4.56 g of NNNN'N'N'-hexamethyl-1.6-hexanediammonium salt to 200 ml of pure water to prepare a gel. The composition of this product is expressed in molar ratios: SiO ₂ /Al ₂ O ₃ = 100 ammonium salt/Si + Al = 0.02 OH ^- /Si + Al = 0.20 H ₂ O / Si + Al = 257 OH ^- /H ₂ O = 7.8 x 10 ^-3 . It was hot. This gel was placed in a 500 ml stainless steel autoclave and reacted for one week at 160°C under autogenous pressure while being gently stirred. After removing and separating the reactants, wash the washing solution with pure water at 50%
The crystalline zeolite (hereinafter referred to as TPZ-3
) 24.2g was obtained. The composition of this TPZ-3 is 0.63 RO; 0.88 Na ₂ O; Al ₂ O ₃ ; 62.7 SiO ₂ ;
11.2 H ₂ O (R represents N,N,N,N',N',N'-hexamethyl-1,6-hexanediammonium group.) Also, the X-ray diffraction data is shown in Table 1. It is shown in Figure-1.

[Table] Furthermore, even when heated in air at 800°C for 12 hours, the X-ray diffraction data is essentially the same as this, indicating good heat resistance. In addition, I/I ₀ in the table indicates the strongest peak (4.33d (Å)).
Indicates the strength ratio (%) when set to 100 (the same applies below). Example 2 18.4g of sulfuric acid, N, N,
A gel was prepared in the same manner as in Example 1, except that 5.14 g of N,N',N',N'-hexamethyl-1,6-hexanediammonium salt was used. The composition of this gel is expressed in molar ratios: SiO ₂ /Al ₂ O ₃ = 100 ammonium salt/Si + Al = 0.02 OH ^- /Si + Al = 0.008 H ₂ O / Si + Al = 25.2 OH ^- /H ₂ O = 3 x 10 ^-4 It was hot. TPZ-3 was adjusted to 32.8 in the same manner as in Example 1.
I got g. The composition of this thing is 0.86 RO; 0.94
Na ₂ O; Al ₂ O ₃ ; 75.2 SiO ₂ ; 13.7 H ₂ O (R is N,
N, N, N', N', N'-hexamethyl-1,6-
(indicating a hexanediammonium group). The X-ray diffraction data and chart are shown in Table 2 and Figure 2, and the absolute intensity was obtained in Example 1.
The purity will be lower than that of TPZ-3.

[Table] Even after heat treatment at 800°C as in Example 1, the X-ray diffraction data remained unchanged, indicating good heat resistance. Example 3 Silica sol (Catalyst Kasei Co., Ltd. Cataloid S-30L SiO ₂ 30Wt%) as a silica source 100 g Sodium aluminate (Wako Pure Chemical Industries, Ltd. Na ₂ O) as an alumina source;
Al ₂ O ₃ = 1.56 ± 1) 1.27g OH -4.16g ^of caustic soda (special grade 98% manufactured by Wako Pure Chemical Industries, Ltd.) as the source, N, N, N, synthesized in Example 1 as the organic ammonium,
Add 4.56 g of N', N', N'-hexamethyl-1,6-hexanediammonium salt, and 30 g of sodium sulfate decahydrate (special grade manufactured by Wako Pure Chemical Industries, Ltd.) as a mineralizing agent to pure water.
Add to 150ml and prepare gel. The composition of this gel was: SiO ₂ /Al ₂ O ₃ = 100 ammonium salt/Si+Al = 0.02 OH ⁻ /Si+Al = 0.20 H ₂ O/Si+Al = 24.0 OH ⁻ /H ₂ O = 8.4×10 ⁻³ . TPZ-3 28.0g was prepared in the same manner as in Example 1.
I got it. When this was fired at 800℃ for 6 hours, the composition was 1.31 Na ₂ O; Al ₂ O ₃ ; 76.9 SiO ₂ .
3. Figure 3 shows the X-ray diffraction data and chart.

[Table] Example 4 500% of TPZ-3 obtained in Examples 1, 2, and 3
℃ for 6 hours, ion-exchanged with 10% ammonium chloride aqueous solution under reflux to form the ammonium form, dry again and bake at 500°C for 6 hours to form the hydrogen form.
Obtained TPZ-3. As shown in Table 4, the sodium content of this product was extremely low, indicating that ion exchange was almost complete. Moreover, the X-ray diffraction of this H ⁺ -TPZ-3 was essentially the same as that before ion exchange, and remained unchanged even after heat treatment at 800°C.

[Table] Example 5 250 g of silica sol as a silica source, 16.66 g of aluminum sulfate 18 hydrate as an alumina source, 13.89 g of caustic soda as an OH ^- source, and N,N,,N',N', -tetramethyl- as an organic ammonium source. 1,
6-hexanediamine 6.0g, methyl iodide 9.9g
A gel was prepared from 500 g of pure water. The composition of this product, expressed in molar ratio, is: SiO ₂ /Al ₂ O ₃ = 50 ammonium salt/Si+Al = 0.027 OH ^- /Si+Al = 0.10 H ₂ O/Si+Al = 28.9 OH ^- /H ₂ O = 3.5×10 ^-3 It was hot. This gel was placed in a 1-volume stainless steel autoclave and heated to 160°C under autogenous pressure while stirring gently.
I reacted for a week. After removing and separating the reactants, wash the washing solution with pure water.
Wash until it becomes 50μ/cm or less, wash at 60℃,
81.5g of zeolite was obtained. This zeolite had the X-ray diffraction pattern shown in Figure 4 and was TPZ-3. Example 6 Water glass (SiO ₂ manufactured by Wako Pure Chemical Industries, Ltd.) was used as a silica source.
36.24 wt%, Na ₂ O 17.30 wt%, H ₂ O 46.46 wt%)
3315 g, 266 g of aluminum sulfate 18 hydrate as an alumina source, 668 g of sulfuric acid as a neutralizing agent, 500 g of sodium chloride as a mineralizing agent, N,N,N',N'-tetramethyl-1,6-hexanediamine as an organic ammonium source. A gel was prepared from 339 g of methyl iodide, 567 g of methyl iodide, and 10 g of pure water. The composition of this product is expressed in molar ratios: SiO ₂ /Al ₂ O ₃ = 50 ammonium salt/Si + Al = 0.096 OH ^- /Si + Al = 0.10 H ₂ O / Si + Al = 30.9 OH ^- /H ₂ O = 3.3 x 10 ^-3. It was hot. This gel was placed in a 20-volume stainless steel autoclave and heated to 160°C under autogenous pressure while stirring gently.
I reacted for a week. After removing and separating the reactants, wash the washing solution with pure water at 50%
It was washed until it became less than μ/cm and dried at 60°C overnight. This product weighed 1.2Kg, and from the X-ray diffraction diagram shown in Figure 5, it was found to be TPZ-3.
This was ion-exchanged in the same manner as in Example 4 to form H ⁺ -TPZ.
- got 3. The analytical values of this product, expressed as the molar ratio of oxides, were SiO ₂ /Al ₂ O ₃ = 42.03 Na ₂ O/Al ₂ O ₃ = 0.024. Example 7 H ⁺ -TPZ-3 obtained in the same manner as Example 4
Each of these was pelletized, the particle size was adjusted to 10 to 20 meshes, and the pellets were activated at 450°C for 8 hours. This catalyst was packed in a glass reaction tube, and mixed xylene was fed under conditions of normal pressure and no carrier gas to carry out a xylene isomerization reaction. The results are shown in Table 5, all of which show extremely high xylene isomerization activity.

[Table] Here, PX equilibrium attainment rate (%) = PX concentration in xylene of product - PX equilibrium concentration in xylene / PX concentration in xylene of feed - PX concentration in xylene of feed x 100 Xyl loss (%) = Xylene concentration in the feed - xylene concentration in the product / xylene concentration in the feed x 100 EB disappearance rate (%) = EB concentration in the feed - EB concentration in the product / EB concentration in the feed x 100 However, in the formula Each concentration represents weight percent. Example 8 Using H ⁺ -TPZ-3 derived from Example 5, a long-term xylene isomerization reaction was carried out in the same manner as in Example 7. The reaction conditions are temperature 430℃WHSV=
4 HR ^-1 , and the composition of the product 72 hours after the start of oil passing is shown in Table 6, and its change over time is shown in Figure 6. It maintains extremely high xylene isomerization activity over a long period of time. There is. Although the disproportionation/transalkylation activity shows some deterioration in the initial stage, it becomes stable thereafter, and the isomerization activity does not deteriorate at all during this period.

[Table] Example 9 Xylene isomerization reaction was carried out in the same manner as in Example 7 using H ⁺ -TPZ-3 derived from Example 6. The temperature was sequentially raised to 400°C, 430°C, and 450°C while mixed xylene was being passed through the oil at WHSV = 4HR ^-1 , and the temperature continued for 6 days. As shown in Figure 7, the results show that extremely high xylene isomerization activity is maintained, but it can be further increased by gradually increasing the temperature. During this time, the disproportionation/transalkylation activity is stable, and under these conditions, the increase due to temperature increase is not so large. Example 10 Xylene isomerization reaction was carried out in the same manner as in Example 7 using H ⁺ -TPZ-3 derived from Example 2. For the first 9 hours, mixed xylene containing 1% propylamine was passed through the oil, and then mixed xylene containing no amine was passed through the oil. The results after 18 hours are
Table 7 also shows comparative examples that do not undergo such treatment.
Shown below.

【table】

[Table] By poisoning acid sites such as amine oil, disproportionation and
It is possible to reduce transalkylation activity. Example 11 H ⁺ -TPZ-3 derived from Example 6 was
as a carrier gas at 500℃WHSV0.44HR ^-1
Steaming treatment was performed for 48 hours. Table 8 shows the results of an isomerization reaction of xylene using the steamed material as a catalyst, together with a comparative example in which no steaming treatment was performed. The results show that the steaming treatment can reduce the disproportionation/transalkylation activity without substantially reducing the xylene isomerization activity.

[Table] Example 12 Using H ⁺ -TPZ-3 derived from Example 5, various metals were supported and ion-exchanged according to conventional methods. To this was added alumina gel for chromatography (300 mesh) in a weight ratio of 1:1, and the mixture was thoroughly mixed to form pellets. After adjusting the particle size to 10 to 20 mesh, the pellets were activated at 450 DEG C. for 8 hours. This catalyst was packed in a glass reaction tube, and mixed xylene was fed to carry out the isomerization reaction of xylene under normal pressure and gas phase. Hydrogen was used as the carrier gas. The results are shown in Table 9.

[Table] Example 13 Using 0.5% Pd-supported TPZ-3 obtained in Example 12,
Gas phase xylene isomerization reaction under hydrogen pressure was carried out. As shown in Table 10, the xylene isomerization activity is high even under extremely mild conditions, and no deterioration is observed over a long period of time.

[Table] Example 14 Using H ⁺ -TPZ-3 derived from Example 5, various metals shown in Table 11 below were supported and ion-exchanged according to a conventional method. Add alumina gel for chromatography (300 mesh) to this at a weight ratio of 1
Add 1:1 and mix thoroughly and make pellets, 10
After adjusting the particle size to ~20 meshes, it was activated at 450°C for 8 hours. Fill a glass reaction tube with this catalyst,
The xylene isomerization reaction was carried out by feeding mixed xylene in the gas phase at normal pressure. Hydrogen was used as the carrier gas. The results are shown in Table 11.

[Table] Example 15 TPZ-3 obtained in Example 6 was ion-exchanged in the same manner as in Example 4 using a 10% NaCl aqueous solution.
Na ⁺ -TPZ-3 was obtained. Using this, various metal ions were exchanged according to conventional methods in the same manner as in Example 12, and xylene isomerization reaction was performed. The results are shown in Table 12.

【table】 [Brief explanation of the drawing]

Figure-1 is the X-ray diffraction chart of TPZ-3 obtained in Example 1, Figure-2 is the TPZ-3 obtained in Example 2.
Figure 3 is an X-ray diffraction chart of TPZ-3 obtained in Example 3, Figure 4 is an X-ray diffraction chart of TPZ-3 obtained in Example 5, Figure 5 is an X-ray diffraction chart obtained in Example 6, Figure 6 is the result of the time course of the isomerization reaction obtained in Example 8, and Figure 7 is the time course of the isomerization reaction obtained in Example 9. It shows the results of the changes. In Figures 6 and 7, “PX ATE” represents the PX equilibrium attainment rate, and “EB Disapp” represents the EB disappearance rate.
"Loss" indicates xylene loss.

Claims (1)

[Claims] 1 The following general formula (1) M2/nO・Al ₂ O ₃・XSiO ₂ ...(1) [However, the formula is expressed in the form of an oxide in an anhydrous state, and At least one ion selected from the group consisting of hydrogen ions, alkaline earth metal ions, group metal ions of the periodic table, and rare earth metal ions, n is the valence of these ions, and
indicates 10 or more. ] X-rays having a composition represented by the following and substantially represented by the following values: A catalyst containing crystalline aluminosilicate zetolite having a lattice spacing is brought into contact with a raw material mixture containing xylene isomers, at least one of which has a thermodynamic equilibrium concentration or less, in the gas phase. Isomerization method. 2. The isomerization method according to item 1, wherein the X is in the range of 10 to 1000. 3. The isomerization method according to item 1, wherein the raw material mixture contains ethylbenzene. 4. The isomerization method according to item 1, wherein the contacting is carried out at a temperature in the range of 280 to 500°C. 5. The isomerization method according to item 1, wherein the contact is carried out in the presence of hydrogen. 6. The isomerization method according to item 1, wherein the contact is carried out at a pressure in the range of normal pressure to 30 kg/cm ² G. 7. The isomerization method according to item 1, wherein the contact is carried out at a weight hourly space velocity (WHSV) of 0.1 to 200 based on the zeolite.