JPS61176539A - Dealkylation process - Google Patents

Abstract

PURPOSE:To carry out the selective dealkylation of an alkylbenzene using a specific catalyst composition prepared by adding a compound of a specific metal such as platinum to a specific crystalline aluminosilicate zeolite in the presence of ammonium ion. CONSTITUTION:The hydrogenation of ring and the decomposition of the product are suppressed, and the yield of the objective aromatic compound is increased keeping the hydrogenative dealkylation activity of the catalyst at a high level, in the vapor-phase catalytic dealkylation of an alkylbenzene in the presence of hydrogen, by using a catalyst composition containing (A) a crystalline aluminosilicate having an SiO2/Al2O3 molar ratio of 10-100 and the X-ray lattice spacings shown in the table-A, (B) a compound of one or more metals selected from Pt, Pd, Rh and Ir, and (C) a refractory inorganic oxide. The contents of the component A and the component B (metal) in the catalyst are 10-90wt% and 0.001-5wt%, respectively, and the component B is included in the component A in the presence of ammonium ion.

Description

DETAILED DESCRIPTION OF THE INVENTION a9 TECHNICAL FIELD OF THE INVENTION The present invention relates to catalyst compositions and methods of dealkylating alkylbenzenes using the catalyst compositions.

More specifically, a catalyst composition containing a crystalline aluminosicacate zeolite characterized by a specific X-ray lattice spacing, and an alkylbenzene having at least one alkyl group having 2 or more carbon atoms on the core carbon of the benzene nucleus;
Alternatively, the present invention relates to a method for selectively dealkylating alkyl groups from polymethylbenzene having three or more methyl groups.

Furthermore, from the above catalyst 9 composition and alkylbenzene containing at least one alkyl group having 2 or more carbon atoms in the core carbon of the benzene nucleus and/or polymethylbenzene and/or toluene having 3 or more methyl groups, these The present invention relates to a method of selectively dealkylating an alkyl group of and, if necessary, transmethylating a portion of the methyl groups of the dealkylated alkyl group to toluene.

b. Prior art Among the aromatic hydrocarbons currently used industrially,
Benzene, toluene, and xylene (hereinafter these three aromatic hydrocarbons may be collectively abbreviated as "BTX") are industrially the most useful in terms of their production volume and demand.

Conventionally, such BTX is obtained by separating aromatic hydrocarbon components from a raw material oil such as catalytic reformed oil or pyrolyzed gasoline by melt extraction or the like, and then distilling the extracted liquid. On the other hand, the high-boiling point residue that remains in the pot residue after separating BTX, which mainly contains aromatic hydrocarbons with carbon atoms of 9 or more, has low utility value as it is (although conventionally most of it has been used only as fuel). .

On the other hand, the industrially most valuable p-
In order to recover as much xylene as possible, C
The Cs fraction is treated in the presence of an isomerization catalyst, and industrially it involves a process of subjecting the Cs fraction to an isomerization reaction, a process of separating xylene isomers from the resulting isomerization reaction mixture, and The remaining components after separation are appropriately combined in the isomerization reaction step. In this isomerization reaction step, in addition to the main reaction of isomerization of xylenes, disproportionation of xylenes, disproportionation of ethylbenzenes, and trans-alkylation of xylenes and ethylbenzene occur. As a result of this side reaction, ethyltoluenes, trimethylbenzenes, and ethylxylenes are produced.

9 or more carbon atoms such as diethylbenzenes (Cs ”
) of alkyl-substituted aromatic hydrocarbons (hereinafter sometimes referred to as 'heavy ends').

Therefore, an object of the present invention is to effectively convert the Cs'' alkyl-substituted aromatic hydrocarbon mixture into BTX, which has higher industrial value, by subjecting it to hydrogenation-alkylation treatment.

A further object of the present invention is to hydrogenate and dealkylate a mixture of toluene and the above-mentioned 09+ alkyl-substituted aromatic hydrocarbon, and to transmethylate a portion of the methyl groups of the dealkylated alkyl groups to toluene. By doing so, it is an object of the present invention to provide a method for effectively recovering a xylene fraction that is more valuable among BTX to bulk xylene manufacturers.

Furthermore, another object of the present invention is to provide an economically stable process in which side reactions such as hydrogenation and decomposition reactions of benzene rings are small and the amount of coke produced by the catalyst is small under hydrogenation-alkylation conditions. It is about providing.

If these above objectives are achieved, the bulk xylene production process will have significant industrial benefits in terms of improved xylene yield, reduced fuel consumption due to reduced circulation flow rate, and increased value of by-products. It is self-evident that this will generate significant profits.

Hitherto, various proposals have been made regarding catalyst compositions and/or treatment conditions for this hydro-alkylation treatment. Examples include the following:

(υ A method of carrying out a dealkylation reaction of Cy-Cs alkyl aromatic hydrocarbons on a chromia-alumina catalyst at a temperature of 590°C or higher and a Hz/HC molar ratio of 4 or higher (see Eida Patent No. 959,609) ).

(i) a distillate containing alkyl aromatic hydrocarbons together with hydrogen in the presence of a small amount of sulfur at a temperature of 540 to 820 °C;
A method of carrying out a hydrodealkylation reaction using a chromia-alumina catalyst under pressure conditions of 20 to 68 atmospheres (see Belgian Patent No. 618,928).

(iii) an aromatic-rich feedstock with a boiling point of 220°F or higher combined with a hydrodehydrogenation component in the presence of hydrogen with a 28M-5 catalyst at 500-1000°F and about 100-600 psi;
(1, WH8VO, 5 to 1.5. Hz / HC molar ratio in the range of 1 to 6 conditions to produce aromatic hydrocarbons (see US Pat. No. 3,948,958 ).

(to) Aromatic hydrocarbons with a molecular weight larger than C6 in the presence of hydrogen at 550-1000'''F, about 100-200
0 psio, H2/HC molar ratio o, s-i, o,
wH8V t'ZS under conditions in the range of 0.5 to 200 (7)
Method for producing C6-Cs aromatic hydrocarbons in which substantially no heavy aromatic hydrocarbons are produced by conventional disproportionation or transalkylation reactions by contacting with M-5 catalyst (U.S. Pat. No. 3,945,913) (see specification).

Disadvantages of hydrogeno-alkylation processes using the catalyst compositions described in these prior art techniques are generally the relatively high temperatures (450-650°C) and pressures (1-3 ONf/
Furthermore, there are many side reactions such as benzene ring condensation reaction, benzene ring hydrogenation reaction, and decomposition reaction, and the stability of the catalyst composition itself is poor.

On the other hand, no process has yet been developed that can industrially perform transalkylation at a high level simultaneously with hydrodealkylation on the same catalyst.

Therefore, in order to improve the drawbacks of the conventional hydrodealkylation method as described above, the present inventors have created a specific dealkylation reaction, such as the hydrogenolysis reaction of benzene rings, etc. As a result of research into a method with fewer side reactions and a method that can perform the transalkyl reaction simultaneously with the above hydrodealkylation reaction, we found that a specific crystalline aluminosilicate zeolite with selected metals and The inventors have discovered that a method using a catalyst composition containing a refractory inorganic oxide in a fixed proportion and under defined conditions can intentionally achieve the above object, and have thus arrived at the present invention.

That is, the present invention provides a specific crystalline aluminosilicate zeolite with a metal having a hydrogenation/dehydrogenation function, especially platinum,
When containing at least one metal selected from the group consisting of palladium, rhodium and iridium and a refractory inorganic oxide, it is characterized in that it is carried out using a catalyst composition containing it in the coexistence of ammonium ions.

Conventionally, a catalyst composition containing a metal having a hydrogenation/dehydrogenation function as described above in a specific crystalline aluminosilicate,
It is known to those skilled in the art that it exhibits significant dealkylation activity towards alkyl aromatic hydrocarbons. However, the metal has the function of hydrogenating the benzene ring of the alkyl aromatic hydrocarbon, and furthermore, together with the acid active sites of the crystalline aluminosilicate, a ring decomposition reaction occurs, resulting in the desired aromatic yield. It is also well known that there is a significant decrease in To this end, methods have been proposed such as adding a second metal component to weaken the hydrogenation/dehydrogenation function of the metal, or strictly controlling the reaction conditions. From this point of view, it is still not enough.

However, as a result of intensive studies to solve these problems, the present inventors found that when incorporating the above-mentioned metal into crystalline aluminosilicate, coexisting ammonium ions is effective for hydrodealkylation of the catalyst composition. It has been found that ring hydrogenation and heptalysis activities can be significantly reduced while maintaining a high level of activity. Although it is not clear what kind of change in the catalyst composition is responsible for this effect,
The present inventors have discovered that the coexisting ammonium cations have some effect on the dispersibility9 particle size of the above metals, and that this results in hydrogenation to benzene rings while maintaining dealkylation activity toward alkyl aromatic hydrocarbons. It is speculated that this suppresses the 1-degrading activity. Furthermore, according to the method of the present invention, by using a specific crystalline aluminosilicate, a part of the dealkylated alkyl group is converted into a specific alkyl aromatic carbonization contained in the raw material in addition to hydrogenation-alkylation. It also becomes possible to efficiently trans-alkylate to hydrogen.

Thus, according to the present invention, A, Si 02 /AJ1203 <molar ratio) is 10
-100 and has an X-ray lattice spacing shown in Table 8, a crystalline aluminosilicate zeolite B, at least one metal selected from the group consisting of platinum, palladium, Odium, and iridium; A catalyst composition consisting mainly of a C0 refractory inorganic oxide, the catalyst composition being obtained by incorporating the compound of the old metal into the crystalline aluminosilicate zeolite of A above in the presence of ammonium ions. A catalyst composition containing o, ooi to 5% by weight of the metal B and 10 to 90% by weight of the crystalline aluminosilicate zeolite A, based on the catalyst composition. A process is provided for dealkylation by contacting a hydrocarbon feedstock containing alkylbenzenes in the presence of hydrogen in the gas phase.

The crystalline aluminosilicate zeolite (hereinafter sometimes simply referred to as "zeolite"), which is a component of the catalyst composition used in the method of the present invention, has a high molar ratio of 5102/AUzO3, similar to ZSM-5. ZSM-5 in terms of lattice spacing in X-ray diffraction
It is clearly distinguished from

The zeolite forming the catalyst composition used in the method of the present invention will be explained in more detail below. The zeolite mentioned above has a high St like zeolite 25M-5.
02/AJ120g (molar ratio), and the ratio is in the range of 10-100, preferably in the range of 15-70, more preferably in the range of 20-50.

Furthermore, the zeolite described above has the characteristics of the X-ray lattice spacing shown in Table 8 below, but according to the analysis of the present inventors, the X-ray diffraction chart of the zeolite is different from that of ZSM-5. A detailed comparison revealed that there were some differences. One major difference is that the X-ray lattice spacing d (in) that gives the strongest peak of ZSM-5 is d (in) - according to Yoneyama Patent No. 3,702,886.
3,85<20-23.14>, but the strongest peak of this zeolite is separated, and d(^)-3
, 86 and 3.83 (2θ-23,05) -3,00 (2θ-29,76)
In the zeolite, one peak of d(in) −
This is observed as a separate concave peak at 3,00 (2θ=29.75). This latter concave peak is not observed in all of the zeolites, but is observed in most cases. Next, the X-ray lattice spacing d (in) of the zeolite and its relative intensity are shown.

This relative intensity (I/Io> is d(A)=3.86(2θ
= 23.05), the relative intensity of each peak [I/Io (%)] is 100 to 6.
0 is VS (very strong), 60-40 is S (strong), 4
0 to 20 is represented by M (medium), and 20 to 10 is represented by W (weak).

Table-8 11.26 7.85
Moderate 10.118.75 Weak to Moderate 9
．． 83 9.00 little
i9.129.70 weak i7
．． 51 11.80 Weak 6.78 13.05
Weak 6.05 14,65 Weak to Moderate 5.74 15.45
weak s, ei is, go
Weak 5.41 16
．． 40 weak 5.00
17,75 weak 4.65
19.10 Weak 4.39 20.25
Weak 4.28 20.75 Weak to moderate 4.11 21.65 Weak to moderate 4.
04 22.05 weak
3.86 23.05 Very strong 3
．． 83 23.25 Very strong 3.75
23.70 Strong 3
．． 74 23.80 strong
3.66 24.30 Moderate to strong 3
．． 61 24.65 Weak 3.50 25.45 Weak to moderate 3.46 25.75 Weak to moderate 3.3
6 26.50 little
Yes 13.33 26.80
Weak to moderate 13.28 27.
20 weak $
3.26 27.35
Weak Pu 3.06 29,1
5 Weak to moderate 13.00 29
,75 Weak to moderate 2.98 29.95
Weak to moderate 2.96 30.20
Furthermore, the composition of the catalyst 1 used in the method of the present invention is d (in) = 3.86 and 2 of 3.83, which are characteristic of the zeolite which is a component of the product.
Two “very strong” (peaks) are generally d(in”)=
3.86 (2θ-23,05) peak intensity (I
o) is 100 - d (in) = 3.8
The relative intensity (I/Io) of 2 (2θ-23,25) is at least 70, preferably at least 75, more typically between 77 and 80.
The correlation is within the range of .
Preferred embodiments of the zeolite used (furthermore, as a component of the catalyst composition in the method of the present invention) also exhibit unique properties in terms of chemical activity, e.g. The cyclohexane decomposition ratio measured by Tomiyoshi is at least 1.1, preferably at least 1.5, and more preferably 1.7 or more.

In this specification, the above-mentioned "activated state" refers to a state in which most of the alkali metal ions contained in the zeolite immediately after synthesis are replaced with hydrogen ions according to the known glue method. It means. That is, 70 of the alumina-based cation exchange sites in the zeolite
% or more, preferably 90% or more, are substantially hydrogen ions?
This means that the zeolite is in an active H state (zeolite storage in such a state is sometimes referred to as "H-type zeolite").

In general, zeolites are 5iOz/AJlz)3 (
The activity, especially the acidity, has a roughly calculated value depending on the molar ratio. However, one characteristic of the zeolite that is a component of the catalyst composition used in the process of the present invention is that it has approximately the same 3i02 /A 1203 (MoEL/ratio).
The activity of ZSM-5 is higher than that of ZSM-5. In other words, if the cyclohexane decomposition activity of the standard ZSM-5 is 1, then 5102/A11, which is almost the same as that, is 1.
As mentioned above, the cyclohexane decomposition activity of the zeolite according to the present invention having a molar ratio of 203 is 1.1 or more, preferably 1.5 when expressed as a cyclohexane decomposition index ratio.
That's all.

This means that the catalyst used in the method of the invention.

The present inventors speculate that this is due to the fact that the zeolite, which is a component of the composition, has a higher acid strength within its pores than ZSM-5. The upper limit of the cyclohexane decomposition index ratio of the zeolite according to the present invention is generally 3, preferably 2.5 or less.

The catalyst composition used in the method of the present invention includes (A) zeolite having the above characteristics (component A), (B) platinum (Pt)
, at least one metal (C component) selected from the group consisting of palladium (Pd), Clradium (Rh), and iridium (Ir), and (C) a refractory inorganic oxide (C component), and the B It is obtained by incorporating a metal compound of component B into the crystalline aluminosilicate zeolite in the presence of ammonium ions, and the metal of component B is 0.001% based on the composition.
-5% by weight, and 10-90% by weight, preferably 30-70% by weight of zeolite A component. Such a catalyst composition may contain the components A, B, and C in the proportions described above, but a specific and preferred method for preparing it will be explained in detail later, but before that, a method for synthesizing the zeolite will be explained. I will also explain.

■ Zeolite synthesis method The zeolite used in the present invention has the above-mentioned 5tOz/
It may be any material having a molar ratio of 203 molar ratios and the above-mentioned characteristics of the X-ray lattice spacing, and is not particularly influenced by the type of synthesis method. Among the preferred zeolites, the cyclohexane decomposition index ratio is at least 1.1;
Preferably, the zeolite has a molecular weight of at least 1.5, and more preferably a zeolite synthesized by the method described below.
The synthesis method shown below is an example, and the zeolite used in the present invention is not limited thereto.

Method A Method A is a method previously proposed by the present inventors, and its details will be explained below.

That is, in this method, a crystalline aluminosilicate zeolite ZSM-5 having a Si 02 /Auz Os (molar ratio) of 20 to 300 is used, and 0.1 to 1 g of alkali metal hydroxide is contained per 1 g of the zeolite ZSM-5. This is a method of heating in an aqueous solution to a temperature between 80 and 250°C. This method is explained specifically and in detail in the specification filed by the present inventors on June 17, 1982 (title of invention: "Novel crystalline aluminosilicate zeolite and method for producing the same"). .

ZSM-5, which is the raw material for this method, is
It can be manufactured by the method described in Japanese Patent No. 064, and it can also be used since it is commercially manufactured by Mobil Oil Corporation.

The 5iOz/A Emperor 203 molar ratio of this 28M-5 is 20~
A range of 300, preferably a range of 30 to 200, is advantageously used to produce the zeolite of process A. ZSM-5 with a 5iOz/Alz03 molar ratio of less than 20 is not only extremely difficult to manufacture, but also not easily available. However, according to method A, Si
3i02/AuzO using ZSM-5 having a molar ratio of 02/A11203 of 20 or more, preferably 30 or more as a raw material.
It is surprising that it is not only possible to easily produce a zeolite having a molar ratio of 20 or less, but also that such an olide exhibits the above-mentioned unique activity.

Examples of the alkali metal oxide used in the treatment of the raw material zeolite ZSM-5 include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. Among them, sodium hydroxide is particularly preferred. The amount of such alkali metal hydroxide used is 0.1 g to 1 g, preferably 0.2 g to 0.7 g, per 1 g of ZSM-5 used.
, more preferably 0.39 to 0.5 g.

The alkali metal hydroxide is generally brought into contact with the starting zeolite ZSM-5 particles in the form of an aqueous solution. In this case, the amount of water is not critical and can be varied widely depending on the type and amount of ZSM-5 and/or alkali metal hydroxide used, but usually the total amount of ZSM-5 supplied is It is sufficient that the amount is sufficient to be sufficiently immersed in the aqueous solution. The concentration of the alkali metal hydroxide in the aqueous solution is not limited and can be varied over a wide range, but is generally in the range of 1 to 10% by weight, preferably 7% by weight.

The reaction is carried out at 80°C to 250°C, preferably 100°C to 200°C.
This is done by heating to a temperature in the range of °C.

The reaction can be carried out until a zeolite having the above characteristics is substantially produced, and the weight ratio of the formed zeolite/raw theolite ZSM-5 can be used as a measure of the production. That is, the reaction is carried out when the weight ratio is 10 to
This can be continued until it reaches a range of 80%, preferably a range of 20 to 70%, more preferably a range of 30 to 60%.

The zeolite thus obtained has the above characteristics and its chemical composition is represented by the following formula.

XM2 /no-Auz O8・ysL 02...
...(I) [However, the formula is expressed in the form of an oxide in an anhydrous state, M is one or more zero-valent cations, X is 0.5 to 4, and ■ is 10 to 200] Here, M represents an alkali metal, particularly sodium, in the zeolite immediately produced by method A, but it can be replaced with hydrogen ions, ammonium ions, etc. according to the commonly known ion exchange method. .

Can be exchanged for cations such as other metal ions. Of course, even if the zeolite is exchanged with cations other than sodium ions, it essentially meets the requirements of the zeolite of the present invention.

Further, in the above formula (I), X is an indicator of the amount of cations bonded to the zeolite, and in the case of the zeolite described above, it is within the range of 0.5 to 4, preferably 0.9 to 3. I can do it.

In addition to the above-mentioned characteristics, the zeolite obtained by this method also has the following characteristics compared to the known seolide ZSM-5 and other similar zeolites. One of its characteristics is that the (cyclohexane/n-hexane) adsorption ratio is abnormally large. The zeolite according to this method A has an adsorption ratio of at least 0.7, preferably at least 0.8, more preferably at least 0.9 (cyclohexane/n-hexane).

The adsorption ratio is a value measured according to the definition described below, and for ZSM-5, the values are all lower than 0.7, and as far as the inventors know, the adsorption ratio is lower than 0.7. not exist.

This adsorption ratio is a value indicating the adsorption ratio of cyclohexane to n-hexane, and the higher this value is, the larger the diameter (size) of the pores in the zeolite is.

The upper limit of the adsorption ratio of zeolite according to method A is generally 1
．． 3, typically about 1.2, and this zeolite has an appropriate pore size.

Next, the definition and measurement method of "(cyclohexane/n-hexane) adsorption ratio" and "cyclohexane decomposition index ratio", which are indicators expressing the characteristics of the zeolite obtained by this method A, will be explained in detail.

This (cyclohexane/n-hexane) adsorption ratio represents the weight ratio of cyclohexane to the weight of n-hexane adsorbed per unit weight of zeolite, and is a parameter that defines the pore diameter of zeolite, and the larger this value is, the more This means that molecules with a large molecular cross-section, such as cyclohexane, can more easily diffuse into the pores.

The amount of adsorption per unit weight of zeolite is measured as follows. That is, at 450°C in an electric furnace,
The time-calcined pellet-shaped zeolite is accurately weighed using the spring balance of the adsorption device. Next, after evacuating the inside of the adsorption tube, cyclohexane or n? was added until 60±2 M HQ was reached. - Introducing hexane in gaseous form, 20±
Hold at 1°C for 2 hours. The amount of cyclohexane or n-hexane adsorbed on zeolite can be measured from the difference in spring balance length before and after adsorption.

The cyclohexane decomposition index ratio is defined as the ratio of the cyclohexane decomposition index of the H-type zeolite obtained by method A above to the H-type ZSM-5 in the activated state with the same silica/alumina (molar ratio). be done.

The cyclohexane degradation index is 50 weight percent γ-
Zeolite containing alumina formed into pellets of 10 to 20 meshes was calcined in an electric furnace at 450°C for 8 hours, and then a certain weight of the zeolite was charged into a fixed bed reactor and heated to 350°C.
, - under atmospheric pressure conditions (weight unit hourly space velocity WH8V-
2HR-1 (total weight basis) of cyclohexane and hydrogen/
It is measured by supplying hydrogen in a molar ratio of cyclohexane = 2/1. The amount of cyclohexane converted (per 100 weight of feed) at this time is called the cyclohexane decomposition index. Note that WH8V is a value calculated by the following formula.

friend? fB This method B is also a method that the present inventors have previously proposed, and the application was filed on July 5, 1981 entitled "Production method of crystalline aluminosilicate zeolite and novel crystalline aluminosilicate zeolite" An application was filed under the title of the invention. The contents are specifically and detailedly explained in the specification of the application, and the gist thereof will be explained below.

In this method B, a silica source, an aluminium, a sulfuric acid source, and a zeolite selected from zeolite ZSM-5 and zeolite having the properties shown below are added at a concentration of 1 to 200 per gram of the zeolite.
In an aqueous solution containing millimoles of alkali metal hydroxide,
maintained under temperature, pressure and time conditions such that a crystalline aluminosilicate zeolite is formed, having the following properties; ) The X-ray lattice spacing d is as shown in Table 8 of the specification, and (C) The amount of chemical deposition of n-hexane is at least 0.0.
7979, is a method for producing crystalline aluminosilicate zeolite.

In this method aB, ZSM-5 is produced without substantially using organic amines as in the conventional production of ZSM-5, in other words, under conditions in which organic cations derived from such organic amines are substantially absent. Alternatively, the essential feature is that zeolite is produced in the presence of zeolite previously produced by method B.

This method B only uses as raw materials a silica source, an alumina source and an aqueous solution of alkali metal hydroxide, which are usually used in the synthesis of zeolites, and a starting zeolite selected from zeolite ZSM-5 and the zeolite produced by method B. This makes it possible to synthesize zeolite at an extremely high yield, several times that of the starting zeolite used as a raw material, and under suitable conditions, several times as much.

In this method B, any silica source that is commonly used for zeolite production can be used,
For example, silica powder.

Examples include colloidal silica, water-soluble silicon compounds, 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 such as aerosil silica, fuming silica, and silica gel is suitable, and as the colloidal silica, various Particle sizes can be advantageously used, for example between 10 and 50 microns. Examples of water-soluble silicon compounds include alkali metal silicates, such as water glass, containing 1 to 5 moles, particularly 2 to 4 moles of 5iO2 per mole of alkali metal oxide.

Examples include sodium silicate and potassium silicate.

Colloidal silica or water glass is particularly preferred as the silica source.

On the other hand, any alumina source that is generally used in the production of zeolite can be used, such as alumina, aluminum mineral salts, aluminates, etc. Specifically, colloidal Alumina in a hydrated or hydrateable state such as alumina, pseudoboehmite, boehmite, γ-alumina, α-alumina, β-alumina trihydrate: aluminum chloride, aluminum nitrate, aluminum sulfate; aluminium Examples include sodium acid and potassium aluminate, among which sodium aluminate and mineral acid salts of aluminum are preferred.

It is also possible to use aluminosilicate compounds, such as naturally occurring feldspars, kaolin, acid clay, bentonite, montmorillonite, etc., as a common source of silica and alumina, and these aluminosilicates can be used as silica and alumina. Part or all of the source may be replaced.

The amount of silica source in the raw material mixture of the present invention is generally in the range of 0.1 to 200 mmol, preferably 1 to 100 mmol per gram of the starting zeolite, calculated as 5102.
It is advantageous to be in the mmol range, more preferably in the range from 5 to 80 mmol, and the amount of alumina source is generally from 0.01 to 20 mmol, preferably 0.1 mmol per g of starting zeolite, calculated as AlI303. The amount is preferably within the range of 10 mmol to 10 mmol, more preferably 0.5 to 5 mmol. Although the mixing ratio of this silica source and alumina source is not limited, generally,
Each S! S i 0 in terms of Oz and Aρ203
2/A4120s molar ratio is preferably in the range of 1 to 200, preferably in the range of 5 to 100. If this molar ratio is less than 1, the desired zeolite cannot be obtained, and if it exceeds 200, the rate of modification will be low.

Particularly suitable alkali metal hydroxides are sodium hydroxide and potassium hydroxide, and each of these may be used alone or in combination.

Such alkali metal hydroxides are used in amounts ranging from 1 to 200 mmol, preferably from 5 to 100 mmol, more preferably from 10 to 80 mmol per gram of starting zeolite. Further, the alkali metal hydroxide for the silica source and alumina source is alkali metal hydroxide/(S
In terms of i 02 + AAl2S3 molar ratio, general Ni 0
．． It is preferably used in an amount within the range of 1 to 10, 2 to 5, and 0.3 to 1.

The above alkali metal hydroxide is usually used in the form of an aqueous solution, and the concentration of the alkali metal hydroxide in the aqueous solution is generally 1 to 100 mmol per mol of water based on the total amount of water in the reaction system. , preferably 5 to 50 mmol, more preferably 10 to 40 mmol.

Furthermore, in this method B, the starting ZSM-5 that can serve as the crystal matrix of the produced zeolite is a known one, which is hydrothermally synthesized in an alkaline aqueous solution together with a silica source and an alumina source by combining a specific organic cation with an alkali metal cation. It can be obtained according to known methods under which conditions are synthesized (for example, Japanese Patent Publication No. 46-1
(See Publication No. 0064).

Zeolite zSM-5 synthesized by this known method is usually thoroughly washed with water and then calcined at a temperature in the range of, for example, 300 to 700°C, preferably 400 to 600°C, to remove organic cations. However, the ZSM-5 used in Method B may be one in which such organic cations are incinerated or remain.

In addition, ZSM-5 zeolite, which is a raw material mixture, is prepared by converting some or all of the ions originally present in the zeolite into other cations such as lithium, silver, ammonium, etc. according to a known method after the above-mentioned calcination device. Thione;
Divalent alkaline earth cations such as magnesium, barium: cobalt, nickel, platinum.

Group (1) metal cation such as palladium: It may be ion-exchanged with a group (1) valent cation such as a rare earth metal.

In general, in this method B, the same purpose can also be achieved by using the zeolite obtained in this method B as the starting zeolite instead of the 28M-5 zeolite. The form of such zeolite may be in the form of a slurry immediately after synthesis, which is separated from the filtrate and dried.

It may also be one that has undergone a firing process. Further, the zeolite may be ion-exchanged with the metal cations, similar to the 28M-5 zeolite.

In Method B, a raw material mixture of silica source, alumina source, alkali metal hydroxide, zeolite and water in the proportions as described above is prepared at a concentration, pressure and temperature sufficient to produce crystalline zeolite. The synthesis of zeolite is carried out by maintaining the time conditions.

Although the temperature of the above zeolite synthesis reaction is not limited,
The temperature conditions can be essentially the same as those for conventional ZSM-5 production, and are usually 90°C or higher, preferably 10°C or higher.
Temperatures in the range from 0 to 250°C, more preferably from 120 to 200°C are advantageously used.

Furthermore, if this method B is used, the reaction time is usually 30 minutes as a result of the reaction rate being significantly accelerated compared to the conventional method.
minutes to 7 days, preferably 1 hour to 2 days, particularly preferably 2 days
Time I11 to 1 day is sufficient. The pressure applied is the autoclave's autogenous pressure or higher pressure, and the autoclaving is generally carried out under the autoclave, and may also be carried out under an inert gas atmosphere such as nitrogen gas.

When synthesizing zeolite according to this method, a batch method can be used in which all of the above-mentioned raw material components are charged as a mixture into a reaction vessel and the reaction is carried out under the above-mentioned conditions. Alternatively, a slurry of silica source,
A continuous method may be used in which the reaction is carried out in stages while continuously feeding the alumina source.

Additionally, some of the products obtained by the above method.

It is also possible to carry out the reaction by taking out the alkali metal hydroxide aqueous solution, a silica source, and an alumina source and supplying it batchwise or continuously.

The zeolite formation reaction is continued by heating the raw material mixture to the desired temperature, with stirring if necessary, until the zeolite is formed.

After crystals are thus formed, the reaction mixture is cooled to room temperature, washed with water until the ionic conductivity is, for example, 50 μO/as or less, and the crystals are separated. Furthermore, in order to dry the crystals, the crystals may be heated for 5 to 24 hours at 50°C or higher under normal pressure or reduced pressure.
time is retained.

Thus, if the method B is used, zeolite ZSM-5 or the zeolite obtained by method B is used as a raw material in addition to the silica source, alumina source, and alkali metal aqueous solution that are normally used for zeolite synthesis. Compared to the zeolite used, the batch method produces several times the amount of zeolite used.
Under suitable conditions, it is possible to synthesize zeolite in an amount equivalent to several times as much, and in a continuous system, it is also possible to synthesize more than 100 times as much zeolide.

The zeolite thus obtained contains an alkali metal ion as a cation, and is prepared by a method known per se.
For example, this can be ion-exchanged by applying an aqueous ammonium chloride solution to replace the cation sites with ammonium ions, and if this is further calcined, the ammonium ions can be converted to hydrogen ions in an activated state.

Furthermore, some or all of the alkali metal ions in the obtained zeolite can be exchanged with other cations. Examples of ion-exchangeable cations include monovalent metal cations such as lithium, potassium, and silver; alkaline earth metal cations such as magnesium, calcium, and barium; and divalent transitions such as manganese, iron, cobalt, nickel, copper, and zinc. Metal cations: Cations containing noble metals such as rhodium, palladium, and platinum; and rare earth metal cations such as lanthanum and cerium.

In the case of exchanging with the various cations mentioned above, it may be carried out according to a known method, and the zeolite may be contacted with a water-soluble or water-insoluble catalyst containing an aqueous solution containing the desired cation. Such contact processing can be accomplished in either a batch or continuous manner.

The zeolite thus obtained may be calcined at a temperature of 100 to 600°C, preferably 300 to 500°C, for 5 to 40 hours, preferably 8 to 24 hours, and this calcined product can also be used as the zeolite of the present invention. Ru.

In addition to the above-mentioned characteristics, the zeolite obtained by this method B has the following characteristics in comparison with the known seolide ZSM-5 and other similar zeolites.

One of its characteristics is that the amount of chemical conversion deposition of n-hexane is small (both have an extremely high value of 0.07 g/g).

The amount of chemical conversion deposition of n-hexane is a value measured according to the definition below. The amount of chemical deposition of n-hexane is a factor related to the pore volume of the zeolite, and a large value means that the pore volume of the channels of the zeolite is large. However, there is naturally an upper limit to the amount of chemical deposition of n-hexane, and the upper limit of the amount of chemical deposition of n-hexane in the zeolite produced by method B is generally about 0.1 g/g, typically 0.08 g/g. The specific adsorption amount of n-hexane is approximately 9, and preferably has a specific adsorption amount of n-hexane in the range of 0.07 to 0.099/9.

Yet another zeolite produced by the method described above.
One characteristic is the (2-methylpentane/cyclohexane) adsorption ratio. This adsorption ratio is a value measured by the method described below, and this zeolite generally has a value in the range of 1.1 to 1.6, preferably 1.2 to 1.5, and more preferably 1.25 to 1.45. (2-methylpentane/cyclohexane) adsorption ratio.

This (2-methylpentane/cyclohexane) adsorption ratio is a factor related to the pore size of the zeolite channel, and a large value means that molecules with large cross sections, such as cyclohexane molecules, can enter the zeolite channel. On the other hand, its cross section is smaller than that of cyclohexane2
-Means that methylpentane molecules can easily enter the channel.

Therefore, when a zeolite having a channel pore size with an adsorption ratio in the above range is used as a catalyst, it exhibits unique shape selectivity and becomes a novel catalyst of high industrial value.

Next, “n” is an index representing the characteristics of the zeolite of method
-specific adsorption amount of hexane” and “(2-methylpentane/
The definition and measurement method of ``cyclohexane adsorption ratio'' will be explained in detail.

(1) Specific adsorption amount of n-hexane This index is determined by 1 g of zeolite under the following certain conditions.
It is defined as the weight of n-hexane adsorbed to the top and is measured as follows. That is, at 450°C in an electric Matsufuru furnace.
The pelleted zeolite calcined for 8 hours is accurately weighed using the spring balance of the adsorption device. Next, the inside of the adsorption tube was evacuated (OamH, Q) L/L for 1 hour, and then n-hexane was introduced in gaseous form until the inside of the adsorption tube reached 50±1 s H (J). Hold for 2 hours.The weight of adsorbed n-hexane can be calculated from the difference in spring balance length before and after adsorption.

0i) (2-methylpentane/cyclohexane) adsorption ratio This index is determined by the adsorption ratio of 1 g of zeolite under certain conditions.
It is expressed as the weight ratio of 2-methylpentane to the weight of cyclohexane adsorbed per unit. The method for measuring the adsorption amount of each component is exactly the same as in the above (+) section.

Note that the chemical composition of the zeolite obtained by the method B is almost the same as that of the zeolite obtained by the method A, so a description thereof will be omitted here.

Method C Zeolite obtained by the method described in JP-A-56-17926.

Zeolite obtained by the method described in JP-A-56-123815.

Method E Zeolite described in JP-A-51-67299.

The zeolites of these methods C to 6 have the characteristics specified in the zeolites of the catalyst component used in the method of the present invention, but also have the adsorption ratio (cyclohexane/n-hexane) smaller than 0.7. , generally 0.4 to 0.
One of the characteristics is that it is 7. Yet another feature is n-
The specific adsorption amount of hexane is a relatively small value of 0.03 to 0.06 g/g.

Among the specific examples of the zeolite synthesis methods described above, when zeolites obtained by method A and method B are used,
This is preferable because it has higher dealkylation activity, which is the object of the present invention, and allows transalkylation to occur in parallel.

(2) Preparation of catalyst composition In order to prepare the catalyst mainly consisting of the zeolite (component A), the metal (component B) and the refractory inorganic oxide (component C), various commonly known preparation methods are employed. However, the catalyst composition used in the method of the present invention is obtained by incorporating the metal (component B) into the zeolite (component A) in the presence of ammonium ions. be.

The supply of ammonium ions, which is essential to the preparation step of the catalyst composition, involves converting the cations (usually alkali metal or alkaline earth metal ions) occupying the cation sites of the synthesized zeolite into ammonium ions according to a known method. After treatment with a compound containing a compound in an aqueous solution and thorough washing with water, treatment is carried out with ammonium ions contained in the zeolite, or when the metal (component B) is incorporated into the zeolite (component A), an arbitrary ammonium compound is used. This is achieved by adding a new . Furthermore, it is of course possible to use a combination of both of the above.

One of the ammonium cations necessary for preparing the catalyst composition used in the method of the present invention is the amount of the metal (component B) to be contained.

Usually, ammonium cations/
The metal is expressed in terms of molar ratio, preferably 0.01 to 10
0, more preferably in the range of 0.05 to 50 ammonium cations. Furthermore, the ammonium compound may be an inorganic compound as long as it is soluble in a soluble solvent (for example, water, alcohol, ketone, etc.).

Although any organic compound may be used, water-soluble salts such as ammonium nitrate, ammonium chloride, ammonium acetate, and ammonium hydroxide are usually preferably used.

Methods for incorporating a metal compound as component B into a composition containing zeolite as component A are broadly classified into impregnation methods and ion exchange methods.

In the case of the impregnation method, a chloride or nitrate of component B such as chloroplatinic acid or palladium chloride is dissolved in a soluble solvent (e.g., water, alcohol, ketone, etc.), this solution is impregnated into a composition containing zeolite, and then the solvent is In the case of the ion exchange method, a composition containing zeolite is immersed in an aqueous solution of a metal compound (for example, a metal amine complex) as component B having ion exchange ability, and then filtered and washed. It's a method.

The preferable content of the metal of component B varies slightly depending on the type of metal, but the weight of metal per catalyst composition is 0.001 to 3% for platinum (Pt), and 0.001 to 3% for palladium (Pt).
d), rhodium (Rh) and iridium (Ir), a range of 0.01 to 5% is suitable. The preferred metal is platinum (Pt), the preferred amount of which is between 0.002 and 2
．． A suitable range is 0%, more preferably o, oos to 1.0%.

Furthermore, as the refractory inorganic oxide of component C, those generally used as binders in zeolite molding can be used, and they may be natural or synthetic. . For example, silica, alumina, silica-alumina, silica magnesia, kaolin, etc. are used, and alumina is particularly preferred.

As a method for preparing the catalyst composition used in the method of the present invention, the following commonly known method can be employed. That is, (1') A method in which zeolite (component A) is modified with a metal (component B), and then mixed with a refractory inorganic oxide (component C) and shaped: (○) Zeolite (component A) and refractory A method of mixing a refractory inorganic oxide (component C) and modifying the resulting mixture with a metal (component B); (c) modifying a refractory inorganic oxide (component C) with a metal (component B); A method of mixing this with zeolite (component A) and molding; (d) Modifying the zeolite (component A) with a metal (component B), and modifying the refractory inorganic oxide (component C) with a metal (component). However, in the step of modifying with the metal (component B), any method can be used as long as ammonium cations are present together by the above method. There is no problem. Catalyst compositions prepared by the method (A) or (C1) are preferably used in the present invention.

After the prepared catalyst composition is shaped as necessary, it is heated with oxygen (02), nitrogen (N2), helium (He) at a temperature of, for example, 200 to 600°C, preferably 250 to 550°C.
It is fired for 1 to 5 hours under a gas atmosphere such as

The preparation methods explained above are merely preferred examples, and it goes without saying that improvements or combinations of these preparation methods can be used as catalyst compositions as long as they satisfy the requirements of the present invention. Nor.

The catalyst composition manufactured by II can be used in the form of powder, or in the form of molded products such as pellets or tablets.

Before being subjected to the reaction, it is heated at, for example, 200 to 600°C, preferably 250°C, under a reducing atmosphere (for example, under a hydrogen-containing gas atmosphere).
Preferably, the reduction heat treatment is performed at a temperature of ~550°C. This reduction heat treatment may be performed before or after the catalyst is charged into the reactor.

'2. Dealkylation reaction The method of the present invention using the catalyst composition obtained as described above has an extremely high dealkylation activity for alkylbenzene, and the activity has various characteristics. .

One major feature is that when the method of the present invention is followed, the nuclear hydrogenation reaction and decomposition reaction of benzene nuclei are much less likely to occur under the reaction conditions described below than in the prior art (as a result, the aromatic yield is high). That's what it means.

Yet another reason is that when a methyl group bonded to a benzene nucleus and an alkyl group having 2 or more carbon atoms coexist in the hydrocarbon raw material to be subjected to the dealkylation reaction, the methyl group is less susceptible to demethylation, and the carbon It is possible to carry out a reaction in which two or more alkyl groups are preferentially dealkylated. Therefore, if an alkylbenzene or an alkylbenzene mixture containing an alkyl group such as an ethyl group, a biOvyl group, a butyl group, and a methyl group separately or similarly in the benzene nucleus is used as a raw material, an ethyl group, a biOvyl group, a butyl group, etc. Corresponding benzenes whose groups are dealkylated with relatively high selectivity can be obtained in high conversion and good yield.

Another feature is that it has the ability to demethylate polymethylbenzene containing three or more methyl groups in the benzene nucleus. That is, for example 1,2.4-
Trimethylbenzene.

1.3.5-trimethylbenzene, 1,2,4.
When polymethylbenzene such as 5-tetramethylbenzene is subjected to the dealkylation reaction of the present invention, one of the methyl groups,
In this case, it can be converted into industrially most valuable xylenes in which two xylenes are eliminated. In particular, for example 1,3
．． Even in the case of bulky polymethylbenzenes such as 5-trimethylbenzene and 1,2,4,5-tetramethylbenzene, demethylation occurs more favorably than in the prior art, and xylenes can be obtained.

Another feature is that simultaneously with the dealkylation reaction,
It is possible to efficiently transalkylate a portion of the alkyl group generated from the dealkylation reaction to other alkyl aromatic hydrocarbons. That is, more specifically, an alkyl aromatic hydrocarbon having at least one alkyl group having two or more carbon atoms bonded to a benzene nucleus, and a raw material containing polymethylbenzene and monomethylbenzene or benzene are added to the catalyst composition. In supplying polymethylbenzene, an alkyl group having two or more carbon atoms is selectively dealkylated and the alkyl group is converted to the corresponding alkane, and a part of the methyl group dealkylated from polymethylbenzene is Transalkylation to monomethylbenzene or benzene is possible.

The present invention makes it possible to perform various industrially practical dealkylation reactions by utilizing the characteristics of the catalyst composition described above.

The hydrocarbon raw material used as a starting material for dealkylation in the method of the present invention contains at least one alkylbenzene containing at least one alkyl group having 2 or more carbon atoms bonded to a benzene nucleus. be able to. Such a hydrocarbon feedstock can consist of only one type of the alkylbenzenes, or can consist of a mixture of two or more of the alkylbenzenes, or at least one of these alkylbenzenes and other types. of alkylbenzenes and/or aliphatic and/or cycloaliphatic hydrocarbons.

The above alkylbenzenes have 2 carbon atoms as a substituent.
It can have only 1 or more, preferably 2 to 4, lower linear or branched alkyl groups, or it can optionally further have a methyl group bonded to the benzene nucleus in addition to such alkyl groups. can. Examples of such alkyl substituents having 2 or more carbon atoms include ethyl, n-propyl,
Isopropyl, n-butyl, isobutyl, 5ec-
Butyl, tert-butyl groups, etc. are included, and the method of the present invention can be particularly advantageously applied to hydrocarbons containing ethyl groups as substituents. The carbon number is 2
The number of alkyl substituents is not particularly limited, but is generally 1 to 3, preferably 1 or 2. Further, the number of methyl substituents that may be present is also not particularly limited, but when present, it can be generally 1 to 5, particularly 1 to 4.

Examples of alkylbenzenes to which the method of the present invention can be advantageously applied include ethylbenzene, ethyltoluene, and diethylbenzene.

Examples include ethylxylene, n-propylbenzene, cumene and cymene.

Further, as described above, the method of the present invention includes, for example, 1, 2.
-4-Trimethylbenzene, 1,3.5-trimethylbenzene, 1,2,4.5-tetramethylbenzene When using polymethylbenzene having three or more methyl groups, these methyl groups A portion undergoes demethylation and becomes useful xylenes. Therefore, hydrocarbons containing such polymethylbenzene can also be used as raw materials.

Furthermore, the method of the present invention can be used, for example, when a raw material containing benzene and/or toluene is used in addition to polymethylbenzenes having three or more methyl groups such as the above-mentioned trimethylbenzenes and tetramethylbenzenes. teeth,
Polymethylbenzene undergoes demethylation and is converted into useful xylenes, and the methyl groups generated by the demethylation are transalkylated to benzene and/or toluene to form useful toluene and/or toluene. Can be converted to xylenes. In addition to such raw materials, the number of carbon atoms bonded to the benzene nucleus as described above is 2.
Even when alkylbenzenes containing at least one alkyl group of 3 or more are included, each reaction can be carried out independently in the above reaction method.

From the characteristics of the catalyst composition of the present invention, the dealkylation is carried out using an alkylbenzene containing at least one alkyl group having two or more carbon atoms, an alkylbenzene containing three or more methyl groups, or a mixture of these two types of alkylbenzenes. It is advantageous to use as a raw material a hydrocarbon containing an alkylbenzene having a total carbon number of 9 or more and 11 or less. Furthermore, in addition to the hydrocarbon feedstocks mentioned above, feedstocks containing benzene and/or toluene are also advantageously used.

Furthermore, it is industrially extremely advantageous to carry out the dealkylation of the method of the present invention on a heavy fraction of a side reaction product, so-called heavy end, in the xylene isomerization step described below. After all, this heavy end contains ethyltoluene.

This fraction contains a relatively high concentration of alkylbenzenes having 9 to 11 carbon atoms, such as diethylbenzene, ethylxylene, trimethylbenzene, and tetramethylbenzene, and has little utility value. This is because by carrying out the dealkylation method of the invention, it can be easily converted into a useful component.

In other words, benzene, toluene, and xylene are industrially obtained by separating aromatic hydrocarbon components from feedstock oils such as catalytic reformed oil and pyrolysis gasoline by solvent or medium extraction, and then distilling the extracted liquid. It is being - All-purpose benzene.

The high boiling point residue that remains in the pot residue after toluene and xylene are separated, mainly containing aromatic hydrocarbons having 9 or more carbon atoms, has low utility value as it is, and conventionally most of it has been used only as fuel.

On the other hand, the industrially most valuable p-
In order to recover as much xylene as possible, C
The C8 fraction is treated in the presence of an isomerization catalyst, and industrially, the process is a process of subjecting the C8 fraction to an isomerization reaction and a process of separating xylene isomers from the resulting isomerization reaction mixture. , and the step of recycling the remaining components after separation to the isomerization reaction step. In this isomerization reaction step, in addition to the main reaction of isomerization of xylenes, disproportionation of xylenes, disproportionation of ethylbenzenes, and trans-alkylation of xylenes and ethylbenzene occur. As a result of the reaction, a mixture of alkylbenzenes having 9 or more carbon atoms (Cs''), such as ethyltoluenes, trimethylbenzenes, ethylxylenes, diethylbenzenes, etc., ie, heavy ends are generated.

By subjecting this heavy end to the dealkylation reaction of the present invention, it can be effectively converted into benzene, toluene, and xylene, which have higher industrial value. Improvement 1
, a reduction in the amount of fuel consumed due to the reduction in the circulating flow rate, and an increase in the value of by-products, resulting in many industrial benefits.

Therefore, the hydrocarbon raw material to be subjected to the method of the present invention contains the alkylbenzene, particularly alkylbenzene having 9 or more carbon atoms, at a concentration of at least 20% by weight, preferably 30% or more, more preferably 40% by weight or more. It can be contained in In addition, in the hydrocarbon raw material, the proportion of the above-mentioned alkylbenzene having an alkyl group having 2 or more carbon atoms in the alkylbenzene having 9 or more carbon atoms is at least 60% by weight, preferably 70% by weight or more, particularly preferably 80% by weight or more.
It is desirable that it accounts for at least % by weight.

Furthermore, in addition to containing alkylbenzene having 9 or more carbon atoms in the above proportion, the hydrocarbon raw material to be subjected to the method of the present invention contains benzene and/or toluene, preferably 30% by weight or more, preferably toluene. It can also be contained in a concentration of 40% by weight or more.

In addition, the hydrocarbon raw material has a ratio of alkylbenzene having a carbon number of 92 or more and benzene and/or toluene to 70%.
It is desirable that it accounts for at least 80% by weight, preferably at least 80% by weight.

In carrying out the dealkylation of the present invention, 250 to
It is advantageous to carry out at a temperature in the range 500°C, preferably 300-450°C, particularly preferably 320-430°C. Temperatures lower than this range are undesirable because dealkylation reactions are less likely to occur and hydrogenation reactions of benzene rings occur more frequently, while temperatures higher than the above range promote ring decomposition reactions and result in dealkylation. This is unsuitable because the selectivity of the catalyst decreases and the catalyst activity deteriorates significantly over time.

The reaction pressure is normal pressure to 300 psto, preferably normal pressure to
200 psig, particularly preferably normal pressure to 100 ps
Advantageously, it is in the range of ig. If the reaction pressure is too high, the selectivity of the dealkylation reaction decreases, and nuclear hydrogenation and decomposition reactions occur, which is not preferable.

When dealkylating a hydrocarbon raw material according to the method of the present invention, the feed ratio of the hydrocarbon raw material can vary widely depending on the type of hydrocarbon raw material and/or catalyst used, but generally 0.2 to 50, It is advantageous to feed at a hourly space velocity by weight, preferably in the range from 0.5 to 40, more preferably from 1 to 20.

In this specification, "weight unit hourly space velocity" is a value calculated from the following formula: weight of hydrocarbon feedstock supplied per unit time, weight of catalyst, where "weight of catalyst" is calculated based on the base of the catalyst. means the weight of crystalline aluminosilicate zeolite.

Additionally, the dealkylation of the present invention is carried out in the presence of hydrogen. The hydrogen supply ratio at this time can be varied widely depending on the type of hydrocarbon raw material and/or catalyst used, but it is generally 0.
．． It is appropriate to supply them at a ratio of 5 to 10, preferably 1 to 8.

According to the method of the present invention described above, it is possible to achieve various excellent advantages as described below as compared with conventional similar techniques, and the method contributes greatly to industry.

The advantages of the dealkylation method of the present invention are as follows.

(1) In the present invention, even if an alkyl aromatic hydrocarbon raw material, especially a raw material having 9 or more carbon atoms such as those produced by-product in the p-xylene production process, is reacted at a high conversion rate, benzene nuclei During the formation of naphthenes by hydrogenation of
Since the hydroxylation/decomposition reaction of the benzene ring is extremely small, a product with an excellent aromatic yield can be obtained.

(2) L, according to the present invention, if a methyl group bonded to a benzene nucleus and an alkyl group having 2 or more carbon atoms coexist in the alkyl aromatic hydrocarbon raw material, the methyl group will not undergo demethylation. Alkyl groups having 2 or more carbon atoms are preferentially dealkylated.

(3) Also 1,2,4-trimethylbenzene,
Polymethylbenzenes having three or more methyl groups such as 1,3,5-trimethylbenzene and tetramethylbenzene are effectively converted into xylenes by removing one or two of the methyl groups by the method of the present invention. .

(4) Furthermore, in addition to the above-mentioned polymethylbenzenes having three or more methyl groups, raw materials containing benzene and/or toluene undergo demethylation of polymethylbenzene by the method of the present invention, and become useful xylene. At the same time, the methyl group generated by the demethylation can be converted to useful toluene and/or xylenes by trans-alkylation to benzene and/or toluene. Furthermore, even when the above-mentioned alkylbenzenes containing at least one alkyl group having 2 or more carbon atoms bonded to the benzene nucleus are included in addition to such raw materials, each reaction may be carried out as described above. The methods can be performed independently.

(5) Therefore, according to the method of the present invention, carbon mainly contained in the heavy end, which is discharged from the xylene isomerization process and has almost no industrial utility value as it is, can be removed.
Aromatic hydrocarbons of 9 or more, such as ethyltoluene and ethylxylene, can be converted extremely efficiently into industrially valuable toluene, xylene, etc., and polymethylbenzene can be advantageously converted into xylenes. Moreover, the toluene, xylene, etc. produced by the conversion can be easily purified by a simple distillation operation since by-products such as naphthene are less produced.

(6) Furthermore, according to the method of the present invention, the reaction is carried out under mild reaction conditions of relatively low temperature and low pressure;
The formation of coke is very low, the lifetime of the catalyst can be maintained for a long time, and the frequency of regeneration of the catalyst can be greatly reduced.

(Power) According to the method of the present invention, since the reaction temperature and pressure are relatively low, it is possible to reduce costs such as construction of reaction equipment, maintenance costs, and energy consumption.

The method of the present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

Example-1 (ω) The silica/alumina molar ratio was 71.
No. 9 ZSM-5 zeolite was synthesized.

That is, tri-n-
Propylamine and n-propyl bromide were added.

The resulting composite was filtered, thoroughly washed with water, dried in an electric dryer at 100°C for 16 hours, then at 200°C for 8 hours, and further calcined at 500°C for 16 hours under air circulation.

Next, 30 g of the above ZSM-5 was taken and suspended in 520 d of an aqueous solution containing 9,669 9,669 ml of sodium hydroxide in a flask. After holding this at 90°C for 3 hours with stirring, the residue was filtered, thoroughly washed with water, and placed in an electric dryer for 3 hours.
It was dried at 0°C for 16 hours. The weight after drying was 14.59, the silica/alumina molar ratio decreased to 37.1, and the X
In the line diffraction pattern, as shown in Table A above, <ZS
It was observed that the strongest peak of d(in)-3,84 obtained with M-5 was clearly separated into d(in)-3,86 and d(in)-3,83 (zeolite A-1 ). Furthermore, ion exchange of the powdered zeolite A-1 was performed at 70° C. for 16 hours using a 5 wt % ammonium chloride aqueous solution.

The amount of ammonium chloride aqueous solution used was 1
51&g/g and this operation was repeated twice. After ion exchange, the zeolite was thoroughly washed with water as described above and left in an electric dryer at 90°C for 16 hours to remove NH4+.
A type zeolite (zeolite A-2) was obtained. Furthermore, a part of the zeolite A-2 was taken and exchanged into H+ type zeolite (zeolite A-3) by calcining it at 500° C. for 16 hours in an electric Matsufuru furnace with air circulation.

Zeolite A-1 was molded into a size of 10 to 20 meshes, and then calcined in an electric Matsufuru furnace at 450°C for 8 hours. Approximately 0.5 g of the zeolite was placed on a spring balance suspended inside the adsorption tube, and the weight of the zeolite was precisely measured from the elongation of the spring. Next, after evacuating the inside of the adsorption tube,
A gas holder filled with n-hexane or n-hexane was introduced into the adsorption tube. Adsorption is 20℃, 60am
The test was carried out for 2 hours under HO conditions. The weight of adsorbate adsorbed on zeolite was calculated from the difference in spring balance length before and after adsorption. The amount of n-hexane and cyclohexane adsorbed on the zeolite is 6.6wt each per zeolite weight.
%, 6.3 wt%, and the adsorption ratio of cyclo-hexane to n-hexane was 0.95.

(C) Alumina gel for chromatography (300 mesh or less) is added to the zeolite A-2 at a weight ratio of 1/1.
In addition, the mixture was thoroughly mixed and molded into a size of 10 to 20 meshes. The molded product was fired at 450° C. for 8 hours in an electric Matsufuru furnace, and then filled into a fixed bed reaction tube. After bringing the catalyst bed temperature to 350°C, cyclohexane 89/Hr.

and hydrogen/cyclohexane-271 (molar ratio) of hydrogen was supplied and the cyclohexane decomposition index was measured: 22
．． It was 0. The cyclohexane decomposition index of ZSM-5, which has the same silica/alumina (molar ratio) as Zeolite 8-2, is 12.5 from the correlation curve in Figure 1, and therefore the cyclohexane decomposition index ratio of Zeolite A-2 is 1.76.
It turns out that.

(7g of small NH4+ type zeolite A-2 was taken and immersed in a 35M! aqueous solution containing 37.2μ of chloroplatinic acid hexahydrate. After stirring at 50°C for 6 hours, water was added using a rotary evaporator. was distilled off and heated to 100°C in an electric dryer.
It was dried for 16 hours.

To this, add an equal weight of gel-like y-alumina (30'0 mesh or less), mix thoroughly, and form the catalyst into a size of 10 to 20 meshes. Catalyst-■ was prepared from H+ type zeolite A-3 in exactly the same manner as described above. The platinum content of both catalysts was 0.1 wt%.

(e) In order to confirm the effectiveness of the method of the invention, catalyst I
, a hydrodealkylation reaction of Ca + alkyl aromatic hydrocarbon was carried out using catalyst ①.

Before filling the catalytic reactor, calcination was carried out at 450° C. in an electric Matsufuru furnace, and 6 g was charged into a fixed bed reaction tube. After raising the catalyst bed temperature to 400°C under nitrogen flow, hydrogen was passed through (1
00d/Win) L/, and was maintained at this temperature for 2 hours to reduce the platinum in the catalyst.

After that, catalyst bed temperature 400℃9 reaction pressure 120 ps
ia as shown in Table 1 at 12 g/Hr and hydrogen/aromatic hydrocarbon -4/
It was fed with a 1 molar ratio of hydrogen. Table 1 shows the product composition 10 hours after the start of oil passage. This result shows that the catalyst π
This shows that the method of the present invention using a catalyst is significantly superior in terms of aromatic yield compared to a catalytic method.

Example-2 (ω Sodium hydroxide (special grade reagent manufactured by Wako Pure Chemical Industries) 11.
Aluminum sulfate 16-18 hydrate (special grade reagent made by Wako Pure Chemical Industries, Ltd.) 32.09 was added as an alumina source to an alkaline aqueous solution in which 3 g was dissolved in 227 m of pure water.
A gel was prepared by adding SiOz (30 wt%) 70.59.

Next, this gel was charged into a 300 m stainless steel autoclave.
Zeolite 4.09 was added. The composition of the preparation is ZSM
- Expressed per 51g, S i 02 = 88.1111 + 110I, A l
l 20g = 1,270°N a OH-70,9
iaol and expressed in molar ratio, Si 02 /AfLz 02 = 70.

OH-/Si 02 +A 203-0.71,
"OH-/Hz O-0,016 That's right. The materials were reacted at 180℃ autogenous pressure for 6 hours while stirring gently. The reactants were taken out and filtered, and the washing solution was washed with pure water until it was 50μ07α or less. Wash thoroughly until 9
After drying at 0°C overnight, the weight was measured and it was 10.0.
9, and 1.86 for the charged 28M-5 zeolite.
I got a product that weighs twice as much. As a result of quantifying silica and alumina, the silica/alumina (mole ratio) was -19,0, and the X-ray diffraction pattern had the characteristics shown in the table above, especially the di person) -3
, 84's strongest peaks are d(in)-346 and d(in)-3
, 83 (zeolite B-1).

From this powdered zeolite B-1, NH4+ type zeolite (zeolite B-2),
H+ type zeolite (zeolite B-3) was obtained.

;) After molding the zeolite B-1 into a size of 10 to 20 meshes, it was heated at 450°C in an electric Matsufuru furnace for 8 hours.
Baked for an hour. Approximately 0.5 g of the zeolite was placed on a spring balance suspended in an adsorption tube, and the weight of the zeolite was precisely measured from the elongation of the spring. Next, after evacuating the inside of the adsorption tube, the gas holder was filled with n-hexane, 2-methylpentane, or cyclohexane until the inside of the adsorption tube was 50±1a*HC.
It was introduced until it reached I. After being kept at room temperature (20° C.±1° C.) for 2 hours, the weight of adsorbate adsorbed on the zeolite was calculated from the difference in spring balance length before and after adsorption.

The specific adsorption amounts of n-hexane, 2-methylpentane and cyclohexane to the zeolite were each 0.0859/g per zeolite weight.

0.0549/g and 0.040g/g,
The adsorption ratio of 2-methylpentane to cyclohexane was 1.35.

Further, the cyclohexane decomposition index ratio of zeolite B-2 was measured according to the method described in Example 1-(C) and was found to be 2.1.

(7g of CINH4+ type zeolite B-2 was taken and immersed in a 35RR aqueous solution containing 37,2 #I9 of chloroplatinic acid hexahydrate. After continuing stirring at 50°C for 6 hours, using a rotary evaporator The water was distilled off, and the mixture was dried at 100°C for 16 hours in an electric drying mold.An equal weight of gel-like 8-alumina (300 mesh or less) was added thereto, thoroughly mixed, and molded into a size of 10 to 20 mesh. Catalyst - ■).

Catalyst-■ was prepared from H+ type zeolite B-3 in exactly the same manner as described above.

Furthermore, 7 g of H+ type zeolite was taken, and 37.2 IPJ of chloroplatinic acid hexahydrate and 0.861 g of ammonium nitrate were added.
40#Ii including! immersed in an aqueous solution of

After continuing stirring at 50° C. for 6 hours, the same treatment as above was performed to obtain catalyst V.

(Small) In order to demonstrate the effect of the present invention, dealkylation of Ca + alkyl aromatic hydrocarbon was carried out according to the procedure of Example i-(e) and under the same reaction conditions using Catalyst (1), Catalyst (2), and Catalyst (V). The reaction was carried out. The composition of the duct 10 hours after the start of oil passage is shown in Table 2. The results also show that the method of the present invention using catalysts ① and ② is superior to the method using catalyst ②. It can be seen that the aromatic yield is significantly superior.

(The following is a blank space) Table 2 Example 3 This example shows that the dealkylation reaction of the method of the present invention is selective. Example 2 - (13 g of catalyst Tf prepared in C1 was packed into a fixed bed atmospheric pressure reactor. 1
The platinum in the catalyst was reduced by flowing hydrogen at 400° C. for 2 hours at a rate of 00 d/Hr. Then, 6 g/Hr of ethylxylene and hydrogen at a molar ratio of hydrogen/ethylxylene=1/4 were supplied at a reaction temperature of 400° C. under pressure in the rear chamber. The product composition based on 100 weight of the feed 4 hours after the start of oil passing is as follows: Non-aromatic content: 20.1. Benzene: 1,1°Toluene: 2,6. Xylene: 69.5. Ethylxylene: 6.5. Heavy content: 0.9 (unit: weight), and 95 vol% of non-aromatic content was ethane.

These results show that the ethyl groups in ethylxylene are selectively deethylated, most of the methyl groups in ethylxylene are retained, and therefore the xylene yield is high.

Reference Example This example shows that the catalyst used in the process of the invention is effective in transmethylating methyl groups demethylated from polymethylbenzene. That is, the raw material ethylxylene in Example 3 was reacted with toluene/1,2,4-trimethylbenzene-1 in exactly the same manner as in Example 3.

The product composition based on 100 weight of the feed 4 hours after the start of oil passage is: non-aromatic content: 1.4, benzene:
2.9, Toluene: 26.0, Xylene: 36.
8.

Trimethylbenzene: 34.1, heavy content 1.9 (unit duplex weight).

Example 4 In order to demonstrate the effects of the present invention, a reaction between toluene and a Ca+aromatic hydrocarbon mixed raw material was carried out using the catalyst (1) prepared in Example 2-(C). The catalyst charging and reduction methods were exactly the same as those described in Example i-(e). The reaction was carried out using a catalyst at 165F and a temperature of 400℃. Pressure 120 psia
, raw material supply rate 12g/Hr.

The experiment was carried out under the conditions of hydrogen/aromatic hydrocarbon=4/1 molar ratio. Table 3 shows the feed composition and product composition over time. These results show that the method of the present invention allows the transalkyl reaction to proceed effectively along with the hydrodealkylation reaction.

Furthermore, it has been found that the method of the present invention has an excellent aromatic yield and is stable over time.

(Margin below) Table-3

[Brief explanation of the drawing]

The attached drawing shows the correlation between the silica/alumina (mole ratio) of H-type zSM-5 zeolite and the cyclohexane decomposition index, which is the standard for calculating the cyclohexane decomposition index ratio (C.D,R). Patent applicant: Teijin Yuka Co., Ltd. Sμ) zlAbOs (with Mono L) Procedural amendment dated p. 1985

Claims (1)

[Claims] 1, A, SiO_2/Al_2O_3 (molar ratio) is 10
A crystalline aluminosilicate zeolite B having an X-ray lattice spacing of 100 to 100 and having the characteristics shown in Table A, at least one metal selected from the group consisting of platinum, palladium, rhodium and iridium, and C , a catalyst composition mainly consisting of a refractory inorganic oxide, which is obtained by (i) containing a compound of the metal B in the crystalline aluminosilicate zeolite A in the presence of ammonium ions; (ii) The metal B is 0 based on the catalyst composition.
．． 001 to 5% by weight, and (iii) containing 10 to 90% by weight of the crystalline aluminosilicate zeolite of A above based on the catalyst composition. A dealkylation method characterized by catalyzing a hydrocarbon feedstock containing alkylbenzenes in the presence of hydrogen in the phase. 2. The dealkylation method according to item 1, wherein the hydrocarbon raw material contains an alkylbenzene having at least one alkyl group having 2 or more carbon atoms bonded to a benzene nucleus. 3. The dealkylation method according to item 1, wherein the hydrocarbon raw material contains at least one alkylbenzene selected from the group consisting of ethyltoluene, ethylxylene, and diethylbenzene. 4. The dealkylation method according to item 1, wherein the hydrocarbon raw material contains tolumethylbenzene. 5. The dealkylation method according to item 1, wherein the hydrocarbon raw material contains toluene and trimethylbenzene. 6. The method according to item 1, wherein said contacting is carried out at a temperature in the range of 250 to 500°C. 7. The dealkylation process of paragraph 1, wherein said contacting is carried out at a pressure in the range of 0 to 300 psig. 8. The contact is expressed as weight unit hourly space velocity (WHSV)
2. The dealkylation method according to item 1, wherein the dealkylation is carried out so that the 9. The dealkylation method according to item 1, wherein the contact is carried out in the presence of hydrogen in an amount of 0.5 to 10 times the mole of the hydrocarbon raw material.