JPH0825921B2 - Method for producing aromatic hydrocarbon, catalyst and method for producing the catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention uses a raw material containing an aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms as a main component, a crystalline aluminozine cosilicate, Alternatively, the present invention relates to a method for producing an aromatic hydrocarbon by bringing it into contact with a catalyst containing a transition metal, the catalyst, and a method for producing the catalyst.

[Prior Art] Many methods for converting aliphatic hydrocarbons and / or alicyclic hydrocarbons to aromatic hydrocarbons for the purpose of reforming petroleum products have been proposed, and among them, ZSM-5 and A method for converting a hydrocarbon composed of paraffin, olefin and / or naphthene into an aromatic compound with a high selectivity using a so-called zeolite catalyst is already known (Japanese Patent Publication No. 56-42639).

Further, it is also disclosed in the above-mentioned patent publication that the yield of aromatic compounds is improved by using zinc-H-ZSM-5 in which ZSM-5 type zeolite is substituted with zinc cation, or a catalyst supporting zinc is used.

Further, it is possible to synthesize a zincosilicate having a structure in which aluminum is replaced with zinc of ZSM-5, and such a zincosilicate catalyst and a platinum-supported zincosilicate catalyst are excellent choices for producing an aromatic hydrocarbon from a lower paraffin hydrocarbon. It is also known to exhibit the properties (USP Re29948, JP-A-63-8342).

[Problems to be Solved by the Invention] However, in a zinc-H-ZSM-5 catalyst substituted with a zinc cation or a zeolite catalyst supporting zinc, zinc is lost from the catalyst during the reaction, and the catalytic activity decreases with time. .

Zinc silicate having a structure in which aluminum of ZSM-5 is replaced with zinc has a low acid strength, and its catalytic activity and life are not sufficient.

In order to solve the above-mentioned drawbacks, some of the present inventors previously replaced the aluminum of ZSM-5 type zeolite (aluminosilicate) with zinc partially to obtain a specific Si / Al atomic ratio and Si / Al. A method for producing an aromatic hydrocarbon from an aliphatic hydrocarbon having 2 to 7 carbon atoms and / or an alicyclic hydrocarbon by using a crystalline aluminozin cosilicate catalyst having a Zn atomic ratio has been proposed (Japanese Patent Application No. 232963).

This catalyst is highly active and has a high aromatic selectivity,
Further, the catalyst life is longer than that of conventional catalysts, and it is an excellent catalyst, but there are still insufficient points to maintain the catalytic activity for an extremely long time. Therefore, improvement of the above crystalline aluminodine cosilicate catalyst According to the above, as a result of studying a catalyst for producing an aromatic hydrocarbon having a longer catalyst life, it was found that the catalyst life is remarkably improved by setting the content of the alkali metal in the catalyst to a specific amount or less, and the present invention has been achieved. did.

[Means for Solving the Problems] That is, the present invention provides a raw material containing at least 50% by weight of an aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms and having a Si / Al atomic ratio of 14 to 35. And the Si / Zn atomic ratio is 30-350
And a method for producing an aromatic hydrocarbon comprising contacting with a crystalline aluminozine cosilicate having an alkali metal content of 0.4% by weight or less, and an Si / Al atomic ratio of 30 to 3
50, and an alkali metal content of 0.4 wt% or less for the catalyst for the above aromatic hydrocarbon production consisting of crystalline aluminozine cosilicate, further crystalline aluminozine cosilicate or transition metal-containing crystalline aluminozine cosilicate The aromatic carbonization is carried out by treating with an ammonium ion-containing solution to replace the alkali metal in the crystalline aluminozine cosilicate with ammonium ion, and calcining this to reduce the alkali metal content to 0.4% by weight or less. It is a method for producing a catalyst for hydrogen production.

Crystalline aluminosilicates containing cations are known as zeolites in natural and synthetic products. Aluminosilicate has a three-dimensional skeleton structure in which SiO ₄ tetrahedron and AlO ₄ tetrahedron share oxygen atom sharing and are crosslinked, and the ratio of aluminum and silicon atoms to oxygen atoms is 1: 2.

On the other hand, the crystalline aluminosine cosilicate used in the present invention is aluminosilicate whose aluminum is partially replaced with zinc, and has the same skeleton structure as that of the crystalline aluminosilicate in which silicon, aluminum and zinc atoms are crosslinked by sharing oxygen. Have. In this case, all of the silicon, aluminum, or zinc atoms do not necessarily have to have the same crystal structure, and some of them may coexist in other forms such as their respective oxides.

Incidentally, the aluminosine cosilicate of the present invention, by performing the elemental analysis by substituting most of the cations with sodium ions, by determining the Na / Al ratio, aluminosilicate or zinc substituted with zinc ions by ion exchange. It can be distinguished from the supported aluminosilicate. That is, aluminosilicate substituted with zinc ions or aluminosilicate supported with zinc is Na / Al
The ratio is less than 1, but aluminozine silicate is Na / A
l ratio is greater than 1. This is because zinc, which constitutes the crystal lattice of aluminosine cosilicate, provides a cation exchange site together with aluminum.

Further, the aluminozincosilicate and the zincosilicate of the present invention can be distinguished by the temperature programmed desorption measurement of ammonia. That is, in zincosilicate, it originates from a strong acid point.
The desorption of ammonia at 350 to 450 ° C is small, whereas this is noticeable in aluminodilyconsilicate. This is because zinc forming the crystal lattice does not generate a strong acid point, whereas aluminum forms a strong acid point.

Si / Al in the crystalline aluminozine cosilicate of the present invention
Has an atomic ratio of 14 to 35 and an atomic ratio of Si / Zn of 30 to 350.

When the Si / Al atomic ratio is less than 14, it is difficult to form crystals with slow deterioration of catalyst performance over time. On the other hand, when the Si / Al atomic ratio is more than 35, the activity of the catalyst is insufficient and deterioration over time becomes faster.

If the Si / Zn atomic ratio is less than 30, the formation of crystals is poor and the deterioration of the catalyst over time is rapid. On the other hand, if the atomic ratio is larger than 350, the aromatic selectivity is low.

Furthermore, in the present invention, the alkali metal content is 0.4
It is characterized in that it is not more than 0.1% by weight, preferably not more than 0.1% by weight. When the content of alkali metal, especially sodium, in the catalyst exceeds 0.4% by weight, the life of the catalyst becomes short.

The alkali metal content in the catalyst is reduced to a desired content by various methods described below, such as exchanging the alkali metal ions in the aluminozine cosilicate with H ⁺ ions, ammonium ions, and alkaline earth metal ions. be able to.

The crystalline aluminozin cosilicate used in the present invention is ZS
Those having an X-ray diffraction pattern shown in Table 1 similar to M-5 type zeolite are preferable.

Table 1 X-ray powder diffraction of aluminozine cosilicate Lattice spacing (d value) Relative intensity 11.2 ± 0.3 Strong 10.1 ± 0.3 Strong 5.99 ± 0.2 Weak 5.58 ± 0.1 Weak 5.02 ± 0.1 Weak 4.62 ± 0.08 Weak 4.27 ± 0.08 Weak 3.85 ± 0.07 Strong 3.72 ± 0.05 Strong 3.65 ± 0.05 Weak 3.05 ± 0.03 Weak 2.99 ± 0.03 Weak The crystalline aluminozine cosilicate of the present invention can be used as it is as a catalyst for aromatic hydrocarbon production, but it can be used as a crystalline aluminozine cosilicate. A catalyst containing a transition metal by an ion exchange method, an impregnation method, or the like has further improved activity and aromatic selectivity. Examples of the transition metal to be contained include platinum, palladium, nickel, cobalt, group VIII metals such as iron, copper, chromium, molybdenum, tin, lead, rhenium, etc., among which platinum and chromium are active and It is particularly preferable because of its excellent aromatic selectivity.

Further, two or more kinds of these transition metals may be contained as an alloy.

The crystalline aluminozine cosilicate is a silicon compound,
Aluminum compounds, zinc compounds, alkali metal salts,
Water, and optionally an organic nitrogen compound and an acid may be mixed and maintained at a temperature of 100 ° C to 220 ° C for 3 to 200 hours for synthesis.

As an example of the silicon compound, sodium silicate, potassium silicate, silica, or a mixture of two or more thereof can be used.

As the aluminum compound, aluminum sulfate, aluminum nitrate, aluminum chloride, sodium aluminate, potassium aluminate, aluminum hydroxide, alumina, or a mixture of two or more thereof can be used.

As the zinc compound, zinc sulfate, zinc nitrate, zinc chloride, zinc oxide, zinc hydroxide, or a mixture of two or more thereof can be used.

As the alkali metal salt, sodium, potassium hydroxide, chloride, bromide, sulfate, nitrate, acetate, or a mixture of two or more thereof can be used.

Examples of organic nitrogen compounds include hydroxides, bromides and chlorides of quaternary ammonium such as tetrapropylammonium, tetrabutylammonium and triprobylmethylammonium, amines such as tripropylamine, tributylamine and morpholine, and triethanolamine. , Amino alcohols such as diethanolamine, amides such as acetamide and propionamide, alkylureas such as methylurea and 1,3-dimethylurea, nitriles such as acetonitrile and propionitrile, or a mixture of two or more thereof. it can.

As the acid, sulfuric acid, nitric acid, hydrochloric acid, acetic acid, phosphoric acid, or a mixture of two or more thereof can be used.

Further, these raw materials do not have to be used alone, and may be in a premixed state such as silica alumina, or may be a compound. The raw materials are not limited to those exemplified here.

The synthesized aluminosine cosilicate is ion-exchangeable, and most of the cations can be used by exchanging them with H ⁺ ions.

In the present invention, the content of alkali metal is 0.4% by weight.
Since it is necessary to make the following, it is necessary to exchange aluminazine cosilicate containing an alkali metal as a cation for H ⁺ ion or ammonium ion as described later.

The aluminosine cosilicate synthesized prior to the exchange may be calcined in air, for example at 540 ° C. The exchange with H ⁺ ions can be performed by immersing in an aqueous solution of nitric acid, hydrochloric acid, sulfuric acid or the like, or by immersing in an aqueous solution of ammonium salt and exchanging for ammonium ions. In these ion exchanges, an operation of removing the gas by immersing it in an aqueous solution and heating or reducing the pressure may be added.

In order to reduce the amount of alkali metal contained in the aluminosine cosilicate containing the alkali metal to a desired content, for example, the following method is used.

First, when an aluminozin cosilicate containing an alkali metal is immersed in an aqueous solution containing H ⁺ ions or ammonium ions, ions are exchanged and a part of the alkali metal is transferred into the aqueous solution. This makes it possible to reduce the content of alkali metal in the aluminozine cosilicate, but if the content of alkali metal does not decrease to the desired content in one ion exchange, further add this aqueous solution to H ⁺ ion or ammonium ion. By replacing the alkali metal with an aqueous solution containing a small amount of alkali metal, thereby sequentially advancing ion exchange to reduce the content of alkali metal contained in the aluminosine cosilicate. It is advisable to continue this operation until the alkali metal is sufficiently reduced.

In addition, a method in which a part of the alkali metal contained in the aluminozine cosilicate is exchanged with ammonium ions and then baked, and then re-immersed in an aqueous solution of ammonium salt to replace part of the remaining alkali metal with ammonium ions is repeated. It is also possible to reduce the alkali metal content.

Further, aluminosine cosilicate in which most of the alkali metal ions are replaced with alkaline earth metal ions can also be used.

It is possible to use a transition metal supported on an aluminosine cosilicate ion-exchanged with H ⁺ or an alkaline earth metal ion.

The crystalline aluminozine cosilicate can be used as a catalyst as it is, or can be used as a catalyst by adding a granulating agent and molding. As the granulating agent, commonly known ones such as silica, alumina, clay, inorganic salts, organic polymers and surfactants can be used.

Such a crystalline aluminozin cosilicate is used as a catalyst for producing an aromatic hydrocarbon from an aliphatic hydrocarbon having 2 to 7 carbon atoms and / or an alicyclic hydrocarbon, and an aliphatic carbon having 2 to 7 carbon atoms. As hydrogen, ethane, propane, n-butane, iso-butane, n-pentane, iso-pentane, neopentane, n-hexane, methylpentane, dimethylbutane, n-heptane, methylhexane,
Saturated hydrocarbons such as dimethylpentane, ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, hexadiene, heptene, heptadiene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, cyclohexadiethyl, methylcyclohexadiene, etc. Includes saturated hydrocarbons.

Further, examples of the alicyclic hydrocarbon include cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, cycloheptane, ethylcyclopentane and the like.

The raw material supplied to the reaction contains at least 50% by weight of the above-mentioned aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms, and components other than the above, such as benzene, toluene and carbon number. C ₈ or more carbon hydrogen, methanol,
It does not matter even if dimethyl ether is mixed.

The aromatization reaction is suitably carried out in the temperature range of 350 to 600 ° C. If the reaction temperature is lower than 350 ° C, the yield of aromatic hydrocarbons is not sufficient, while if it is higher than 600 ° C, the catalyst performance deteriorates rapidly due to coke formation. The feed rate of the raw material depends on the composition of the raw material, the reaction temperature, and the kind of the catalyst, but the weight hourly space velocity is suitably in the range of 0.1 to 10 hr- ¹ . When the weight hourly space velocity is less than 0.1 Hr ^-1, the production efficiency of aromatic hydrocarbon is low, while when it is more than 10 Hr ^-1 , the yield of aromatic hydrocarbon is not sufficient.

A suitable pressure for the aromatization reaction is 0 to 10 kg / cm ² · G. At a pressure of 10 kg / cm ² · G or higher, the yield of aromatic hydrocarbons is not high. The aliphatic hydrocarbon having 2 to 7 carbon atoms, which is a reaction raw material, may be supplied as it is, but may also be supplied together with hydrogen, nitrogen, and carbon dioxide.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples.

Preparation of supported catalyst In C liquid in which 26 g of sodium chloride and 1.9 g of tetrapropylammonium bromide were dissolved in 104 ml of distilled water, 60 ml of distilled water
Zinc sulphate 1.34g, aluminum sulphate 1.71g, tetrapropylammonium bromide 5.6g, concentrated sulfuric acid 5.3g solution A and solution B in which distilled water 45ml was dissolved in water glass No. 3 69g simultaneously and continuously. I added it. At that time, sodium hydroxide or sulfuric acid was added and adjusted so that the pH of the mixed solution was maintained at 10. The gel was recovered from this mixture by centrifugation, crushed for 1 hour and combined with the supernatant by centrifugation. The mixture was transferred to an autoclave and allowed to stand for 16 hours in 3 hours.
The temperature was raised to 0 ° C., and the temperature was maintained at 160 ° C. for 20 hours while stirring. Let it cool, take out the solid, wash with water, and dry. By calcining A at 540 ° C., an aluminozine cosilicate having a lattice spacing according to the X-ray diffraction diagram shown in Table 1 was obtained. A5g is 1N ammonium nitrate aqueous solution 250
It is immersed in ml, stirred at 80 ° C. for 2 hours to remove the supernatant, washed with water, dried, and calcined at 540 ° C. to give B-1.

While replacing the supernatant with a new ammonium nitrate aqueous solution, treat A with the ammonium nitrate aqueous solution every 2 times.
Repeated 3 times, 4 times, 5 times, 6 times, 7 times, washed with water, dried and calcined to obtain B-2 and B, respectively.
-3, B-4, B-5, B-6, B-7.

Further, the product obtained by treating the baked B-1 once again with ammonium nitrate, washing with water, drying and baking is designated as C.

A baked as it is, B-1, B-2, B-
The compositions of 3, B-4, B-5, B-6, B-7 and C are shown in Table 2.

What was burnt A, B-1, B-2, B-3, B-
Each of 4, B-5, B-6, B-7 and C was immersed in an aqueous solution of tetraaminedichloroplatinum to obtain 0.5% by weight of platinum.
Carried.

Example 1 Next, Platinum-supported B-7 was loaded as a catalyst, and 500
The reaction raw material n-pentane was diluted with nitrogen to 24 vol% at a weight hourly space velocity of 2 Hr ^-1 and circulated in a reactor maintained at 0 ° C to carry out an aromatization reaction. The reactor outlet gas was sampled, its composition was analyzed by gas chromatography, and the n-pentane conversion rate and aromatic selectivity were calculated by the following formulas from the analyzed values.

However, C ₁ = concentration of 9n-pentane in reactor outlet gas (wt%) C ₂ = concentration of product in reactor outlet gas (wt%) C ₃ = concentration of aromatic hydrocarbon in reactor outlet gas (wt%) Along with Examples 2-3 and Comparative Examples 1-6, the n-pentane conversion rate and aromatic selectivity 1 hour after the start of raw material distribution, and the time at which the n-pentane conversion rate reaches 80% and the aromatic selectivity at that time are shown. It is shown in Table 3.

Example 2 The aromatization reaction of n-pentane was carried out in the same manner as in Example 1 using B-6 carrying platinum as a catalyst.

Example 3 The aromatization reaction of n-pentane was carried out in the same manner as in Example 1 by using C carrying platinum as a catalyst.

Comparative Examples 1 to 6 Catalysts obtained by firing A and supporting platinum, and B-1 and B
-2, B-3, B-4, and B-5 were used to carry out the aromatization reaction of n-pentane in the same manner as in Example 1 using the catalysts carrying platinum, respectively, and Comparative Examples 1, 2, 3, and 4,
Set to 5 and 6.

Example 4 Using a hydrocarbon mixture containing 5% of benzene having a composition shown in Table 4 as a raw material, diluted to 20 vol% with nitrogen at a weight hourly space velocity of 1.9 Hr ^-1 , and supported on platinum at a reaction temperature of 500 ° C by B.
It was circulated to -7 to carry out an aromatization reaction.

The conversion and aromatic selectivity were calculated from the composition of the gas at the outlet of the reactor. The conversion and aromatic selectivity 1 hour after the start of distribution were 99%, 55 wt% and 95% and 33% after 33 hours, respectively.
It was wt%.

However, the conversion and the aromatic selectivity were calculated from the following formulas.

However, A = (total hydrocarbon concentration in the reactor outlet gas (wt
%)) B = (C _{5 to} C ₇ paraffin in reactor outlet gas, cycloparaffin concentration (wt%)) C = (aromatic hydrocarbon concentration in reactor outlet gas (wt%)) [Effect of the Invention] The invention has a Si / Al atomic ratio and a Si / Zn atomic ratio in a specific range, and by using a catalyst containing an aluminosine cosilicate having an alkali metal content of a specific amount or less, an aliphatic hydrocarbon. And / or an aromatic hydrocarbon can be obtained from an alicyclic hydrocarbon with high conversion and aromatic selectivity, and since the catalyst activity can be maintained for a long time, the catalyst life is extremely long and an industrially advantageous method. Is.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C07C 5/41 // C07B 61/00 300 (72) Inventor Satoshi Fukase 3-17, Shinzonan, Toda City, Saitama Prefecture No. 35 In Japan Mining Co., Ltd. (72) Inventor Moriji, Kojima No. 3 Mizusawa-cho, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture (72) Inquirer Shigehisa Imafuku 3-46, Minami-sachi-cho, Kawasaki-shi, Kanagawa (56) Reference Documents JP-A 1-236947 (JP, A) JP-A 63-8342 (JP, A) JP-A 3-178934 (JP, A)

Claims (9)

[Claims] 1. A raw material containing at least 50% by weight of an aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms,
Si / Al atomic ratio is 14-35, Si / Zn atomic ratio is 30-350,
A method for producing an aromatic hydrocarbon, which comprises contacting with a crystalline aluminozine cosilicate having an alkali metal content of 0.4% by weight or less. 2. A raw material containing at least 50% by weight of an aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms,
Si / Al atomic ratio is 14-35, Si / Zn atomic ratio is 30-350,
A method for producing an aromatic hydrocarbon, which comprises contacting a crystalline aluminazine cosilicate having an alkali metal content of 0.4% by weight or less with a catalyst containing a transition metal. 3. The method for producing an aromatic hydrocarbon according to claim 2, wherein the transition metal is platinum and / or chromium. 4. The method for producing an aromatic hydrocarbon according to claim 1, 2 or 3, wherein the crystalline aluminosine cosilicate has a powder X-ray diffraction pattern shown below. Lattice plane spacing (d value) Relative strength 11.2 ± 0.3 Strong 10.1 ± 0.3 Strong 5.99 ± 0.2 Weak 5.58 ± 0.1 Weak 5.02 ± 0.1 Weak 4.62 ± 0.08 Weak 4.27 ± 0.08 Weak 3.85 ± 0.07 Strong 3.72 ± 0.05 Strong 3.65 ± 0.05 Weak 3.05 ± 0.03 a little 2.99 ± 0.03 a little 5. A Si / Al atomic ratio of 14 to 35 and a Si / Zn atomic ratio of 30 to
350 and at least an aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms, which is made of crystalline aluminosine cosilicate having an alkali metal content of 0.4% by weight or less,
A catalyst for producing an aromatic hydrocarbon from a raw material containing 50% by weight. 6. A Si / Al atomic ratio of 14 to 35 and a Si / Zn atomic ratio of 30 to
350 and at least 50% by weight of an aliphatic hydrocarbon and / or alicyclic hydrocarbon having 2 to 7 carbon atoms, which is obtained by adding a transition metal to a crystalline aluminozine cosilicate having an alkali metal content of 0.4% by weight or less. A catalyst for producing an aromatic hydrocarbon from the contained raw materials. 7. A crystalline aluminozine cosilicate or a transition metal-containing crystalline aluminozine cosilicate is treated with an ammonium ion-containing solution to replace the alkali metal in the crystalline aluminozine cosilicate with ammonium ions, and then calcined. 6. The method according to claim 5, wherein
Or a method for producing a catalyst for producing an aromatic hydrocarbon according to Item 6. 8. The method according to claim 7, wherein the ion exchange between the alkali metal and the ammonium ion by the treatment with the ammonium ion-containing solution is repeated, and then this is fired.
A method for producing a catalyst for producing the aromatic hydrocarbon described. 9. The method for producing a catalyst for producing an aromatic hydrocarbon according to claim 7, wherein the ion exchange between the alkali metal and the ammonium ion by the treatment with an ammonium ion-containing solution and the calcination operation are repeated.