JP3153342B2 - Method for producing aromatic hydrocarbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a raw material mainly composed of aliphatic hydrocarbons and / or alicyclic hydrocarbon having 2 to 7 carbon atoms, crystalline aluminozincosilicate and white to
The present invention relates to a method for producing an aromatic hydrocarbon by contacting with a catalyst containing gold .

[0002]

2. Description of the Related Art Many methods have been proposed for converting aliphatic and / or alicyclic hydrocarbons to aromatic hydrocarbons for the purpose of reforming petroleum products, among which ZSM-5 and ZSM-5 have been proposed. A method of converting a hydrocarbon comprising paraffin, olefin and / or naphthene into an aromatic compound with high selectivity by using a so-called zeolite catalyst has already been known (JP-B-56-42639).

Further, it is disclosed in the above-mentioned patent publication that the use of a zinc-H-ZSM-5 obtained by substituting a ZSM-5 type zeolite with a zinc cation or a catalyst carrying zinc increases the yield of aromatic compounds. ing.

Also, it is possible to synthesize a zincosilicate having a structure in which aluminum of ZSM-5 is substituted with zinc, and such a zincosilicate catalyst and a platinum-supported zincosilicate catalyst are useful for producing aromatic hydrocarbons from lower paraffinic hydrocarbons. It is also known to show excellent selectivity. (USP Re 29948, Tokuhei 1-
No. 16767, JP-A-63-8342)

[0005]

However, in the case of a zinc-H-ZSM-5 catalyst substituted with a zinc cation or a zeolite catalyst carrying 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,
Both catalytic activity and life are not sufficient.

SUMMARY OF THE INVENTION The inventors of the present invention have previously prepared an aromatic hydrocarbon having 2 to 7 carbon atoms and / or an alicyclic hydrocarbon at a high selectivity and for a long time to produce an aromatic hydrocarbon stably. As a result of studying the catalyst of the above, the aluminum of the ZSM-5 type zeolite (aluminosilicate) was partially replaced with zinc, and a specific Si / Al atomic ratio and Si / Zn
It has been found that crystalline aluminodine cosilicate having an atomic ratio is excellent as a catalyst. (Japanese Patent Application No. 2-22
4436)

In the above invention, it has been proposed that the crystalline aluminozincosilicate containing a transition metal such as platinum or chromium can also be used as a catalyst for the aromatization reaction. The inventors have further studied these catalysts in detail, and found that for the aromatization reaction,
It has been found that both have characteristics. That is, the reactivity of an aliphatic hydrocarbon and / or an alicyclic hydrocarbon increases as the number of carbon atoms increases. However, when only a crystalline aluminodine cosilicate containing a transition metal is used as a catalyst in this reaction, the catalytic activity becomes higher. Although the conversion rate of the raw material is high, the yield of aromatics cannot be said to be sufficiently high because, in addition to aromatic hydrocarbons, many hydrocarbons having a low carbon number and low reactivity such as ethane are produced as by-products. On the other hand, the crystalline aluminodine silicate containing no transition metal has a low catalytic activity, but has a low selectivity to ethane, and has a relatively large number of carbon atoms and a relatively large amount of highly reactive hydrocarbon as a by-product.

[0009] Therefore, the inventors have found that, based on the above findings, taking advantage of the strengths of the respective catalyst, overall result of intensive studies on how to increase the yield of aromatic hydrocarbons, firstly white
Crystalline aluminodine silicate that does not contain gold ,
Contacting the reactants to produce aromatic hydrocarbons,
Then, by contacting the platinum- containing crystalline aluminodine cosilicate to convert the unreacted raw materials and by-product hydrocarbons to aromatic hydrocarbons, it is possible to obtain aromatic hydrocarbons in higher yield. I found it.

[0010]

That is, the present invention provides a raw material containing at least 50% by weight of an aliphatic hydrocarbon and / or an alicyclic hydrocarbon having 2 to 7 carbon atoms and having a Si / Al atomic ratio of 14 to 35. And the atomic ratio of Si / Zn is 30 to 350.
And then contacting with a crystalline aluminodine cosilicate, which has a Si / Al atomic ratio of 14-35,
A method for producing an aromatic hydrocarbon, comprising contacting a crystalline aluminodine silicate having an n atomic ratio of 30 to 350 with a catalyst containing platinum .

Crystalline aluminosilicates containing cations are known as zeolites in natural and synthetic products. Aluminosilicate is made of SiO4 tetrahedron and AlO4
The tetrahedron has a three-dimensional skeletal structure in which oxygen atoms are shared and crosslinked, and the ratio of aluminum and silicon atoms to oxygen atoms is 1: 2.

On the other hand, the crystalline aluminosilicate used in the present invention is obtained by partially substituting the aluminum of the aluminosilicate with zinc. Silicon, aluminum and zinc atoms share oxygen and crosslink to form the same as the crystalline aluminosilicate. It has a skeletal structure. It is not necessary that all of the silicon, aluminum or zinc atoms constitute the same crystal structure, and some of them may coexist in other forms such as respective oxides.

The aluminozincosilicate of the present invention is obtained by substituting most of the cations with sodium ions and conducting elemental analysis to determine the Na / Al ratio. Can be distinguished from aluminosilicate carrying zinc. That is, aluminosilicate substituted with zinc ions or aluminosilicate carrying zinc has a Na / Al ratio of less than 1, whereas aluminozincosilicate has a Na / Al ratio of greater than 1. This is because zinc constituting the crystal lattice of aluminozincosilicate provides a cation exchange site together with aluminum.

The atomic ratio of Si / Al in the crystalline aluminodine silicate of the present invention ranges from 14 to 35, and the atomic ratio of Si / Zn ranges from 30 to 350. When the atomic ratio of Si / Al is smaller than 14, crystals with slow deterioration of the catalyst performance with time are difficult to be formed. On the other hand, when the atomic ratio is larger than 35, the activity of the catalyst is not sufficient and the deterioration with time is accelerated. Also, Si /
When the atomic ratio of Zn is less than 30, the formation of crystals is poor and the catalyst deteriorates with time rapidly. On the other hand, when the atomic ratio is larger than 350, the selectivity of aromatic is low.

The crystalline aluminodine silicate used in the present invention preferably has an X-ray diffraction pattern shown in Table 1 similar to the ZSM-5 type zeolite.

[0016]

[Table 1]

The crystalline aluminodine silicate is prepared by mixing a silicon compound, an aluminum compound, a zinc compound, an alkali metal salt, water, and optionally an organic nitrogen compound and an acid, and keeping the mixture at a temperature of 100 ° C. to 220 ° C. for 3 to 200 hours. Can be synthesized.

As an example of the silicon compound, sodium silicate, potassium silicate, silica or a mixture of two or more of these 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 of these 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, hydroxides of sodium and potassium, chlorides, bromides, sulfates, nitrates, acetates, and mixtures of two or more of these can be used.

As the organic nitrogen compound, hydroxide, bromide, chloride or tripropylamine of quaternary ammonium such as tetrapropylammonium, tetrabutylammonium and tripropylmethylammonium;
Amines such as tributylamine and morpholine; amino alcohols such as triethanolamine and diethanolamine; amides such as acetamide and propionamide;
Alkyl urea such as methyl urea and 1,3-dimethyl urea, nitrile such as acetonitrile and propionitrile, or a mixture of two or more of these can be used.

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

These raw materials do not need to be used alone, and may be in a state of being mixed in advance or a compound such as silica alumina. The raw materials are not limited to those exemplified here.

The synthesized aluminodine cosilicate is ion-exchangeable, and most of the cations can be exchanged for H + ions before use. The aluminozincosilicate synthesized prior to the exchange may be calcined, for example, at 540 ° C. in air. The exchange to H + ion is nitric acid, hydrochloric acid,
It can be carried out by immersing in an aqueous solution of sulfuric acid or the like, or by immersing in an aqueous solution of ammonium salt and exchanging it for ammonium ions and firing. In these ion exchanges, an operation of immersing in an aqueous solution to remove gas by heating, decompression, or the like may be added.

Since the catalyst life of an aluminosine silicate having a large alkali metal content is short, it is desirable to reduce the content to a certain level or less. In order to reduce the content of the alkali metal from the aluminodicosilicate containing the alkali metal to a desired content, for example, the following method is employed.

First, when an aluminodicosilicate 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. As a result, the alkali metal content in the aluminodine cosilicate can be reduced. However, if the alkali metal content does not decrease to the desired content in one ion exchange, the aqueous solution is further converted to H + ions or ammonium ions. By replacing the aqueous solution with an aqueous solution containing a small amount of alkali metal, the ion exchange is sequentially performed to reduce the alkali metal content in the aluminodine cosilicate. This operation may be continued until the alkali metal content is sufficiently low.

In addition, after baking a product obtained by exchanging part of the alkali metal contained in the aluminodine cosilicate with ammonium ions, immersing it again in an aqueous ammonium salt solution, and exchanging a part of the remaining alkali metal with ammonium ions. The alkali metal content can also be reduced by repeating the method.

Further, one obtained by exchanging most of the cations of the aluminodine cosilicate with alkaline earth metal ions can also be used.

According to the present invention, when producing an aromatic hydrocarbon from a raw material containing an aliphatic hydrocarbon and / or an alicyclic hydrocarbon having 2 to 7 carbon atoms, both the conversion and the selectivity to the aromatic hydrocarbon are determined. to improve, the two crystalline aluminozincosilicate combination used as a catalyst, the raw material gas first contacted platinum crystalline aluminozincosilicate catalyst which does not contain and then, the crystalline aluminosilicate which contains platinum It is characterized in that aromatic hydrocarbons are produced in high yield by contact.

The inclusion of platinum in the crystalline aluminodine cosilicate can be carried out by a usual ion exchange method, impregnation method or the like.

The crystalline aluminodine silicate containing the crystalline aluminodine silicate and platinum can be used as a catalyst either as it is or by molding by adding a granulating agent. As the granulating agent, generally known agents such as silica, alumina, clay, minerals, inorganic salts, organic polymers and surfactants can be used.

The step of forming the crystalline aluminodine cosilicate by adding the granulating agent may be performed before, during, or after the step of exchanging the contained cations with H + ions, ammonium ions or alkaline earth metal ions. Although it can be carried out even at the point of time, it is preferable to perform the molding before or during the ion exchange because the solid-liquid separation and the calcination can be performed efficiently.

Such a crystalline aluminozincosilicate is used as a catalyst for producing an aromatic hydrocarbon from an aliphatic hydrocarbon and / or an alicyclic hydrocarbon having 2 to 7 carbon atoms. Examples of the aliphatic hydrocarbon include ethane, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, n-hexane, methylpentane, dimethylbutane, n-heptane, methylhexane, and dimethylpentane. Saturated hydrocarbon, ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, hexadiene, heptene, heptadiene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, hepclohepten,
Unsaturated hydrocarbons such as cyclohexadiene and methylcyclohexadiene are included.

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

The raw materials supplied to the reaction are those having 2 to 2 carbon atoms as described above.
7, containing at least 50% by weight of an aliphatic hydrocarbon and / or an alicyclic hydrocarbon of component 7,
For example, benzene, toluene, hydrocarbons having C8 or more, methanol, dimethyl ether, and the like may be mixed.

The aromatization reaction according to the present invention is carried out using two types of crystalline aluminodine cosilicate catalysts.
As a reactor, a method in which two reactors filled with respective catalysts are connected in series, or in the first half of one reactor
For example, a method can be used in which a crystalline aluminozincosilicate catalyst containing no platinum is filled with a crystalline aluminozincosilicate catalyst containing platinum in the latter half.

It is appropriate to carry out the aromatization reaction in the first half and the second half in a temperature range of 350 to 600 ° C. If the reaction temperature is lower than 350 ° C., the yield of aromatic hydrocarbon is not sufficient, while if it is higher than 600 ° C., the deterioration of the catalyst performance due to coke formation is rapid.

The feed rate of the raw material depends on the composition of the raw material, the reaction temperature,
Depending on the type of catalyst, the weight hourly space velocity is 0.1 to 10
The range of Hr-1 is appropriate. Weight hourly space velocity is 0.
If it is less than 1 Hr-1, the production efficiency of aromatic hydrocarbons is low, while if it is more than 10 Hr-1, the yield of aromatic hydrocarbons is not sufficient.

The pressure of the aromatization reaction is 0 to 0 in both the first half and the second half.
A pressure of 30 kg / cm 2 · G is appropriate. 30kg /
At a pressure of cm 2 · G or more, the yield of aromatic hydrocarbon is not high. The aliphatic hydrocarbon having 2 to 7 carbon atoms, which is a reaction raw material, may be supplied as it is, or may be supplied together with hydrogen, nitrogen, and carbon dioxide.

[0041]

The present invention will be described below in detail with reference to examples. Example 1 A solution C in which 26 g of sodium chloride and 1.9 g of tetrapropylammonium bromide were dissolved in 104 ml of distilled water,
Liquid A prepared by dissolving 1.34 g of zinc sulfate, 1.71 g of aluminum sulfate, 5.6 g of tetrapropylammonium bromide and 5.3 g of concentrated sulfuric acid in 60 ml of distilled water, and distilled water 4
Solution B in which 69 g of water glass No. 3 was dissolved in 5 ml was added simultaneously and continuously with stirring. At that time, the pH of the mixture
Was adjusted to 10 by adding sodium hydroxide or sulfuric acid. The gel was recovered from this mixture by centrifugation, crushed for 1 hour, and combined with the supernatant obtained by centrifugation. Transfer the mixture to an autoclave and 160 ° C. for 3 hours
The temperature was maintained at 160 ° C. for 20 hours while stirring. The solid was taken out by cooling, washed with water, immersed in an aqueous solution of ammonium nitrate to replace cations with NH 4+ ions, and calcined at 540 ° C. for 3.5 hours. It was immersed again in an aqueous solution of ammonium nitrate, dried and calcined at 540 ° C. to obtain 18 g of an H-type crystalline aluminozincosilicate having lattice spacing according to the X-ray diffraction diagram shown in Table 1. This is designated as catalyst A. The atomic ratio Si / Al in this catalyst is 3
0, and Si / Zn was 70. The H-type catalyst A
Was treated with NaCl, most of the cations were replaced with Na, and the Na / Al ratio was found to be 1.3.

The catalyst A was immersed in an aqueous solution of tetraamminedichloroplatinum and contained 0.05% by weight of platinum to obtain a catalyst B. Next, the catalyst A was charged in the first half and the catalyst B in the second half by equal weights. N-pentane was charged at a weight hourly space velocity of 2 Hr-1
An aromatization reaction was carried out at atmospheric pressure without using a diluent gas. The reactor outlet gas was sampled and its composition was analyzed by gas chromatography. From the analytical values, the n-pentane conversion, aromatic selectivity, and n-pentane conversion after one hour from the start of raw material distribution became 80%. Time and aromatic selectivity at that time were determined. Table 2 shows the results.

[0043]

[Table 2]

The n-pentane conversion and the aromatic selectivity were calculated by the following equations. n-pentane conversion (%) = 100−C1 / (C1 +)
C2) × 100 Aromatic selectivity (wt%) = C3 / C2 × 100 where C1 = n-pentane concentration in reactor outlet gas (wt
%) C2 = concentration of product in reactor outlet gas (wt%) C3 = concentration of aromatic hydrocarbon in reactor outlet gas (wt
%)

Comparative Example 1 An aromatization reaction of n-pentane was performed in the same manner as in Example 1 except that only the catalyst A was charged into the reactor. The results are shown in Table 2.

Comparative Example 2 An aromatization reaction of n-pentane was carried out in the same manner as in Example 1 except that only the catalyst B was charged into the reactor. The results are shown in Table 2.

As is apparent from the results in Table 2, the method of the present invention was subjected to sequential reaction with a crystalline aluminozincosilicate catalyst which contains a crystalline aluminozincosilicate platinum which does not contain platinum, respectively plain This method is generally superior in terms of conversion, aromatic selectivity, and catalyst life as compared with the method used in Example 1.

Example 2 Colloidal silica in an amount of 10% by weight as SiO2 was added to Catalyst A as a granulating agent, and the mixture was granulated in a spherical shape and calcined at 540 ° C. to obtain Catalyst C. In the same manner as in Example 1, catalyst D was obtained by adding 0.05% by weight of platinum to catalyst C.

The catalyst C was charged in the first half and the catalyst D in the latter half by the same weight, and the reactor was maintained at 520 ° C. and the reaction pressure was 5 kg / c.
At m2 · G, n-pentane was allowed to flow at a weight hourly space velocity of 1.5 Hr−1 without using a diluting gas to carry out an aromatization reaction. The conversion and selectivity at 1 hour and 500 hours after the start of the raw material distribution were determined from the gas composition at the outlet of the reactor, and the results were as follows. After 1 hour n-pentane conversion 100% Aromatic selectivity 42wt% Ethane selectivity 17wt% After 500 hours n-pentane conversion 99% Aromatic yield 40wt%

Example 3 The catalyst C was charged in the first half and the catalyst D in the second half by equal weight.
A hydrocarbon mixture having a composition shown in Table 3 was passed through a reactor maintained at 05 ° C. at a reaction pressure of 3 kg / cm 2 G without using a diluent gas at a weight hourly space velocity of 0.7 Hr−1, and an aromatization reaction was performed. Was performed.

[0051]

[Table 3]

The conversion and the aromatic selectivity at 1 hour and 500 hours after the start of the flow of the raw materials were determined from the gas composition at the outlet of the reactor. The conversion and the selectivity were as follows. After 1 hour Conversion 100% Aromatic selectivity 48wt% Ethane selectivity 26wt% After 500 hours Conversion 99% Aromatic yield 45wt%

However, the conversion and the aromatic selectivity were determined from the following equations. Conversion (%) = (1-B / A × 0.98) × 100 Aromatic selectivity (wt%) = (C−A × 0.02) × 100) /
(A × 0.98−B) where A = concentration of total hydrocarbons in reactor outlet gas (wt
%) B = concentration of C5 to C7 paraffin and cycloparaffin in the reactor outlet gas (wt%) C = aromatic hydrocarbon concentration in the reactor outlet gas (wt%)

[0054]

According to the present invention, an aliphatic hydrocarbon and / or an alicyclic hydrocarbon is brought into contact with a catalyst containing an aluminodine cosilicate having a specific range of Si / Al atomic ratio and Si / Zn atomic ratio. Then, by contacting the aluminozincosilicate catalyst containing platinum , not only can aromatic hydrocarbons be obtained with high conversion and aromatic selectivity, but also the catalyst activity can be maintained for a long time, so that the catalyst life can be maintained. Is a long and industrially advantageous method.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoji Igarashi 3-17-35 Niisonanami, Toda City, Saitama Prefecture Inside Nihon Mining Co., Ltd. (56) References JP-A-3-178934 (JP, A) JP 50-5029 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 5/41 C07C 15/02 C07C 2/12 C07C 2/76

Claims (2)

(57) [Claims] 1. A raw material containing at least 50% by weight of an aliphatic hydrocarbon and / or an alicyclic hydrocarbon having 2 to 7 carbon atoms, wherein Si / Al atomic ratio is 14 to 35, and Si / Zn
Contacting with a crystalline aluminodine cosilicate having an atomic ratio of 30 to 350, and then having a Si / Al atomic ratio of 14 to 350;
35. A method for producing an aromatic hydrocarbon, comprising contacting a crystalline aluminodine silicate having a Si / Zn atomic ratio of 30 to 350 with a catalyst containing platinum . 2. The method for producing an aromatic hydrocarbon according to claim 1, wherein the crystalline aluminozin cosilicate has the following powder X-ray diffraction pattern. 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 0.62 ± 0.08 weak 4.26 ± 0.08 weak 3.85 ± 0.07 strong 3.72 ± 0.05 strong 3.65 ± 0.05 weak 3.05 ± 0.03 weak 2.98 ± 0.03