JP3110560B2 - Method for producing aromatic hydrocarbon and catalyst thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for producing an aromatic hydrocarbon by contacting a raw material mainly containing an aliphatic hydrocarbon and / or an alicyclic hydrocarbon having 2 to 7 carbon atoms with a crystalline aluminodine cosilicate as a catalyst. The present invention relates to a method for producing a hydrocarbon and a catalyst thereof.

[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 in which ZSM-5 type zeolite is substituted with a zinc cation or a catalyst carrying zinc improves 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 exhibit excellent selectivity (USP Re 29948;
8342).

[0005] Zinc substituted with such a zinc cation
The H-ZSM-5 catalyst or the zeolite catalyst supporting zinc has a disadvantage that 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 5 is replaced with zinc has a low acid strength and cannot be said to have sufficient catalytic activity and life. Therefore, in order to solve the above-mentioned drawbacks, some of the present inventors have further The aluminum of ZSM-5 type zeolite (aluminosilicate) is partially substituted with zinc, and the carbon number is 2 to 2 using a crystalline aluminodine cosilicate catalyst having a specific Si / Al atomic ratio and a Si / Zn atomic ratio. A method for producing an aromatic hydrocarbon from an aliphatic hydrocarbon and / or an alicyclic hydrocarbon of No. 7 was proposed (Japanese Patent Application No. 1-223968).

Further, in order to maintain the activity of the crystalline aluminodine silicate catalyst over a long period of time, the crystalline aluminodine silicate catalyst containing 2 wt% or less of alkali metal in the catalyst is used. A method for producing an aromatic hydrocarbon from an aliphatic hydrocarbon and / or an alicyclic hydrocarbon has been proposed (Japanese Patent Application No. 2-210466).

[0007]

This catalyst is highly active, has a high aromatic selectivity, has a longer catalyst life than conventional catalysts, and is an excellent catalyst. In order to maintain the above, there are still insufficient points, and as a result of studying catalysts for producing aromatic hydrocarbons having a longer catalyst life by improving the above crystalline aluminosine cosilicate catalyst, these catalysts were found to be silica, alumina It is found that the catalyst life is affected by the amount of the strong acid of the solid acid, and the catalyst life is remarkably improved by setting the amount of the solid strong acid contained in the catalyst to a specific amount. The inventors have found that the present invention has been achieved.

[0008]

Means for Solving the Problems That is, the present invention relates to a Si
/ Al atomic ratio 14-35, Si / Zn atomic ratio 30-30
50. A catalyst comprising a crystalline aluminodine cosilicate having an alkali metal content of 0.4% by weight or less and a strong acid content in the solid acid content of 20 to 30%;
A method for producing an aromatic hydrocarbon, comprising contacting a raw material containing at least 50% by weight of an aliphatic hydrocarbon and / or an alicyclic hydrocarbon according to any one of (1) to (7) with the aluminodine cosilicate catalyst.

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

[0010] On the other hand, the crystalline aluminosilicate used in the present invention is obtained by partially substituting aluminum in aluminosilicate with zinc. Silicon, aluminum and zinc atoms share oxygen and crosslink to form the same as crystalline aluminosilicate. It has a skeletal structure. In this case, it is not necessary that all of the silicon, aluminum or zinc atoms constitute the same crystal structure, and a part thereof may coexist in another form such as a respective oxide.

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

Further, the alumino gin silicate and the gin silicate of the present invention can be distinguished from each other by the measurement of thermal desorption of ammonia. That is, in the case of zinc silicate, FIG.
A temperature-induced desorption curve as shown in B of FIG.
While the desorption of ammonia at 0 ° C. is small, this is remarkably recognized in the temperature rising desorption curve A of aluminodine cosilicate. This is because zinc forming the crystal lattice does not generate strong acid sites, whereas aluminum generates strong acid sites.

The atomic ratio of Si / Al in the crystalline aluminodine cosilicate of the present invention is 14 to 35,
The atomic ratio is 30 to 350, and the alkali metal content is 0.4% by weight or less. If the atomic ratio of Si / Al is less than 14, it is difficult to form a crystal whose catalytic performance deteriorates slowly with time, while if the atomic ratio is greater than 35, the activity of the catalyst is not sufficient and the temporal deterioration is accelerated.

When the atomic ratio of Si / Zn is less than 30, the formation of crystals is poor, and the change over time of the catalyst is fast. On the other hand, when the atomic ratio is larger than 350, the selectivity of aromatic is low.

When the content of alkali metal, especially sodium, in the catalyst exceeds 0.4% by weight, the life of the catalyst is shortened.

Further, in the present invention, the amount of the solid strong acid contained in the catalyst is in the range of 20% to 30% of the amount of the solid acid. Here, the solid strong acid refers to a solid acid having an acidity function H ₀ of −8.2 or less.
The total solid acid amount can be measured by a thermal desorption method of ammonia. The temperature-programmed desorption method of ammonia is a method in which ammonia is adsorbed on a catalyst at a predetermined temperature, and after the adsorption is equilibrated, desorption of ammonia is observed while increasing the temperature of the catalyst layer. The amount of ammonia desorbed up to 650 ° C is defined as the total solid acid amount, and the amount of ammonia desorbed up to 300 ° C to 650 ° C is defined as the solid strong acid amount. Specifically, ammonia is equilibrium-adsorbed at a catalyst temperature of 100 ° C. and 100 Torr, and unadsorbed ammonia is degassed. Then, the temperature is raised from 100 ° C. to 650 ° C. at a rate of 7 ° C./min. The amount of released ammonia was measured, and from the obtained temperature-programmed desorption curve in FIG. 1, 3 with respect to the peak area of 100 ° C. to 650 ° C.
The ratio of the peak area (shaded area) between 00 ° C and 650 ° C was determined,
This is defined as the ratio of the amount of solid strong acid to the amount of solid acid.

The ratio of the amount of the solid strong acid to the amount of the solid acid is 30.
%, The catalyst life is short, and if it is less than 20%, sufficient catalytic activity cannot be obtained. The ratio of the amount of the solid strong acid to the amount of the solid acid can be adjusted by various methods described below.

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

[0019]

[Table 1] Powder X-ray diffraction of aluminodine 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 4.1 weak 5.02 ± 0.1 weak 4.62 ± 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 Weak

The crystalline aluminodine cosilicate 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 of these can be used.

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

As the organic nitrogen compound, hydroxide, bromide, chloride or tripropylamine of a quaternary ammonium such as tetrapropylammonium, tetrabutylammonium, and triprobermethylammonium;
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, for example, such as silica alumina, or in a compound. 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.

In order to adjust the amount of the solid strong acid contained in the crystalline aluminozincosilicate to 20% to 30% of the total solid acid amount, the aluminozincosilicate having an alkali metal content of 0.4% by weight or less is treated with air, nitrogen or moisture. It may be heated at 450 ° C. to 700 ° C. in the air or nitrogen containing.

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

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, iso-butane, n-pentane, iso-pentane, neopentane, n-hexane, methylpentane, dimethylbutane, n-heptane, methylhexane, and dimethylpentane. Unsaturated hydrocarbons such as saturated hydrocarbons, ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, hexadiene, heptene, heptadiene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, cyclohexadiene, and methylcyclohexadiene Murrell.

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

The raw materials to be 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 at least ₈ carbon atoms, methanol, dimethyl ether, and the like may be mixed.

The aromatization reaction is suitably carried out at a temperature in the range of 350 to 600 ° C. If the reaction temperature is lower than 350 ° C., the yield of aromatic hydrocarbon is not sufficient,
If the temperature is higher than ℃, the catalyst performance is rapidly degraded due to coke formation.
The feed rate of the raw material depends on the composition of the raw material, the reaction temperature, and the type 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 the aromatic hydrocarbon is low,
If it is higher than Hr- ^1, the yield of aromatic hydrocarbons is not sufficient.

The pressure for the aromatization reaction is 0 to 10 kg / cm.
^Two -G pressure is appropriate. 10kg / cm^Two・ G or more
At pressure, the yield of aromatic hydrocarbons is not high. With reaction raw materials
C2 to C7 aliphatic hydrocarbons are supplied as they are
Or with hydrogen, nitrogen or carbon dioxide
Good.

[0036]

The present invention will be described below in detail with reference to examples. Preparation of Catalyst In solution C obtained by dissolving 26 g of sodium chloride and 1.9 g of tetrapropylammonium bromide 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. Allow to cool, remove solids, wash with water, dry, 540 ° C
To obtain an aluminozincosilicate having a lattice spacing according to the X-ray diffraction diagram shown in Table 1. This aluminodine cosilicate catalyst is designated as A.

A4 g was placed in a nitrogen stream containing 0.6 VOL% of water for 24 hours at 500 ° C. and 90 hours at 450 ° C., respectively.
r, and heat-treated at 500 ° C. for 200 hours, and the obtained products are referred to as B, C, and D, respectively. A4g
Is obtained by heating at 500 ° C. for 200 hours in an air stream.

With respect to each of the catalysts A to E thus obtained, the acid amount was measured by a temperature-programmed desorption method of ammonia.
The ratio of the solid strong acid amount to the total solid acid amount was calculated from the ratio of the peak areas at ６650 ° C.

Table 2 shows the composition of each of the catalysts A to E and the ratio of the solid strong acid amount to the total solid acid amount obtained by the above measurement.
Shown in

[0040]

[Table 2]

Example 1 B was charged as a catalyst, and n-pentane, a raw material for reaction, was passed through a reactor maintained at 500 ° C. at a weight hourly space velocity of 2 Hr ^-1 under atmospheric pressure without dilution to carry out an aromatization reaction. went. The gas at the outlet of the reactor was collected, and its composition was analyzed by gas chromatography. The conversion of n-pentane and the aromatic selectivity were calculated from the analytical values according to the following equations. n-pentane conversion (%) = 100−C ₁ / (C ₁ + C ₂ ) × 100 Aromatic selectivity (wt%) = C ₃ / C ₂ × 100 where C ₁ = n-pentane in reactor outlet gas Concentration (wt
%) C ₂ = product concentration in reactor outlet gas (wt%) C ₃ = aromatic hydrocarbon concentration in reactor outlet gas (wt%)

One hour after the start of the raw material distribution, the n-pentane conversion, the aromatic selectivity, and the n-pentane conversion were 80%.
And the aromatic selectivity at that time were determined. Example 2
Table 3 shows the results of Comparative Examples 1 to 4.

[0043]

[Table 3]

Example 2 An aromatization reaction of n-pentane was carried out in the same manner as in Example 1 using C as a catalyst.

Example 3 An aromatization reaction of n-pentane was carried out in the same manner as in Example 1 except that D was used as a catalyst.

Example 4 An aromatization reaction of n-pentane was carried out in the same manner as in Example 1 except that E was used as a catalyst.

Comparative Example 1 Aromatization reaction of n-pentane was carried out in the same manner as in Example 1 except that A was used as a catalyst.

As is apparent from Table 3, the aluminodine cosilicate-containing catalyst of the present invention in which the ratio of the amount of the solid strong acid to the amount of the solid acid is in a specific range, can be used for a long time in a hydrocarbon aromatization reaction. High conversion and aromatic selectivity are maintained. In comparison, a catalyst having the above ratio of more than 30% has a high initial activity, but is inevitably reduced in activity due to long-time operation.

[0049]

The present invention provides a specific range of the atomic ratio of Si / Al,
The use of a catalyst containing aluminodine cosilicate in which the Si / Zn atomic ratio and the alkali metal content are set to a specific amount or less and the ratio of the amount of the solid strong acid to the amount of the solid acid is set in a specific range is used to produce an aliphatic hydrocarbon. And / or aromatic hydrocarbons can be obtained from alicyclic hydrocarbons at a high conversion and aromatic selectivity, and the catalytic activity can be maintained for a long time, so that the catalyst life is extremely long, which is an industrially advantageous method. .

[Brief description of the drawings]

Fig. 1 Thermal desorption curve of ammonia for alumino-zinc silicate and gin-co silicate

[Explanation of symbols]

A Thermal desorption curve of ammonia of alumino silicate silicate B Thermal desorption curve of ammonia of gin silicate

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomomi Okada 3-17-35 Shinsouminami, Toda City, Saitama Japan Inside Mining Co., Ltd. (56) References JP-A-4-95034 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) C07C 2/76 C07C 2/12 C07C 15/02

Claims (3)

(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
The atomic ratio is 30 to 350, the alkali metal content is 0.4% by weight or less, and the ratio of the solid strong acid amount to the solid acid amount is 2%.
A method for producing an aromatic hydrocarbon, which is brought into contact with 0 to 30% of a crystalline aluminozin cosilicate. 2. The method for producing an aromatic hydrocarbon according to claim 1, wherein the crystalline aluminodine cosilicate has a powder X-ray diffraction pattern shown below. 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 3. An Si / Al atomic ratio of 14 to 35,
Zn atomic ratio is 30 to 350, alkali metal content is 0.4
An aromatic hydrocarbon production catalyst comprising a crystalline aluminozincosilicate having a weight percentage of not more than 20% and a solid strong acid content of 20 to 30% of the solid acid content.