JPH0745416B2 - Aromatic hydrocarbon manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing an aromatic hydrocarbon by heating an aliphatic hydrocarbon feedstock having 1 to 12 carbon atoms into contact with a zeolite catalyst. is there.

<Technical background of the invention and its problems> In an oil refinery, a large amount of cracked gas composed of paraffins having 1 to 4 carbon atoms and / or olefins is produced from a fluid catalytic cracking device, a thermal cracking device, a hydrocracking device, or the like. It is a byproduct. These are usually consumed as private fuels and household fuels, but development of applications with increased added value is desired.

When ethylene and propylene are produced by thermally decomposing petroleum fractions such as naphtha in the presence of steam, a considerable amount of pyrolysis gasoline is produced. Since this pyrolysis gasoline contains a large amount of diolefin and tends to polymerize to form a large amount of gum during storage, an effective method for removing diolefin is desired.

On the other hand, straight-run light naphtha from a distillation column is usually blended with gasoline and used, but a new aromatization method is desired because of its low octane number.

In addition, the heavy naphtha fraction from the distillation column is introduced into the reformer to produce reformed gasoline.
It contains a large amount of saturated aliphatic hydrocarbons such as C ₅ and C ₆ , which lowers the octane number of the product.

The polymerized gasoline method is one of the effective methods of utilizing the olefin gas having 2 to 5 carbon atoms in the cracked gas. In this method, the olefin gas is converted into gasoline by low polymerization. A solid acid is usually used as a catalyst, and it is well known that phosphoric acid is adsorbed and immobilized on diatomaceous earth or quartz sand. In this case, phosphoric acid is adsorbed and immobilized frequently because the phosphoric acid is washed away at a high rate. There is a need.

It is also known to use zeolite as a catalyst. In particular, ZSM-5, ZSM-11, mordenite, Y type, and dealkalized type of porphyrisite, whose zeolite pores are composed of a 10-membered ring or a 12-membered ring of oxygen, show excellent OTG reaction activity. For example, Japanese Unexamined Patent Publication (Kokai) No. 56-103292 discloses that aromatic hydrocarbons can be obtained in a high yield by using a catalyst having a high Cavan ratio such as ZSM-5 and ZSM-11.

The zeolite catalyst is also effective for aromatization of diolefin in pyrolysis gasoline. JP-A-54-24835
It is disclosed in the publication.

It is possible to convert not only unsaturated aliphatic hydrocarbons but also saturated aliphatic hydrocarbons into aromatic hydrocarbons in a catalyst in which various metal elements are supported on the zeolite.
No. 9 and JP-A No. 57-93918.

However, in the aromatization with these zeolite catalysts, the catalytic activity rapidly decreases due to the accumulation of coke, and it is necessary to frequently perform the regeneration work of the catalyst by air calcination.

<Object of the Invention> The present invention has been made in order to solve the drawbacks of the conventional method. A catalyst having a small amount of coke accumulation and a long life is used to produce an aromatic hydrocarbon from an aliphatic hydrocarbon raw material having 1 to 12 carbon atoms. The purpose is to obtain hydrogen in high yield.

<Outline of the invention> That is, the present invention is a zeolite, a fluorine compound selected from aluminum fluoride and ammonium fluoride and Ib, IIb, IIIa, VI, VIIb and VIII of the periodic table of the elements.
A catalyst composed of one or more metal elements selected from the group consisting of group metal elements having 1 to 1 carbon atoms as a feedstock.
The present invention relates to a method for producing an aromatic hydrocarbon, which comprises heating 12 aliphatic hydrocarbons into contact with each other.

The zeolite used in the present invention has a crystal pore size of 3 to 9
Å, the silica / alumina molar ratio is 1 to 500, preferably 1
To 100 natural or synthetic zeolites, such as phaujasite, gmelinite, zeolite L, mordenite, zeolite Ω, zeolite X, zeolite Y,
Examples include ferrierite, ZSM-5, ZSM-11, clinoptiolite, and transition metal silicates, but especially ZSM.
-5, ZSM-11, mordenite, zeolite Y, faujasite, and transition metal silicate are preferably used.

Transition metal silicates are zeolites that have an X-ray diffraction pattern similar to ZSM-5 or ZSM-11 and that contain a transition metal element as one of its constituents. In the present invention, transition metals include Fe, Cr, V, Bi, Ti, B, Be and Ga as 1
One kind or a transition metal silicate containing two or more kinds is preferably used.

The aromatization reaction partially includes an acid-catalyzed reaction. Therefore, in order to use the above zeolite as the catalyst of the method of the present invention,
It is preferable to dealkalize with an acid or an ammonium salt to reduce the proportion of alkali in the zeolite.

The dealkalization ratio is preferably 50 mol% or more of the alkali metal or alkaline earth metal contained in the zeolite, and particularly preferably 90 mol% or more. In this case, examples of the dealkalizing agent include mineral acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, water-soluble organic acids such as formic acid, acetic acid and malic acid, and salts containing ammonium ions such as ammonium chloride and ammonium nitrate. However, these acids or salts may be used alone or in combination. Among them, hydrochloric acid, nitric acid, ammonium chloride,
Ammonium nitrate and the like are preferable. These acids or salts are used in the form of an aqueous solution. The acid concentration in that case varies depending on the treatment conditions, but it is preferably 1 to 6 N, and when an ammonium salt is used, the concentration is 1 to 30%, particularly 5 to 15%. The treatment temperature may be room temperature, but in order to shorten the treatment time, heating to 80-100 ° C is preferable. Since the treatment time depends on the temperature and cannot be generally stated, it is generally preferably 5 hours to 3 days.

As aluminum fluoride, aluminum trifluoride hydrate or basic aluminum fluoride is preferably used.

In particular _{α-AlF 3 · 3H 2 O} , β-AlF 3 · 3H 2 O and these 70
Aluminum fluoride obtained by firing at a temperature of 0 ° C. or lower, preferably 200 to 500 ° C. is preferably used. Further, aluminum fluoride, which is effective similarly to these, is alumina,
By passing excess anhydrous hydrogen fluoride at 200 to 500 ° C through a reaction tube filled with aluminum hydroxide and a mixture thereof, it is also possible to pass excess hydrogen fluoride at 20 to 400 ° C in a reaction tube filled with aluminum chloride. It can also be obtained by passing through anhydrous hydrogen fluoride. When these aluminum fluorides are prepared as components of the catalyst of the method of the present invention, it is not necessary to prepare them purely for use, and those obtained as a mixture thereof are sufficient.

The metal elements used in the present invention are Ib and II of the periodic table.
It is a group b, IIIa, VI, VIIb or VIII metal element, and one or more of them may be mixed and used.
The group Ib is Cu, Ag, Au, and the group IIb is Zn, Cd, I.
Al, Ga, In, Tl as IIa group, Cr, Mo as VI group,
Examples of the W, Se, Te, and VIIb groups include Mn, Tc, Re, and the VIII groups include Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt metal elements.

Among the metal elements, particularly Cu, Ag, Zn, Cd, Ga, Cr, W,
Se, Te, Re, Co, Ni, Pd, Ir and Rt are preferably used.

The composition ratio of the catalyst used in the method of the present invention varies depending on the reaction conditions, but usually the zeolite is 20 to 99 wt%, preferably 40
~ 90wt%, fluorine compound 1 ~ 80wt%, preferably 5 ~
40 wt%, the metal element is (metal state) in the range of 0.1 to 30 wt%, preferably 1 to 20 wt%.

The catalyst used in the method of the present invention can be produced by adding a metal element to a zeolite that has not been dealkalized or a dealkalized zeolite by a conventional method such as an ion exchange method or an impregnation method.

The metal element is usually added to zeolite by dissolving salts of mineral acids or organic acids, various chelate compounds, complex salts and oxides in various solvents such as water and bringing them into contact with zeolite. It

The metal concentration in this case varies depending on the metal species and the treatment conditions, but is preferably 0.1 to 1.0 Mol / l.

The treatment temperature may be room temperature in the case of the ion exchange method, but it is preferably heated to 80 to 100 ° C. in order to shorten the exchange time, and in the case of the impregnation method, it is preferably near the boiling point of the solvent.

The treatment time depends on the temperature and cannot be generally stated, but 30 minutes to 3 days is generally preferable. The metal element may be present in the metal oxide or (if the cations in the zeolite have been replaced by the metal cations) in the metal cation or metal state.

Next, the zeolite to which the metal element is added is usually 50 to 200.
At 100 ° C, preferably 100 to 150 ° C, for 0.5 to 100 hours, preferably 1 to 8 hours, and then add a fluorine compound to the zeolite, and then add a suitable shape such as powder or granules (1 to 5 mmφ) For example, molding with a compression molding bar, etc., 100 ~ 700
The catalyst of the present invention can be obtained by calcining at 0 ° C, preferably 300 to 600 ° C for 0.5 to 100 hours, preferably 1 to 8 hours.

Firing is normally performed in air, but it is of course possible to perform firing in an inert gas such as nitrogen or carbon dioxide or hydrogen gas.

The addition of metallic elements to zeolite is the addition of fluorine compounds,
You may go after baking.

The feedstock used in the present invention is an aliphatic hydrocarbon having 1 to 12 carbon atoms, and may be, for example, one kind or a mixture of two or more kinds. Particularly, one kind or a mixture of two or more kinds of the aliphatic hydrocarbon having 2 to 4 carbon atoms is preferable. Further, a straight-run light naphtha fraction, a reformed naphtha fraction, or a pyrolysis gasoline can be mentioned. The feedstock may contain aromatic hydrocarbons in an amount of 30% or less in the usual case and 70% or less in the case of reformed naphtha.

The aromatization reaction of the present invention is carried out with the feed materials alone or under various gas atmospheres. Examples of the atmosphere gas include nitrogen, steam, hydrogen, carbon dioxide and the like.

In the present invention, the aromatization reaction is preferably accomplished in a hydrogen gas atmosphere. Hydrogen mainly has the effect of reducing the amount of carbonaceous deposits.

In the present invention, the amount of hydrogen added to the raw material hydrocarbon is not particularly limited, but the raw material hydrocarbon: hydrogen molar ratio is 1:50.
The following is sufficient, and the range of 1: 1 to 1: 5 is particularly preferable.
Hydrogen to be added can be covered by a part of hydrogen generated by the reaction.

The reaction pressure is preferably 1 to 100 atm, particularly 5 to 20 atm. The reaction temperature is preferably 250 to 700 ° C, particularly 400 to 600 ° C. Feed gas supply rate per unit weight of catalyst, WHSV
The (g-source gas / g-cat · hr) is also not particularly limited, but in order to obtain a high conversion rate, it is preferably 10 or less, and particularly preferably 0.5 to 2.0.

In the present invention, the aromatization reaction can be carried out by a conventionally known fixed bed, fluidized bed or other method.

<Effects of the Invention> The catalyst used in the present invention has a small amount of coke accumulation and a long life, and by using such a catalyst, an aromatic hydrocarbon can be obtained in a high yield.

<Examples of the Invention> The method of the present invention will be described in detail below with reference to specific examples.

Example 1 ZSM-5 Na type having a SiO ₂ / Al ₂ O ₃ ratio of 78 was calcined at 500 ° C. for 5 hours and then acid-treated with 2N hydrochloric acid at a temperature of 90 to 100 ° C. for 5 hours. It was thoroughly washed with water and then dried at 120 ° C. for 5 hours to obtain dealkalized ZSM-5. Then 3 Mo
A 2 wt% Zn-introduced dealkalized ZSM-5 was obtained by suspending in a 1 / l ZnCl ₂ aqueous solution at 70 ° C. for 1 hour (catalyst A).

20 wt% of aluminum trifluoride was added to and mixed with the above catalyst A, and compression molded into pellets of 3 × 4 mmφ at 500 ° C.
It was calcined for 8 hours (Catalyst B).

Using 2.0 g of the catalyst thus obtained, a temperature of 480
° C, flow rate of hydrogen 4.2 l / hr, flow rate of raw material butane-butene gas 2.0 g / hr, and therefore molar ratio of hydrogen to source gas ≈5, W
A life test was performed under normal pressure with HSV = 1 hr ⁻¹ .

The results are shown in Table 1.

It can be seen that the catalyst B treated with aluminum fluoride has a high C ₅ ⁺ gasoline yield and an aromatic hydrocarbon yield, and is an excellent catalyst having a long life.

Example 2 ZSM-5 Na type having a SiO ₂ / Al ₂ O ₃ ratio of 30 was calcined at 500 ° C. for 5 hours and then acid-treated with 2N hydrochloric acid at a temperature of 90 to 100 ° C. for 5 hours. It was thoroughly washed with water and then dried at 120 ° C. for 5 hours to obtain dealkalized ZSM-5.

Then, it was suspended in a 2Mol / l GaCl ₃ aqueous solution at 70 ° C. for 1 hour to obtain a 2 wt% Ga-added dealkalized ZSM-5 (catalyst C).

20 wt% of aluminum trifluoride was added to and mixed with the above catalyst C, and compression molded into pellets of 3 × 4 mmφ at 500 ° C.
It was calcined for 8 hours (Catalyst D).

Using 2.0 g of the catalyst thus obtained, a temperature of 550
° C, flow rate of hydrogen 4.2 l / hr, flow rate of raw material butane-butene gas 2.0 g / hr, and therefore molar ratio of hydrogen to source gas ≈5, W
A life test was performed under normal pressure with HSV = 1 hr ⁻¹ .

The results are shown in Table 2.

It can be seen that the catalyst D treated with aluminum fluoride has a high C ₅ ⁺ gasoline yield and an aromatic hydrocarbon yield, and is an excellent catalyst having a long life.

Example 3 ZSM-5 Na type having a SiO ₂ / Al ₂ O ₃ ratio of 50 was calcined at 500 ° C. for 5 hours and then acid-treated with 2N hydrochloric acid at a temperature of 90 to 100 ° C. for 5 hours. It was thoroughly washed with water and then dried at 120 ° C. for 5 hours to obtain dealkalized ZSM-5.

Then, it was suspended in a 3Mol / l CdCl ₂ aqueous solution at 70 ° C. for 1 hour to obtain a 4 wt% Cd-added dealkalized ZSM-5 (catalyst E).

20 wt% of ammonium fluoride was added to and mixed with the catalyst E, compression molded into a pellet of 3 × 4 mmφ, and calcined at 500 ° C. for 8 hours (catalyst F).

Using 2.0 g of the catalyst thus obtained, a temperature of 600
° C, flow rate of hydrogen 4.2l / hr, flow rate of butane gas as raw material 2.0g / h
r, therefore the molar ratio of hydrogen and source gas ≈ 5, WHSV = 1h
A life test was carried out at r ^-1 under normal pressure.

The results are shown in Table 3.

It is understood that the catalyst F treated with ammonium fluoride has a high C ₅ ⁺ gasoline yield and an aromatic hydrocarbon yield, and is an excellent catalyst having a long life.

Example 4 Using the same catalysts A and B as in Example 1, the temperature was 500 ° C., the flow rate of hydrogen was 3.6 l / hr, the feed rate of the raw material was 2.0 g / hr, and WHSV = 1 h.
A lifetime experiment of the aromatization reaction of n-hexane was carried out under r ⁻¹ and atmospheric pressure.

The results are shown in Table 4.

It can be seen that the catalyst B treated with aluminum fluoride has a long life.

Example 5 A transition metal silicate having a SiO ₂ / Al ₂ O ₃ molar ratio of 90 and containing 0.5 wt% Fe ₂ O ₃ was hydrothermally synthesized, calcined at 500 ° C. for 5 hours, and then 90% with 1N hydrochloric acid. The acid treatment was carried out at a temperature of -100 ° C for 5 hours. After thoroughly washing with water and drying at 120 ° C. for 5 hours, a dealkalized iron-containing transition metal silicate having a ZSM-5 type crystal structure was obtained.

Then, by loading 3 wt% of Cu, Cr, Te, Re or Ni by the impregnation method, catalysts G, H,
I, J and K were obtained respectively.

20 wt% of aluminum trifluoride was added to and mixed with these 5 types of catalysts, and compression molded into pellets of 3 × 4 mmφ.
The catalyst was calcined at 00 ° C. for 8 hours to obtain catalysts L, M, N, O and P.

Using 2.0 g of each of the 10 kinds of catalysts thus obtained, the temperature was 480 ° C., the flow rate of hydrogen was 4.2 l / hr, the feed rate of the raw material propylene gas was 2.0 g / hr, and thus the hydrogen and the raw material gas were used. The life test was carried out under a normal pressure and a molar ratio of 4 and WHSV = 1 hr ⁻¹ . The results are shown in Table 6.

Aluminum fluoride treated catalysts L, M, N, O, P
Indicates that the catalyst has a high aromatic yield and a long life.

Example 6 ZSM-5 having a SiO ₂ / Al ₂ O ₃ molar ratio of 45 was hydrothermally synthesized at 500 ° C.
After baking for 5 hours, acid treatment was performed with 2N hydrochloric acid at a temperature of 90 to 100 ° C. for 5 hours. After thoroughly washing with water, it was dried at 120 ° C. for 5 hours to obtain dealkalized ZSM-5.

Then, 3 wt% of Zn was carried by the impregnation method, and 0.5 wt% of Pt was carried by the ion exchange method to obtain a catalyst Q.

15 wt% ammonium fluoride was added to and mixed with the catalyst Q, compression molded into a pellet of 3 × 4 mmφ, and calcined at 500 ° C. for 8 hours to obtain a catalyst R.

Using 2.0 g of the catalyst thus obtained, the temperature was 490 ° C.
Flow rate of hydrogen 5.0l / hr, feed rate of raw material 2.0g / hr, WHSV = 1
A lifetime experiment of aromatization reaction of reformate was carried out under normal pressure for hr ^-1 . The results are shown in Table 5.

It can be seen that the catalyst R treated with ammonium fluoride has a high aromatic yield and a long life.

Claims (7)

[Claims] 1. A fluorine compound selected from zeolite, aluminum fluoride and ammonium fluoride, and one or two selected from the group consisting of Ib, IIb, IIIa, VI, VIIb and VIII metal elements of the Periodic Table of Elements. A process for producing an aromatic hydrocarbon, which comprises heating and contacting an aliphatic hydrocarbon having 1 to 12 carbon atoms as a feed material with a catalyst composed of one or more kinds of metal elements. 2. The zeolite has a SiO ₂ / Al ₂ O molar ratio of 1 to 100.
The method for producing an aromatic hydrocarbon according to claim 1, wherein 3. The metal element is Cu, Ag, Zn, Cd, Ca, Cr, W, Se, Te, R.
The method for producing an aromatic hydrocarbon according to claim 1, wherein the aromatic hydrocarbon is at least one element selected from e, Co, Ni, Pd, Ir and Pt. 4. The method for producing an aromatic hydrocarbon according to claim 1, wherein the raw material is an aliphatic hydrocarbon having 2 to 4 carbon atoms. 5. The process for producing an aromatic hydrocarbon according to claim 1, wherein the raw material is a straight-run light naphtha fraction. 6. The method for producing an aromatic hydrocarbon according to claim 1, wherein the raw material is a reformed naphtha fraction. 7. The method for producing an aromatic hydrocarbon according to claim 1, wherein the raw material is pyrolysis gasoline.