JP3171877B2 - Process for producing liquid hydrocarbon mixtures from ethane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a liquid hydrocarbon mixture containing an aromatic hydrocarbon in the presence of a catalyst from ethane or a gas composition containing ethane.

[0002]

2. Description of the Related Art In recent years, the importance of natural gas has been recognized, and research on its chemical use has been actively conducted. Natural gas typically contains large amounts of methane, which is very chemically stable. Therefore, most of natural gas is used as city gas and fuel for power generation,
At present, utilization as a raw material for the chemical industry is limited. However, recently, methane and ethylene are partially oxidized with air or oxygen in the presence of a catalyst to produce ethane and ethylene, which are further reacted to produce a liquid fuel. In this case, it is important to efficiently convert ethane, which is one of the products, to liquid fuel. Generally, in order to produce a liquid hydrocarbon mixture containing an aromatic hydrocarbon from a paraffinic hydrocarbon, a pentasil-type zeolite or a catalyst obtained by modifying this with hydrogen or various metals is used. In particular, liquefied petroleum gas (LPG) such as propane and butane is known to be easily converted to aromatic hydrocarbons by this catalyst, and it is said that a commercial-scale plant is already operating in the UK. .

[0003] However, ethane is a raw material having poor reactivity after methane. For example, even if the reaction is carried out in the presence of a pentasil-type zeolite catalyst modified with hydrogen ions, the desired liquid hydrocarbon can hardly be obtained. . As a contrivance for reacting ethane, for example, Japanese Patent Application Laid-Open No. 61-246135, which is a published patent publication of British Petroleum Co., Ltd., discloses ethane and at least one kind in the presence of a gallium-doped zeolite catalyst at an elevated temperature. A method for producing an aromatic hydrocarbon from a raw material containing a C ₃ -C ₆ paraffinic hydrocarbon is described.

[0004]

However, the above-mentioned conventional method has a drawback that the presence of a hydrocarbon raw material of C ₃ or more besides ethane as a raw material is indispensable and the process is complicated. Further, according to the embodiment, the reaction of ethane is performed at a high temperature of 625 ° C. Generally, in a reaction using a zeolite catalyst, the higher the temperature, the more the carbon-like substance is precipitated, the faster the catalytic activity decreases, and the lower the yield of the target liquid hydrocarbon mixture.
Therefore, it is important to carry out the reaction under milder conditions in terms of improving yield and catalyst life. The low reactivity of ethane can be compensated to some extent by converting it to ethylene. That is, ethane is once converted to ethylene in the presence of a dehydrogenation catalyst, and then ethylene is converted to liquid hydrocarbon in the presence of a zeolite catalyst.
Each reaction is carried out by a known method, but in this case, there is a disadvantage that the dehydrogenation reaction is an equilibrium reaction, so that the conversion of ethylene is restricted by the equilibrium. Furthermore, a separate apparatus is required for the reaction and the separation, and the process becomes complicated. In view of the above points, it is desired to develop a method which is more mild and which is simplified in terms of process when obtaining a liquid hydrocarbon mixture directly from ethane.

[0005] An object of the present invention is to produce a liquid hydrocarbon mixture containing an aromatic hydrocarbon directly from ethane, in which the dehydrogenation of ethane to ethylene and the reaction of ethylene to the liquid hydrocarbon mixture in separate reactors. Instead of doing
One reactor is filled with a composite catalyst having an activity in each reaction, and the two reactions are allowed to proceed simultaneously to shorten the process, eliminate restrictions on the equilibrium of the dehydrogenation reaction, and further reduce the temperature at the lowest possible temperature. An object of the present invention is to provide a manufacturing method in which the process efficiency is improved by reacting.

[0006]

Means for Solving the Problems The inventors of the present invention use ethane or a gas composition containing ethane as a raw material to convert ethane into a liquid hydrocarbon mixture containing aromatic hydrocarbons. By using a catalyst supported on a carrier capable of converting ethylene into ethylene and a catalyst capable of converting ethylene into a liquid hydrocarbon mixture containing aromatic hydrocarbons in the same system, the conversion of ethane, As a result of intensive studies aimed at improving the yield of aromatic hydrocarbons, the present inventors have found that the problem can be solved by using a specific composite catalyst and completed the present invention.

That is, the gist of the present invention is to provide a method for producing a liquid hydrocarbon mixture containing an aromatic hydrocarbon in the presence of a catalyst using ethane or a gas composition containing ethane as a raw material. The present invention provides a method for producing a liquid hydrocarbon mixture from ethane, characterized by using a composite catalyst comprising a catalyst supported on a carrier capable of converting ethylene into ethylene and a catalyst capable of converting ethylene into aromatic hydrocarbon. In the present invention, the composite catalyst is a pentasil-type zeolite or a catalyst obtained by modifying the pentasil-type zeolite with a hydrogen ion or an alkaline earth metal, and one or two selected from the group consisting of platinum, chromium, zinc and gallium supported on a carrier. It is prepared by physically mixing at least one kind of metal or its oxide. Usually, such a composite catalyst is charged into a reactor, and ethane or a raw material containing ethane is charged with the weight hourly space velocity (WHSV) of 0.1 to 400 hr.
^-1 , temperature 400 to 700 ° C, pressure 0.1 to 100 atm (1
(0-10132 kilopascals) to carry out the reaction to obtain a liquid hydrocarbon mixture containing an aromatic hydrocarbon. When a pentasil-type zeolite is used alone, ethylene can be converted to an aromatic hydrocarbon, but ethane hardly reacts and is not converted to an aromatic hydrocarbon. Also, when the ethane dehydrogenation catalyst is used alone, ethylene is simply generated, and ethane cannot be converted to an aromatic hydrocarbon. However, when ethane is reacted using a composite catalyst prepared by physically mixing the two, a liquid hydrocarbon mixture containing aromatic hydrocarbons can be easily obtained, and more surprisingly, the ethane dehydrogenation reaction Compared to the case where the product was directly subjected to an aromatization reaction, the fact that the generation rate of aromatic hydrocarbons relative to the starting ethane was significantly increased was recognized. That is, 2 filled with these two catalysts respectively.
Compared to a case where two reactors are connected in series and reacted,
The product could be obtained with high selectivity.

Hereinafter, the present invention will be described in detail.
In the present invention, a catalyst for dehydrogenating ethane to ethylene,
A composite catalyst is used in which a zeolite catalyst for converting the obtained ethylene into a liquid hydrocarbon mixture containing an aromatic hydrocarbon is mixed at a certain ratio. First, as the zeolite catalyst, for example, a light aromatic hydrocarbon which can be used as a raw material of a liquid fuel for automobiles, particularly a catalyst having a high generation rate of benzene, toluene and xylenes is desirable. Examples of such a zeolite catalyst include a pentasil-type zeolite. The pentasil-type zeolite is a general term for synthetic zeolites in which ten five-membered rings composed of oxygen atoms and silicon or aluminum atoms are gathered among aluminosilicates and zeolites composed of silica and alumina, thereby forming unique pores. is there. More specifically, ZSM-5, ZSM-11, ZSM-12, and ZS, which are special synthetic zeolites developed by Mobile Company, USA
M-23, ZSM-35 and ZSM-48 type zeolites can be mentioned. Among these, ZSM-5 zeolite is particularly preferred for the purpose of the present invention. The molar ratio of silica and alumina constituting the pentasil-type zeolite (S
iO ₂ / Al ₂ O ₃ ratio) is preferably from 15 to 3000, most preferably from 20 to 100. As the pentasil-type zeolite, a calcined product obtained by hydrothermal synthesis and removing an organic base can be used as it is, or a product obtained by modifying this with hydrogen ions may be used. Denaturation with hydrogen ions can be performed, for example, as follows. 40 g of ammonium nitrate (special grade reagent) in 1000 ml of distilled water
, And 10 g of ZSM-5 type zeolite is added thereto. After stirring at 80 ° C. for 3 hours, the zeolite is separated from the solution by filtration. This zeolite is further suspended in the above-mentioned aqueous solution of ammonium nitrate and treated similarly. This operation is performed a total of 10 times to complete the hydrogen ion exchange. After that, first, it is dried in air at 120 ° C. for 15 hours,
Bake at 2 ° C for 2 hours.

Further, in order to better achieve the object of the present invention, it is necessary to further modify the hydrogen ion-modified zeolite with an alkaline earth metal. As the alkaline earth metal used for the modification, magnesium and calcium are particularly preferable. The denaturation can be carried out by using an alkaline earth metal salt, oxide or hydroxide thereof by an ion exchange method or an impregnation method. An example of denaturation by the ion exchange method is as follows. 32 g of magnesium nitrate (special grade of reagent) is dissolved in 500 ml of distilled water, and 5 g of hydrogen-exchanged zeolite ZSM-5 is added thereto, followed by stirring at 80 ° C. for 3 hours. After the zeolite is separated from the solution by filtration, it is further suspended in the above-mentioned magnesium nitrate solution, and the same treatment is performed a total of five times. Then, first, it is dried in air at 120 ° C. for 15 hours.
Bake at 0 ° C. for 2 hours.

On the other hand, an ethane dehydrogenation catalyst is usually platinum,
It is prepared by using an organic salt of chromium, zinc or gallium, an inorganic salt such as chloride or nitrate, or an oxide or hydroxide. What carried these on the support | carriers, such as silica, alumina, or activated carbon, is used. The ethane dehydrogenation catalyst
It can be prepared as follows. A predetermined amount of a metal compound is dissolved in distilled water, a specified amount of alumina is added thereto, the mixture is left under reduced pressure for 30 minutes, and then evaporated to dryness in a steam bath. After that, first, it is dried in air at 120 ° C. for 15 hours, and further baked in air at 550 ° C. for 2 hours. In the method of the present invention, the ethane dehydrogenation catalyst thus obtained and the pentasil-type zeolite catalyst are mixed at a weight ratio of 1: 1.
１ ： 1: 10, preferably 1: 4. The mixing may be performed between solid powders, or may be performed in a slurry using an appropriate dispersion medium. These catalysts may be used for the reaction as they are, or may be used after calcination in air or a nitrogen stream. In some cases, the reduction may be carried out in a stream of hydrogen or carbon monoxide. The amount of platinum, chromium, zinc or gallium metal contained in the mixed catalyst is 0.1 to 15% by weight in terms of metal.
The platinum and gallium content is preferably 0.1 to 5% by weight, and the zinc and chromium content is preferably 0.2 to 10% by weight.

Next, a method for producing a liquid hydrocarbon mixture containing an aromatic hydrocarbon from an ethane-containing gas using the catalyst obtained above will be described. The reaction is performed at a temperature of 400 to 70.
0 ° C, preferably 400-600 ° C, weight hourly space velocity
0.1 to 400 hr ^-1 , preferably ¹ to 50 hr ^-1 , total pressure 0.1.
It can be carried out under the conditions of 1 to 100 atm (10 to 10132 kPa), preferably 0.1 to 20 atm (10 to 2026 kPa). As a raw material, in addition to ethane separated from natural gas or the like, natural gas itself containing ethane can be used as a raw material. Further, a gas containing ethane and ethylene generated by a partial oxidation reaction of methane can be used as it is. These raw materials can be diluted with steam or an inert gas such as nitrogen, helium, or argon and supplied onto the catalyst. The product aromatic hydrocarbon and unreacted raw material are separated and purified from each other by a known method. This reaction may be performed in any reaction form, as long as the raw material is supplied as a gas and can be sufficiently contacted with a solid catalyst.
The object of the present invention can be achieved by any reaction type such as a fixed bed reaction system, a fluidized bed reaction system, and a moving bed reaction system.

[0012]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Example 1 (1) Preparation of catalyst a) Preparation of H-Z5 catalyst 40 g of ammonium nitrate (special grade reagent) was added to 1000 parts of distilled water.
Then, 10 g of ZSM-5 type zeolite was added thereto, followed by stirring at 80 ° C. for 3 hours. After the zeolite was separated from the solution by filtration, the same treatment as described above was performed on the zeolite a total of 10 times. Thereafter, the resultant was dried in air at 120 ° C. for 15 hours, and further fired in air at 550 ° C. for 2 hours. B) Preparation of Pt + H-Z5 catalyst (composite catalyst) 9.50 g of alumina was added to a solution of 1.33 g of chloroplatinic acid (special reagent grade) in 25 ml of distilled water, and the mixture was left under reduced pressure for 30 minutes. And evaporated to dryness. Then, it is dried in air at 120 ° C. for 15 hours.
Calcination was performed at 2 ° C for 2 hours. The catalyst powder obtained here and the H-Z5 catalyst obtained in a) were weighed so as to have a weight ratio of 1: 4, and mixed with a milk stick. (2) Reaction The catalyst powder obtained in the above b) was tableted at a pressure of 400 kg / cm ² , and then crushed and granulated to 20 to 40 mesh, and 1 g of the powder was placed in a quartz glass reaction tube having an inner diameter of 10 mm. Filled. The reaction was carried out under atmospheric pressure using a mixed gas for reaction in which ethane was diluted with nitrogen (C ₂ H ₆ / N ₂ = 20/80: volume ratio), W / F = 110 g · h / mol, reaction temperature: 6
00 ° C, amount of catalyst: 1.00 g (for two-stage reaction: 1.00 g
+1.00 g). The product that came out of the reaction tube was directly analyzed by gas chromatography. Table 1 shows the results.

[Table 1] In Table 1, ethane conversion is the percentage of ethane reacted,
The selectivity indicates the production ratio of the reaction product. In the table, C
₁ , C ₂ , C ₃ and C ₄ each have ₁ , ₂ , ₃ , ₄ carbon atoms
Represents a hydrocarbon. In addition, C ₅ ⁺ aliphatic represents a hydrocarbon having 5 or more carbon atoms, aromatic represents an aromatic hydrocarbon, and the total of both represents a liquid hydrocarbon mixture.

Comparative Example 1 Using the H-Z5 catalyst obtained in Example 1 (1) a), the reaction was carried out under the same conditions as in Example 1 (2). Table 1 shows the results.

Example 2 (1) Preparation of catalyst a) Preparation of Mg-Z5 catalyst 32 g of magnesium nitrate (special grade reagent) was added to 500 ml of distilled water.
And 5 g of H-Z5 catalyst was added thereto, followed by stirring at 80 ° C. for 3 hours. After the zeolite was separated from the solution by filtration, this zeolite was subjected to the same treatment as above for a total of five times. Thereafter, the resultant was dried in air at 120 ° C. for 15 hours, and further fired in air at 550 ° C. for 2 hours. B) Preparation of Pt + Mg-Z5 catalyst (composite catalyst) A catalyst was prepared in the same manner as in Example 1 (1) b) except that the Mg-Z5 catalyst obtained in the above a) was used as the zeolite. (2) Reaction The reaction was carried out in the same manner as in Example 1, (2). Table 1 shows the results.

Comparative Example 2 Using the Mg-Z5 catalyst obtained in Example 2 (1) a), the reaction was carried out under the same conditions as in Example 1 (2). Table 1 shows the results.

Example 3 7.70 g of chromium nitrate (special grade reagent) and 9.00 g of alumina
And Cr + by the same operation as (1) b) of Example 2
An Mg-Z5 catalyst was prepared and reacted under the same conditions as in (2) of Example 1. Table 2 shows the results.

[Table 2] The experimental conditions in Table 2 are the same as in Table 1.

Example 4 Using 2.24 g of zinc nitrate (special reagent grade), a Zn + Mg-Z5 catalyst was prepared in the same manner as in (1) b) of Example 2, and the same as (2) of Example 1 The reaction was carried out under the conditions. Table 2 shows the results.

Example 5 Example 2 was conducted using 3.00 g of gallium nitrate (special grade reagent).
(1) b) A Ga + Mg-Z5 catalyst was prepared in the same manner as in (b), and reacted under the same conditions as in (2) of Example 1. Table 2 shows the results.

Comparative Example 3 To a solution of 1.33 g of chloroplatinic acid (special grade reagent) dissolved in 25 ml of distilled water, 9.50 g of alumina was added, the mixture was allowed to stand under reduced pressure for 30 minutes, and evaporated to dryness in a steam bath. . Then, it is dried in air at 120 ° C. for 15 hours.
1 g of the dehydrogenation catalyst prepared by calcining at 2 ° C. for 2 hours was placed in a first quartz reaction tube, and the Mg—
1 g of Z5 catalyst was filled in each of the second quartz reaction tubes, and the two reaction tubes were connected in series, and reacted under the same conditions as (2) of Example 1. Table 2 shows the results.

[0020]

According to the method of the present invention, ethane is directly
It can be converted into a liquid hydrocarbon mixture containing an aromatic hydrocarbon with a high selectivity, and the process can be simplified.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C07C 2/12 C07C 2/12 5/333 5/333 11/04 11/04 15/02 15/02 // C07B 61/00 300 C07B 61/00 300 (56) Reference JP-A-59-25336 (JP, A) JP-A-50-5335 (JP, A) JP-A-61-7218 (JP, A) JP-A-60-156793 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10G 35/04-35/14 C07C 2/12 C07C 5/333 C07C 11/04 C07C 15/02

Claims (4)

(57) [Claims] 1. A method for producing a liquid hydrocarbon mixture containing an aromatic hydrocarbon using ethane or a gas composition containing ethane as a raw material, wherein ethane is dehydrogenated to ethylene. Contact carried on a carrier
Medium, and a composite catalyst obtained by physically mixing a catalyst capable of converting ethylene to an aromatic hydrocarbon,
A method for producing a liquid hydrocarbon mixture from ethane. 2. A catalyst containing one or two metals of platinum, chromium, zinc or gallium as the ethane dehydrogenation catalyst, and a pentasil-type zeolite or a catalyst capable of converting ethylene into an aromatic hydrocarbon. 2. The method for producing a liquid hydrocarbon mixture from ethane according to claim 1, wherein said zeolites are modified with hydrogen ions or alkaline earth metals. 3. The method according to claim 1, wherein the pentasil-type zeolite is ZSM-
The method for producing a liquid hydrocarbon mixture from ethane according to claim 2, which is a type 5 synthetic zeolite. 4. The method for producing a liquid hydrocarbon mixture from ethane according to claim 2, wherein the alkaline earth metal for modifying the pentasil-type zeolite is magnesium or calcium.