JPS6241695B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing lower olefins from methanol and/or dimethyl ether using a modified crystalline zeolite catalyst. According to the production of lower olefins of the present invention, CO
It is possible to obtain lower olefins with high selectivity due to less decomposition into CO 2 and CO ₂ , and there are few paraffin and aromatic by-products, and carbon deposition on the catalyst is suppressed, and even at high temperatures, there is no reduction in catalyst activity or deterioration of the catalyst. In recent years, there has been concern about the supply of petroleum resources, especially as Japan's dependence on foreign sources exceeds 99%, and the effective use of coal, natural gas, etc. has become an important issue. There is a need to establish an industrial synthesis method for organic compounds such as olefins, paraffins, and aromatic compounds from methanol obtained from olefins, paraffins, aromatics, etc. The present invention meets this need. Various types of crystalline aluminosilicate have been known so far, and among them, crystalline aluminosilicate zeolite is the most representative one. Crystalline aluminosilicate zeolites exist in large quantities in nature and can also be obtained by synthesis, and have a certain crystal structure, with many voids and tunnels within the structure, which allow molecules up to a certain size to be adsorbed. However, it has the function of excluding anything larger than that, and is also called a molecular sieve. Pores caused by voids and tunnels are determined by the form in which SiO ₂ and Al ₂ O ₃ bond by sharing oxygen in the crystal structure. The electronegativity of the aluminum-containing tetrahedra is usually kept electroneutral by alkali metal ions, especially sodium and/or potassium. Normally, to produce crystalline aluminosilicate zeolite, a method is used in which SiO ₂ , Al ₂ O ₃ , alkali metal ion sources, and water are mixed in desired proportions, and then hydrothermal treatment is performed under normal pressure or increased pressure. It is taken.
There is also a method of using an organic nitrogen compound or an organic phosphorus compound as a base, and various zeolites with various adsorption capacities and catalytic activities have been synthesized using this method, and the synthesis of this type of zeolite has become very popular in recent years. Especially by Mobil Oil Co.
ZSM zeolites are tetraalkylammonium compounds, tetraalkylphosphonium compounds,
It is synthesized using pyrrolidine, ethylenediamine, choline, etc., and its unique adsorption ability and catalytic action are attracting attention. Among them, ZSM-5 is 5-6 Å
Because of its medium pore size, it has the property of adsorbing linear hydrocarbons and slightly branched hydrocarbons, but not highly branched hydrocarbons. This ZSM-5 is usually made of SiO ₂ , Al ₂ O ₃ ,
It is synthesized by hydrothermally treating a mixture consisting of each source of alkali metal, water, and a tetra-n-propylammonium compound. In recent years, much research has been conducted to obtain hydrocarbons by reacting methanol and/or dimethyl ether. The catalyst used in this reaction is generally what is called a solid acid, and many patents have been filed regarding various zeolites, heteropolyacids, etc. In particular, the aforementioned ZSM-5 by Mobil Oil uses methanol as a raw material and has a carbon number of
It is a catalyst that is excellent for synthesizing hydrocarbons mainly composed of gasoline fractions up to 10, and has a relatively long life as a catalyst and exhibits stable activity. It is unsuitable for Similarly, ZSM-34 is
In the same reaction, although it has high selectivity to ethylene and propylene as a catalyst for producing lower olefins, its activity decreases extremely quickly.
Not practical. The present inventors have developed a method for producing hydrocarbons, especially ethylene, using methanol and/or dimethyl ether as raw materials.
As a result of intensive research into the development of catalysts that selectively produce lower olefins such as propylene and have stable activity, ZSM-5, ZSM-11
It has been found that a crystalline zeolite modified by contacting it with a solution of at least one alkaline earth metal-containing compound selected from calcium, strontium, and barium is suitable for that purpose. It has been widely known to modify crystalline aluminosilicate with alkaline earth metal ions, and the usual method is to support alkaline earth metal ions on proton (H ⁺ ) type crystalline aluminosilicate by ion exchange. is used. However, with this ion exchange method, it is difficult to support a large amount of alkaline earth metal ions, and it requires a lot of labor and is not economical.
For example, the limit is to introduce up to about 80% of the theoretical amount, and normally only about 50% can be introduced. However, surprisingly, the present inventors
Crystalline zeolites such as ZSM-5 and ZSM-11,
By modifying with an alkaline earth metal, it is possible to very easily contain a desired amount of alkaline earth metal ions, and it is also possible to contain alkaline earth metal ions in an amount more than isoelectric with respect to aluminum, and furthermore, methanol and / Or in the conversion reaction of dimethyl ether, the catalyst containing alkaline earth metal ions according to the method of the present invention is used for C ₂ such as ethylene or propylene.
It has been found that the selective production of ~ _C4 lower olefins and the suppression of carbon production are excellent in the connectivity of catalytic activity. The treatment for obtaining modified zeolite in the present invention involves mixing a conventionally known zeolite with a SiO ₂ /Al ₂ O ₃ molar ratio of 12 or more with an aqueous solution of a compound containing calcium, barium or strontium, and then evaporating and drying the mixture. harden In this case, the calcium-, barium-, or strontium-containing compound includes various inorganic and organic compounds. The amount of alkaline earth metal contained in the modified zeolite is at least 0.25% by weight in terms of metal, preferably 1 to 20% by weight for calcium and strontium, and preferably 1 to 35% by weight for barium.
It is. The catalyst of the present invention can be used as it is or, if desired, mixed with a suitable carrier such as clay, kaolin, alumina, etc. Next, a method for producing lower olefins from methanol and/or dimethyl ether using the catalyst obtained by the method of the present invention will be described. The conversion reaction of methanol and/or dimethyl ether may be carried out in any reaction format as long as these raw materials are supplied as a gas and can be brought into sufficient contact with a solid catalyst, such as a fixed bed reaction method, a fluidized bed reaction method, or a moving bed reaction method. Examples include methods. The reaction can be carried out under a wide range of conditions.
For example, reaction temperature 300-600℃, weight time space velocity
0.1-20hr ^-1 , preferably 1-10hr ^-1 , total pressure 0.1
It can be carried out under conditions of ~100 atmospheres, preferably 0.5~10 atmospheres. The raw material can also be diluted with water vapor or an inert gas such as nitrogen, argon, etc. and then fed onto the catalyst. In the process of the present invention, the product stream consists of steam, hydrocarbons, and unreacted raw materials, and by appropriately setting the reaction conditions, the proportion of lower olefins such as ethylene and propylene in the hydrocarbons can be increased. The steam and hydrocarbon products are separated and purified from each other by known methods. In the olefin production reaction in which the catalyst of the present invention is used, methanol and dimethyl ether are both starting materials, so when calculating selectivity, dimethyl ether produced from methanol may be regarded as an unreacted material. What should be noted is that the alkaline earth metal-containing crystalline aluminosilicate zeolite catalyst produced by the method of the present invention has a higher selectivity for lower olefins than other comparative examples, produces less paraffin and BTX, and can be used at high temperatures. The point is that there is no decrease in catalyst activity. Next, the present invention will be explained in detail using Examples and Comparative Examples, but the present invention is not limited thereto unless it exceeds the gist thereof. Reference Examples 1-2, Examples 1-7 and Comparative Examples 1-3
The modified zeolite powder obtained was heated to a pressure of 400Kg/ ^cm2.
This was then crushed into 10 to 20 meshes, and 2 ml of the mixture was filled into a reaction tube with an inner diameter of 10 mm. 4 ml/hr of liquid methanol (the reaction is a gas phase reaction, but if the raw material supply amount is expressed in the liquid phase, the LHSV
= 2hr ^-1 ) to the vaporizer, where 10ml/
The mixture was mixed with argon gas, which was sent at a rate of 100 min, and sent to the reaction tube at approximately normal pressure to carry out the reaction. Analysis of the product was performed using a gas chromatograph. A summary of the results is shown in Table 1. As can be seen from the results shown in Table 1, it is understood that the catalyst obtained by the method of the present invention provides a high yield of ethylene + propylene and maintains high catalytic activity without deterioration even in a high temperature range. Reference example 1 Dissolve 1.14 g of aluminum nitrate nonahydrate in 90 g of water to make solution A, and add 60 g of Cataloid SI-30 water glass (Catalyst Kasei Co., Ltd., SiO ₂ 30.5%, Na ₂ O 0.42%) to water.
It was dissolved in 40g and used as liquid B. Add liquid B to liquid A while stirring vigorously, then add 1.26 g of sodium hydroxide dissolved in 20 g of water. Furthermore, add tetrapropyl aluminum bromide to 30g of water.
8.11 g of the solution was added and stirring was continued for about 10 minutes to obtain an aqueous gel mixture. This charging molar ratio is SiO ₂ /Al ₂ O ₃ =200. This aqueous gel mixture was charged into an autoclave with an internal volume of 300 ml, and hydrothermally treated at 160°C under autogenous pressure for 18 hours with stirring (500 rpm). The reaction product is separated into a solid component and a solution part using a centrifuge.
Thoroughly wash the solid components with water and heat them at 120℃ for 5 minutes.
Dry for an hour. Next, it was treated in air at 520°C for 5 to 10 hours. Next, 15 ml of a 0.6N aqueous hydrogen chloride solution was mixed with 1 g of this calcined crystalline aluminosilicate, and the mixture was stirred at room temperature for 24 hours. After that, it was thoroughly washed with water at room temperature, dried at 120℃, and then dried at 520℃.
Calcination was performed in air at ℃ for 5 hours to convert it to hydrogen form and obtain H form ZSM-5. Reference Example 2 Form H ZSM-11 was obtained in the same manner as in Reference Example 1 except that 9.82 g of tetrabutylaluminum bromide was used as the crystallization regulator. Example 1 H-type ZSM-5 (SiO ₂ /
Add 5 g of Al ₂ O ₃ = 200) to 10 ml of water and add Ca (CH ₃ COO) ₂ .
It was mixed with a solution containing 3.14 g of H ₂ O. After keeping this mixture at approximately 80°C for 20 hours, the mixture was placed in a dryer.
Evaporate to dryness at 100-110℃. After that, in the air
Ca-type by firing at 200℃ for 2 hours and 500℃ for 18 hours.
ZSM-5 was obtained. Examples 2 to 3 Using the same method as described in Example 1, only the SiO ₂ /Al ₂ O ₃ ratio of H-type ZSM-5 was changed to produce Ca-type ZSM.
-5 was obtained. Example 4 6.0 g of H-type ZSM-5 (SiO ₂ /Al ₂ O ₃ = 70) was added to water.
It was mixed with a solution containing 6.0 g _of Ca(NO ₃ ) 2.4H ₂ O in 10 ml and kept at about 80° C. for 2 hours. The zeolite was separated from this mixture by centrifugation, dried at 90°C overnight, and then calcined at 500°C for 3 hours to produce Ca-type ZSM.
-5 was obtained. Examples 5-6 Using the same method as shown in Example 1, just
Sr as Sr salt (CH ₃ COO) ₂ 1/2H ₂ O2.07g, Ba
Ba( _CH3COO ) ₂ as salt 1.67g each
Sr type ZSM-5 and Ba type ZSM-5 were obtained. Example 7 ZSM using a method similar to that described in Example 1
-11 (SiO ₂ /Al ₂ O ₃ = 200) is modified with Ca to form Ca type.
ZSM-11 was obtained. Comparative Example 1 ZSM-5 with charging molar ratio (SiO ₂ /Al ₂ O ₃ = 300)
After converting to the hydrogen form, ion exchange with calcium ions was performed using a conventional method. That is, 40 g of 1N CaCl ₂ solution was added to 5 g of sample at first time.
ml was added and stirred in an oil bath equipped with a reflux condenser and adjusted to 80°C. Approximately every 3 hours, the exchange solution was removed by decantation and 30 ml of new exchange solution was added. This operation
After repeating this process 20 times, the mixture was thoroughly washed and filtered with water until no Cl ^- ions were observed, dried, and then calcined at 500°C for 3 hours to obtain a calcium-supported type. The amount of calcium supported was 45% of the isoelectric amount. Comparative Example 2 H-type ZSM-5 (SiO ₂ /Al ₂ O ₃ =300) was ion-exchanged with strontium ions in the same manner as described in Comparative Example 1. Comparative Example 3 H-type ZSM-11 (SiO ₂ /Al ₂ O ₃ =200) was ion-exchanged with calcium ions in the same manner as shown in Comparative Example 1.

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Claims (1)

[Claims] 1. methanol and/or dimethyl ether,
Reaction temperature 250~750℃, weight time space velocity 0.1~
A method for producing a lower olefin comprising contacting with a crystalline zeolite catalyst under conditions of 20 hr ^-1 and a total pressure of 0.1 to 100 atm, wherein the zeolite catalyst has a SiO ₂ /Al ₂ O ₃ molar ratio of 12 or more. A modified zeolite is used in which zeolite is treated with at least one alkaline earth metal-containing compound selected from calcium, strontium, and barium to precipitate at least 0.25% by weight of the metal in the zeolite. A method for producing a lower olefin. 2. The method according to claim 1, wherein the temperature is 300 to 650°C. 3. The method according to claim 1 or 2, wherein the amount of calcium is 1 to 20% by weight of the modified zeolite catalyst. 4. Claim 1, wherein the amount of strontium is 1 to 30% by weight of the modified zeolite catalyst.
or the method described in paragraph 2. 5. The method according to claim 1 or 2, wherein the amount of barium is 1 to 35% by weight of the modified zeolite catalyst. 6. The method according to any one of claims 1 to 5, wherein the zeolite is mixed with a binder. 7 The zeolite is ZSM-5, ZSM-11,
Claims 1 to 3 are ZSM-12, ZSM-23, ZSM-35, ZSM-38, or ZSM-48.
The method according to any of paragraph 6.