JPS633655B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a porous crystalline catalyst for olefin synthesis, which is characterized by intercalating silicon oxide between smectite layers. Conventionally, a method for synthesizing olefins by subjecting lower alcohols such as methanol to a heating reaction in the presence of a catalyst has been known. In this method, catalyst development is an important technical issue, and at present, a synthetic zeolite catalyst proposed by Mobil Oil Company is considered to be the most advantageous catalyst of this type. however,
In the case of this synthetic zeolite catalyst, there are difficulties in its synthesis, and it is extremely difficult to synthesize a highly active catalyst with good reproducibility. The catalyst of the present invention is characterized in that smectite, which has a different crystal structure from such synthetic zeolites, is used as a host compound, and silicon oxide as a guest compound is interposed between the layers. The smectite used in the present invention is an ion-exchangeable swelling clay mineral having a layered structure, and both natural products and artificial products obtained by hydrothermal synthesis are applicable. This smectite is a conventionally well-known clay mineral, and includes, for example, montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and the like. Further, in the present invention, materials such as clay containing smectite as a main component, such as acid clay and bentonite, can be used. In order to prepare the catalyst of the present invention, first, the smectite or a substance containing smectite as a main component is treated with an aqueous solution in which a silicon ion donor is dissolved, and as shown by the following reaction formula, Exchanges cations and silicon ions contained in smectite. In this case, organic and inorganic salts of silicon such as silane derivatives, silicon tetrachloride, and silicic acid are optionally used as the silicon ion donor. M ⁺ L ^-・nH ₂ ^O +Si ⁺ X ^{- +} lH ₂ O→ Si ⁺ L ^-・mH ₂ O ₊ M ⁺ It represents an ion, such as alkali metals and alkaline earth metals, L ^- represents a giant anion layer of layered particles that make up smectite, and nH ₂ O represents interlayer water. X ^- is an organic or inorganic anion. lH ₂ O indicates water in an aqueous solution. l, m and n are all arbitrary positive integers. The ion exchange reaction can be carried out in a temperature range of room temperature to 100°C by stirring and heating or refluxing, or can be carried out under hydrothermal conditions by heating to 100°C or higher under pressure. The smectite containing silicon ions that has undergone the ion exchange reaction is then dried and heat treated to convert the silicon ions contained therein into silicon oxide. In this case, the heat treatment is carried out at a temperature of 100 to 700°C, preferably 300 to 700°C, in a suitable gas atmosphere such as air, nitrogen gas, or oxygen gas.
This is done by heating to a temperature of 600°C. The catalyst of the present invention obtained as described above is a so-called intercalation compound having a structure in which columnar blocks of silicon oxide as a guest compound are formed between layers of smectite as a host compound. ,
Between the layers, voids (pores) of about 3 Å to 6 Å are formed depending on the heating temperature and heating time when heat-treating the silicon ion-containing smectite.
The material as a whole is porous. In addition, this catalyst is a crystalline substance according to X-ray crystallography,
It has a primary basal reflection of 12.6 Å to 15.6 Å. The silicon content in smectite is 2 in terms of SiO ₂
-60% by weight, preferably 10-30% by weight. The catalyst of the present invention is used as a catalyst for olefin synthesis using alcohol or dialkyl ether, which is a dehydrated product thereof, as a raw material. That is, to synthesize an olefin using the catalyst of the present invention, the catalyst of the present invention is brought into contact with alcohol, dialkyl ether, or a mixture of both under reaction conditions. In this case, the reaction conditions are:
A temperature of 200 to 500°C, preferably 300 to 400°C is adopted, and the reaction pressure is 0.1 to 50 Kg/partial pressure of alcohol and/or alkyl ether.
cm ² , preferably 0.5 to 20 Kg/cm ² . As a raw material, a lower alcohol having 1 to 4 carbon atoms or a lower dialkyl ether derived therefrom is used, but it is preferable to use methanol or dimethyl ether as the raw material. This reaction can be carried out either by a flow method or a batch method. The olefin obtained by this reaction is mainly an olefin having 2 to 4 carbon atoms. Next, the present invention will be further explained by examples. Example 1 4.21 g (0.01 mol) of naturally produced montmorillonite (from Sazawa Mine, Yamagata Prefecture, Japan) was added to 500 ml of 0.3 M tetramethylammonium chloride (Me ₄ NCl) aqueous solution, and the mixture was stirred at room temperature for 24 hours to perform ion exchange of montmorillonite. Exchange the sexual cations with Me ₄ NCl. After the ion exchange is completed, the sample is thoroughly washed with water using a decanting method, and then dried in air at 60°C for 5 hours using an electric drying oven. Using the thus obtained montmorillonite with completely substituted interlayer ions as a raw material, it was first encapsulated in 100 ml of benzaldehyde. Then, it is soaked in 200 ml of Sicl ₄ -benzene solution (1:1) and then hydrolyzed to obtain catalyst PIC-2. SiCl ₄ +C ₆ H ₅ CHO →C ₆ H ₅ CHCl ₂ + (-SiOCl ₂ -) _o (-SiOCl ₂ -) _o +H ₂ O→SiO ₂・XH ₂ O+HCl By the above formula, between the layers of montmorillonite
It is possible to form SiO ₂ . The X-ray diffraction patterns of naturally occurring montmorillonite, montmorillonite exchanged with Me ₄ NCl, and catalyst PIC-2 are shown in Tables 1, 2, and 3, respectively. For X-ray diffraction measurements, each sample powder is fixed on an X-ray diffraction sample glass plate, and an X-ray source (X-ray tube with applied voltage
The test was carried out at a goniometer scanning speed of 20/min and a chart scanning speed of 2 cm/min while irradiating the sample plate with 40 KV, 30 mA current, using a Ni filter.

[Table] As is clear from the X-ray diffraction pattern in Table 1,
Naturally produced montmorillonite has a primary basal reflection of 12.3 Å.
d001, typical alkali montmorillonite (ideal chemical composition Na1/3 [Mg1/3Al5/3)
It can be seen that Si ₄ O ₁₀ (OH) ₂ ]2H ₂ O). On the other hand, in the X-ray diffraction pattern of montmorillonite ion-exchanged with Me ₄ NCl, the first diffraction line is d = 13.8 Å (Table 2), indicating that Me ₄ NCl ions replace alkali ions between the layers of montmorillonite. It shows that it was replaced and inserted. Further, the first diffraction line of the catalyst PIC-2 produced by the above method is d=14.7 Å. Therefore, the so-called deionized and dehydrated montmorillonite ((Mg1/3Al5/3)Si ₄ O ₁₀
Considering that d001 of (OH) ₂ ] is 9.6 Å,
The effective gap (pore diameter) between the layers of catalyst PIC-2 obtained by this method is calculated to be 5.1 Å (=14.7 Å − 9.6 Å). Example 2 The activity of the intercalation compound catalyst PIC-2 produced by the method of Example 1 for converting methanol into hydrocarbons mainly consisting of lower olefins was tested while comparing it with naturally produced montmorillonite. The experimental method was as follows. 2 ml of catalyst sample was filled into a normal pressure flow stainless steel reaction tube (inner diameter 10 mm), and argon gas stream (40 mm) was filled with 2 ml of catalyst sample.
A heating pretreatment was performed at 500° C. for 3 hours at a flow rate of ml/min. Next, argon gas was used as a carrier gas (flow rate 2 ml/min), methanol was introduced into the reaction tube (charge amount 2 ml/hr), and the components of the reaction products were analyzed every hour by gas chromatography using the carrier gas as an internal standard. Ivy.
LHSV is 1.0hr ^-1 . Tables 4 and 5 show the reaction results of the intercalation compound catalyst PIC-1 and naturally produced montmorillonite as the yield of reaction products with carbon numbers from 1 to 5 per 100 g of methanol charge (g).
Shown in units of numbers. Further, Table 6 shows the selectivity of each hydrocarbon component in the hydrocarbons having 1 to 5 carbon atoms calculated from the yields obtained in Table 4 in weight %.

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[Table] As is clear from the comparison between Tables 4 and 5, naturally produced montmorillonite produces almost no hydrocarbons other than methane, making it unsuitable as a catalyst for lower olefin synthesis, but as an intercalation compound catalyst.
PIC-2 produces significant lower hydrocarbons. Moreover, as is clear from Table 6, this catalyst PIC-2
At a reaction temperature of 300°C, the selectivity for lower olefins is also quite high, and the total selectivity of olefins in hydrocarbons with carbon numbers from 1 to 5 is about 46%, and at a reaction temperature of 350°C, It is 43.4%.
Furthermore, the ratio of olefins (ethylene and propylene) in hydrocarbons with 2 and 3 carbon atoms is 300
It can be concluded that the intercalation compound catalyst PIC-2 of the present invention is useful as a catalyst for lower olefin synthesis.

Claims (1)

[Claims] 1. A porous crystalline catalyst for olefin synthesis using a lower alcohol and/or lower dialkyl ether as a raw material, characterized in that smectite or a substance mainly composed of smectite has silicon oxide interposed between the layers.