JPS6334850B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing tertiary olefin. More specifically, the present invention relates to a method for producing a tertiary olefin using an alkyl tertiary alkyl ether as a raw material. <Prior Art> Tertiary olefins have conventionally been produced industrially by a sulfuric acid extraction method. Since all of these sulfuric acid extraction methods use concentrated sulfuric acid, it is essential to use expensive equipment materials. Furthermore, tertiary olefins undergo side reactions such as polymerization and hydration during extraction with concentrated sulfuric acid, and this is not necessarily an industrially advantageous method. On the other hand, in the presence of an acid catalyst, tertiary olefin
It is known that they readily react with alkyl alcohols to form the corresponding alkyl tertiary alkyl ethers. Furthermore, even when tertiary olefin is mixed with other olefinic hydrocarbon compounds, tertiary olefin
It is also known that only primary olefins react selectively with primary alcohols. Conventionally, several methods for producing tertiary olefins using the thus obtained alkyl tertiary alkyl ethers as raw materials have been proposed. For example, Tokkosho
No. 47-41882 proposes a method using gamma alumina as a catalyst, JP-A-51-39604 proposes a method using alumina modified with a silicon compound, and JP-A-51-26401 proposes a method using a metal sulfate. In JP-A-55-2695, silica modified with various metal ions is used as a catalyst. However, none of these methods was satisfactory in that the alcohol recovery rate was low due to ether by-product, the reaction temperature was high, catalyst preparation was very troublesome, and expensive reagents were required. <Problems to be Solved by the Invention> The present invention is a method for producing tertiary olefin using an alkyl tertiary alkyl ether as a raw material, and overcomes the disadvantages of conventional methods, such as low alcohol recovery rate and complicated catalyst preparation. The purpose is to improve the disadvantages of tertiary olefins and obtain tertiary olefins in high yield. <Means for Solving the Problems> The present inventors have discovered that a highly purified tertiary olefin can be obtained in high yield by contacting an alkyl tertiary alkyl ether with a specific catalyst, and have completed the present invention. did. That is, the present invention provides a method for producing tertiary olefin using an alkyl tertiary alkyl ether as a raw material, in which an aluminum compound is supported on a composite oxide carrier consisting of silicon oxide and aluminum oxide, and then the aluminum compound is The present invention relates to a method for producing a tertiary olefin, which is characterized in that a tertiary olefin heated and calcined at a temperature higher than the decomposition temperature is used as a catalyst. That is, according to the method of the present invention, the method for producing the catalyst is very simple, and a highly purified tertiary olefin can be obtained in high yield in the presence of the catalyst of the present invention. The present invention will be explained in detail below. The raw material used in the method of the present invention is an alkyl tertiary alkyl ether, which is usually obtained by the reaction of the above-mentioned tertiary olefin and primary alcohol, but is not limited to this. It can be used as a raw material in any way. Examples of the raw material alkyl tertiary alkyl ether include methyl-tertiary butyl ether, ethyl-tertiary butyl ether, methyl-tertiary amyl ether, and the like. The catalyst used in the method of the present invention is one in which an aluminum compound is supported on a composite oxide carrier consisting of silicon oxide and aluminum oxide, and the aluminum compound is heated and calcined at a temperature higher than the temperature at which the aluminum compound decomposes. As a method for supporting the aluminum compound used in the present invention, a method of impregnating an aluminum compound into a composite oxide support consisting of silicon oxide and aluminum oxide (equilibrium adsorption method, evaporation drying method, spray method, etc.) is available. Although preferred, various methods can be adopted, such as a method in which the carrier powder and the aluminum compound are thoroughly mixed and molded, and a method in which the carrier powder and the aluminum compound are kneaded in a slurry state and molded.
In short, the catalyst of the present invention can be obtained by heating and firing in a state where a composite oxide support consisting of silicon oxide and aluminum oxide and an aluminum compound coexist. There are no particular restrictions on the aluminum compound, but it is usually selected based on the firing temperature and the heat resistance of the carrier.
An aluminum compound that decomposes below 1500°C is selected. Specific examples include aluminum sulfate,
Examples include nitrates, halides, organic acid salts, hydroxides, etc., but sulfates and nitrates are particularly preferred. The firing temperature is usually selected from the temperature at which the aluminum compound decomposes to 1500°C. The temperature at which an aluminum compound decomposes here is not the so-called decomposition temperature described in the literature, but the temperature at which the compound actually starts to decompose while supported on a carrier.Although it depends on the purity of the aluminum compound, it usually decomposes. lower than the temperature. This heating and baking is usually carried out in an air atmosphere, but may also be in an atmosphere of an inert gas such as nitrogen, carbon dioxide, or argon, water vapor, or a mixed gas thereof. Firing time depends on firing temperature, but usually 0.1~24
time, preferably about 0.5 to 10 hours. Regarding the amount of aluminum compound supported on the carrier, it is 0.1 to 100 parts (parts by weight, same below) of the carrier.
parts, preferably 1 to 50 parts, more preferably 5 to 50 parts
30 parts are adopted (anhydrous equivalent for aluminum compounds with water of crystallization). Examples of the composite oxide support comprising silicon oxide and aluminum oxide used in the method of the present invention include montmorillonite, kaolinite,
Examples include those obtained from mineral groups such as attapulgite, bentonite, and acid clay, as well as silica alumina and mixtures thereof. Particularly preferred are carriers prepared from montmorillonite minerals. Further, there is no particular restriction on the surface area of these carriers, but it is desirable that the surface area is 1 m ² /g or more. The performance of the catalyst used in the method of the present invention is superior in terms of activity and selectivity to either a composite oxide carrier consisting of silicon oxide and aluminum oxide or a carrier prepared by simply thermally decomposing an aluminum compound. Although it is unclear, it shows that the presence of silicon oxide is essential when aluminum compounds are thermally decomposed. When carrying out the method of the present invention, a fixed bed gas phase reaction is usually employed, but other methods such as a fluidized bed method are also possible. Also, the reaction temperature is usually
A temperature of 100-400°C, preferably 150-300°C is employed. The reaction pressure is not particularly limited, but is usually normal pressure to
20Kg/cm ² , preferably normal pressure to 10Kg/cm ² . The feed rate of the raw materials varies depending on the reaction temperature, pressure, desired conversion rate of alkyl tertiary alkyl ether, etc., but is usually 1 to 50 hr ^-1 , preferably 3 to 20 hr ^-1 at LHSV. The reaction can also be carried out by adding an inert gas, steam, etc. to the raw material ether. The present invention will be explained in more detail in Examples below, but the present invention is not limited to these Examples. <Example> Example 1 Montmorillonite carrier (Nissan Girdler catalyst)
Co., Ltd., trade name KA-1) was impregnated with 19.2 parts of aluminum sulfate in terms of anhydride. This product was dried at 350°C for 3 hours and then fired at 900°C for 5 hours. The generation of sulfur oxide gas was observed during firing. A quartz reaction tube equipped with a vaporizer was filled with 10 to 24 meshes of this catalyst, and a decomposition reaction of methyl tert-butyl ether was carried out at normal pressure while heating the outside of the reaction tube at 190° C. in an electric furnace. As a result of supplying raw materials at LHSV5hr ^-1 , the temperature at the center of the catalyst layer was 120°C, and analysis of the reaction tube outlet gas showed that the conversion rate of methyl tertiary butyl ether was 92.4.
% and dimethyl ether selectivity (based on reaction methyl tertiary butyl ether) of 0.03%, isobutylene was quantitatively obtained. Comparative Example 1 An experiment was conducted in the same manner as in Example 1. however,
A carrier not supporting aluminum sulfate was used as a catalyst, and the outside of the reaction tube was heated to 209°C. The temperature at the center of the catalyst layer was 165°C, and the conversion rate of methyl tertiary butyl ether was 69.2%. Compared to Example 1, the activity was lower despite the higher reaction temperature, clearly demonstrating the effects of the present invention. Examples 2 to 5 Experiments were conducted in the same manner as in Example 1 except as shown in Table 1. The results are shown in Table 1.

[Table] Example 6 An experiment was conducted in the same manner as in Example 1. however,
As a catalyst, silica alumina (JGC Chemical Co., Ltd. trade name N-631 (L) was crushed into 10 to 24 meshes)
Support aluminum sulfate in an amount of 20 parts per 100 parts by evaporation to dryness, and after drying at 350°C for 3 hours,
The one that was fired at 900°C for 5 hours was used. When the reaction tube outside temperature was 189℃ and LHSV5.2hr ^-1 ≠, the catalyst layer center temperature was 111℃, methyl tertiary butyl ether conversion rate was 97.2%, and dimethyl ether selectivity was 0.2%.
It was hot. Comparative Example 2 A reaction was carried out in the same manner as in Example 6. However, as a catalyst, Rica alumina (trade name N-631 (L) manufactured by JGC Chemical Co., Ltd., pulverized into 10 to 24 meshes) calcined at 900 DEG C. for 5 hours was used. When the external temperature of the reaction tube was 190°C and LHSV5.2hr ^-1 ≠, the temperature at the center of the catalyst layer was 106°C, the conversion rate of methyl tert-butyl ether was 89.6%, and the selectivity for dimethyl ether was 0.1%. Example 7 The same experiment as in Example 1 was conducted in a pressurized system.
Using a SUS reaction tube, the reaction system pressure was 6Kg/cm ²
When the temperature outside the reaction tube was maintained at 208°C, the temperature at the center of the catalyst layer was 170°C. LHSV
was 5.3hr ^-1 ≠. However, methyl tertiary butyl ether containing 1.6 wt% of water was used as a raw material. Conversion rate 95.9%, dimethyl ether selectivity 0.16
It was %. <Effects of the Invention> As described above, according to the present invention, an aluminum compound is supported on a composite oxide carrier consisting of silicon oxide and aluminum oxide, and then the catalyst is heated and calcined at a temperature higher than the temperature at which the aluminum compound decomposes. By decomposing alkyl tertiary alkyl ether in the presence of tertiary olefins, it has become possible to obtain tertiary olefins in good yield.

Claims (1)

[Claims] 1. In a method for producing a tertiary olefin using an alkyl tertiary alkyl ether as a raw material, after supporting an aluminum compound on a composite oxide carrier consisting of a silicon oxide and an aluminum oxide,
A method for producing a tertiary olefin, which comprises using as a catalyst a product heated and calcined at a temperature higher than the temperature at which the aluminum compound decomposes.