JPS5913482B2 - Method for producing olefin from aldehyde - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for obtaining isobutene in high yields by catalytic conversion of isobutyraldehyde.

Many attempts have been made to catalytically convert isobutyl aredehyde.

For example, (1) Al supported on platinum (pt) or rhodium (Rh). A method for decomposing propylene, carbon monoxide and hydrogen over a Mina catalyst ("Idrocarbon Processing" November issue, 1971, p. 166), (2
), a method of completely gasifying hydrogen and carbon dioxide in the presence of water vapor or oxygen (Japanese Patent Publication No. 49-45475, Publication No. 49-45476), but these methods require expensive catalysts. It is not necessarily an economically advantageous method because it requires severe reaction conditions such as high temperature and high pressure. Also, manganese oxide (
It has been discovered that 5-isobutene can be obtained from isobutyraldehyde by using a catalyst supported on MnO2 (Journal of Chemical Society Chemical Communications, 1969, p. 461), but this method requires heating at 550°C under pressure. This method requires high temperatures and is difficult to implement industrially. 10 The present inventors have conducted various studies in order to convert isobutyraldehyde, which is a considerable by-product in propylene oxo reactions, etc., into higher value-added products. They discovered that olefins, especially isobutene, can be obtained in high yield by contacting isobutyraldehyde with isobutyraldehyde at high temperatures for 15 minutes, and the present invention was achieved based on this discovery.

That is, the present invention is characterized in that isobutyraldehyde is brought into contact with a catalyst made of alumina, silica-alumina, or silica containing molybdenum, chromium, iron, cobalt, or nickel at high temperature in the presence or absence of hydrogen. The gist of this paper is a method for producing isobutene.

Catalysts that are effective in the present invention include metal acids such as molybdenum, chromium, iron, cobalt, and nickel in Group I of the Periodic Table, and carboxylic acids such as ammonium salts, nitrates, and acetates of the metal acids. It is prepared by supporting a salt on alumina, silica-alumina, or silica by a conventional supporting method, such as an impregnation method, drying it, and then calcining it at a temperature of 0.1400 to 500°C.

When using a silica-alumina composite oxide, it is preferable that the alumina content be 7 to 40% by weight. Furthermore, when using this catalyst, it is preferable to activate it by reduction treatment at 400 to 500'C in a hydrogen stream. Alumina, silica in the present invention - Alumina or silica usually has a high surface area and is neutral to acidic, and any of them are effective in the present invention, but among these, the use of alumina in particular provides the best The result is obtained. The amount of the metal supported on these alumina, silica-alumina or silica varies depending on changes in various conditions and cannot be unconditionally defined, but the amount of the metal supported on 100 parts by weight of alumina, silica-alumina or silica is 1 to 1. It is desirable that the amount is 10 parts by weight. The conversion reaction from aldehyde to olefin of the present invention is carried out by bringing the catalyst prepared by the above method into contact with isobutyraldehyde. Although any type may be used, fixed bed type, fluidized bed type, etc. are usually adopted.

Regarding the reaction conditions such as reaction temperature and space velocity in the present invention, a suitable reaction temperature is 300 to 600°C, but it is possible to reduce side reactions such as decomposition, convert isobutyraldehyde at a high conversion rate, and achieve high selectivity. To obtain 1 isobutene at a rate of
A temperature of 400 to 500°C is particularly effective.

In addition, the space velocity (SV) is 500 to 10,000.
hr-1, preferably in the range of 1,000 to 5,000 hr-1, is most practical and yields good results. Although the objects of the present invention can be achieved by contacting isobutyraldehyde with the above catalyst at high temperatures, the presence of hydrogen in this contact reaction system provides even better results.

The effect of the presence of hydrogen is remarkable in maintaining and improving catalyst activity, but there is also a certain optimum range for the amount of hydrogen present. If the partial pressure of hydrogen in the reaction system is too high, it will promote the decomposition of isobutyraldehyde into lower hydrocarbons and will also involve hydrogenation of olefins, so hydrogen/isobutyraldehyde (
The molar ratio) is suitably in the range of 1 to 20, preferably 5 to 10. Only a small amount of hydrogen is consumed in the reaction, and most of it can be recycled. The catalyst used in the present invention shows a tendency for its catalytic activity to decrease over time due to coke formation reactions, etc., but the catalytic activity can be almost completely recovered by calcination treatment with air or oxygen-containing gas. The method of the present invention can be implemented industrially and can be said to be an extremely useful invention. The present invention has a high conversion rate of 50 to 80% from isobutyraldehyde to isobutene, and a high conversion rate of 60 to 80%.
It is produced with a high selectivity of 75%, and other olefins such as propylene, butene, and butadiene are also produced, and these can be easily converted into high-purity olefins using current olefin separation and purification techniques.

As described above, the present invention is a method for converting isobutyraldehyde into an olefin mainly composed of isoptenes using a catalyst and reaction conditions that can be easily carried out industrially, and thus makes a great contribution to the industry. EXAMPLES The present invention will be explained in detail below with reference to Examples, but the present invention is not limited thereto. Example 1 Ammonium heptamolybdate [(NH4)6M07024・4H20] 9.17 to 5
In addition to 0 ml of water, add 5 ml of ammonia water to completely dissolve.

Add commercially available γ-alumina (surface area 150 I/7,
37! 100 y of Tmφ pellets were added until the solution was almost completely absorbed. Then, after drying at 100°C, it was fired in air at a temperature of 500°C for 3 hours. In this way, a molybdenum oxide/γ-alumina catalyst containing 5 parts by weight of molybdenum metal per 100 parts by weight of r-alumina was obtained. 10 ml of this catalyst was packed into a stainless steel reactor with an inner diameter of 151 Emφ, heated and raised in an external electric furnace, and hydrogen was flowed at a rate of 100 ml/min at 450°C to reduce and activate the catalyst, and then the reaction was started. I went. The reaction is isobutyraldehyde: hydrogen: nitrogen - 1:10:4 (
(volume ratio) mixed gas at reaction temperature 450℃, SV36OO
The reaction was carried out by contacting the catalyst with the catalyst under normal pressure at hr-1. The results are shown in Table 1. As a comparative example, a similar reaction was carried out using only γ-alumina containing no molybdenum oxide (Comparative Example 1), and the results are also shown in Table 1.
It can be seen that the molybdenum oxide/γ-alumina catalyst of the present invention is excellent in both the conversion rate of isobutyraldehyde and the selectivity to isobutene. Example 2 A reaction was carried out in the same manner as in Example 1 except that hydrogen was not used in Example 1, and the results are shown in Table 1.

As a comparative example, a similar reaction was carried out using only γ-alumina containing no molybdenum oxide (Comparative Example 2), and the results are shown in Table 1. I know that there is. Examples 3 to 6 Metal oxide/γ-alumina catalysts were prepared from nitrates of chromium, iron, cobalt, and nickel in exactly the same manner as in Example 1 (5 parts by weight of each metal was added to 100 parts by weight of γ-alumina). (including parts by weight), the reaction was carried out in the same manner as in Example 1.

The results are shown in Table 2. Examples 7-8 Instead of γ-alumina, η-alumina (surface area 285 I/7, 3 m 1 φ pellet) and silica-alumina (alumina content 14% by weight, surface area 450 m 7 V) were used as carriers.
The reaction was carried out in exactly the same manner as in Example 1, except for using the following:

The results are shown in Table 3. Examples 9 to 11 The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was changed.

The results are shown in Table 4. Comparative Examples 3 to 4 A MnO2/r-alumina catalyst was prepared using manganese nitrate (11) in exactly the same manner as in Example 1 (containing 5% by weight of manganese based on 100 parts by weight of γ-alumina).
The reaction was carried out in the same manner as in Example 1 and Example 2.

Claims (1)

[Claims] 1. A method for producing isobutene, which comprises contacting isobutyraldehyde with a catalyst made of alumina, silica-alumina or silica containing molybdenum, chromium, iron, cobalt or nickel at high temperature in the presence or absence of hydrogen.