JPH0148316B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for selectively hydrogenating dienes and acetylenes to monoenes. More specifically, low degree of unsaturation containing unsaturated hydrocarbons with 4 or more carbon atoms (hereinafter referred to as highly unsaturated hydrocarbons) having 2 or more double bonds and/or 1 or more triple bonds in the molecule. In the method of selectively hydrogenating only the highly unsaturated hydrocarbons described above by bringing hydrogen into contact with hydrogen in the presence of a hydrogenation catalyst, only the highly unsaturated hydrocarbons are treated without isomerization of olefins. The present invention relates to a method for converting hydrocarbons into hydrocarbons with a low degree of unsaturation. A highly unsaturated hydrocarbon with a carbon number of 4 or more or a hydrocarbon with a low degree of unsaturation containing this highly unsaturated hydrocarbon is reacted with hydrogen in the presence of a hydrogenation catalyst to produce a highly unsaturated hydrocarbon with a corresponding low degree of unsaturation. It is widely known to selectively hydrogenate hydrocarbons (hereinafter referred to as selective hydrogenation). -C4 unsaturated hydrocarbons containing monoolefins such as butene, 2-butene, and isobutene are combined with hydrogen together with palladium, platinum,
A method of selectively hydrogenating dienes and acetylenes by reacting them in the presence of a hydrogenation catalyst such as nickel is also used industrially. However, in these known selective hydrogenation methods, intramolecular movement of double bonds easily occurs at the same time as selective hydrogenation of highly unsaturated bonds such as two or more double bonds and one or more triple bonds. The disadvantage was that the composition of the selective hydrogenation reaction product changed significantly. For example, when unsaturated hydrocarbons with 4 carbon atoms, including butadienes and butynes, are selectively hydrogenated, the isomerization from 1-butene to 2-butene occurs simultaneously with the selective hydrogenation of butadienes and butynes to butenes. 1-butene concentration in the reaction product is greatly reduced. 1-Butene is important as a monomer for producing polyolefins, and various studies have been conducted on methods for separating 1-butene from a mixture of hydrocarbons with 4 carbon atoms. - From the standpoint of making effective use of butene, there has been a strong desire for a method that can selectively hydrogenate only highly unsaturated hydrocarbons without causing isomerization. The present inventors have conducted extensive research into a method for selective hydrogenation of highly unsaturated hydrocarbons that does not involve isomerization of olefins, and have arrived at the present invention. That is, the present inventors used a catalyst obtained by supporting palladium on an aluminum oxide support material having a specific surface area (BET) of more than 80 m ² /g and then calcining it at a temperature of 900° C. or more as a hydrogenation catalyst. We have discovered that by this method, only highly unsaturated hydrocarbons can be selectively hydrogenated to corresponding hydrocarbons with a low degree of unsaturation without isomerization of olefins. In the method of the present invention, aluminum oxide having a specific surface area (BET) of more than 80 m ² /g is used as a carrier material, and palladium is supported on this carrier material and then calcined at a temperature of 900° C. or more. It is necessary to use a catalyst. Even when a carrier other than aluminum oxide or aluminum oxide having a specific surface area (BET) of 80 m ² /g or less was used as a carrier material, the effects of the method of the present invention could not be achieved. Also, before loading palladium,
900℃ after firing at 900℃ or higher or supporting palladium
The effects of the method of the present invention could not be achieved even with the use of a catalyst calcined at temperatures below .degree. The support used in the present invention is aluminum oxide having a specific surface area (BET) of more than 80 m ² /g, and aluminum oxide, generally so-called γ-alumina, is preferably used. Palladium may be supported on aluminum oxide by a generally known method. For example, this is carried out by immersing an aluminum oxide support in an aqueous solution of a palladium salt such as palladium chloride. At this time, if necessary, other metal salts may be allowed to coexist.
Other metal salts may be co-supported on the carrier together with the palladium salt, or other metal salts may be supported on the carrier after the palladium salt is supported on the carrier. Examples of metals supported on the carrier together with palladium include chromium, copper, zinc, calcium, and sodium. The amount of palladium supported on the aluminum oxide support is not particularly limited, but is usually 0.01.
-2% by weight, preferably 0.02-0.5% by weight
It is. The firing temperature of palladium-supported aluminum oxide must be 900℃ or higher, preferably 1100℃ or higher.
It is preferable to bake at a temperature of ℃ or above. Baking time is usually
0.5-24 hours. Firing may be performed in an air atmosphere. Further, depending on the case, firing may be performed in a hydrogen atmosphere to perform palladium reduction treatment at the same time. Regarding the reduction treatment of the catalyst, reduction may be carried out using hydrogen gas, or formalin or other reducing agent may be used. By using the catalyst thus obtained as a hydrogenation catalyst, highly unsaturated hydrocarbons can be selectively hydrogenated to corresponding hydrocarbons with a low degree of unsaturation without isomerization of olefins. became possible. Such an effect can be obtained simply by using a palladium catalyst supported on γ-alumina or by firing only γ-alumina at high temperature.
- This could not be achieved using a palladium catalyst supported on alumina. The reaction conditions for the selective hydrogenation reaction of the method of the present invention are not particularly limited, but the reaction temperature is usually -20 to
The reaction is carried out at a temperature of 200° C. and a reaction pressure of normal pressure to 50 atmospheres. In addition, the raw material unsaturated hydrocarbon is LHSV
=1 to 100 and is preferably introduced into the reactor as an upward or downward flow. The raw material unsaturated hydrocarbon and the hydrogenation catalyst are usually brought into contact in a fixed bed system, but depending on the case, a moving bed system or a fluidized bed system can also be employed. Hydrogen gas is usually used in a molar ratio of 1 to 10 times that of the highly unsaturated hydrocarbon. Furthermore, there is no problem even if the hydrogen gas contains methane or other gas. The method of the present invention will be explained below using Examples, but the scope of the present invention is not limited by these. Example 1 A specific surface area of 150 m ² /g in an aqueous solution of palladium chloride,
A catalyst was prepared by soaking spherical (4 mm diameter) alumina with a pore volume of 0.7 ml/g so that 0.1% by weight of palladium was supported on the alumina, and then in a constant temperature bath.
The catalyst was prepared by drying at 150°C followed by calcination at 1000°C for 4 hours in an air atmosphere. In the selective hydrogenation reaction of the C ₄ mixture, a so-called spent B-B fraction, obtained by subjecting a C ₄ hydrocarbon mixture by-produced from an ethylene production plant to a butadiene extraction process to remove most of the butadiene, was used as a raw material. The composition of the raw materials is shown in the raw material column of Table 1. The reaction was carried out using 50 ml of the catalyst obtained as described above in a tube with an inner diameter of 12 mm.
Fill the vertically arranged reaction tube with
After reduction treatment through hydrogen gas at 100℃,
Spent B-B under the conditions of temperature 50℃ and pressure 10 atm.
fraction 2/hr (LHSV=40) and hydrogen 20
The selective hydrogenation reaction was carried out by introducing the hydrogen into the reactor at a feed rate of /hr (in terms of NTP). The composition of the obtained product was as shown in the product column of Table 1.

[Table] As is clear from Table 1, dienes and acetylenes have almost disappeared, but from 1-butene to 2
- Only a small amount of isomerization to butenes occurs. Comparative Example 1 A catalyst was prepared by carrying out the same operation as in Example 1 except that the calcination was performed at 600°C instead of 1000°C. Using the catalyst thus obtained, a selective hydrogenation reaction was carried out under the reaction conditions shown in Example 1, and the results shown in Table 2 were obtained.

【table】

[Table] As is clear from Table 2, the hydrogenation activity of butadiene is slightly stronger than that of the catalyst of the method of the present invention, but
1-Butene is significantly isomerized to 2-butene. Comparative Example 2 A specific surface area of 7 m ² /g in an aqueous solution of palladium chloride,
A catalyst was prepared by soaking spherical (diameter 4 mm) alumina with a pore volume of 0.4 ml/g so that 0.1% by weight of palladium was supported on the alumina, and then in a constant temperature chamber.
Fill the reactor with the dried material at 150℃,
Reduction treatment was performed with hydrogen gas. A hydrogenation reaction was carried out using this catalyst under the conditions shown in Example 1, and the results shown in Table 3 were obtained.

[Table] Comparative Example 3 Same specific surface area as used in Example 1, 150 m ² /g,
Spherical alumina (diameter 4 mm) with a pore volume of 0.7 ml/g was calcined at 1000°C for 4 hours in an air atmosphere, and then immersed in an aqueous solution of palladium chloride to give a concentration of 0.1% by weight.
Palladium impregnation is carried out so that palladium is supported on alumina, and then it is heated in a constant temperature bath at
The catalyst was prepared by drying at °C. At this time, the specific surface area of the alumina after firing at 1000° C. for 4 hours was 17 m ² /g. Using this catalyst, a hydrogenation reaction was carried out under the conditions shown in Example 1, and the results shown in Table 4 were obtained.

【table】

[Table] In Comparative Example 3, contrary to the essential requirement of the present invention that palladium is supported on a support material (alumina) and then fired at a temperature of 900°C or higher, palladium was not supported on a support material (alumina). This is an example of firing at a temperature of 900℃ or higher (1000℃).
As is clear from the results, not only was the hydrogenation reaction of the dienes of 1,3-butadiene and propadiene insufficient, but also the isomerization of 1-butene to 2-butene. objective has not been achieved at all.

Claims (1)

[Claims] 1. A method of selectively hydrogenating only the highly unsaturated hydrocarbons by contacting hydrogen with a low degree of unsaturation, including highly unsaturated hydrocarbons having 4 or more carbon atoms, in the presence of a hydrogenation catalyst, Selective hydrogen characterized in that a catalyst obtained by supporting palladium on an aluminum oxide support having a specific surface area (BET) of more than 80 m ² /g and then calcining it at a temperature of 900°C or higher is used as a hydrogenation catalyst. Addition method.