JPH10180102A - Dehydrogenation catalyst - Google Patents

Abstract

(57) [Problem] To provide a dehydrogenation catalyst used for production of an alkene by dehydrogenation of an alkane, which is stable with little deterioration at high temperatures. SOLUTION: The surface area is 150 m ² / g or more and the pore volume is 0.1 m ² / g.
Composite comprising zinc oxide supported on a γ-alumina carrier having a pore size of 55 cm ³ / g or more, an average pore size of 90 to 200 Å and pores having a pore size of 90 to 200 Å occupying 60% or more of the total pore volume. A dehydrogenation catalyst obtained by subjecting a catalyst composition having platinum and tin supported on a support to a high-temperature reduction treatment in the presence of a reducing gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dehydrogenation catalyst,
More specifically, it relates to a dehydrogenation catalyst used for producing an alkene by a dehydrogenation reaction of an alkane.

[0002]

2. Description of the Related Art In recent years, demand for alkenes represented by propylene and isobutylene has been increasing. This is because the demand for polypropylene using propylene as a raw material is increasing as a resin for packaging materials and automobile parts, and the addition of methyl-t-butyl ether (MTBE), a high octane fuel additive for gasoline produced from isobutylene as a raw material. This is because demand is increasing. These propylene and isobutylene are obtained by fluidized bed catalytic cracking (FCC) for gasoline production or as a by-product of pyrolysis for ethylene production, but the amount obtained by such a method is limited. Therefore, establishment of another manufacturing method is desired. Under these circumstances, alkane such as C ₃ and C ₄ , which is used only as a fuel, is used as a raw material to produce propylene, isobutylene, or n-
Various attempts have been made to produce alkenes such as butenes. As a method for producing an alkene using an alkane as a raw material, a method based on a catalytic dehydrogenation reaction in the presence of a catalyst has been conventionally known as an effective method (see, for example, JP-A-3-288548). As a dehydrogenation catalyst for this purpose, a catalyst in which an active substance such as a metal or a metal oxide is supported on a carrier such as silica, alumina, zeolite, or activated carbon is conventionally used. In particular, a chromium oxide / alumina catalyst is often used. (See, for example, US Pat. No. 4,581,339).

[0003]

However, since the dehydrogenation reaction is an endothermic reaction, the reaction is generally carried out at a high temperature. Therefore, a catalyst that is more stable at such a high temperature is desired. That is, the present invention provides a dehydrogenation catalyst for use in the production of alkenes by dehydrogenation of alkanes, which is less degraded at high temperatures and more stable.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a method for fabricating a surface having a surface area of 150.
m ² / g or more, pore volume 0.55 cm ³ / g or more, average pore diameter 90 to 200 Å, and pore diameter 9
The pores of 0 to 200 angstroms have a total pore volume of 60
% Of a catalyst composition in which platinum and tin are supported on a composite carrier comprising zinc oxide supported on a γ-alumina carrier occupying not less than 10% by mass in the presence of a reducing gas. The problem is solved by providing a catalyst.

[0005]

DETAILED DESCRIPTION OF THE INVENTION Since the dehydrogenation of alkanes using a solid catalyst is essentially a gas-solid contact operation, it is important to increase the surface area of the catalyst together with the selection of the active metal in order to increase the activity. is there. In order to increase selectivity and suppress activity deterioration, it is necessary to suppress the isomerization reaction or decomposition reaction and to form the target compound preferentially, and to provide surface characteristics that suppress coke deposition. is important. Therefore, in order to prevent a decrease in activity and selectivity, it is important that changes in the surface area and surface characteristics are small. In the present invention, a specific carrier is used in which a specific amount of zinc oxide is supported on a specific γ-alumina carrier, platinum and tin are supported on the composite carrier, and this is subjected to a high-temperature reduction treatment in the presence of a reducing gas. This fulfills the above requirements.

The specific porous γ-alumina support has a surface area of 150 m ² / g or more and a pore volume of 0.55 cm ³ / g.
As described above, the average pore diameter is 90 to 200 angstroms, and the pores having a pore diameter of 90 to 200 angstroms occupy 60% or more of the total pore volume. If the average pore diameter is smaller than 90 angstroms, diffusion of alkane molecules and alkene molecules in the pores is rate-determining, and the entire catalyst surface area cannot be used effectively. On the other hand, if the average pore diameter is larger than 200 angstroms, the surface area cannot be increased. A γ-alumina support satisfying the above conditions is:
The slurry of aluminum hydroxide produced by the neutralization of the aluminum salt was filtered and washed, and dehydrated and dried.
It is obtained by baking at 00 to 800 ° C. for about 1 to 6 hours.

The above specific porous γ-alumina carrier includes:
Zinc oxide [ZnO] is preferably supported at 5 to 50% by weight. It is believed that this zinc oxide forms a complex with alumina on the alumina surface and plays a role in providing favorable surface properties. If the loading amount is less than 5% by weight, the surface of the γ-alumina carrier cannot be uniformly covered with the composite of alumina and zinc oxide, so that a sufficient effect cannot be obtained.
If the content exceeds 0% by weight, the surface characteristics of the composite of alumina and zinc oxide will change, and the surface area will decrease significantly. In order to carry zinc oxide on the γ-alumina carrier, the carrier may be impregnated with an aqueous solution of a zinc compound such as zinc nitrate, dried and fired.

[0008] Platinum, preferably 0.0
5 to 1.5% by weight is supported. Examples of the platinum compound used herein include chloroplatinic acid, ammonium platinate, platinum bromide, platinum dichloride, platinum tetrachloride hydrate, carbonyl platinum dichloride dichloride, dinitrodiamine platinum salt, and the like. . For supporting platinum, a step of impregnating the composite carrier with an aqueous solution of a platinum compound such as chloroplatinic acid, followed by calcining and then reducing at a high temperature in hydrogen gas is usually used. Other reduction methods may be used instead of reduction.

[0009] Tin is supported together with platinum on the composite carrier. The supported amount of tin is preferably 0.5 to 10% by weight. The tin compound used here is preferably a water-soluble compound and / or a compound soluble in an organic solvent such as acetone. Examples of such tin compounds include stannous bromide, tin acetate, stannous chloride, stannic chloride, and hydrates thereof, stannic chloride acetylacetonate complex, tetramethyltin, tetraethyltin , Tetrabutyltin,
And tetraphenyltin. The supporting of tin is usually carried out by impregnating the carrier after the above-mentioned reduction step with an aqueous solution of a tin compound and / or an organic solvent solution to dry and remove water or an organic solvent, and then reducing at high temperature in hydrogen gas. However, in the present invention, other reduction methods may be used instead of hydrogen reduction.

[0010] The catalyst composition obtained as described above is finally subjected to a high-temperature reduction treatment in the presence of a reducing gas. As the reducing gas used here, hydrogen or a mixed gas containing hydrogen is preferable, and it is more preferable to use hydrogen gas alone. Usually, the high temperature reduction treatment is performed at a temperature of 500 to 700 ° C, preferably 550 to 650 ° C, for about 1 to 20 hours. Note that this high-temperature reduction treatment does not necessarily need to be performed before the catalyst is filled in the reaction tube, and after the catalyst is filled in the reaction tube, the hydrogen gas is reacted before introducing the raw material alkane and performing the dehydrogenation reaction. What is necessary is just to distribute to a pipe.

[0011]

The following is an example of performing a dehydrogenation reaction using a dehydrogenation catalyst of the present invention that has been subjected to a final high-temperature reduction treatment and a conventional dehydrogenation catalyst that has not been subjected to a final high-temperature reduction treatment. Show. In the following, all values of% are% by weight. (1) Production of γ-alumina support A γ-alumina support was produced as described in Example 1 in JP-B-6-72005. In brief, this method was used to obtain a suspension of an aluminum hydroxide slurry (pH 10) by instantly adding an aqueous sodium aluminate solution while stirring vigorously in hot dilute sulfuric acid. Is repeated by alternately adding hot dilute sulfuric acid and aqueous sodium aluminate solution for a certain period of time to obtain a filter washing cake, extruding and drying it, and then baking it at 500 ° C. for 3 hours. . The properties of γ-alumina thus obtained are typically as shown in Table 1 below.

[Table 1]

(2) Production of a platinum / tin supported catalyst 27.5 g of the above-mentioned γ-alumina carrier was taken, and ZnO was added thereto.
30% zinc nitrate [Zn (NO ₃ ) ₂ ] aqueous solution so that the / Al ₂ O ₃ ratio becomes 30/70.
The composite support was prepared by firing at 00 ° C. for 3 hours. The composite carrier is impregnated with 2.0% aqueous solution of chloroplatinic acid [H ₂ PtCl ₆ ] so that the amount of Pt carried is 0.3%, and after impregnation, the carrier is dried.
It was calcined at 0 ° C. for 3 hours, and further reduced at 400 ° C. for 3 hours in a hydrogen stream. Next, the platinum-supported composite carrier after the reduction was impregnated with a 3% aqueous solution of stannous chloride [SnCl ₂ ] so that the amount of supported Sn became 3.5%. After drying, hydrogen reduction was performed at 400 ° C. for 30 minutes. A platinum / tin supported catalyst was obtained.

(3) Dehydrogenation reaction test [Example] The platinum / tin-supported catalyst obtained above was filled in a quartz reaction tube having a diameter of 18 mm, and the catalyst was placed under a hydrogen flow of 600 mm.
After performing the treatment at 3 ° C. for 3 hours, a sufficient purge was performed with nitrogen. Then, using isobutane as a raw material, at a temperature of 560
A dehydrogenation reaction test was performed at a temperature of 500 ° C. and a space velocity of 500 hr ^-1 for 30 hours, and the gas at the reactor outlet was analyzed by gas chromatography. Table 2 shows the results. [Comparative Example] A dehydrogenation reaction test was performed under the same conditions as above except that the hydrogen circulation treatment was not performed for 3 hours at 600 ° C. Table 2 shows the results.

[Table 2] As is clear from Table 2, when the dehydrogenation reaction was finally performed using the catalyst that had been subjected to the high-temperature reduction treatment, the reduction in the catalytic activity and the selectivity was remarkably alleviated.

[0014]

As described above, when the dehydrogenation catalyst of the present invention is used, when an alkene is produced by a dehydrogenation reaction of an alkane, deterioration of the catalyst at a high temperature is remarkably alleviated.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C07C 11/02 C07C 11/02 // C07B 61/00 300 C07B 61/00 300 (72) Inventor Susumu Yamamoto Tsurumi, Yokohama City, Kanagawa Prefecture 2-1-1, Tsurumi-Chuo-ku, Chiyoda Chemical Works Construction Co., Ltd. (72) Inventor Sachio Asaoka 2-1-1, Tsurumi-Chuo 2-chome, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Chiyoda Chemical Works, Ltd.

Claims (6)

[Claims] 1. A surface area of 150 m ² / g or more and a pore volume of 0.1 m ² / g.
Composite comprising zinc oxide supported on a γ-alumina carrier having a pore size of 55 cm ³ / g or more, an average pore size of 90 to 200 Å and pores having a pore size of 90 to 200 Å occupying 60% or more of the total pore volume. A dehydrogenation catalyst obtained by subjecting a catalyst composition having platinum and tin supported on a support to a high-temperature reduction treatment in the presence of a reducing gas. 2. The catalyst according to claim 1, wherein the amount of zinc oxide carried on the composite carrier is 5 to 50% by weight. 3. The amount of platinum supported on the composite carrier is 0.0
3. The catalyst according to claim 1, wherein the amount is 5 to 1.5% by weight. 4. The amount of tin carried on the composite carrier is 0.5
The catalyst according to any one of claims 1 to 3, which is 10 to 10% by weight. 5. The high-temperature reduction treatment of the catalyst composition is 500
The catalyst according to any one of claims 1 to 4, which is carried out at a temperature of -700C. 6. The method according to claim 1, wherein the reducing gas is hydrogen.
5. The catalyst according to any one of the above items 5.