JPH0341450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing methanol and/or dimethyl ether by catalytic hydrogenation of carbon monoxide. More specifically, the present invention relates to a method for producing methanol and/or dimethyl ether, which comprises catalytically hydrogenating carbon monoxide in the presence of a catalyst comprising palladium and sodium supported on a carrier. Conventionally, methanol synthesis using carbon monoxide and hydrogen as raw materials has been carried out industrially under conditions of 300-400°C and 300-350 atm in the presence of a catalyst consisting of zinc-chromium oxide. But then,
Catalysts consisting of zinc-chromium-copper oxides and catalysts in which zinc-copper oxides are supported on alumina carriers have been developed, and a method that is carried out under conditions of 250 to 300°C and 50 to 150 atm is now industrially available. It has been implemented. However, despite these improvements in catalysts, the latter method still requires high temperature and high pressure reaction conditions, which causes problems with reactor materials, disaster prevention and safety issues, production equipment construction costs, and reaction Disadvantages related to the cost of pressurizing gas, etc., have not been resolved. On the other hand, the synthesis of methanol by catalytic hydrogenation of carbon monoxide using a catalyst in which palladium is supported on silica is known (J. Catal. 52 , 157-168).
(1978)), this catalyst has no methanol synthesis activity under mild conditions below 200°C and normal pressure;
High temperature and pressure conditions of 16,000 psig are required.
This method has the same drawbacks as the conventional method described above. Recently, attempts have been made to synthesize methanol using a metal carbonyl cluster-supported catalyst under relatively mild conditions at about 200°C under normal pressure (Brethane of the Chemical Society of Japan). (Bull, Chem Soc.Jap)
51, 2268-2272 (1978)), it is not easy to synthesize the metal carbonyl cluster, which is the raw material for the catalyst, and the cluster structure decomposes in air, so an inert gas atmosphere is required when preparing and handling the catalyst. It has new drawbacks as a practical catalyst, such as the need for , and is unsuitable for industrial implementation. As a result of intensive studies to solve the above-mentioned problems in conventional methods, the present inventors have found that the above-described drawbacks of conventional catalysts can be solved by using a catalyst in which palladium and sodium are supported on a carrier. On the other hand, when carbon monoxide is catalytically hydrogenated, some dimethyl ether is generally produced along with methanol, but in the method of the present invention, it is important to appropriately select the type of support used for preparing the catalyst. It was also newly discovered that the production of methanol and dimethyl ether can be easily controlled, leading to the completion of the present invention. That is, the present invention provides a method for producing methanol and/or dimethyl ether, which is characterized by catalytically hydrogenating carbon monoxide in the presence of a catalyst in which palladium and sodium are supported on a carrier. The greatest feature of the present invention is that sodium is used as a co-catalyst along with palladium as the main catalyst. Due to the action of this co-catalyst, catalytic performance was significantly superior to that of a catalyst that simply supported palladium (Journal of Catalysis).
catal) and Comparative Example 1). Further, the catalyst used in the present invention can be produced by supporting an extremely stable and easily available catalyst component-containing compound on an easily available general-purpose catalyst carrier using a very normal method, as described below. , it is also excellent in terms of ease of industrial implementation. In the process of the invention, various palladium salts, such as palladium chloride, palladium nitrate, palladium sulfate,
Palladium salts such as organic carboxylates and various palladium complex ions, such as PdCl ₄ ^2- , Pd
Salts such as (NH ₃ ) ₄ ²⁺ can be used. Furthermore, as a cocatalyst component, Na, which is in group A of the periodic table, is effective and essential, but this element can also be used in various salts, such as chlorides, nitrates, sulfates, carbonates, and organic carboxylic acids. Salts such as salts are suitable, and one or more of these can be selected and used. The amount of this promoter component (referred to as M) added is such that the atomic ratio of Pd to M is
1:0.01 to 1:100, preferably 1:0.1 to 1:10
is within the range of In addition to the method of obtaining palladium and the co-catalyst component in separate compounds, it is also possible to use a compound containing both of these components at the same time, such as sodium chloride palladate. In addition to impregnating promoter components in the form of salts, it is also possible to use carriers in which these components have been ion-exchanged in advance, such as NaY-type zeolite. A support for a compound containing a palladium compound and a cocatalyst component can be carried out by a conventional impregnation method or an ion exchange method using a solution of these compounds in water or other solvents. The supported catalyst thus obtained was heated at 200° C. in the presence of hydrogen gas.
It can be made active for the synthesis of methanol and/or dimethyl ether by heat treatment at ~600°C, but the optimal treatment conditions must be selected depending on the type of catalyst component and support and the applicable reaction conditions. It is essential. As the carrier used in the present invention, oxides having surface hydroxyl groups are particularly effective; for example, one or more of synthetic or naturally occurring zeolites, amorphous silica/alumina, alumina, silica, titania, zirconia, etc. Two or more types can be selected and used. In the catalyst of the present invention, the selectivity of the main products methanol and dimethyl ether varies significantly depending on the difference in the properties of these phases. In other words, when the carrier is alumina or silica, which does not exhibit properties as a solid acid, dimethyl ether is hardly produced, and methanol is produced with high selectivity, whereas dimethyl ether has properties as a solid acid. When the zeolite (crystalline silica/alumina) is amorphous silica/alumina, dimethyl ether can be obtained with high selectivity. This is presumed to be due to the fact that methanol produced in the initial reaction is dehydrated at acid sites on the carrier to produce dimethyl ether. Furthermore, when zeolite is used as a carrier, the selectivity of the main products, methanol and dimethyl ether, changes significantly depending on the method of supporting the palladium compound. That is, a catalyst supported by an impregnation method using a complex anion compound of palladium, such as an aqueous solution of palladate chloride (Example 3), has high methanol selectivity, whereas a complex cation compound of palladium, such as tetraammine, supports the catalyst by an impregnation method. A catalyst supported by a cation exchange method using a palladium salt (Example 4) has high dimethyl ether selectivity. The reaction of the present invention can be carried out in a conventional gas phase flow system, but it can also be carried out in a liquid phase flow system by dispersing the catalyst in a suitable solvent. The molar ratio of carbon monoxide to hydrogen in the reaction gas can normally be within the range of 1:20 to 20:1, but is particularly preferably within the range of 1:10 to 10:1. The mixed gas may be in a reduced pressure, normal pressure, or pressurized state as required. The reaction can also be carried out at low temperatures, preferably in the range of 50 to 400°C. EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. Example 1 1.382 g of crystals of sodium chloropalladate Na ₂ [PdCl ₄ ] were dissolved in 324.1 ml of distilled water, 9.28 g of alumina powder was added thereto, and the mixture was stirred at room temperature for about 1 hour. This slurry was evaporated to dryness using a rotary evaporator and further dried in air at 120°C for 5 hours. 1 g of the catalyst powder thus obtained was added to a Pyrex glass closed circulation reactor (volume:
250 ml), placed a liquid nitrogen trap in the reaction system, and heated to 300 mL under circulating hydrogen gas (approx. 50 cmHg).
Heat treatment was performed at ℃ for 2 hours. Next, a mixed gas of carbon monoxide and hydrogen with a molar ratio of 1:2 was added to the reactor.
cmHg was introduced, a liquid nitrogen trap was placed in the reaction system, and the reaction was carried out at 180°C under gas circulation.
After the reaction for a certain period of time, the products in the gas phase and the products collected in the liquid nitrogen trap were analyzed and quantified by gas chromatography, and confirmed by mass spectrometry. Small amounts of methane were detected as gas phase products;
The products detected in the liquid nitrogen trap were methanol, dimethyl ether and water, as well as traces of carbon dioxide and C2 _and higher hydrocarbons. This reaction treatment was repeated, and the synthesis activity of methanol and dimethyl ether was maintained even after a total of 300 hours of reaction. The results are shown in Table 1. Example 2 1.631 g of sodium chloride palladate crystals were dissolved in 156.6 ml of distilled water, 9.160 g of silica alumina powder (Si/Al=2.1) was added thereto, and the mixture was stirred at room temperature for about 1 hour. This slurry was evaporated to dryness using a rotary evaporator, and further heated to 120°C in air.
It was dried for 5 hours. 1 g of the catalyst powder thus obtained was packed into a Pyrex glass closed circulation reactor (volume 250 ml), a liquid nitrogen trap was placed in the reaction system, and hydrogen gas (approximately 50 cmHg) was circulated.
Heat treatment was performed at 300°C for 2 hours. Next, a hydrogenation reaction of carbon monoxide was carried out in the same manner as in Example 1, and the results are shown in Table 1. Example 3 2.447 g of sodium chloropalladate crystals were dissolved in 234.9 ml of distilled water, 13.74 g of NaY type zeolite powder (Si/Sl=2.4) was added thereto, and the mixture was stirred at room temperature for about 1 hour. This slurry was evaporated to dryness in a rotary evaporator, and further
It was dried at ℃ for 5 hours. 1 g of the catalyst powder thus obtained was packed into a Pyrex glass closed circulation reactor (volume 250 ml), a liquid nitrogen trap was placed in the reaction system, and hydrogen gas (approximately 50 cmHg) was circulated at 450°C for 50 minutes. Heat treatment was performed for a period of time. Next, a hydrogenation reaction of carbon monoxide was carried out in the same manner as in Example 1, and the results are shown in Table 1. Example 4 1.155 g of tetraamine palladium () chloride [Pd(NH ₃ ) ₄ ]Cl ₂ crystals was added to 158.8 ml of distilled water.
and add NaY type zeolite (Si/Al=
2.4) After adding 9.500 g and stirring at room temperature for 59 hours, the slurry was filtered to separate the precipitate. The ultraviolet absorption spectrum of the zeolite solution was measured, and it was found that the absorption at 296 nm, which is the characteristic absorption of the tetraammine palladium () chloride aqueous solution, disappeared, indicating that the tetraammine palladium () ions charged in the aqueous solution and the sodium ions in the zeolite were completely ionized. I confirmed that it was replaced. The precipitate after separation was washed with distilled water until no chlorine ions were detected, and then dried in air at 120°C for 5 hours. 1 g of the catalyst powder thus obtained was charged into a closed circulation reactor (volume 250 ml) made of Pyrex glass.
A liquid nitrogen trap was placed in the reaction system, and heat treatment was performed at 450° C. for 5 hours while circulating hydrogen gas (approximately 50 cmHg). Next, a hydrogenation reaction of carbon monoxide was carried out in the same manner as in Example 1, and the results are shown in Table 1. Example 5 1037 g of sodium chloride palladate crystals were dissolved in 243.1 ml of distilled water, and 6870 g of silica powder was added to this.
was added and stirred at room temperature for about 1 hour. This slurry was evaporated to dryness using a rotary evaporator.
It was further dried in air at 120°C for 5 hours. 1 g of the catalyst powder thus obtained was packed into a Pyrex glass closed circulation reactor (volume 250 ml), a liquid nitrogen trap was placed in the reaction system, and hydrogen gas (approx.
Heat treatment was performed at 500°C for 5 hours under a circulating atmosphere (50cmHg). Next, a hydrogenation reaction of carbon monoxide was carried out in the same manner as in Example 1, and the results are shown in Table 1. Comparative example 1 Ammonium chloropalladate (NH ₄ ) ₂
Dissolve 1336 g of [PdCl ₄ ] crystals in 324.1 ml of distilled water,
9,500 g of silica powder was added to this, and the mixture was stirred at room temperature for about 1 hour. This slurry was evaporated to dryness using a rotary evaporator and further dried in air at 120°C for 5 hours. 1 g of the catalyst powder thus obtained was packed into a closed circulation reactor made of Pyrex glass, a liquid nitrogen trap was placed in the reaction system, and heat treatment was performed at 500°C for 5 hours while circulating hydrogen gas (approximately 50 cmHg). I did this. Next, a hydrogenation reaction of carbon monoxide was carried out in the same manner as in Example 1, but methanol and dimethyl ether were not detected even at a reaction temperature of 210°C, and trace amounts of methane, carbon dioxide, and
Only hydrocarbons higher than _C2 were detected. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1. A method for producing methanol and/or dimethyl ether, which comprises catalytically hydrogenating carbon monoxide with palladium and sodium in the presence of a catalyst supported on a carrier. 2. The method according to claim 1, wherein the carrier is an oxide having surface hydroxyl groups. 3 The molar ratio of the reactive gases carbon monoxide and hydrogen is
0.05 to 20 (1:20 to 20:1). 4. The method according to claim 1, 2 or 3, wherein the reaction temperature is 50 to 400°C.