JP2000000466A - Catalyst for syngas production and method for syngas production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst and a production method capable of obtaining a synthesis gas at a low temperature and a high yield. A catalyst for generating a synthesis gas from dimethyl ether and water vapor, characterized by containing at least one of iridium, platinum, rhodium, or a palladium-supported metal oxide and a solid acidic compound as active components. Solved by

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for producing a synthesis gas from a mixed gas containing dimethyl ether and steam, and a method for producing a synthesis gas using the catalyst.

[0002]

2. Description of the Related Art Synthetic gas is a gas composed of carbon monoxide and hydrogen, and is directly used as a raw material gas for methanol synthesis, oxo synthesis, Fischer-Tropsch synthesis, etc., and is widely used as a raw material for ammonia synthesis and various chemical products. Has a use.

Conventionally, several methods for producing synthesis gas are known. For example, (1) a method by gasification of coal,
(2) a method for steam reforming of hydrocarbons using natural gas, LPG, naphtha, etc. as raw materials; (3) a method for natural gas, LPG, naphtha,
There is a method of partially oxidizing hydrocarbons using heavy oil or the like as a raw material.

As a catalyst for producing hydrogen, carbon monoxide and the like from dimethyl ether and water vapor, a catalyst made of copper or nickel and containing no alkali metal is known (Japanese Patent Application Laid-Open No. 9-510178).

[0005]

SUMMARY OF THE INVENTION
In the coal gasification method (1), an extremely complicated and expensive coal gasification furnace is required, and there is a problem that the equipment becomes a large-scale plant. Further, in the hydrocarbon steam reforming method (2), since the reaction is a large endothermic and requires a high temperature of 700 to 1200 ° C. for the progress of the reaction,
There is a problem that a special reforming furnace is required, and that the catalyst used is required to have high heat resistance. Also in the method for partially oxidizing hydrocarbons of the above (3), 1200 to 1500 ° C.
Requires a special partial oxidation furnace because of the high temperature required, and a large amount of soot is generated during the reaction, which poses a problem in the treatment.If a catalyst is used, the carbonaceous substance However, there is a problem that a large amount of the catalyst precipitates to deteriorate the catalyst.

On the other hand, a catalyst comprising copper or nickel and containing no alkali metal has a high yield of carbon dioxide and a low yield of carbon monoxide in the produced gas, and is unsatisfactory as a catalyst for producing synthesis gas. there were.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a catalyst and a production method capable of obtaining a synthesis gas at a low temperature and a high yield.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have come to focus on dimethyl ether as a raw material gas. Iridium, platinum, rhodium and palladium-supported metal oxides and solid acidic compounds are extremely effective as catalysts for reacting dimethyl ether and water vapor to generate synthesis gas, and that synthesis gas can be efficiently generated at low temperatures. It was found that the present invention was completed.

That is, the present invention is characterized in that a synthesis gas is produced from dimethyl ether and water vapor, characterized in that it contains at least one of iridium, platinum, rhodium or palladium-supported metal oxide and a solid acidic compound as active ingredients. A synthesis gas characterized by contacting a catalyst and a mixed gas containing dimethyl ether and water vapor with a catalyst containing at least iridium, platinum, rhodium, or a metal oxide supported on palladium and a solid acidic compound as an active ingredient. And a method for producing the same.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The active ingredients iridium, platinum and rhodium are these metals and / or compounds. As iridium compounds, iridium oxides,
Chloride is preferred, with the oxide of iridium being IrO ₂ and the chloride being IrCl ₃ . Platinum compounds are preferably platinum oxides and chlorides. The oxides of platinum are PtO and PtO ₂ , and the chlorides are PtCl ₂ , PtCl ₃ and PtCl ₄ . The rhodium compound is preferably an oxide or chloride of rhodium. Rhodium oxide is R
h ₂ O ₃ and the chloride is RhCl ₃ .

The iridium, platinum and rhodium catalysts can be used by being supported on a catalyst carrier. Preferred catalyst carriers are oxides such as alumina, silica gel, silica-alumina, zeolite, titania, zirconia, zinc oxide, tin oxide, lanthanum oxide, and cerium oxide, among which alumina has a high synthesis gas yield. preferable. The content of iridium, platinum or rhodium in the catalyst is about 0.05 to 10% by weight, preferably 0.1 to 10% by weight.
1 to 5% by weight. If the content is less than about 0.05% by weight and not less than 10% by weight, the yield of synthesis gas decreases. Iridium, platinum and rhodium are these two
More than one species can be combined, in which case the above content is the sum of them.

The catalyst of the present invention may use other metals or compounds in addition to the metals and / or compounds of iridium, platinum and rhodium. Examples of other metals and compounds include metals and / or compounds of copper, cobalt, nickel and iron.
In addition, these metals and compounds are used alone and
Mixtures of more than one species can be used. The content of these third components is 20% by weight or less, particularly 10% by weight or less, and when they are contained, they are usually about 1 to 5% by weight.

For the preparation of these catalysts, general methods for preparing such catalysts can be applied. For example, as a raw material for producing a catalyst, as a compound of iridium, platinum or rhodium, an inorganic acid salt such as nitrate, carbonate, halide and the like and an organic acid salt such as acetate and oxalate are used. Also,
For the loading operation on the catalyst carrier, techniques such as ordinary precipitation method, kneading method, impregnation method and ion exchange method can be used. The catalyst composition thus prepared is calcined by a conventional method, if necessary. Calcination is performed in nitrogen or air in 3
It is preferable to heat at a temperature of 00 to 700 ° C. for 1 to 10 hours.

The catalyst is generally subjected to an activation treatment before the reaction.
The treatment is preferably performed at a temperature of 00 ° C. for 1 to 10 hours.

The palladium catalyst of the present invention is a catalyst obtained by physically mixing a metal oxide having palladium supported thereon and a compound having solid acidity.

One of the catalyst components constituting the catalyst is a metal oxide having palladium supported thereon. The metal oxides used are silica gel, titania, alumina,
Silica / alumina, zirconia, tin oxide, zinc oxide and the like are preferable, and among them, silica gel and titania are preferable because of high synthesis gas yield. The amount of palladium supported on the metal oxide is about 0.05 to 30% by weight, preferably 0.1 to 20% by weight, based on the metal oxide. When the loading of palladium is less than about 0.05% by weight and 30% by weight or more, the yield of synthesis gas decreases. Further, as one of the catalyst components constituting the catalyst of the present invention, other metals or compounds can be used in addition to palladium. Examples of other metals and compounds include Li ₂ O, Na
Oxides of alkali metals such as ₂ O, K ₂ O, Rb ₂ O, Cs ₂ O, oxides of alkaline earth metals such as BeO, MgO, CaO, SrO, BaO, Y ₂ O ₃ , La ₂ O ₃ And a mixture of two or more of oxides of rare earth elements such as CeO ₂ and the above-mentioned metal oxides. The content of these third components is 20% by weight.
Or less, especially 10% by weight or less, and when contained,
Usually, it is about 1 to 5% by weight.

For the preparation of the palladium-supported metal oxide catalyst, a general preparation method of this type of catalyst can be applied. For example, as a raw material for producing a catalyst, inorganic salts such as nitrates, carbonates and halides and organic acid salts such as palladium acetate and palladium oxalate are used as palladium compounds. For the operation of loading palladium on the metal oxide carrier, techniques such as ordinary precipitation, kneading, impregnation, and ion exchange can be used. The catalyst composition thus prepared is calcined by a conventional method, if necessary. The calcination is preferably performed by heating at a temperature of 300 to 600 ° C. for 1 to 10 hours in nitrogen or air.

Next, in a hydrogen atmosphere, 300 to 6
The treatment is preferably performed at a temperature of 00 ° C. for 1 to 10 hours.

The other catalyst component constituting the catalyst of the present invention is a compound having solid acidity. Compounds having solid acidity include alumina, silica-alumina, silica-titania, zeolite, aluminum phosphate, and the like. Of these, alumina is preferred because of its high synthesis gas yield.

In the method of mixing the above two types of catalyst components, both components may be pelletized and then physically mixed. Alternatively, both components may be powdered, physically mixed and then compression-molded into pellets. It may be. The mixing ratio of the two components is not particularly limited, and may be appropriately selected depending on the type of each component or the reaction conditions, but is usually about 1:10 to 10: 1 by weight, preferably about 10: 1. 1: 5
It is about 5: 1.

In the above catalyst, dimethyl ether is hydrolyzed to produce methanol by the catalytic action of a compound having solid acidity (formula (1)), and the produced methanol is used to carry palladium on a metal oxide. The catalyst is brought into contact with a catalyst to decompose methanol to generate synthesis gas (formula (2)). By physically mixing the above two types of catalysts and using them, synthesis gas can be produced in high yield. Obtainable. CH ₃ OCH ₃ + H ₂ O → 2CH ₃ OH (1) CH ₃ OH → CO + 2H ₂ (2)

By allowing a mixed gas of dimethyl ether and steam to flow through the catalyst thus prepared,
Syngas is obtained in high yield.

In the present invention, steam is supplied together with the raw material dimethyl ether. The steam to be supplied only needs to be a stoichiometric amount or more with respect to the dimethyl ether as the raw material.
The molar amount is 0 times, preferably 1 to 10 times. If the supply of steam is less than 1 mole, a high dimethyl ether conversion cannot be obtained, and if it is more than 20 moles, it is not economical. This raw material gas can also contain components other than dimethyl ether and water vapor. Other components may include gases inert to the reaction, such as nitrogen, inert gases, and the like. The content of these is suitably not more than 30% by volume. If the content is more than 30% by volume, the reduction of the reaction rate becomes a problem.
On the other hand, air (oxygen) burns dimethyl ether, so it is better to exclude it as much as possible, and the allowable content is 5% or less as air.

The reaction temperature is 200 to 600 ° C., preferably 300 to 500 ° C. for the iridium catalyst and the rhodium catalyst.
℃, platinum catalyst 250-450 ℃, palladium catalyst 2
50-500 ° C. If the reaction temperature is lower than 200 ° C., a high conversion of dimethyl ether cannot be obtained, and the production ratio of carbon dioxide increases to lower the yield of synthesis gas.
On the other hand, when the reaction temperature is higher than 600 ° C., generation of hydrocarbons mainly composed of methane becomes remarkable, and the ratio of synthesis gas in the product is undesirably reduced.

The reaction pressure is preferably normal pressure to 10 kg / cm ² . If the reaction pressure is higher than 10 kg / cm ² , the conversion of dimethyl ether decreases.

The space velocity (the supply rate m ³ / h of the mixed gas in a standard state per m ^{3 of the} catalyst) is 1000 to 2
0000 m ³ / m ³ · h is preferred. Space velocity 2000
If it is greater than 0 m ³ / m ³ · h, the conversion of dimethyl ether is low, and if it is less than 1000 m ³ / m ³ · h, the reactor becomes extremely large and is not economical.

In the method of the present invention, a fixed bed,
Any apparatus of a fluidized bed may be used.

Thus, in the case of the iridium catalyst, the conversion of dimethyl ether is about 60 to 100%, usually 70 to 100%.
At about 100%, synthesis gas can be obtained at a yield of about 60 to 95%, usually about 70 to 95%. As for by-products, methanol is 10% or less, usually 5% or less, and hydrocarbon is 20% or less, usually 10% or less.

In the case of a platinum catalyst, the conversion of dimethyl ether is about 60 to 100%, usually about 70 to 100%.
The synthesis gas can be obtained in a yield of about 50 to 90%, usually about 60 to 80%. For by-products, methanol is less than 20%, usually less than 10%, hydrocarbons less than 5%,
Usually, it is 1% or less.

In the case of a rhodium catalyst, the conversion of dimethyl ether is about 50 to 100%, usually about 60 to 90%, and the synthesis gas is produced in a yield of about 50 to 90%, usually 60 to 80%.
%. As for by-products, methanol is 10% or less, usually 5% or less, and hydrocarbon is 20% or less, usually 10% or less.

In the case of a palladium catalyst, the dimethyl ether conversion is about 50 to 100%, usually 60 to 10%.
At about 0%, the synthesis gas yield is about 40-90%, usually about 5%.
It can be obtained at about 0 to 90%. As for by-products, methanol is 20% or less, usually 5% or less, and hydrocarbon is 20% or less, usually 5% or less.

[0032]

EXAMPLES [Examples 1 to 6] Preparation of catalyst 0.777 g of iridium chloride (IrCl ₃ ) was dissolved in about 300 ml of ion-exchanged water, and 99.5 g of γ-alumina (Catalyst Society, ALO-4) was added to the aqueous solution, and the mixture was evaporated to dryness. Then, put this in air at 120 ° C for 2 hours.
It was dried for 4 hours and fired in air at 500 ° C. for 3 hours. Then, a treatment was performed at 500 ° C. for 3 hours in a hydrogen stream to obtain a catalyst. The composition of the obtained catalyst was Ir: Al ₂ O ₃ =
0.5: 99.5 (weight ratio).

II. Reaction Method A predetermined amount of the above catalyst was charged into a stainless steel reaction tube having an inner diameter of 20 mm. A predetermined amount of dimethyl ether and water vapor were supplied to the reaction tube and reacted at a predetermined temperature. The reaction products and unreacted products obtained by the above operations were analyzed by gas chromatography.

III. Reaction conditions and experimental results Reaction conditions and experimental results are shown in Tables 1 and 2.

[0035]

(Equation 1)

[0036]

(Equation 2)

[0037]

(Equation 3)

[0038]

(Equation 4) All units of each speed are [mol / g-cat · h]

[0039]

[Table 1]

[0040]

[Table 2]

Examples 7 to 12 Preparation of Catalyst 0.863 g of platinum chloride (PtCl ₄ ) was dissolved in about 300 ml of a 10 wt% aqueous hydrochloric acid solution, and γ was added to the aqueous solution.
99.5 g of alumina (catalyst society, ALO-4) was charged and evaporated to dryness. And put this in the air, 120
C. for 24 hours, and calcined in air at 500.degree. C. for 3 hours. Then, a treatment was performed at 500 ° C. for 3 hours in a hydrogen stream to obtain a catalyst. The composition of the obtained catalyst is Pt: Al
₂ O ₃ = 0.5: 99.5 (weight ratio).

II. Reaction method It carried out similarly to Examples 1-6.

III. Reaction conditions and experimental results Reaction conditions and experimental results are shown in Tables 3 and 4.

[0044]

[Table 3]

[0045]

[Table 4]

Examples 13 to 18 Preparation of catalyst 1.40 g of rhodium nitrate (Rh (NO ₃ ) ₃ ) was dissolved in about 300 ml of ion-exchanged water, and 99.5 g of γ-alumina (Catalyst Society, ALO-4) was added to this aqueous solution and evaporated to dryness. Hardened. Then, put this in air at 120 ° C for 2 hours.
It was dried for 4 hours and fired in air at 500 ° C. for 3 hours. Then, a treatment was performed at 500 ° C. for 3 hours in a hydrogen stream to obtain a catalyst. The composition of the resulting catalyst was Rh: Al ₂ O ₃ =
0.5: 99.5 (weight ratio).

II. Reaction method It carried out similarly to Examples 1-6.

III. Reaction conditions and experimental results Reaction conditions and experimental results are shown in Tables 5 and 6.

[0049]

[Table 5]

[0050]

[Table 6]

Examples 19 to 23 Preparation of Catalyst 0.833 g of palladium chloride (PdCl ₂ ) was dissolved in 5 ml of hydrochloric acid, and ion-exchanged water was added thereto, and the resulting mixture was added to about 500 ml.
silica gel (Catalysis Society of Japan, SIO-
4) 99.5 g was charged and evaporated to dryness. Then, it was dried in air at 120 ° C. for 24 hours, and further baked in air at 500 ° C. for 3 hours. Then, put this thing in 2
After sizing to 0-40 mesh, 500 ° C in a hydrogen stream
For 3 hours. Its composition is Pd: Si
O ₂ = 0.5: 99.5 (weight ratio). Further, this was physically mixed with γ-alumina (catalyst society, ALO-4) sized to 20 to 40 mesh at a weight ratio of 1: 1 to obtain a catalyst.

[Examples 24 to 28] 0.833 g of palladium chloride (PdCl ₂ ) was dissolved in 5 ml of hydrochloric acid, and ion-exchanged water was added to the solution to make about 500 ml. ) 98.5 g were charged and evaporated to dryness. And this thing in the air, 1
Dry at 20 ° C for 24 hours, and further in air at 500 ° C for 3 hours.
Fired for hours. Then, this was put into an aqueous solution in which 1.46 g of potassium carbonate (K ₂ CO ₃ ) was dissolved in about 500 ml of ion-exchanged water, and evaporated to dryness. Then, it was dried in air at 120 ° C. for 24 hours and fired in air at 500 ° C. for 3 hours. In addition, this thing 20-
After sieving to 40 mesh, the mixture was placed in a hydrogen stream at 500 ° C for 3 hours.
Time processing was performed. Its composition is Pd: K ₂ O:
Al ₂ O ₃ = 0.5: 1.0: 98.5 (weight ratio). Furthermore, this was physically mixed with γ-alumina (catalyst society, ALO-4) sized to 20 to 40 mesh at a weight ratio of 1: 1 to obtain a catalyst.

[Examples 19 to 33] Catalysts were prepared in the same manner as in Examples 19 to 23, except that titania (catalyst society, TIO-4) was used instead of silica gel.

II. Reaction Method A predetermined amount of the above catalyst was charged into a stainless steel reaction tube having an inner diameter of 20 mm. A predetermined amount of dimethyl ether, steam and / or carbon dioxide was supplied to the reaction tube and reacted at a predetermined temperature. The reaction products and unreacted products obtained by the above operations were analyzed by gas chromatography.

III. Reaction conditions and experimental results Reaction conditions and experimental results are shown in Tables 7 to 9.

[0056]

[Table 7]

[0057]

[Table 8]

[0058]

[Table 9]

[0059]

The catalyst for syngas production according to the present invention is obtained by mixing a mixed gas of dimethyl ether and steam at 200 to 600 ° C.
A high synthesis gas yield can be obtained at low temperatures.

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. Hei 10-1006832 (32) Priority date April 17, 1998 (April 17, 1998) (33) Priority claim country Japan (JP) (72) Inventor Yotaro Ohno 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Kaoru Fujimoto 6-18-1031 Minamioi, Shinagawa-ku, Tokyo

Claims (6)

[Claims] 1. A catalyst for producing a synthesis gas from dimethyl ether and water vapor, comprising at least one of iridium, platinum, rhodium, or a palladium-supported metal oxide and a solid acidic compound as active ingredients. 2. The catalyst according to claim 1, wherein said active ingredient is iridium. 3. The catalyst according to claim 1, wherein said active component is platinum. 4. The method according to claim 1, wherein said active ingredient is rhodium.
The catalyst described in 5. The catalyst according to claim 1, wherein the active components are a palladium-supported metal oxide and a solid acidic compound. 6. A mixed gas containing dimethyl ether and steam is brought into contact with a catalyst containing at least one of iridium, platinum, rhodium, or a metal oxide supported on palladium and a solid acidic compound as an active component. Synthesis gas production method