JPH05170403A - How to convert carbon dioxide with methane - Google Patents

Abstract

PURPOSE:To provide the converting method of carbon dioxide being a cause material for making the earth warm and not evaluated up to the present as an useful industrial raw material to carbon monooxide and hydrogen which are useful for industries. CONSTITUTION:A gaseous mixture incorporating carbon dioxide and methane at a specified ratio is allowed to pass through a catalyst supporting an alkaline earth metal oxide and a metal or a metal oxide as effective components to recover carbon monooxide and hydrogen.

Description

Detailed Description of the Invention

[0001]

The present invention uses carbon dioxide, which is a major causative agent of global warming, by using methane as a reducing agent,
The present invention relates to a method for converting industrially useful carbon monoxide and hydrogen (hereinafter abbreviated as "synthesis gas").

[0002]

2. Description of the Related Art As carbon dioxide is a major causative agent of global warming, reduction of emission and effective use are urgently required, and in recent years, chemical conversion methods of carbon dioxide have been widely used (electric reduction method, photosynthesis method). , Catalytic hydrogen reduction method, etc.).

[0003] Among them, there are very few reports of converting carbon dioxide into a synthesis gas useful as a raw material when synthesizing various organic compounds by hydroformylation using methane as a reducing agent.
Catalytic method using Group III transition metal catalyst (React.
Kinet. catal. , 24 (3-4), 253
(1984), and 68th Catalytic Discussion Group (A) Proceedings,
3H327 (1991)).

[0004]

However, when a catalyst supporting a noble metal is used, the noble metal is expensive and economically disadvantageous. In addition, a less expensive Group VIII transition metal having the same catalytic activity and life as a noble metal, especially a nickel catalyst, exhibits the same activity, but on the other hand, the tendency of carbon precipitation is strong, so that the activity tends to deteriorate. There is.

[0005]

As a result of examining various additive effects in the catalyst, the present inventors have found that a catalyst containing an alkaline earth metal oxide has a stable activity without carbon deposition. The inventors have found what is shown and have completed the present invention.

That is, a feature of the present invention is that when a gas containing carbon dioxide and methane is brought into contact with a catalyst to produce carbon monoxide and hydrogen, a metal containing an alkaline earth metal oxide as a catalyst or a metal oxide. It is to use a physical catalyst.

The present invention will be described in detail below.

The catalyst used in the present invention may be composed of an alkaline earth metal oxide and a metal or a metal oxide, or both of them may be silica, alumina, zirconia, niobia, titania, plasma. It may be supported on an oxide such as aluminosilicate.

As the alkaline earth metal oxides, those containing at least one oxide selected from magnesium oxide, calcium oxide, barium oxide and strontium oxide can be used at zero time. When the alkaline earth metal oxides are composed of two or more oxides, their weight ratio is not particularly limited.

The content of the alkaline earth metal oxides in the catalyst is not particularly limited as long as it is 0.01% by weight or more, but more preferably 0.1 to 95% by weight.

Metals or metal oxides are noble metals, VII
Any metal or metal oxide selected from Group I transition metals and oxides of these metals may be used.

Specific examples thereof include rhodium, iridium, ruthenium, cobalt, nickel and oxides thereof. Among them, nickel or nickel oxide, which is cheaper in terms of cost, is economical and advantageous.

The content of metal or metal oxide in the catalyst is preferably 0.01 to 70% by weight. Content is 0.0
If it is less than 1% by weight, a sufficient carbon dioxide conversion rate may not be obtained. On the other hand, when it exceeds 70% by weight, the expected improvement in conversion is not observed.

The method for preparing the metal or metal oxide containing the alkaline earth metal oxides is not particularly limited, and it can be produced by a usual impregnation method, coprecipitation method or the like.

For example, the following method can be mentioned for nickel or nickel oxide catalysts containing alkaline earth metal oxides.

(1) A silica molded product is impregnated with an aqueous solution of an alkaline earth metal salt, dried and fired, and the resulting oxide is impregnated with an aqueous nickel salt solution for activation.

(2) Ammonia is added to an aqueous solution in which alkaline earth metal salts and aluminum salts are mixed to form a precipitate, and the resulting gel is dried and impregnated with an aqueous nickel salt solution for activation treatment.

(3) To silica alkoxide, an alkaline earth metal salt and a nickel salt are added and hydrolyzed to obtain a precipitate, which is dried, calcined and reduced.

(4) The titania molded product is simultaneously impregnated with a mixed aqueous solution of an alkaline earth metal salt and a nickel salt, and dried and fired.

(5) The nickel oxide and magnesium oxide are physically mixed and an activation treatment is carried out. Note that metals other than nickel can be manufactured in the same manner.

The catalyst may contain lanthanum or cerium metal oxide by the above-mentioned preparation method.

The nickel salt and alkaline earth metal salt used for preparing the catalyst in the present invention are not particularly limited, but nitrates, carbonates and organic complexes which are easily decomposed during the activation treatment are more preferable.

The catalyst activation treatment means calcination with air or the like and reduction with hydrogen, hydrogen sulfide or the like. In order to obtain a sufficient carbon dioxide conversion rate, it is preferable to carry out a reduction treatment. The catalyst may be used by molding or may be used as a powder, and may be molded into a desired size according to the reaction method.

The amount of methane in the present invention can be defined as the molar ratio of methane to carbon dioxide.
Specifically, the methane / carbon dioxide ratio is 0.05 to 25.
And 0.1 to 20 is preferable. methane/
If the ratio with carbon dioxide is less than 0.05, the amount of carbon dioxide to be recycled increases, while if the ratio of methane / carbon dioxide exceeds 25, a sufficient carbon monoxide generation rate cannot be obtained, which is uneconomical. There is.

In the present invention, nitrogen, air or steam may be added to the system as a diluent gas.

The reaction temperature in the present invention is 300 to 100.
The temperature is 0 ° C, more preferably 400 to 950 ° C. If the reaction temperature is lower than 300 ° C, a sufficient conversion rate of carbon dioxide cannot be obtained, and if the reaction temperature exceeds 1000 ° C, the activity may decrease due to the sintering of the catalyst.

The reaction pressure is not particularly limited, and the reaction may be carried out at atmospheric pressure to 20 atm, preferably atmospheric pressure to 10 atm.

The raw material supply rate to the catalyst can be defined by the raw material supply rate (SV) per unit catalyst volume. The method h and SV of the present invention are 500 to 100,000 / h.
Is. If the SV is less than 500 / h, the carbon monoxide generation rate is low, and if the SV is more than 100,000 / h, the conversion rate of the raw material is lowered, which may be uneconomical.

The reaction method is not particularly limited as long as the catalyst and the raw material can be efficiently contacted, and the reaction can be carried out in a fixed bed, a fluidized bed or a moving bed.

[0030]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited by these examples.

Example 1 4.2 g of spherical silica having a diameter of 3 mm (made by Fuji Davison, Carriact-30) was immersed in an aqueous solution of 2.5 g of magnesium acetate tetrahydrate dissolved in 8 cc of water for 3 hours, and then 110 C., and dried for 11 hours. Then this is 600 ℃
4.6 g of the carrier which had been air-calcined for 2 hours was immersed in an aqueous solution of 2.3 g of nickel nitrate hexahydrate dissolved in 9 cc of water for 3 hours, then dried at 110 ° C. overnight and then at 500 ° C. for 1 hour
Reduced under a 10% hydrogen flow, nickel 10% by weight,
A catalyst containing 10% magnesium oxide and 80% silica was obtained.

1.5 g of this catalyst was added to SUS with an inner diameter of 14 mm.
The reaction tube was filled, the reaction temperature was kept at 500 ° C., and a mixed gas having a carbon dioxide: methane: nitrogen molar ratio of 1: 1: 3 was supplied at 100 cc / min. The analysis of the outlet gas was carried out by gas chromatography, and the yield of carbon monoxide and the degree of carbon deposition were calculated from the mass balance of carbon by the following formulas.

CO yield (%) = moles of outlet CO / (moles of supplied CO ₂ + moles of supplied CH ₄ ) × 100 (%) Deposition degree of carbon (%) = (1-total carbon of outlet gas Number of moles /
(Moles of supplied CO ₂ + moles of supplied CH ₄ )) × 100
(%) The results are shown in Table 1.

Example 2 A predetermined amount of calcium nitrate tetrahydrate was used in place of magnesium acetate, and the same catalyst preparation procedure as in Example 1 was used to prepare nickel 10%, calcium oxide 10% and silica 80% by weight. The contained catalyst was obtained. Using 1.5 g of this catalyst, the same reaction operation as in Example 1 was performed. The results are shown in Table 1.
Shown in.

Example 3 A catalyst containing nickel 10%, barium oxide 10% and silica 80% by weight was prepared by the same catalyst preparation procedure as in Example 1 except that a predetermined amount of barium nitrate was used instead of magnesium acetate. Obtained. Using 1.5 g of this catalyst, the same reaction operation as in Example 1 was performed. The results are shown in Table 1.

Example 4 5.9 g of nickel nitrate hexahydrate, 2.3 g of calcium nitrate tetrahydrate and 0.75 g of magnesium nitrate hexahydrate were dissolved in 10 cc of water, and then spherical alumina having a diameter of 3 mm (Sumitomo 10g of KHA-24) manufactured by Kagaku Co., Ltd. was immersed for 3 hours. 1
After drying overnight at 10 ° C, air calcination at 600 ° C for 2 hours, followed by reduction treatment in a 10% hydrogen stream at 500 ° C for 1 hour, weight ratio nickel 10%, calcium oxide 5%, magnesium oxide 1%. A catalyst composed of 84% alumina was obtained. Using 1.5 g of this catalyst, the same reaction operation as in Example 1 was performed. The results are shown in Table 1.

Example 5 5 g of nickel nitrate hexahydrate and 4.1 g of calcium nitrate tetrahydrate were dissolved in 100 cc of ethylene glycol and then heated to 80 ° C. with stirring. While maintaining the temperature, 32.4 g of aluminum isopropoxide was added dropwise thereto, and the mixture was further stirred at the same temperature for 3 hours. Then water 1
3 g was added and hydrolyzed, followed by stirring for 3 hours to obtain the desired gel. The gel was dried at 110 ° C. for 24 hours, pressure-molded, air-baked at 700 ° C. for 2 hours, and further reduced at 600 ° C. for 1 hour in a 10% hydrogen stream. 10% by weight of nickel, calcium oxide, and alumina, respectively, 1
A catalyst consisting of 0% and 80% was obtained. 1.5g of this catalyst
Was used and the same reaction operation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 14 g of spherical silica having a diameter of 3 mm (manufactured by Fuji Davison) was immersed in an aqueous solution prepared by dissolving 6.9 g of nickel nitrate hexahydrate in 20 cc of water for 3 hours, and then the same treatment as in Example 1 was performed. A catalyst containing nickel 10% and silica 90% by weight was obtained. Using 1.5 g of this catalyst, the same reaction operation as in Example 1 was performed. The results are shown in Table 1.

[0039]

[Table 1]

[0040]

When carbon dioxide is reduced by methane,
By using the catalyst of the present invention, it is possible to suppress carbon deposition on the catalyst surface and produce synthesis gas.

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[Procedure amendment]

[Submission date] January 20, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The catalyst used in the present invention may be composed of an alkaline earth metal oxide and a metal or a metal oxide, and both of them may be silica, alumina, zirconia, niobia, titania, crystals. It may be supported on an oxide such as aluminosilicate.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

Examples of the alkaline earth metal oxides include those containing at least one oxide selected from magnesium oxide, calcium oxide, barium oxide and strontium oxide. When the alkaline earth metal oxides are composed of two or more oxides, their weight ratio is not particularly limited.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

The method for preparing the metal or metal oxide catalyst containing the alkaline earth metal oxides is not particularly limited,
It can be produced by a usual impregnation method, a coprecipitation method or the like.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016] The (1) silica molded product, a process of dipping and dried and baked in an aqueous solution obtained by dissolving an alkaline-earth metal salts, performs immersed activation treatment aqueous nickel salt solution and the resulting oxide ..

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

(2) Ammonia is added to an aqueous solution in which alkaline earth metal salts and aluminum salts are mixed to form a precipitate, and the obtained gel is dried and then immersed in an aqueous nickel salt solution for activation treatment.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

(4) The titania molded product is immersed in a mixed aqueous solution of an alkaline earth metal salt and a nickel salt, and dried and fired.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Asakawa 6-7-5, also known as Yokkaichi-shi, Mie (72) Inventor Sotaro Nakamura 6-19-18 Nagataasa-cho, Suzuka-shi, Mie

Claims (2)

[Claims] 1. In producing carbon monoxide and hydrogen by bringing a gas containing carbon dioxide and methane into contact with the catalyst, the catalyst is a metal or metal oxide catalyst containing alkaline earth metal oxides. A method for converting carbon dioxide by methane, which is characterized by: 2. The conversion method according to claim 1, wherein the metal or metal oxide is nickel or nickel oxide.