JPH05170404A - Method for converting carbon dioxide by 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 lanthanum oxide or cerium oxide and nickel or nickel oxide as effective components to recover carbon monooxide and hydrogen.

Description

Detailed Description of the Invention

[0001]

The present invention relates to industrially useful carbon monoxide and hydrogen (hereinafter abbreviated as syngas) for carbon dioxide, which is a major causative agent of global warming using methane as a reducing agent. On how to convert to.

[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 carrying a noble metal is used, it is considered that the noble metal is expensive and economically disadvantageous, and has the same catalytic activity and life as noble metal. There is a problem that the cheaper Group VIII transition metals, especially nickel catalysts, have a strong tendency to deposit carbon, and therefore activity tends to deteriorate.

[0005]

Means for Solving the Problems As a result of examining various additive effects in the catalyst, the present inventors have found that the catalyst containing lanthanum or cerium metal oxide shows stable activity without carbon deposition. They have found the present invention and completed the present invention.

That is, the feature of the method for converting carbon dioxide by methane 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 lanthanum metal oxide is used as the catalyst. Alternatively, a metal or metal oxide catalyst containing at least one of cerium metal oxide is used.

The present invention will be described in detail below.

The catalyst used in the present invention may be composed of at least either lanthanum metal oxide or cerium metal oxide and metal or metal oxide,
Alternatively, both of them may be supported on an oxide such as silica, alumina, zirconia, niobia, titania, or crystalline aluminosilicate.

When both lanthanum metal oxide and cerium metal oxide are contained, their weight ratio is not particularly limited.

The content of lanthanum metal oxide or cerium metal oxide in the catalyst is not particularly limited as long as it is 0.01% by weight or more, more preferably 0.1 to 95% by weight. It is also possible to add alkaline earth metal oxides such as magnesium oxide and calcium oxide onto the carrier containing the lanthanum metal oxide or the cerium metal oxide.

The metal or metal oxide may be any metal or metal oxide selected from noble metals, Group VIII transition metals and oxides of these metals.

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 economically advantageous.

The content of metal or metal oxide in the catalyst is
0.01 to 70% by weight is preferable. If the content is less than 0.01% 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.

There is no particular limitation on the method for preparing a catalyst containing a metal or a metal oxide containing at least one of lanthanum metal oxide and cerium metal oxide, and a conventional impregnation method,
It is manufactured by a method such as a coprecipitation method.

For example, a nickel or nickel oxide catalyst containing at least one of lanthanum metal oxide and cerium metal oxide can be prepared by the following method.

(1) A silica molding is impregnated with an aqueous solution of lanthanum or cerium metal salt and dried and fired, and the resulting oxide is impregnated with an aqueous nickel salt solution for activation. I do.

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

(3) A lanthanum or cerium metal salt and a nickel salt are added to silica alkoxide 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 lanthanum or cerium metal salt and nickel salt,
Performs drying and baking.

(5) The nickel oxide and the lanthanum or cerium metal oxide are physically mixed and activated.

It should be noted that other metals and metal oxides other than nickel can be manufactured in the same manner.

The catalyst may contain an alkali metal oxide such as magnesium oxide or calcium oxide by the above-mentioned preparation method.

The nickel salt and lanthanum or cerium metal salt used for preparing the above catalyst are not particularly limited, but nitrates, carbonates and organic complexes which are easily decomposed during the activation treatment are more preferable.

The above-mentioned 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, reduction treatment is preferably performed.

The catalyst may be molded or used as it is, and may be molded into a desired size according to the reaction method.

The amount of methane in the raw material gas in the method of the present invention can be defined as the molar ratio of methane to carbon dioxide. Specifically, the ratio of methane / carbon dioxide is 0.05 to 25, preferably 0.1 to 20. When the ratio of methane / carbon dioxide is less than 0.05, the amount of carbon dioxide to be recycled increases, while when the ratio of methane / carbon dioxide exceeds 25, a sufficient carbon monoxide generation rate cannot be obtained, which is uneconomical. May be.

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 it is preferable to carry out the reaction 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 of the present invention has an SV of 500 to 100,000 / h.
Can be carried out preferably. If the SV is less than 500 / h, the production rate of carbon monoxide is low, and the SV is 100,000 / h.
If it exceeds h, the conversion rate of the raw material may be lowered and it may not be economical.

The reaction method is not particularly limited as long as the catalyst and the raw materials can be efficiently brought into contact with each other. For example, the reaction can be carried out in a fixed bed, a fluidized bed or a moving bed.

[0032]

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

Example 1 10 g of spherical silica having a diameter of 3 mm (made by Fuji Devison, Carriact-30) was immersed in an aqueous solution prepared by dissolving 3 g of lanthanum nitrate hexahydrate in 20 cc of water for 3 hours, and then 110
C., and dried for 11 hours. Next, 5 g of the carrier obtained by air-calcining this at 600 ° C. for 2 hours was added with 2.4 g of nickel nitrate hexahydrate.
Was immersed in an aqueous solution of 10 cc of water for 3 hours, then
After drying at 10 ° C. overnight, reduction was carried out at 500 ° C. for 1 hour under a 10% hydrogen flow to obtain a catalyst containing 10% by weight of nickel, 10% of lanthanum oxide and 80% of silica.

1.5 g of this catalyst was added to SUS having 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 passed therethrough 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 (%) = number of moles of outlet CO / (number of moles of supplied CO ₂ + number of 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 catalyst containing nickel 10%, cerium oxide 10% and silica 80% by weight was prepared by the same catalyst preparation procedure as in Example 1 except that cerium nitrate hexahydrate was used instead of lanthanum nitrate. Got

Using 1.5 g of this catalyst, the reaction was carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 3 A solution of 2.95 g of lanthanum nitrate hexahydrate dissolved in 10 cc of water was added to an aqueous solution of spherical alumina having a diameter of 3 mm (K, manufactured by Sumitomo Chemical Co., Ltd.).
After immersing 10g of HA-24) for 3 hours, it is 1 at 110 ° C.
It was dried for 1 hour. Next, 11 g of the carrier obtained by air-calcining this at 700 ° C. for 2 hours was impregnated with an aqueous solution in which 5.5 g of nickel nitrate hexahydrate was dissolved in 11 cc of water for 3 hours.
Air calcination at ℃ for 2 hours, then 500 ℃ in 10% hydrogen flow.
Reduction treatment for 1 hour at 10% by weight of nickel,
A catalyst containing 10% lanthanum oxide and 80% alumina was obtained.

A reaction was carried out in the same manner as in Example 1 using 1.5 g of this catalyst. The results are shown in Table 1.

Example 4 5 g of nickel nitrate hexahydrate, lanthanum nitrate hexahydrate 2.
After dissolving 6 g in 100 g ethylene glycol,
Warm 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
5 g was added and hydrolyzed, followed by stirring for 3 hours to obtain a desired gel. After pressure molding, air calcination is performed at 700 ° C. for 2 hours, and then reduction is performed at 600 ° C. for 1 hour in a 10% hydrogen flow, and nickel, lanthanum oxide, and alumina are 10%, 10%, and 80% by weight, respectively. A catalyst containing was obtained.

Using 1.5 g of this catalyst, a reaction was carried out in the same manner as in Example 1. 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 of 6.9 g of nickel nitrate hexahydrate dissolved 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.

1.5 g of this catalyst was charged into a reaction tube, and the reaction was carried out under the same reaction temperature and SV conditions as in Example 1.
The results are shown in Table 1.

[0044]

[Table 1]

[0045]

When carbon dioxide is reduced by methane,
By using the catalyst of the present invention, it is possible to suppress carbon deposition on the surface of the catalyst and produce a 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] 0014

[Correction method] Change

[Correction content]

The method for preparing the metal or metal oxide catalyst containing at least one of the lanthanum metal oxide and the cerium metal oxide is not particularly limited, and the usual impregnation method, coprecipitation method, etc. may be used. Manufactured by the method.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016] (1) silica molded product was immersed in an aqueous solution obtained by dissolving lanthanum or cerium metal salt, followed by drying and baking process, immersed activating process the obtained oxide to nickel salt solution I do.

[Procedure 3]

[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 a lanthanum or cerium metal salt and an aluminum salt are mixed to form a precipitate, and the resulting gel is dried and then a nickel salt aqueous solution is added.
It is immersed in and activated.

[Procedure amendment 4]

[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 lanthanum or cerium metal salt and nickel salt, and dried and fired.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

Example 3 In an aqueous solution prepared by dissolving 2.95 g of lanthanum nitrate hexahydrate in 10 cc of water, spherical alumina having a diameter of 3 mm (K, manufactured by Sumitomo Chemical Co., Ltd.)
After immersing 10g of HA-24) for 3 hours, it is 1 at 110 ° C.
It was dried for 1 hour. Next, 11 g of the carrier obtained by air-calcining this at 700 ° C. for 2 hours was immersed in an aqueous solution in which 5.5 g of nickel nitrate hexahydrate was dissolved in 11 cc of water for 3 hours.
Air calcination at ℃ for 2 hours, then 500 ℃ in 10% hydrogen flow.
Reduction treatment for 1 hour at 10% by weight of nickel,
A catalyst containing 10% lanthanum oxide and 80% alumina was obtained.

 ─────────────────────────────────────────────────── ─── 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 a catalyst, the catalyst contains a metal or a metal containing at least one of lanthanum metal oxide and cerium metal oxide. A method for converting carbon dioxide using methane, which is an oxide catalyst. 2. The conversion method according to claim 1, wherein the metal or metal oxide is nickel or nickel oxide.