JP2001163602A - Method of manufacturing for hydrogen-containing gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a hydrogen-containing gas with a small sized device by providing a catalyst exhibiting high activity in the methanol steam reforming of the self heat supply type reaction. SOLUTION: In manufacturing the hydrogen-containing gas by the reaction of methanol and steam with air, a catalyst obtained by mixing an alumina precursor with a precursor mixture containing copper and zinc is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a hydrogen-containing gas by reacting methanol with steam and air. Hydrogen gas is widely used for chemical industry such as ammonia synthesis, hydrogenation of various organic compounds, petroleum refining, desulfurization, etc., atmosphere gas for semiconductors and metallurgy, glass production and the like. In recent years, it has also attracted attention as a raw material for fuel cells as a power source for automobiles and the like, and a significant increase in demand for hydrogen gas is expected in the future.

[0002]

2. Description of the Related Art As a method for producing hydrogen gas, for example, a steam reforming method for hydrocarbons such as naphtha, natural gas, and petroleum liquefied gas is known. This method has disadvantages such as the necessity of desulfurization of the raw material and the fact that the reaction temperature is very high at 800 to 1000 ° C. On the other hand, the method using methanol as a raw material has advantages such as no need for desulfurization and a low reaction temperature, and has attracted attention in recent years, and many small- to large-scale facilities have been installed.

[0003] In the methanol steam reforming reaction, a small amount of carbon monoxide is by-produced by the reverse shift reaction of formula (2) in addition to the main reaction represented by formula (1). CH ₃ OH + H ₂ O = 3H ₂ + CO ₂ + 49.5 kJ / mol (1) CO ₂ + H ₂ = CO + H ₂ O + 41.17 kJ / mol (2) Carbon monoxide by-produced in (2) is It is difficult to remove it when purifying it into high-purity hydrogen, and it is preferable that the amount is as small as possible. From thermodynamic equilibrium, the lower the temperature and the molar ratio of water vapor to methanol (hereinafter,
The larger the (S / C ratio), the lower the concentration of carbon monoxide in the reformed gas.

[0004] If the main reaction of the methanol steam reforming reaction of the formula (1) is an endothermic reaction, heat must be supplied from the outside, so that a heat supply facility is required and the apparatus becomes complicated. On the other hand, air is introduced together with methanol and water vapor to oxidize part of the methanol and use the heat to
There is a self-heat supply type reaction that causes the steam reforming reaction of the formula (1). In this method, a part of methanol is oxidized to hydrogen and carbon dioxide as shown in equation (3), and this heat is used (1)
The steam reforming reaction of methanol of the formula is performed. CH ₃ OH + 1 / 2O ₂ = 2H ₂ + CO ₂ −192.3 kJ / mol (3) According to this method, the reaction is continued except for the temperature that rises to a temperature level necessary for starting the reaction. It does not require heat supply.

As a catalyst used for steam reforming of methanol, for example, a catalyst containing oxides of copper, chromium and manganese (Japanese Patent Publication No. 54-11274) and a catalyst containing copper, zinc and aluminum (Japanese Patent Publication No. 7-177
No. 1), a catalyst containing copper, zinc and vanadium (JP-A-60-96504), a catalyst containing copper, zinc, aluminum and an alkaline earth metal oxide (JP-A No. 1-11)
No. 1445), a catalyst containing copper, zinc, aluminum and thorium oxides (US Pat. No. 4,091,086).
No.) has been proposed.

[0006]

In the case of producing hydrogen for a fuel cell as a power source of an automobile or the like, since the supply of heat from the outside is not required, the above-mentioned self-heat supply type reaction is advantageous. It is. However, in a self-heating supply reaction in which methanol is reacted with steam and air to produce a hydrogen-containing gas, a portion of the methanol is oxidized, so that the vicinity of the reaction is far greater than in the steam reforming reaction. High temperature. Therefore, high heat resistance is required for the catalyst of the self-heat supply type reaction. In addition, when producing hydrogen for a fuel cell as a power source of an automobile or the like, it is necessary to reduce the size of the reforming reactor due to a limitation in a mounting capacity and the like, and a catalyst having higher activity is required. Desired.

As described above, various catalysts have been proposed as steam reforming catalysts for methanol using methanol and steam as raw materials. However, the conventionally known steam reforming catalyst for methanol does not have sufficient heat resistance and activity, and cannot be used for the self-heat supply type reaction as it is.
For example, a catalyst containing two components of copper and zinc can be used for a methanol steam reforming reaction of a self-heat supply type reaction. Activity decreases between the two. Attempts have been made to add a third component to increase heat resistance, and copper, zinc, and aluminum-based catalysts to which aluminum oxide has been added are known, but these catalysts are also insufficient for the self-heat supply type reaction. Absent. An object of the present invention is to develop a catalyst having high activity in the steam reforming of methanol by a self-heat supply reaction, and to provide a method for easily producing a hydrogen-containing gas with a small apparatus.

[0008]

The present inventors have conducted intensive studies on the above-mentioned problems in a method for producing a hydrogen-containing gas by reacting methanol, steam and air, and found that copper oxide and zinc oxide prepared by a specific method. Since the catalyst made of aluminum has high activity, it has been found that the catalyst is suitable for a self-heat supply type reaction, and has reached the present invention.

That is, the present invention uses a catalyst obtained by mixing an alumina precursor with a precursor mixture containing copper and zinc in producing a hydrogen-containing gas by reacting methanol with steam and air. This is a method for producing a hydrogen-containing gas. This precursor mixture containing copper and zinc is:
It is preferably prepared using an aqueous solution of an inorganic acid salt of copper and an alkaline precipitant, and zinc oxide and carbon dioxide in the presence of a boron compound.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Water-soluble salts are used for the copper compound and the zinc compound as the raw materials of the catalyst used in the present invention, and when the precipitate obtained by treating the aqueous solution with a precipitant is calcined. A compound that can be converted to an oxide is used. As a raw material of the copper compound, for example, water-soluble salts of organic acids and inorganic acids such as copper acetate, copper sulfate, and copper nitrate can be used. As a raw material of the zinc compound, for example, water-soluble salts and oxides of organic acids and inorganic acids such as zinc acetate, zinc sulfate and zinc nitrate can be used. When zinc oxide is used, it is preferable that carbon dioxide gas coexist. As a raw material of the aluminum compound, for example, water-soluble salts of organic acids such as acetic acid, sulfuric acid, and nitric acid, and inorganic acids can be used. As a raw material of the boron compound, for example, boric acid can be suitably used. Precipitants include:
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Water-soluble alkali compounds such as potassium carbonate and sodium hydrogen carbonate are used.

The concentration of the aqueous metal salt solution at the time of preparing the precipitate is 0.2
３3 mol / l, preferably 0.5-2 mol / l. The amount of the precipitant relative to the metal salt is 1-2 times, preferably 1.1-1.6 times, the chemical equivalent. Also,
The temperature at the time of preparing the precipitate is 20 to 90 ° C, preferably 35 to 8 ° C.
5 ° C. The composition of the catalyst according to the invention is in the atomic ratio copper / zinc between 0.2 and 12, preferably between 0.5 and 10.
The composition of copper, zinc and aluminum as metals is as follows: copper 30-80%, zinc 15-50%, aluminum 1-2.
0%, preferably 40-70%, respectively, 20-40
%, 4 to 16%. Boron is 0.5-3%.

The slurry of the precursor mixture containing copper and zinc of the catalyst according to the present invention is preferably prepared by a co-precipitation method, for example, a method of precipitating with an aqueous solution containing copper and zinc and a precipitant such as alkali carbonate. A known preparation method such as a method in which zinc oxide is dispersed in a copper precipitation slurry and carbonation is performed with carbon dioxide gas. The precursor mixture containing copper and zinc was prepared using an aqueous solution of an inorganic acid salt of copper and an alkali precipitant, and zinc oxide and carbon dioxide in the presence of a boron compound to improve the catalytic activity. preferable. The alumina precursor is preferably prepared from an aluminum salt soluble in water and a basic precipitant. For example, it can be prepared from an aqueous solution containing aluminum and an aqueous alkali hydroxide solution. The boron compound can be added to an aqueous solution containing copper and zinc or an aqueous solution containing aluminum. The catalyst in the present invention is produced from a mixed slurry obtained by mixing the thus prepared precursor mixture slurry containing copper and zinc and an alumina precursor slurry.

The catalyst of the present invention is prepared by mixing a precursor mixture containing copper and zinc with an alumina precursor. By this preparation method, the catalyst components are intimately mixed to give excellent catalytic performance. As a method of mixing a precursor mixture containing copper and zinc and an alumina precursor, a method of simultaneously preparing a precipitate from a mixed solution of a water-soluble copper, zinc and aluminum salt and a precipitant, a method of preparing a precipitate of copper and zinc, In the presence of an alumina precursor. However, these methods do not allow intimate mixing of the catalyst components, resulting in poor catalytic performance. The mixed slurry thus obtained is usually washed with pure water or the like. When a sulfate is used as a raw material, it is preferable to wash with a diluted alkaline aqueous solution or the like.

The washed mixed slurry prepared by the above method is dried as it is, or dried and calcined, crushed to uniform size, or used after shaping. If necessary, a binder such as alumina sol may be added to the obtained slurry to be supported on a carrier or a carrier structure. After loading, it can be used as it is after drying or after firing. Further, a dried product of the mixed slurry after washing, or a dried and calcined product is pulverized, suspended in water, and added with a binder such as alumina sol as necessary, and supported on a carrier and a carrier structure. Can also be used. In this case, it can be used after being supported and dried, or after firing. The drying temperature is 50-150 ° C, and the firing is 180-500 in air.
C., preferably at 200-450.degree.

In the self-heat supply type reaction in which methanol reacts with steam and air, an activation treatment may be performed using, for example, a gas containing hydrogen or carbon monoxide, or an activation treatment may be performed, as in the case of steam reforming. It can also be used for the reaction without. The steam / methanol ratio (S / C) when reacting methanol with steam and air is 1.0 to 10.
0, preferably 1.0 to 5.0, and the air / methanol ratio is 0.3 to 5.0, preferably 0.5 to 3.0. The exothermicity of the combustion reaction and the endothermicity of the methanol reforming reaction are balanced. Is selected. Reaction temperature is 150
６００600 ° C., preferably 200-500 ° C., and the pressure is normal pressure〜0.5 MPs. The liquid hourly space velocity (LHSV) per unit catalyst volume is 0.1-50, preferably 0.5
４０40 (1 / h). The catalyst according to the present invention has high heat resistance and high activity in a self-heat supply reaction in which methanol reacts with steam and air, so that a hydrogen-containing gas can be easily produced with a small apparatus.

[0016]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited by these Examples.

Production Example 1 (Preparation of Catalyst) 177 g of sodium carbonate (anhydrous) was dissolved in a 5 liter round bottom flask together with 1000 ml of ion-exchanged water, and the temperature was adjusted to 40 ° C. Here, 314 g of copper sulfate (pentahydrate),
Dissolve 19.7 g of boric acid and 800 ml of ion-exchanged water and add 4
The solution adjusted to 0 ° C. is poured, followed by zinc oxide 68.2.
g in 300 ml of deionized water,
Immediately, carbon dioxide gas was blown at a rate of 6 L / h. After 1 hour, the temperature was raised to 80 ° C. and maintained for 30 minutes. Carbon dioxide was stopped in 2 hours and cooled to 60 ° C. Here, 101.3 g of an aqueous solution of aluminum sulfate (8% as alumina) was added to 100 parts.
ml of ion-exchanged water and sodium hydroxide 2
An alumina precursor slurry prepared from a solution of 1.9 g in 160 ml of ion-exchanged water was added and mixed with stirring for 20 minutes. The mixed slurry thus prepared was washed. Subsequently, the catalyst was dried at 80 ° C. to obtain a catalyst containing copper, zinc, and aluminum as main components and having an atomic ratio of copper / zinc of 1.5. This catalyst is designated as A.

Production Examples 2 to 5 Copper and zinc having an atomic ratio of copper / zinc of 0.8, 1.0, 2.0, and 6.0 in the same manner as in Production Example 1 except that the amount of zinc oxide was changed. A catalyst containing aluminum as a main component was prepared. These catalysts are designated B, C, D and E.

Production Comparative Example 1 177 g of sodium carbonate (anhydrous) was dissolved in a 5-liter round bottom flask together with 1000 ml of ion-exchanged water.
° C. Here, 314 g of copper sulfate (pentahydrate) and boric acid 1
A solution prepared by dissolving 9.7 g in 800 ml of ion-exchanged water and adjusting the temperature to 40 ° C. was added thereto, and then a slurry in which 68.2 g of zinc oxide was dispersed in 300 ml of ion-exchanged water was added. I blew it. After 1 hour, the temperature was raised to 80 ° C. and maintained for 30 minutes. Carbon dioxide was stopped in 2 hours. Then, the substrate was cooled to 60 ° C. and washed. 80 ℃
To obtain a catalyst containing copper and zinc as main components and having an atomic ratio of copper / zinc of 1.5. This catalyst is designated as F.

Production Example 6 A mixed slurry containing copper, zinc and aluminum as main components, prepared in the same manner as in Production Example 1, was washed and dried at 80 ° C. This is fired and molded in air at 380 ° C for 2 hours,
A catalyst containing copper, zinc, and aluminum as the main components and having a copper / zinc atomic ratio of 1.3 was obtained. This catalyst is designated G.

Production Comparative Example 2 A precursor mixture containing copper and zinc and having a copper / zinc atomic ratio of 1.3 prepared in the same manner as in Production Example 1 was prepared.
After washing and filtering the cake, 81 g of alumina sol (# 200 manufactured by Nissan Chemical Industries) was added and kneaded. Next, the catalyst was dried at 80 ° C. and calcined at 380 ° C. to obtain a catalyst containing copper, zinc, and aluminum as main components and having an atomic ratio of copper / zinc of 1.3. This catalyst is designated as H.

Example 1, Comparative Example 1 (Methanol LHSV
Evaluation test of catalyst by A) A crushed to 20 to 30 mesh in a reactor of a flow type reactor
1 ml of catalyst or F catalyst is charged, S / C is 1.5, catalyst layer maximum temperature is 250 ° C, molar ratio of air to methanol is 0.6
Under the conditions of 7, the activity of the catalyst was evaluated by a self-heat supply type reaction while changing the methanol LHSV. The reaction results were determined from values analyzed by gas chromatography at the reactor outlet. Table 1 shows the evaluation results.

Table 1 Methanol LHSV (1 / h) 10 15 20 Catalyst Methanol reaction rate (mol%) Example 1 A 68.1 56.7 47.8 Comparative Example 1 F 56.3 44.9 44.2

Example 2, Comparative Example 2 (Methanol LHSV
Evaluation test of catalyst by A) A crushed to 20 to 30 mesh in a reactor of a flow type reactor
The catalyst layer temperature was changed under the conditions of 1 ml of catalyst or F catalyst, S / C of 1.5, methanol LHSV of 20 (l / h), and a molar ratio of air to methanol of 0.67 to 0.72. The activity of the catalyst was evaluated by a self-heating supply type reaction. The reaction results were determined from values analyzed by gas chromatography at the reactor outlet. Table 2 shows the evaluation results.

Table 2 Maximum temperature of catalyst layer (° C.) 250 275 300 Catalyst Methanol conversion (mol%) Example 2 A 49.7 55.1 70.0 Comparative Example 2 F 40.8 52.2 67.9

Examples 3 to 6 (Evaluation test of catalyst by atomic ratio of copper / zinc) B catalyst, C catalyst and D catalyst having different zinc / copper atomic ratios crushed to 20 to 30 mesh in a reactor of a flow-type reactor , E catalyst, 1 ml, water-methanol molar ratio 2.0, methanol LHSV 20 (l / h), air-methanol molar ratio 0.67, maximum temperature of catalyst layer 275 ° C. The activity of the catalyst was evaluated in a feed-type reaction. The reaction results were determined from values analyzed by gas chromatography at the reactor outlet. Table 3 shows the evaluation results.

Table 3 Catalyst Copper / Zinc Atomic Ratio Methanol Reaction Rate (mol%) Example 3 B 0.8 57.9 Example 4 C 1.0 58.8 Example 5 D 2.0 71.8 Example 6E 6.0 63.1

Example 7, Comparative Example 3 (Methanol LHSV
Evaluation test of catalyst) The G catalyst or the H catalyst was charged into a reactor of a flow-through reactor, and the molar ratio of water to methanol was 2.0, and the molar ratio of air to methanol was 0.5 to 0.7. First, the catalyst layer outlet temperature was set to 250 ° C., and the methanol LHSV was changed to evaluate the activity of the catalyst by a self-heat supply type reaction. The reaction results were determined from values analyzed by gas chromatography at the reactor outlet. Table 4 shows the methanol reaction amount per catalytic copper for each methanol LHSV.

Table 4 Methanol LHSV (1 / h) 10 15 20 25 catalyst Methanol reaction amount (mol / h · g-Cu) Example 7 G 0.600 0.760 0.830 0.860 Comparative Example 3 H 0 .493 0.663 0.752 0.790

[0030]

As is clear from the above examples, the catalyst used in the present invention has high activity in the steam reforming of methanol by the self-heat supply type reaction. Therefore, according to the present invention, a hydrogen-containing gas can be produced by a small and simple device, and can be advantageously used for a vehicle-mounted fuel cell or the like.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Taishi Ikoma 182 Niigata-shi Niigata Niigata City Niigata Research Laboratories Niigata Research Laboratories Mitsubishi Gas Chemical Co., Ltd. Address Mitsubishi Gas Chemical Co., Ltd. Niigata Research Laboratory F-term (reference) 4G040 EA02 EA06 EA07 EC01 4G069 AA05 AA15 BA01A BA01B BC16A BC16B BC16C BC31A BC31B BC35A BC35B BD03A BD03B BD03C CC25 CC32 FA01 FB09 5

Claims (5)

[Claims] In producing hydrogen-containing gas by reacting methanol, steam and air, a catalyst obtained by mixing an alumina precursor with a precursor mixture containing copper and zinc is used. Method for producing hydrogen-containing gas. 2. A precursor mixture containing copper and zinc, which is prepared using an aqueous solution of an inorganic acid salt of copper and an alkali precipitant, and zinc oxide and carbon dioxide in the presence of a boron compound. Item 2. The method for producing a hydrogen-containing gas according to Item 1. 3. The method for producing a hydrogen-containing gas according to claim 1, wherein a catalyst obtained by mixing an alumina precursor with a precursor mixture containing copper and zinc, which can be converted into an oxide by firing, is used. 4. The method for producing a hydrogen-containing gas according to claim 1, wherein the precursor mixture containing copper and zinc is a slurry mixture prepared by a coprecipitation method. 5. The method for producing a hydrogen-containing gas according to claim 1, wherein the alumina precursor is a slurry prepared from a water-soluble aluminum salt and a basic precipitant.