JPH07107000B2 - Method for producing ethanol - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing hydrogen by catalytically hydrogenating carbon dioxide. Ethanol is an important basic raw material for various chemical products, pharmaceuticals, agricultural chemicals and the like. .

[0002]

2. Description of the Related Art Ethanol is currently produced by a fermentation method using yeast such as starch and molasses and a method of hydrating ethylene in the presence of an acidic catalyst. In recent years, environmental problems such as global warming have been highlighted. In particular, carbon dioxide emission control, which is considered to be the main causative agent, is being studied worldwide, but the most desirable solution is to collect it. It is to recycle it. As one of the measures, the development of industrial conversion technology from carbon dioxide as a carbon resource to ethanol is of great significance.

[0003]

An object of the present invention is to provide a method for producing industrially useful ethanol by effectively using carbon dioxide as a carbon source from the above viewpoint.

[0004]

Means for Solving the Problems As a result of intensive studies to synthesize ethanol by catalytic hydrogenation of carbon dioxide, the present inventors have found that iron, copper, zinc or iron, copper, zinc, the periodic table It was found that ethanol is produced by carrying out a hydrogenation reaction of carbon dioxide in the presence of a catalyst composed of a group 1a element (hereinafter referred to as an alkali metal element), and completed the present invention. That is, the present invention provides a method for efficiently producing ethanol by catalytic hydrogenation of carbon dioxide using a catalyst composed of iron, copper, zinc or iron, copper, zinc, and an alkali metal element. It is a thing. The ethanol of the present invention
The synthesis reaction is 2CO ₂ + 6H ₂ → C ₂ H ₅ OH + 3H
It can be represented by ₂ O.

In preparing the catalyst of the present invention,
It suffices that each component of iron, copper, zinc, and / or alkali metal element is finally combined, and there is no particular limitation on the compound form etc. as a starting material of each element. Substance, hydroxide, basic carbonate, nitrate,
Acetate or various complexes are used. Considering that the prepared catalyst is generally reduced and used in the reaction, as the starting material for the iron and copper components, an easily reducing compound or a compound that can be converted into an easily reducing compound is preferable. The alkali metal elements used in the preparation of the catalyst of the present invention are potassium, sodium, lithium, and cesium, which are used in the form of hydroxide, chloride, carbonate, nitrate, acetate, phosphate, etc., respectively. it can.

The ratio of each constituent in the catalyst of the present invention is
The atomic ratios of copper / iron and zinc / iron are 0.
01 to 100, preferably 0.1 to 10,
When the alkali metal element is contained, the atomic ratio of alkali metal element / iron is 0.001 to 5, preferably 0.01 to 2.

The method for preparing the catalyst in the present invention is as follows:
There is no particular limitation, but the following method can be adopted. For example, 1) a method of kneading a compound of iron, copper and zinc, 2) a method of coprecipitating a mixed solution of a compound of iron, copper and zinc with a precipitant, 3) a compound of iron and copper It is possible to employ a method of preparing a mixed solution of the above on a suitable zinc compound, 4) a method of preparing a mixed solution of a compound of copper and zinc on a suitable iron compound, and the like. Examples of the method for preparing a catalyst containing an alkali metal element, 1)
Iron, copper, zinc, a method of kneading and preparing a compound of an alkali metal element, 2) impregnating or mixing an alkali metal element compound after coprecipitating a mixed solution of a compound of iron, copper and zinc with a precipitating agent Preparation method, 3) method of preparing a mixed solution of iron, copper and a compound of an alkali metal element on a suitable zinc compound, 4) a method of preparing a mixed solution of a compound of copper, zinc and an alkali metal element with a suitable iron A method of supporting the compound on the compound to prepare it can be adopted. Further, in the preparation of the catalyst of the present invention, any substance that does not adversely influence the reaction for uniformly dispersing or supporting the essential constituents can be used.

The catalyst precursor thus prepared is
After calcination, it can be reduced with hydrogen and used as a catalyst in the reaction. The calcination treatment of the catalyst precursor is not particularly limited in its method, but it is carried out by a method of calcining by leaving it in a furnace, a method of calcination in a gas stream, or the like, and any method of air or oxygen and an inert gas is used. A method of firing in an atmosphere gas or the like mixed in a ratio is adopted. The firing temperature is generally 200
The temperature is preferably in the range of to 600 ° C.
It is about 10 hours. The hydrogen reduction treatment of the catalyst is carried out in pure hydrogen or hydrogen diluted to an arbitrary ratio with an inert gas, and there is no particular limitation on the treatment method, but the above gas is distributed in consideration of removal of water or the like produced. It is preferable to do so. The reduction temperature is preferably in the range of 250 to 500 ° C., and the reduction time is about 0.5 to 20 hours. Since the catalyst after hydrogen reduction is extremely susceptible to oxidation, it is desirable to perform hydrogen reduction treatment in the reactor immediately before using it in the reaction. The catalyst can be reduced not only by hydrogen but also by a mixed gas of hydrogen and carbon monoxide or carbon monoxide.

In the catalyst of the present invention, the shape of the catalyst used in the reaction is not particularly limited, but it may be in the form of powder, tablet-molded product, extrusion-molded product or the like.
When used by molding, alumina as a binder,
Inorganic compounds such as silica, magnesia and diatomaceous earth can be used. The reaction method in the present invention is not particularly limited as long as it is a normal reaction method using a solid catalyst,
A system such as a gas phase fixed bed, a gas phase fluidized bed, or a liquid phase suspension bed can be used.

As the raw material used in the reaction of the present invention, carbon dioxide and hydrogen, or a mixed gas containing an inert gas thereof is used. The mixing ratio of these is not particularly limited, but the CO ₂ / H ₂ molar ratio is preferably in the range of 0.1 to 10. The reaction temperature is in the range of 100 to 600 ° C, preferably 200 to 400 ° C. The reaction pressure is in the range of 2 to 300 atm, preferably 10 to 80 atm. Gas space velocity is 100 to 30000h
r ⁻¹ , preferably in the range of 1000 to 10000 hr ⁻¹ . As reaction products, in addition to ethanol, which is the main product, alcohols such as methanol, propanol, butanol, acetaldehyde, acetic acid ester, hydrocarbons, carbon monoxide, etc. are produced. Liquid products such as ethanol can be separated and recovered by distillation or the like.

[0011]

The present invention provides iron, copper, zinc or iron, copper,
A useful ethanol can be produced by carrying out a catalytic hydrogenation reaction of carbon dioxide in the presence of a catalyst containing zinc and an element of Group 1a of the periodic table, and its industrial significance is great.

[0012]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples. Example 1 3.92 g of basic copper carbonate, 6.56 g of basic zinc carbonate,
To a mixture of 2.63 g of iron hydroxide, 15 ml of deionized water
And kneaded well in a mortar. The slurry obtained here was dried overnight in a dryer at 60 ° C., then transferred to a crucible and calcined in air at 400 ° C. for 3 hours. The powder thus obtained was molded and sized to 16/30 mesh. 1.0 g of this sized product was precisely weighed and charged into a reaction tube, and hydrogen reduction treatment was carried out at 350 ° C. for 30 minutes under normal pressure at a hydrogen flow rate of 100 ml / min. After the reduction treatment, when the catalyst layer was cooled, the raw material gas of CO ₂ / H ₂ = 1/3 molar composition was switched to increase the pressure, and when the inside of the system reached 70 kg / cm ² , the raw material gas flow rate was adjusted to 90 ml / min. Then, the temperature rise was started. The reaction was performed when the temperature reached a predetermined reaction temperature and reached a steady state. The reaction products were analyzed online by gas chromatography. Table 1 shows the results of the catalytic activity test.
Shown in.

Example 2 Basic copper carbonate 3.89 g, basic zinc carbonate 6.55 g,
To a mixture of 2.64 g of iron hydroxide, 0.83 of potassium carbonate
15 ml of ion-exchanged water in which g was dissolved was added and kneaded well in a mortar. The slurry obtained here was dried overnight in a dryer at 60 ° C., then transferred to a crucible and calcined in air at 400 ° C. for 3 hours. The powder thus obtained was molded and sized to 16/30 mesh. Hereinafter, 1.0 g of the catalyst was subjected to an activity test under the same method and conditions as in Example 1 to evaluate the catalyst performance. The results are shown in Table 1. When the catalyst was analyzed by fluorescent X-ray analysis, the atomic ratio of iron, copper, zinc, and potassium was almost the same as the charged atomic ratio.

Example 3 7.27 g of copper nitrate trihydrate, zinc nitrate hexahydrate 17.8
7 g and 12.14 g of ferric nitrate nonahydrate were placed in a beaker and dissolved in 200 ml of ion-exchanged water. 100 ml of ion-exchanged water in which 21.6 g of sodium hydroxide was dissolved was added dropwise while stirring well to obtain a precipitate. This precipitate was washed with about 3 liters of ion-exchanged water, then 10 ml of ion-exchanged water in which 0.83 g of potassium carbonate was dissolved was added and kneaded to form a slurry. This was dried in a dryer at 60 ° C. overnight. Then, it was transferred to a crucible and baked in air at 400 ° C. for 3 hours, and the obtained powder was molded and sized to 16/30 mesh. Hereinafter, 1.0 g of the catalyst was subjected to an activity test under the same method and conditions as in Example 1 to evaluate the catalyst performance.
The results are shown in Table 1. When the catalyst was analyzed by fluorescent X-ray analysis, the atomic ratio of iron, copper, zinc, and potassium was almost the same as the charged atomic ratio.

Example 4 1.0 g of the catalyst of Example ² was subjected to an activity test in the same manner as in Example 1 under the reaction pressure of 40 kg / cm ² . The results are shown in Table 2.

Example 5 7.24 g of copper nitrate trihydrate and 17.8 of zinc nitrate hexahydrate
A catalyst was prepared by the method of Example 2 using 8 g and ferric nitrate nonahydrate 24.33 g, and 1.0 g of the catalyst was subjected to the activity test under the same method and conditions as in Example 1. The results are shown in Table 2. When the catalyst was analyzed by X-ray fluorescence analysis, the atomic ratio of iron, copper, zinc and potassium was almost the same as the charged atomic ratio.

Example 6 10.01 g of iron hydroxide was placed in a 200 ml eggplant-shaped flask and 5.33 g of copper nitrate trihydrate and zinc nitrate hexahydrate 6.
57 g and 100 ml of ion-exchanged water in which 2.22 g of potassium nitrate was dissolved were added, and the pressure was reduced while heating in a water bath at 60 ° C. to evaporate the water. 4 of the powder thus obtained in air
It was baked at 00 ° C. for 3 hours. After firing treatment, molded 16 /
The size was adjusted to 30 mesh. Hereinafter, 1.0 g of the catalyst was subjected to an activity test under the same method and conditions as in Example 1. The results are shown in Table 2.

Comparative Example 1 9.98 g of iron hydroxide was placed in a 200 ml eggplant type flask, 100 ml of ion-exchanged water was added, and the pressure was reduced while heating in a water bath at 60 ° C. to evaporate the water. The powder thus obtained was calcined in air at 400 ° C. for 3 hours. After firing treatment,
It was molded and sized to 16/30 mesh. Hereinafter, Example 1
1.0 g of the catalyst was subjected to the activity test in the same manner and under the same conditions. The results are shown in Table 3.

Comparative Example 2 10.02 g of iron hydroxide was placed in a 200 ml eggplant-shaped flask, 100 ml of ion-exchanged water in which 5.31 g of copper nitrate trihydrate was dissolved was added, and the pressure was reduced while heating in a water bath at 60 ° C. Then the water was evaporated. 4 of the powder thus obtained in air
It was baked at 00 ° C. for 3 hours. After firing, molded 16/3
The size was adjusted to 0 mesh. Hereinafter, 1.0 g of the catalyst was subjected to an activity test under the same method and conditions as in Example 1. The results are shown in Table 3.

Comparative Example 3 To a mixture of 5.41 g of basic copper carbonate and 9.01 g of basic zinc carbonate, 15 ml of ion-exchanged water in which 1.13 g of potassium carbonate was dissolved was added and kneaded well in a mortar. The resulting slurry was dried overnight in a drier at 60 ° C., transferred to a crucible and calcined in air at 400 ° C. for 3 hours. The powder thus obtained was molded and sized to 16/30 mesh. Less than,
Using the same method and conditions as in Example 1, 1.0 g of the catalyst was subjected to the activity test. The results are shown in Table 3.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3] Catalyst 1.0 g, space velocity 4500 hr ^-1 * 1 Carbon standard * 2 Total of methanol, propanol and butanol * 3 Total of saturated and unsaturated hydrocarbon compounds having 1 to 5 carbon atoms

Claims (2)

[Claims] 1. A method for producing ethanol, which comprises catalytically hydrogenating carbon dioxide using a catalyst containing elements such as iron, copper and zinc. 2. The method according to claim 1, wherein a catalyst composed of iron, copper, zinc, and an element belonging to Group 1a of the periodic table is used.