JPH0987217A - Production of ethanol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing ethanol, capable of producing the useful ethanol in a high CO2 conversion and in a high yield by catalytically hydrogenating the carbon dioxide in the presence of a specific catalyst. SOLUTION: This method for producing the ethanol comprises catalytically hydrogenating (B) the carbon dioxide in the presence of (A) a catalyst containing iron, copper, zinc and potassium in copper/iron, zinc/iron and potassium/iron atomic ratios of 0.2-3.0, 0.2-3.0 and 0.01-0.5, respectively. The component A is preferably the catalyst further containing the VIII group element in the periodic table, selected from cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. The ratio of the VIII group element in the catalyst containing the VIII group element to the iron is preferably 0.00001-2. In the catalytic hydrogenation reaction, a mixture gas comprising the carbon dioxide and hydrogen or further containing an inert gas is used as raw materials in a CO2 /H2 molar ratio of 0.1-10 at 200-400 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing ethanol by catalytic hydrogenation of carbon dioxide. Ethanol is an important basic raw material for various chemicals, medicines and agricultural chemicals.

[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, and in particular, suppression of carbon dioxide emission, which is considered to be the main causative agent, is being studied, but the most desirable solution is to recover and recycle it. That is. As one of the measures, the development of an industrial conversion technology for converting carbon dioxide into a carbon resource into ethanol is required.

[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 conducted by the present inventors to synthesize ethanol by catalytic hydrogenation of carbon dioxide, (1) iron, copper, zinc and potassium are composed at a constant ratio. A catalyst, or (2) a periodic table selected from the group consisting of cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum
The inventors have found that ethanol is produced in high yield by carrying out a hydrogenation reaction of carbon dioxide in the presence of a catalyst containing a group II element (hereinafter referred to as a group VIII element), and completed the present invention.

That is, the present invention includes (1) iron, copper, zinc, and potassium, and the atomic ratios of copper / iron, zinc / iron, and potassium / iron are 0.2 to 3.0 and 0.2, respectively. ~ 3.0, 0.
A method for producing ethanol, which comprises catalytically hydrogenating carbon dioxide using a catalyst composed of 01 to 0.5;
And (2) iron, copper, zinc, and potassium, and further, periodic table VI selected from cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum.
This is a method for producing ethanol using a catalyst containing a Group II element.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The ethanol synthesis reaction of the present invention comprises:
It is expressed by the following equation. 2CO ₂ + 6H ₂ → C ₂ H ₅ OH + 3H ₂ O In preparing the catalyst of the present invention, iron, copper, zinc, potassium, or each component of iron, copper, zinc, potassium, and the group VIII element is finally combined. The form of the compound as a starting material for each element is not particularly limited, and for example, oxides, hydroxides, basic carbonates, nitrates, acetates, or various complexes of each element are used. . Considering that the prepared catalyst is generally reduced and used in the reaction, the starting materials for iron and copper are preferably easily reducing compounds or compounds capable of being converted into easily reducing compounds. The composition ratio of each component in the catalyst of the present invention is
The atomic ratios of copper / iron, zinc / iron, potassium / iron,
It is 0.2 to 3.0, 0.2 to 3.0, and 0.01 to 0.5, and when it exceeds these ranges, the production amount of ethanol decreases. Group VIII elements used in the preparation of the catalyst of the present invention are cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, in the form of their respective hydroxides, chlorides, carbonates, nitrates, acetates, etc. Can be used. The composition ratio of the Group VIII element in the catalyst containing the Group VIII element of the present invention is in the range of 0.00001 to 2 in terms of atomic ratio to iron. If the composition ratio of the Group VIII element exceeds this range, the amount of ethanol produced will decrease.

The method for preparing the catalyst in the present invention is as follows:
Although not particularly limited, the following method can be adopted. For example, as an example of a method for preparing a catalyst containing iron, copper, zinc and potassium, 1) a method of kneading and preparing a compound of iron, copper, zinc and potassium, 2) mixing of a compound of iron, copper and zinc A method in which a coprecipitate obtained by mixing a solution and a precipitant is impregnated with or mixed with a potassium compound, 3) iron,
Copper, a method of supporting a mixed solution of a compound of potassium on a suitable zinc compound, 4) a method of supporting a mixed solution of a compound of copper, zinc, potassium on a suitable iron compound, and the like. To be Further examples of the method for preparing a catalyst containing a Group VIII element include 1) iron, copper, zinc, potassium, VIII
A method of preparing a compound of a group element by kneading, 2) impregnating or mixing a potassium compound and a group VIII element compound in a coprecipitate obtained by mixing a mixed solution of a compound of iron, copper and zinc and a precipitant. Method, 3) iron, copper, zinc, a method of impregnating or mixing a potassium compound in a coprecipitate obtained by mixing a mixed solution of a compound of a Group VIII element and a precipitant, 4) iron, A method in which a mixed solution of a compound of copper, potassium and a Group VIII element is supported on an appropriate zinc compound. Five)
Examples thereof include a method in which a mixed solution of a compound of copper, zinc, potassium and a group VIII element is supported on a suitable iron compound to prepare. Further, in the preparation of the catalyst of the present invention, a substance which does not adversely influence the reaction can be further used for the purpose of uniformly dispersing or supporting the essential constituent components. Such substances include alumina, silica, magnesia, titania, diatomaceous earth, carbon and the like.

The catalyst precursor thus prepared is
After calcination, it can be reduced with hydrogen and used as a catalyst in the reaction. The method of firing the catalyst precursor is not particularly limited in its method, but is performed by a method of leaving it in a furnace and firing it, a method of performing it in a gas stream, etc., and mixing it in any proportion of air or an inert gas. A method of firing with the atmosphere gas or the like is adopted. The firing temperature is generally 200 to 600 ° C.
Is preferable, and the firing time is 0.5 to 10 hours.
It is a degree. The hydrogen reduction treatment of the catalyst is carried out in pure hydrogen or hydrogen diluted to an arbitrary ratio with an inert gas,
The treatment method is not particularly limited, but in consideration of removal of generated water and the like, it is preferable to perform the treatment while circulating the above gas.
The reduction temperature is preferably in the range of 250 to 500 ° C,
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 reduction of the catalyst can be performed not only with hydrogen, but also with 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.
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 gas phase fixed bed,
A system such as 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 2
The pressure is in the range of up to 300 atm, preferably 10 to 80 atm. The gas hourly space velocity is in the range of 100 to 50,000 hr ^-1 , preferably 1000 to 30,000 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]

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. The catalyst activity test in each example and comparative example was carried out at a gas hourly space velocity of 5000 hr ⁻¹ with a catalyst amount of 1.0 g.

Example 1 6.04 g of copper nitrate trihydrate and 7.44 of zinc nitrate hexahydrate
g, iron nitrate nonahydrate 30.30g in a beaker 10
It was dissolved in 0 ml of ion-exchanged water. Deionized water 200
26.00 g of sodium hydroxide was dissolved in ml and the aqueous solution kept at 60 ° C. was well stirred, and the above metal salt solution was added dropwise to obtain a precipitate. The precipitate was washed with about 3 liters of ion-exchanged water and then dried overnight in a dryer at 60 ° C.
5.00 g of this dried precipitate was accurately weighed and potassium carbonate was added to 0.0
3 ml of ion-exchanged water in which 60 g was dissolved was added and kneaded,
It was made into a slurry. The charged atomic ratio of the catalyst was iron: copper: zinc: potassium = 1: 0.33: 0.33: 0.026. This was dried in a dryer at 60 ° C. for 2 hours. After that, the powder was transferred to a crucible and baked at 400 ° C. for 3 hours, and the obtained powder was molded and sized to 16/32 mesh. 2.5 g of the sized product was precisely weighed and filled in a reducing tube, and hydrogen reduction treatment was carried out under normal pressure at a hydrogen flow rate of 150 ml / min and 300 ° C. for 1 hour. After the reduction treatment, when the catalyst layer cooled, the reduction tube was sealed and left overnight. When recovering the catalyst from the reduction tube, 1.0 g was precisely weighed and charged into the reaction tube after the heat generation and the increase in weight had subsided, and the hydrogen flow rate was 100 ml / under normal pressure.
Pre-reaction hydrogen reduction treatment was performed for 30 minutes at 350 ° C. for min. After the pre-reaction hydrogen 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 system became 70 kg / cm ² , the raw material gas flow rate was 90 ml / It was adjusted to min and the temperature rise was started. When a predetermined reaction temperature was reached and a steady state was reached, the reaction products were analyzed online by gas chromatography. The results of the catalytic activity test are shown in Table 1.

Example 2 5.00 g of the dry precipitate of Example 1 was precisely weighed and placed in a mortar,
0.16 g of palladium acetate was precisely weighed and added, and kneaded.
After kneading, 3 ml of ion-exchanged water in which 0.060 g of potassium carbonate was dissolved was added and kneaded to form a slurry. The charged atomic ratio of the catalyst is iron: copper: zinc: potassium: palladium =
It was 1: 0.33: 0.33: 0.026: 0.021. Thereafter, a catalyst was prepared by the same preparation method as in Example 1 and a catalyst activity test was conducted. Table 1 shows the test results.

Example 3 5.00 g of the dry precipitate of Example 1 was precisely weighed and placed in a mortar,
0.19 g of tetraammine platinum (II) hydroxide dihydrate was precisely weighed and kneaded. After kneading, potassium carbonate 0.06
3 ml of ion-exchanged water in which 0 g was dissolved was added and kneaded to form a slurry. The charged atomic ratio of the catalyst is iron: copper: zinc:
Potassium: Platinum = 1: 0.33: 0.33: 0.02
It was 6: 0.016. Thereafter, a catalyst was prepared by the same preparation method as in Example 1 and a catalyst activity test was conducted. Table 1 shows the test results.

Example 4 6.04 g of copper nitrate trihydrate and 7.44 of zinc nitrate hexahydrate
g, iron nitrate nonahydrate 30.30 g, and nickel nitrate hexahydrate 0.08 g were placed in a beaker and dissolved in 100 ml of ion-exchanged water. 14.30 g of sodium hydroxide was dissolved in 200 ml of ion-exchanged water, and the above metal salt solution was added dropwise while well stirring the aqueous solution kept at 60 ° C to obtain a precipitate. The charged atomic ratio of the catalyst is iron: copper: zinc: potassium:
Nickel = 1: 0.33: 0.33: 0.026: 0.
It was 0038. Thereafter, a catalyst was prepared by the same preparation method as in Example 1 and a catalyst activity test was conducted. Table 1 shows the test results.

Comparative Example 1 10.01 g of iron hydroxide was placed in a 200 ml eggplant-shaped flask, and 2.67 g of copper nitrate trihydrate and zinc nitrate hexahydrate 3.
29 g and 100 ml of ion-exchanged water in which 1.11 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. The charged atomic ratio of the catalyst is iron:
It was copper: zinc: potassium = 1: 0.1: 0.1: 0.1. Thereafter, a catalyst was prepared by the same preparation method as in Example 1 and a catalyst activity test was conducted. The test results are shown in Table 2.

Comparative Example 2 14.48 g of copper nitrate trihydrate and 4.4 of zinc nitrate hexahydrate
6 g and ferric nitrate nonahydrate 6.06 g were placed in a beaker and dissolved in 100 ml of ion-exchanged water. While stirring well, 200 ml of ion-exchanged water in which 18.65 g of sodium hydroxide was dissolved was added dropwise to obtain a precipitate. This precipitate was washed with about 3 liters of ion-exchanged water and then dried overnight in a dryer at 60 ° C. This dry precipitate (5.00 g) is precisely weighed and ion-exchanged water (10 ml) in which potassium carbonate (0.83 g) is dissolved
Was kneaded and made into a slurry. The charged atomic ratio of the catalyst was iron: copper: zinc: potassium = 1: 2: 4: 0.8. Thereafter, a catalyst was prepared by the same preparation method as in Example 1,
A catalytic activity test was conducted. The test results are shown in Table 2.

Comparative Example 3 7.24 g of copper nitrate trihydrate and 17.8 of zinc nitrate hexahydrate
5 g and ferric nitrate nonahydrate 6.06 g were placed in a beaker and dissolved in 100 ml of ion-exchanged water. While stirring well, 200 ml of ion-exchanged water in which 21.76 g of sodium hydroxide was dissolved was added dropwise to obtain a precipitate. The precipitate was washed with about 3 liters of ion-exchanged water and then dried overnight in a dryer at 60 ° C. The obtained dried precipitate was treated with potassium carbonate (0.1%).
Add 10 ml of ion-exchanged water in which 83 g was dissolved and knead,
It was made into a slurry. The charged atomic ratio of the catalyst was iron: copper: zinc: potassium = 1: 4: 1: 0.8. Thereafter, a catalyst was prepared by the same preparation method as in Example 1 and a catalyst activity test was conducted. The test results are shown in Table 2.

Comparative Example 4 14.51 g of copper nitrate trihydrate, zinc nitrate hexahydrate 35.
69 g and ferric nitrate nonahydrate 24.31 g were placed in a beaker and dissolved in 200 ml of ion-exchanged water. 400 ml of ion-exchanged water in which 43.42 g of sodium hydroxide was dissolved was added dropwise while stirring well to obtain a precipitate. The precipitate was washed with about 3 liters of ion-exchanged water and then dried overnight in a dryer at 60 ° C. 3.96 g of the obtained dry precipitate was precisely weighed, 5 ml of ion-exchanged water in which 0.0033 g of potassium carbonate was dissolved was added and kneaded to form a slurry. The charged atomic ratio of the catalyst was iron: copper: zinc: potassium = 1: 1: 2 :.
It was 0.004. Thereafter, a catalyst was prepared by the same preparation method as in Example 1 and a catalyst activity test was conducted. The test results are shown in Table 2.

[0020]

Table 1 Example 1 Example 2 Example 3 Example 4 Reaction temperature ℃ 300 300 300 300 300 Reaction pressure kg / cm ² 70 70 70 70 70 CO ₂ conversion% 44.4 44.7 45.6 43.4 (Selectivity)% * 1 Carbon monoxide 5.9 5.7 5.5 5.5 6.3 Ethanol 19.5 21.2 22.4 21.0 Other alcohols * 2 7.5 8.1 10.0 8.0 Hydrocarbons * 3 46.1 48.5 49.9 53.5 * 1 Carbon standard * 2 Total of methanol, propanol and butanol * 3 Saturated and unsaturated hydrocarbon compounds with 1 to 5 carbon atoms

[0021]

[Table 2] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Reaction temperature ℃ 300 300 300 300 300 Reaction pressure kg / cm ² 70 70 70 70 70 CO ₂ conversion% 21.3 37.7 35.0 33.8 (Selectivity)% * 1 Carbon monoxide 25.1 9.8 12.0 10.9 Ethanol 6.2 10.2 11.1 9.4 Other alcohols * 2 3.8 7.6 7.6 8.1 Hydrocarbons * 3 35.0 37.3 34.0 71.0 * 1 Carbon standard * 2 Sum of methanol, propanol and butanol * 3 Saturated and unsaturated hydrocarbon compounds with 1 to 5 carbon atoms

[0022]

As is apparent from the above examples, by carrying out the catalytic hydrogenation reaction of carbon dioxide using the catalyst of the present invention, a high CO ₂ conversion and a high ethanol selectivity can be obtained. Therefore, according to the method of the present invention, useful ethanol can be obtained in a high yield, and the industrial significance of the present invention is great.

Claims (2)

[Claims] 1. Iron / copper / zinc / potassium containing copper /
The atomic ratios of iron, zinc / iron, and potassium / iron are 0.
A method for producing ethanol, which comprises catalytically hydrogenating carbon dioxide using a catalyst composed of 2 to 3.0, 0.2 to 3.0, and 0.01 to 0.5. 2. Iron, copper, zinc, and potassium, and further cobalt, nickel, ruthenium, rhodium, palladium,
Periodic table selected from osmium, iridium and platinum
The method for producing ethanol according to claim 1, wherein a catalyst containing a Group VIII element is used.