JPH04364141A - Production of methanol by hydrogenation of carbon dioxide - Google Patents

Abstract

PURPOSE:To obtain the subject compound in high selectivity and yield and prevent sudden deterioration in catalyst activity by using a specific double oxide catalyst in catalytically hydrogenating carbon dioxide and producing methanol. CONSTITUTION:Carbon dioxide is catalytically hydrogenated in the presence of a group IB metal-zinc-chromium double oxide catalyst prepared by mixing a complex carbonate of a group IB metal (e.g. copper, silver or gold)-zinc prepared by a coprecipitation method or a compound oxide of a group IB metal- zinc obtained by burning the aforementioned complex carbonate at 350-400 deg.C, normally at 350 deg.C temperature with an aqueous solution of chromium dioxide to afford methanol in selectivity as high as 80-100%. Furthermore, the conversion rate of the carbon dioxide exhibits a high value of 10-30% under reactional conditions of 200-250 deg.C reaction temperature and 50ml/min flow velocity which are not different from those of conventional methods without any recognized deterioration in catalyst activity.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention uses a group IB metal-zinc-chromium composite oxide catalyst with a uniform composition at the atomic level produced by a new preparation method to react methanol with carbon dioxide and hydrogen. The present invention relates to a method for manufacturing a bottle.

0002

BACKGROUND OF THE INVENTION Research on an effective method for catalytic hydrogenation of carbon dioxide has hardly been established, and no catalyst for efficiently producing methanol is known. As a conventional method, studies have been conducted using copper-zinc catalysts used for methanol synthesis from carbon monoxide, and ternary catalysts using silica or alumina as carriers are known (R .Kieffer, E. Ramaroso
n, A. Deluzarche, Y. Tram
bouze, React. Kinet. Catal
．． Lett. , 16, 207 (1981). )
. In addition, a catalyst using zirconia instead of zinc (Y.
Amenomiya, Appl. Catal. ，
30, 57 (1987)) and Raney copper alloy catalyst (
W. L. Marsden, M. S. Wainw
Right, J. B. Friedrich, I.
nd. Eng. Che. Prod. Res. D
ev. , 19, 551 (1980)) has also been developed. On the other hand, it has been reported that a catalyst in which palladium, platinum, or rhodium is supported on a basic carrier, such as Pd/La2O3, shows good results (E. Ramaroson,
R. Kieffer, A. Kienneman
n, J. Chem. Soc. , Chem. Co
mmun. , 645 (1982)).

0003

In the case of methanol synthesis using a copper-zinc catalyst, the selectivity is low and the main product is carbon monoxide obtained from the reverse water gas shift reaction (CO2+H2→CO+H2O). Among them, there is a method of preparing a catalyst by adding copper oxide and zinc oxide to an aqueous solution of chromium trioxide, which gives relatively good results (Yoshino Ogino, Catalyst, 2,
301 (1960)). However, this method
Since copper oxide powder and zinc oxide powder are simply mixed, the copper and zinc are not uniformly dispersed at the atomic level, resulting in a low methanol yield. Furthermore, it has a fatal drawback as a catalyst in that the catalytic activity decreases to some extent immediately after the reaction starts. On the other hand, palladium or platinum (T. Inou
e, T. Iizuka, J. Chem. So
c. , Faraday Trans. I, 82,
1681 (1986)) or rhenium (T.
uka, M. Kojima, K. Tanabe,
J. Chem. Soc. , Chem. Com
mun. , 638 (1983)), the conversion rate of carbon dioxide itself is low, and even when the methanol selectivity is high, the yield of methanol is very small.
Furthermore, it also has drawbacks such as methane being produced as a by-product in many cases. As described above, conventional methods cannot be said to be sufficient in terms of yield and selectivity for methanol production.

The present invention provides a high performance catalyst for methanol synthesis from carbon dioxide that overcomes the activity and selectivity limitations and constraints of conventional catalysts.

[0005]

[Means for Solving the Problems] The present invention enables methanol to be produced in good yield and with high selectivity from the reaction of carbon dioxide and hydrogen using a group IB element-zinc-chromium catalyst according to a novel preparation method. It is characterized by manufacturing. In general, highly active multi-component catalysts require each metal to have a uniform structure at the atomic level, and such a uniform structure cannot be expected from a simple mixture of copper oxide and zinc oxide. Therefore, as a result of intensive research into a method for preparing a composite oxide of group IB-zinc-chromium that is uniformly dispersed at the atomic level, the present inventors first discovered that the carbonates of group IB elements and the composite salts of zinc carbonate were combined together. Prepared by the precipitation method, this composite carbonate is mixed with a concentrated solution of chromium trioxide and reacted, or this composite carbonate is calcined to obtain a composite oxide of group IB element-zinc, and then mixed with a concentrated solution of chromium trioxide. We succeeded in preparing a highly active methanol synthesis catalyst by mixing it with a concentrated chromium solution and drying it naturally.

[0006] That is, the precipitate (gel), which is a complex salt of carbonate, is produced by adding an aqueous solution of sodium carbonate to an aqueous solution of nitrates of group IB elements and zinc nitrate. Evenly distributed. Furthermore, the composite oxide obtained by firing this gel also has a uniformly dispersed structure. I by adding a complex carbonate or complex oxide to an aqueous solution of chromium trioxide and carrying out a reaction.
A homogeneous ternary catalyst of group B metals, zinc and chromium can be obtained.

[0007] The temperature at which nitrate and sodium carbonate are reacted to prepare a uniform precipitate is 60-100°C, preferably around 90°C. The drying temperature for precipitating the complex salt is 80-120°C, usually around 100°C. The firing temperature for converting composite salt into oxide is 350-4
00°C, and is usually fired at 350°C.

[0008] Examples of the IB group elements include compounds of copper, silver, and gold, which are used singly or in combination. The composite oxide of group IB metal, zinc and chromium may be used in combination with a support such as alumina or silica.

The composite oxide catalyst prepared as described above provides methanol with high selectivity through hydrogenation reaction of carbon dioxide, and no decrease in catalytic activity is observed.

0010

[Operation] The catalyst in the present invention is prepared by adding a composite carbonate obtained by a coprecipitation method or a composite oxide after calcination to chromium trioxide, and is an IB group element, zinc, which hydrogenates carbon dioxide and gives methanol. It is a catalyst consisting of a composite oxide of chromium and chromium, and has the following characteristics. When producing methanol by catalytic hydrogenation of carbon dioxide, most conventional catalysts often have a low conversion rate of carbon dioxide. However, with the newly invented catalyst, carbon dioxide is
Reaction temperature 200-250℃, 50 atm, flow rate 50
Under the same reaction conditions as before, ml/min, 10
- Shows a high conversion rate of 30%.

[0011] Furthermore, the selectivity is at a high level of 80-100%. Few conventional catalysts have been reported to exhibit such high methanol selectivity. Furthermore, the results obtained 24 hours after the start of the reaction were almost unchanged from the results immediately after the start of the reaction. As described above, the present invention has also made it possible to simultaneously prevent the rapid decline in catalytic activity, which was a fatal drawback of conventional catalysts using chromium trioxide.

0012

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

[0013]

Example 1 (1) Preparation of catalyst A copper-zinc-chromium catalyst was prepared as follows. Copper nitrate (
Cu(NO3)2.3H2O) 18g, zinc nitrate (Zn
While keeping the temperature of the solution at about 90°C, add 79 g of sodium carbonate (Na2CO3) to about 750 ml of water.
An aqueous solution dissolved in 1 ml was slowly added dropwise until the pH reached 6.8. After the dropwise addition was completed, the precipitate formed was filtered and washed, and
It was dried at 0°C for about 3 hours. 4.9 g of the copper and zinc composite carbonate thus produced was combined with 1.0 g of chromium trioxide (CrO3).
Slowly add to 10ml aqueous solution of and stir well.
It was left as it was for about 2 days and air-dried.

(2) Reaction: Fill a stainless steel reaction tube with 1.0 g of the above copper-zinc-chromium catalyst classified into 24-40 mesh, and add 1% nitrogen to the reaction tube.
After treatment at 250°C for about 12 hours in a hydrogen stream diluted with
At a predetermined reaction temperature and reaction pressure, a mixed gas of H2/CO2=3 was passed through to carry out the reaction. The reaction products and unreacted products obtained by the above operations were analyzed by gas chromatography. The results are shown in Table 1.

Table 1 Methanol synthesis from carbon dioxide


Reaction temperature CO2 yield (%
) methanol
Conversion rate
selection rate
(℃) (%)
MeOH CO HC (%)



150
5.3 5.3 0.0 0.0
100.0
200 9.6 8.
9 0.7 0.0 92.7
25
0 19.0 8.7 10.3
0.0 45.8
300 25.
3 6.0 19.3 0.0
23.7
(Results after 24 hours)

150 5.2
5.2 0.0 0.0 10
0.0
200 8.5 7.9
0.6 0.0 92.9
250
17.3 7.3 10.0 0.
0 42.2
300 26.1
6.1 20.0 0.0 23.
4 Reaction conditions: catalyst 1 g (24-40 mesh),
Pressure: 50 atm, flow rate: 50 ml/min, H2/CO2=3.

00
16]

Example 2 A copper-zinc composite salt prepared in the same manner as in Example 1 was dried at 100°C for about 3 hours and then calcined at 350°C for about 5 hours. Copper-zinc composite oxide thus obtained
3.2 g was slowly added to an aqueous solution of 1.0 g of chromium trioxide dissolved in 10 ml, thoroughly stirred, and air-dried for 2 days. A reaction was carried out under the same conditions as in Example 1, using the catalyst prepared by the above method instead of the catalyst in Example 1. The results are shown in Table 2. (Margin below)

Table 2 Methanol synthesis from carbon dioxide


Reaction temperature CO2 yield (%)
methanol
Conversion rate
selection rate
(℃) (%) M
eOH CO HC (%)



150 1.9
1.9 0.0 0.0 100.
0
200 7.4 6.9 0.
5 0.0 93.2
250 1
8.7 9.6 9.1 0.0
51.3
300 25.2 6.2
19.0 0.0 24.6
Reaction conditions: catalyst 1 g (24-40 mesh),
Pressure 50 atm, flow rate 50ml/min, H
2/CO2=3.

[0018]

[Example 3] Copper nitrate 5.2g, silver nitrate (AgNO3) 5
．． 20 g of silver-zinc composite carbonate obtained in the same manner as in Example 1 using 5.0 g of chromium trioxide and 42 g of zinc nitrate.
A catalyst was prepared by adding 0 g to 50 ml of an aqueous solution and treating in the same manner as in Example 1. The reaction method was also the same as in Example 1. The results are shown in Table 3. (Margin below)

Table 3 Methanol synthesis from carbon dioxide


Reaction temperature CO2 yield (%)
methanol
Conversion rate
selection rate
(℃) (%) MeOH CO
HC (%)
150 1.3
0.3 0.0 0.0 100.0
200
4.9 0.9 0.0 0
．． 0 100.0
250 14.2 3
．． 2 1.0 0.0 76.7
300
24.3 5.8 8.5 0.
0 40.5 Reaction conditions: catalyst 1 g (24-
40 mesh), pressure 50 atm, flow rate 50 ml/min, H2/CO2=3. that's all

Claims (1)

[Claims] Claim 1: Prepared by mixing an aqueous solution of chromium trioxide with a composite carbonate of group IB metal-zinc prepared by a coprecipitation method or a composite oxide of group IB metal-zinc obtained by calcining the carbonate. A method for producing methanol by catalytic hydrogenation of carbon dioxide using a group IB metal-zinc-chromium composite oxide catalyst.