JPH078799A - Production of catalyst for synthesizing methanol - Google Patents

Abstract

PURPOSE:To provide a catalyst wherein activity is high and durability is excellent by dropping an aqueous solution containing zinc and aluminum or chromium into the aqueous solution of a precipitant to produce precipitate and then dropping an aqueous solution containing copper to furthermore produce precipitate on the precipitate and washing the same and thereafter burning it. CONSTITUTION:While the aqueous solution of a precipitant is thermally insulated at the prescribed temperature and agitated, an aqueous solution containing zinc and aluminum or chromium is firstly dropt into the aqueous solution of the precipitant to produce precipitate. After dropping is finished, an aqueous solution containing copper is dropt and furthermore precipitate is produced on the precipitate. The precipitate is washed and thereafter burned. The composition ratio of the obtained multiple oxide is regulated to about 10-250 (atomic ratio) Zn and about 1-50 Al or Cr for 100 Cu. The aqueous solution of the precipitant is an alkali solution and Na2CO3 aqueous solution having concentration of about 0.1-10M is ordinarily preferable. Further the temperature of the solution in the case of producing precipitate is preferably kept in a range within about 15-90 deg.C.

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 a catalyst for methanol synthesis which is used when synthesizing methanol from a gas containing H ₂ and CO ₂ as main components.

[0002]

2. Description of the Related Art Development and research of a methanol synthesis catalyst has been conducted for a long time, and a catalyst having a composition of zinc oxide-chromium oxide, copper oxide-zinc oxide, etc. is prepared by a coprecipitation method or the like. Particularly, a ternary catalyst composed of copper oxide-zinc oxide- (aluminum oxide and / or chromium oxide) has a high methanol synthesis activity and is widely used.

On the other hand, methanol is expected to be used as a raw material for the production of MTBE (methyl tert-butyl ether), gasoline, petrochemical intermediate products, hydrogen, carbon monoxide, city gas, etc., and as fuels, demand will increase more and more. A large-scale methanol synthesis plant is expected to be constructed all over the world.

Further, at present, methanol is produced by contacting the above-mentioned three-way catalyst with a gas containing hydrogen and carbon monoxide as main components produced by a steam reforming reaction of natural gas as a raw material. As one of the recovery and resource recovery of carbon dioxide gas, which is said to be the main cause of global warming, the methanol synthesis reaction by catalytic hydrogenation of carbon dioxide gas is drawing attention.

From the background described above, a catalyst suitable for a methanol synthesis reaction by catalytic hydrogenation of carbon dioxide has been actively developed recently, but the methanol synthesis activity is low,
Furthermore, since it is difficult to say that the life is sufficient, development of a high-performance methanol synthesis catalyst has been awaited.

[0006]

The catalysts containing copper, zinc, aluminum and / or chromium which have been prepared so far have been prepared by a coprecipitation method. Examples thereof include a method of dropping into a liquid to generate a precipitate, and a method of simultaneously dropping into an aqueous solution of a metal salt and an alkaline precipitation solution to obtain a precipitate in a constant pH range around neutral. As a result, in the former method, the pH range of precipitation differs depending on each metal, and the precipitates of the three kinds of metals tend to be precipitated separately, so that the methanol synthesis activity and durability are not sufficient. On the other hand, in the latter method, three kinds of metals are simultaneously precipitated,
It forms a crystalline seed containing trimetals and has a relatively high specific surface area to form a uniform catalyst, but it does not have high methanol synthesis activity.

In view of the above-mentioned state of the art, the present invention has high activity,
Another object of the present invention is to provide a method for obtaining a catalyst for methanol synthesis containing copper, zinc and (aluminum and / or chromium) which is also excellent in durability.

[0008]

[Means for Solving the Problems] As a result of earnestly carrying out the research and development of a catalyst which exceeds the performance of existing methanol synthesis catalysts, the present inventors have found that a method of highly dispersing copper, which plays the most important role in methanol synthesis activity. The present invention has been completed and the present invention has been completed.

That is, according to the present invention, when a catalyst for a methanol synthesis catalyst containing at least copper, zinc and aluminum and / or chromium as a metal component is produced, a precipitating agent aqueous solution kept at a predetermined temperature is stirred and first mixed with zinc. An aqueous solution containing aluminum and / or chromium is added dropwise to the precipitating agent aqueous solution to form a precipitate, and after the dropping is completed, an aqueous solution containing copper is added dropwise to further form a precipitate on the precipitate, A method for producing a catalyst for synthesizing methanol from a gas containing hydrogen and carbon dioxide as main components, characterized in that the precipitate is washed and then calcined.

The composition ratio of the composite oxide, which is the catalyst for methanol synthesis in the present invention, is Zn: 10 to 250, Al and / or Cr: 1 with respect to Cu: 100 (atomic ratio).
~ 50. Hereinafter, the method for producing the methanol synthesis catalyst of the present invention will be described in more detail. First, keep the precipitant aqueous solution warm,
While stirring, an aqueous solution containing Zn and Al and / or Cr is dropped to deposit a precipitate, and after dropping, an aqueous solution containing Cu is then dropped to generate a precipitate. When the pH at the end of dropping is 4 or more, almost all the dropped metal ions are deposited as a precipitate.

The aqueous solution of the precipitating agent is an alkaline solution, and usually has a concentration of 0.1 to 10 M Na ₂ CO ₃ , NaHCO ₃ , N 2.
An aqueous solution of aOH, K ₂ CO ₃ and NH ₃ is used,
A Na ₂ CO ₃ aqueous solution is particularly preferable. Moreover, it is preferable to maintain the temperature of the solution at the time of producing a precipitate in the range of 15 to 90 ° C.

Further, Cu, Zn and Al and / or C
Each metal salt of r is used in the form of nitrate, chloride, sulfate, or acetate as an aqueous solution having a concentration of 0.01 to 1.0 M, and particularly preferably used as nitrate.

Further, the dropping time and the aging time are not particularly affected, but the conditions are such that the metal ions are uniformly dispersed and the precipitate is deposited. Usually, the dropping time is 0.1 minutes to 3 hours, and the aging time is 0. It is carried out in the range of 1 minute to 3 hours.

The obtained precipitate has various crystal species, but after sufficiently removing alkali metals and anions by washing,
A methanol synthesis catalyst is obtained by firing in the range of 00 to 400 ° C. This catalyst is Cu
Although crystal species of O and ZnO are recognized, it has been confirmed that they are highly dispersed in a state close to an amorphous state. A highly active methanol synthesis catalyst can be obtained by the above production method, and the specific production method will be described in detail in the following examples.

[0015]

【Example】

(Example 1) 2.5 mol of sodium carbonate (Na ₂ CO ₃ ) was dissolved in 2 liters of water and kept at 80 ° C. This alkaline aqueous solution is referred to as solution A. Zinc nitrate {Zn (NO ₃ )
₂ · 6H ₂ O} 0.18 mol of aluminum nitrate {Al
_{(NO 3) 3 · 9H 2} O} 0.03 mol water 600cc
And keep it at 80 ° C., and use this acidic solution as solution B. 0.3 mol of copper nitrate {Cu (NO ₃ ) ₂ .3H ₂ O} and 300 cc of water were dissolved and kept at 80 ° C., and this acidic solution was designated as solution C.

First, the solution B is added to the solution A with stirring 30 times.
A uniform suspension is added dropwise over a minute to obtain a suspension. Next, solution B
After dropping, the solution C is dropped into the suspension at a constant rate over 30 minutes to obtain a precipitate. The pH at the end of the dropping was 8.

After dripping, aging is carried out for 2 hours, and then the precipitate is filtered and washed until Na ions and NO ₃ ions are no longer detected. Furthermore, the methanol synthesis catalyst is obtained by drying at 100 ° C. for 24 hours and then calcining at 300 ° C. for 3 hours. This catalyst is referred to as catalyst 1.

(Example 2) Zinc nitrate {Zn (NO
_{3) 2 · 6H 2 O}} 0.3 mol, aluminum nitrate {A
and producing methanol synthesis catalyst in _{l (NO 3) 3 · 9H} 2 O} the same production method as in Example 1 but using 0.05 mole. This catalyst is referred to as catalyst 2.

Further, the liquid B contains zinc nitrate {Zn (NO ₃ ).
₂ · 6H ₂ O} 0.15 mol, aluminum nitrate {Al
(NO ₃₎ the ₃ · 9H ₂ O} 0.015 mol, also, B
Liquid zinc nitrate _{{Zn (NO 3) 2 ·} 6H 2 O} 0.15
Mole aluminum nitrate _{{Al (NO 3) 3 ·} 9H
₂ O} was produced in the same manner as in Example 1 except that 0.06 mol was used to obtain catalyst 3 and catalyst 4.

(Embodiment 3) The liquid B was mixed with zinc nitrate {Zn (NO
_{3) 2 · 6H 2 O}} 0.225 mol and chromium nitrate {Cr
_{(NO 3) 3 · 9H 2} O} using 0.075 mol, to obtain a catalyst 5 was prepared in the same production method as in Example 1.

Further, the solution B contains zinc nitrate {Zn (NO ₃ ).
₂ · 6H ₂ O} 0.225 mol, chromium nitrate {Cr (N
_{O 3) 3 · 9H 2 O} } 0.05 mol, aluminum nitrate _{{Al (NO 3) 3 ·} 9H 2 O} using 0.05 mol of catalyst 6 was prepared by the same production method as in Example 1 Obtained.

Comparative Example A conventional catalyst was produced by the following method using solutions A, B and C having the same composition as the catalyst 3 of Example 2. First, the solution C is added to the solution B at once to obtain an acidic aqueous solution (pH = 3) containing zinc, aluminum, and copper ions. While stirring Solution A in this aqueous solution, 3
Add dropwise over 0 minutes. The pH at the end of the dropping was 8. After dropping, the mixture was aged for 2 hours, and then a catalyst 7 was obtained by the same production method as in Example 1.

(Experimental Example 4) An activity evaluation test of the methanol synthesis reaction of the catalysts 1 to 7 obtained in Examples 1 to 3 and Comparative Example was conducted under the following conditions. Raw material gas: H ₂ 75 mol%, CO ₂ 25 mol% GHSV: 6000 h ⁻¹ Reaction temperature: 230 ° C. Reaction pressure: 40 kg / cm ² G The catalyst was sized to 16 to 28 mesh and charged into a 2 cc microreactor. , H ₂ 3% / N ₂ base gas was subjected to a reduction treatment, and then a raw material gas was supplied to evaluate the initial activity. Table 1 shows the results of evaluating the initial activity of each catalyst.

[0024]

[Table 1] 50% to 60% of the reacted CO ₂ was methanol.

The catalysts 3 and 7 used for the initial activity evaluation were used as the catalysts for durability test. The reaction conditions were the same as in Example 4 except for the reaction pressure, and the activity results are shown in Table 2.

[0026]

[Table 2] 40-60% of the reacted CO ₂ (pressure 40 kg / cm ²
In the case of G), 60-80% (in the case of pressure 80 kg / cm ² G) was methanol. As shown in Table 2, it was found that the catalyst prepared according to the present invention was superior in durability to the conventional catalyst.

(Embodiment 5) As a source gas, H ₂ : CO
_The test was conducted on the catalysts 3 and 7 under the same conditions as in Example 4 except that a gas of ₂ : CO = 77: 17: 6 mol% was used. The results are shown in Table 3.

[0028]

[Table 3] 100% of the reacted CO ₂ was methanol. Table 3
As shown in (1), it was found that the catalyst prepared according to the present invention has excellent performance in the methanol synthesis reaction even in a gas containing CO other than H ₂ and CO ₂ .

[0029]

Industrial Applicability According to the present invention, a highly active and highly durable methanol synthesis catalyst containing copper, zinc and aluminum and / or chromium can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Imai 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries Ltd. Hiroshima Research Institute (72) Inventor Kennosuke Kuroda 2-5 Marunouchi, Chiyoda-ku, Tokyo No. 1 Sanryo Heavy Industries Co., Ltd.

Claims (1)

[Claims] 1. When producing a methanol synthesis catalyst containing at least copper, zinc and aluminum and / or chromium as a metal component, first, zinc, aluminum and / or Alternatively, an aqueous solution containing chromium is added dropwise to the precipitating agent aqueous solution to form a precipitate, and after the dropping is completed, an aqueous solution containing copper is added dropwise to further form a precipitate on the precipitate, and the precipitate A method for producing a catalyst for synthesizing methanol from a gas containing hydrogen and carbon dioxide as main components, which comprises rinsing after washing.