JPH08215570A - Catalyst for synthesis of methanol, production thereof and synthesis of methanol - Google Patents

Abstract

PURPOSE: To provide a catalyst to be used to produce methanol from CO2 and H2 gas and to provide a production method of the catalyst and a synthesis method of methanol using this catalyst. CONSTITUTION: This catalyst for synthesis of methanol consists of an alloy expressed by general formula TM, (wherein T is at least one element selected from rare earth elements and Mg, Ca, Mn, Zr, Hf, Al and Ga and M is at least one element selected from IB group [Cu, Ag, Au] and VIII group [Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt] in the periodical table). This catalyst has such a structure that metal fine particles of M element are dispersed on an oxide having the surface comprising the T element. The catalyst is produced by heating an alloy containing an amorphous and/or fine crystalline phase of the compsn. above described in an oxidative atmosphere or in an equal atmosphere for synthesis of methanol at 50-700 deg.C. This catalyst is used for the synthesis of methanol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for producing methanol from combustion exhaust gas containing CO ₂ as a main component and H ₂ gas, a method for producing the same, and a method for synthesizing methanol.

[0002]

2. Description of the Related Art CO ₂ emissions tend to increase over the years as economic activities become more active, and global warming due to the accumulation of CO ₂ has recently become more serious, and there is an urgent need to reduce CO ₂ emissions. ing. Various CO ₂ reduction method has been studied as one of the solutions, CO ₂ as inter alia effective method
Is reacted with H ₂ to be converted into an alcohol raw material such as methanol and then recycled. Methanol obtained by this method can be used as an energy source, but since it is also a basic raw material in the synthesis of chemical products, if this method can be established, not only CO ₂ emissions can be reduced, but also petroleum resources can be reduced. It can also contribute to savings. A catalyst for carrying out this kind of reaction has been studied so far, and a Cu—Zn-based catalyst produced by a chemical method such as coprecipitation using a metal salt as a starting material or an impregnation method is considered promising. However, there is a problem that a large amount of electricity is required to remove by-products and recycle unreacted gas, and further improvement of catalyst performance has started. Was expected. Further, since a metal salt is used as a starting material, there are problems that impurity ions remain and the degree of dispersion of catalyst particles is small. Further, Japanese Patent Laid-Open No. 60-87233 discloses a method for producing methanol by directly contacting a synthetic gas composed of hydrogen and carbon monoxide with an amorphous alloy which is a catalyst material. In addition, although it is shown that the amorphous alloy itself functions as a catalyst in this method, the amorphous alloy itself is thermally unstable and has a small surface area. Can't get

[0003]

The object of the present invention is to have a higher activity and selectivity than catalysts such as Cu--Zn type and amorphous alloys prepared by the conventionally known coprecipitation method. C
The present invention provides a catalyst material for producing methanol from O ₂ and H ₂ gas, a method for producing the catalyst, and a method for synthesizing methanol.

[0004]

In order to solve the above problems, it is necessary to remove impurity ions in the catalyst, further miniaturize active metal particles, and further improve the dispersity of ultrafine metal particles. Therefore, the present invention discloses the fact that is achieved by using a rapidly solidified alloy as a starting material. The first aspect of the present invention is the general formula: TM
(However, T is a rare earth element [Y, La, Ce, Pr, N
d, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu] and Mg, Ca, Mn, Z
At least one element selected from r, Hf, Al and Ga, M is Group IB [Cu, Ag, Au] and VI of the periodic table.
Group II [Fe, Co, Ni, Ru, Rh, Pd, Os, I
[at least one element selected from r, Pt]), the surface of which is an oxide of T element and fine metal particles of M element dispersed therein for methanol synthesis. It is a catalyst. In the above general formula, T element is 1 to 99% and M element is 1 to 99% in atomic percent. In addition, the size of the metal fine particles composed of M elements dispersed in an island shape is from sub-nanometer to several tens of nanometers, and more specifically, fine particles of 30 nm or less work particularly effectively as a catalyst.

By combining the T element and the M element represented by the general formula, the rapidly solidified body of the molten alloy is an amorphous alloy or a mixed phase of an amorphous and a fine crystalline phase (amorphous phase). Or an alloy containing a fine crystalline phase, and subjecting it to a predetermined oxidation treatment or oxidation-reduction treatment, the metal fine particles of the M element or the surface layer are formed of a metal on the oxide consisting of the T element. It is possible to obtain a surface layer in which ultrafine metal oxide particles are dispersed. The oxide composed of the T element is bound to the metal fine particles composed of the M element through a strong interaction, stably fixes the metal fine particles as they are, and exhibits great activity. If the combination of the T element and the M element deviates, the activity is low even if the amorphous phase is used as a precursor.

The preferred ranges of the T element and the M element are most effective near the eutectic point on the alloy phase diagram for obtaining an amorphous phase or a fine crystal structure, and therefore the catalytic activity is also high. 1 to 99% of T element and 9 of M element in atomic percent
When the content is in the range of 9 to 1%, a structure in which fine metal particles are dispersed on the oxide is more remarkably exhibited, and high activity is exhibited. As a specific example, for LaAu alloy, La _bal Au is used.
_{10 to 95} , Ce _bal Co _{5 to 50} in CeCo alloy, NdAg
Nd _bal Ag _10-95 for alloys, Gd _{bal for} GdAu alloys
Au _{5 to 90} , Mg _bal Pd _{5 to 30} in the case of MgPd alloy, Ca
Cu _bal Cu _10-50 for Cu alloys, M for MnCu alloys
n _bal Cu _{40 to 80} (however, bal represents the rest and numbers represent atomic percentages) and the like. Of course, the range is about the same for other combinations. Further, the preferable composition range of each element is 30 to 70% of T element and 7 of M element.
0 to 30%. Great activity is obtained in this range.
As described above, when the size of the metal fine particles is from sub-nanometer to several tens of nanometers, more specifically 30 nm or less, particularly 10 nm or less, the catalytic effect is dramatically improved. Furthermore, 5 nm or less is preferable. The target reaction of the catalyst of the present invention is the following methanol synthesis reaction by catalytic hydrogenation of CO ₂ . CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O In the second aspect of the present invention, an alloy containing an amorphous phase and / or a fine crystalline phase is prepared from the molten composition of the alloy represented by the above general formula TM, and the alloy is prepared under an oxidizing atmosphere. Heat to 50-700 ° C with
A method for producing a catalyst for methanol synthesis, which comprises depositing and dispersing fine metal particles of M element on an oxide of element.

As means for producing the alloy containing the amorphous phase and / or the fine crystalline phase, a method of rapidly solidifying a molten metal by a liquid quenching method at a cooling rate of 10 ⁴ to 10 ⁶ K / s, or atomizing. Method, submerged spinning method, MA (mechanical alloying) method, sputtering method, plating method and the like. Such an alloy is oxidized from the surface layer by heating in an oxidizing atmosphere, and it is tens of nanometers on an oxide composed of T element (in the case of two or more kinds, each complex oxide and / or mixed oxide). The fine metal particles composed of the M element are dispersed and exhibit high catalytic activity. The oxidizing atmosphere for producing the catalyst in which the metal fine particles are present on the oxide shown above may be either a liquid phase or a gas phase as long as it is an oxidizing atmosphere, but in view of operability, the gas phase is simpler and desirable, In particular, it is desirable to use air or a mixed gas of oxygen and an inert gas. The concentration ratio of the inert gas and oxygen varies depending on the degree of oxidization of each alloy, and the more easily the alloy is oxidized, the more rapidly it is oxidized and heat is generated, and the sintering of fine particles occurs. There is a need. Further, the oxidation treatment temperature at that time needs to be in the range of 50 to 700 ° C. Although the temperature also varies depending on the type of alloy, it is desirable to carry out the treatment at a high temperature as low as possible because it is easily oxidized if it is treated at a high temperature, but sintering of fine particles is also likely to occur.

Further, depending on the type of alloy, even the M element may be completely oxidized by this oxidation treatment. At that time, it is also necessary to reduce the M element or the surface of the M element by heating in a reducing atmosphere such as a hydrogen stream or a mixed gas stream of hydrogen and an inert gas. Also, regarding the reduction treatment temperature, it is necessary to perform the reduction treatment within the range of 50 to 700 ° C. The temperature also varies depending on the type of alloy, but if the treatment is performed at a high temperature, sintering of fine particles and the like are likely to occur, so it is desirable to perform the treatment at a temperature as low as possible. According to the above invention,
The catalytic hydrogenation reaction of CO _{2 at} a reaction temperature of 200 to 300 ° C. and a pressure of 30 to 100 atm resulted in high activity and high selectivity. The catalyst of the present invention can also be applied when synthesizing methanol from CO and H ₂ gas. A third aspect of the present invention is a method for producing a catalyst for methanol synthesis, which comprises introducing carbon dioxide and hydrogen into a catalyst made of an alloy represented by the general formula TM, and applying pressure and heat. According to this method, the reaction temperature is 200 to 300 ° C. and the pressure is 30 to
In the catalytic hydrogenation reaction of CO _{2 in} the range of 100 atm, methanol can be synthesized with high efficiency due to the high activity and high selectivity of the catalyst.

[0009]

EXAMPLES The present invention will be specifically described below based on examples. Example 1 An alloy of Y ₄₀ Ag ₆₀ was made by an arc melting furnace, inserted into a quartz tube having a small hole at the tip, heated and melted, and the quartz tube was placed directly on a 200 mm copper roll at a rotation speed of 40.
00r. p. The molten metal inside the quartz tube was
It was jetted from a small hole of a quartz tube under a pressure of 0.4 kg / cm ² and rapidly solidified by coming into contact with the surface of a roll to obtain a thin body having a width of about 1 mm. The cooling rate at this time is 10 ⁵
K / s. Using such a thin body, in air at 300 ℃ 5
Oxidation treatment was carried out for a period of time to obtain a catalyst in which Ag ultrafine particles were dispersed in high density on Y ₂ O ₃ .

Example 2 From the La ₇₀ Au ₃₀ alloy, by the same method as in Example 1, L
A catalyst was prepared in which Au ultrafine particles were dispersed at high density on a ₂ O ₃ . Example 3 A catalyst in which ultrafine particles of Cu and Ag were dispersed at high density on CeO ₂ was prepared from the Ce ₄₀ Ag ₅₀ Cu ₁₀ alloy by the same method as in Example 1. Comparative Example Cu-Zn-O prepared by a coprecipitation method using a catalyst salt as a starting material
A system catalyst was used. 250g for 5g of these materials
A mixed gas of CO ₂ and H ₂ (CO ₂ : H ₂ =
The results of the evaluation of the catalyst performance involved in this CO ₂ catalytic hydrogenation reaction when passing 1: 3) at a flow rate of 100 ml / min are shown below.

[0011]

[Table 1]

[0012]

EFFECTS OF THE INVENTION Since the catalyst of the present invention has the property of having both high activity and selectivity for the catalytic hydrogenation reaction of CO ₂ , the by-product removal facility is simpler than that of conventional catalysts. It is advantageous in that it is possible to reduce the number of recycles of unreacted gas. As a result, the present invention is effective as a resource recycling technology by synthesizing methanol from CO ₂ .

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B01J 23/68 B01J 23/78 Z 23/76 23/89 Z 23/78 C07C 29/154 23 / 835 29/156 23/889 9155-4H 31/04 23/89 C07B 61/00 300 C07C 29/154 B01J 23/56 301Z 29/156 23/64 104Z 31/04 23/82 Z // C07B 61/00 300 23/84 311Z

Claims (8)

[Claims] 1. A general formula: TM (where T is a rare earth element [Y, La, Ce, Pr, Nd, Pm, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu] and at least one element selected from Mg, Ca, Mn, Zr, Hf, Al and Ga, and M is a group IB [C] of the periodic table.
u, Ag, Au] and Group VIII [Fe, Co, Ni, R]
u, Rh, Pd, Os, Ir, Pt], and at least one element selected from the group consisting of an alloy of which the surface is an oxide of T element and fine metal particles of M element dispersed therein. A catalyst for methanol synthesis characterized by the following. 2. The atomic percentage of T element is 1 to 99.
%, M element is 99-1%, The catalyst for methanol synthesis according to claim 1. 3. The size of the fine metal particles composed of M element is from sub-nanometer to several tens of nanometers.
The described catalyst for synthesizing methanol. 4. A general formula: TM (where T is a rare earth element [Y, La, Ce, Pr, Nd, Pm, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu] and at least one element selected from Mg, Ca, Mn, Zr, Hf, Al and Ga, and M is a group IB [C] of the periodic table.
u, Ag, Au] and Group VIII [Fe, Co, Ni, R]
u, Rh, Pd, Os, Ir, Pt] and at least one element selected from the melting composition of an alloy containing an amorphous phase and / or a fine crystalline phase. 50 to 700 ℃ in an equivalent atmosphere
A method for producing a catalyst for methanol synthesis, which comprises heating the alloy surface to oxidize the surface of the alloy to deposit and disperse fine metal particles of M element on an oxide of T element. 5. After the heat treatment in the oxidizing atmosphere according to claim 4, by further heating to 50 to 700 ° C. in a reducing atmosphere, the fine metal particles of the M element are deposited and dispersed on the oxide of the T element. A method for producing a catalyst for methanol synthesis, characterized by comprising: 6. A method for synthesizing methanol, characterized in that fine metal particles consisting of M element are deposited and dispersed on an oxide consisting of T element by repeating the oxidation treatment and the reduction treatment described in claim 4. Catalyst manufacturing method. 7. The general formula: TM (where T is a rare earth element [Y, La, Ce, Pr, Nd, Pm, Sm, Eu, G
d, Tb, Dy, Ho, Er, Tm, Yb, Lu] and at least one element selected from Mg, Ca, Mn, Zr, Hf, Al and Ga, and M is a group IB [C] of the periodic table.
u, Ag, Au] and Group VIII [Fe, Co, Ni, R]
u, Rh, Pd, Os, Ir, Pt], and at least one element selected from the group consisting of an alloy of which the surface is an oxide of T element and fine metal particles of M element dispersed therein. A method for synthesizing methanol, which comprises introducing carbon dioxide and hydrogen into a catalyst, and applying pressure and heating. 8. The T element is 1 to 99% in atomic percent,
The method for synthesizing methanol according to claim 7, wherein a catalyst in which the M element is 99 to 1% is used.