JP3143744B1 - Catalyst for synthesizing methyl acetate and acetic acid, method for producing the same, and method for synthesizing methyl acetate and acetic acid using the catalyst - Google Patents

Abstract

Kind Code: A1 The present invention provides a catalyst capable of synthesizing methyl acetate and acetic acid by a simplified process in a liquid phase reaction, a method for producing the same, and a method for synthesizing methyl acetate and acetic acid using the catalyst. Kind Code: A1 A catalyst for synthesizing methyl acetate and / or acetic acid in which rhodium is supported on a carrier comprising a basic compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to methanol and
The present invention relates to a catalyst capable of synthesizing methyl acetate and / or acetic acid by reacting dimethyl ether with carbon monoxide, a method for producing the catalyst, and a method for synthesizing methyl acetate and / or acetic acid using the catalyst.

[0002]

2. Description of the Related Art As a method for synthesizing methyl acetate and acetic acid by carbonylation of methanol,
A liquid phase synthesis method (so-called Monsanto method) performed in the presence of an iodide and a rhodium complex has been put to practical use.

However, in this liquid phase synthesis method, the rhodium catalyst is dissolved in the liquid, and the catalyst must be separated from the product by a method such as distillation. .

On the other hand, methyl acetate and acetic acid are synthesized by flowing methanol or dimethyl ether and iodide, which are dehydration products of methanol, in the gas phase in the presence of a catalyst in which a metal such as nickel is supported on a carrier such as activated carbon. A way to do that has been proposed.

[0005] However, this gas phase synthesis method has a serious problem that the reaction step is more complicated than a liquid phase synthesis method such as a Monsanto method since a step of vaporizing the raw material is required.

[0006]

SUMMARY OF THE INVENTION The present invention provides a catalyst capable of synthesizing methyl acetate and acetic acid by a simplified process in a liquid phase synthesis method, a method for producing the same, and a method for synthesizing methyl acetate and acetic acid using the catalyst. The main purpose is to provide.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that a catalyst in which a basic compound is supported as a carrier and rhodium is supported as a catalyst metal is methyl acetate and / or acetic acid by a liquid phase reaction. When it was used as a catalyst for the synthesis of, it was found that the reaction step could be simplified, and high catalytic activity and high reaction selectivity were exhibited, and the present invention was completed.

That is, the present invention provides the following methyl acetate and
The present invention relates to a catalyst for synthesizing acetic acid, a method for producing the same, and a method for synthesizing methyl acetate and / or acetic acid using the catalyst. 1. A catalyst for synthesizing methyl acetate and / or acetic acid in which rhodium is supported on a carrier comprising a basic compound. 2. The basic compound is hydrotalcite, zinc oxide,
2. The catalyst for synthesizing methyl acetate and / or acetic acid according to the above 1, which is at least one selected from the group consisting of cerium oxide, zirconium oxide, and alumina. 3. 3. The catalyst for synthesizing methyl acetate and / or acetic acid according to any one of the above items 1 to 2, wherein the supported rhodium has an average particle size of 5 nm or less. 4. A method for producing a catalyst for synthesizing methyl acetate and / or acetic acid, comprising: (1) immersing a basic compound in a rhodium compound solution under conditions of pH 2 to 8 to precipitate rhodium hydroxide on the basic compound, Obtaining a precursor, and
(2) A method for producing a catalyst for synthesizing methyl acetate and / or acetic acid, comprising a step of heating the obtained catalyst precursor. 5. In a method for synthesizing methyl acetate and / or acetic acid by reacting methanol and / or dimethyl ether with carbon monoxide in a liquid phase, the synthesis reaction is performed in the presence of a catalyst supporting rhodium on a basic compound and iodide. A method characterized by the following. 6. (5) The above-mentioned (5), wherein the by-produced dimethyl ether and unreacted methanol are separated and recovered, and added to the raw material.
The method described in.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalyst for synthesizing methyl acetate and / or acetic acid in which rhodium is supported on a carrier comprising a basic compound.

The support used in the catalyst of the present invention is not particularly limited as long as it is a basic compound. The basic compound has a basic point on the surface of the compound, and adsorbs an acidic compound such as carbon dioxide. Examples of such a compound include hydrotalcite, zinc oxide, cerium oxide, zirconium oxide, and alumina. Among these, hydrotalcite, zinc oxide,
Cerium oxide and the like are preferred. These compounds may be used alone or in combination of two or more.

Hydrotalcite is one of naturally occurring layered minerals. Natural hydrotalcite is represented by a composition formula such as Mg ₆ Al ₂ (OH) ₁₆ (CO ₃ ) .4H ₂ O. Is done.
In the present invention, in addition to natural hydrotalcite, Mg ₄ Al ₂ (O
H) Synthetic hydrotalcite such as ₁₂ CO _3, and hydrotalcite in which the CO ₃ anion is replaced with another anion (eg, NO ₃ ⁻ , SO ₄ ^2−, etc.) can also be used.

The average particle size of rhodium supported on the catalyst of the present invention is not particularly limited as long as a predetermined effect can be obtained. The average particle size of rhodium is usually about 5 nm or less as measured by a hydrogen adsorption method. The average particle size of rhodium is such that, in the X-ray diffraction pattern, a peak derived from rhodium near 2θ = 41.1 ° is not observed, ie, 3 nm.
It is preferable that it is about the following. Particularly preferred average particle diameter of rhodium, as a value measured by hydrogen adsorption method, 1 to
It is about 2.5 nm. The average particle size of rhodium is 3 nm
When the average particle size of rhodium is about 3 nm or more, a peak having a half width of less than 3 ° is observed around 2θ = 41.1 °.

The supported amount of rhodium in the catalyst of the present invention is
Although it can be appropriately set according to the type of the carrier used, it is usually 0.1 to the total weight of the rhodium and the carrier.
About 5 wt%, preferably about 0.2 to 3 wt%. The smaller the supported amount of rhodium, the higher the degree of dispersion of rhodium, that is, the smaller the particle size of rhodium, so that the catalytic activity per rhodium can be increased. On the other hand, if the supported amount of rhodium is too small, sufficient catalytic activity cannot be obtained.

The shape of the catalyst according to the present invention is not particularly limited, and examples thereof include powder, granules, and strips. The particle size of the catalyst is not particularly limited as long as a predetermined effect is obtained, but is usually about 10 to 100 mesh, preferably about 30 to 80 mesh. The catalyst may be manufactured using a carrier having a desired particle size, or may be supported on rhodium and then ground to a desired particle size. The former is more preferred.

The catalyst of the present invention may be used after being formed into pellets, cylinders or the like according to a conventional method. As a molding method, a method known per se can be used, and for example, a method of mixing with a known binder (for example, silica gel or the like) that does not adversely affect the reaction and molding the mixture can be used. Although the size of the catalyst after molding is not particularly limited, it is usually 0.
It is about 5 to 5 mm, preferably about 1 to 2 mm.

The catalyst of the present invention can be produced, for example, by a production method having the following steps. (1) a step of immersing a basic compound in a rhodium compound solution under conditions of pH 2 to 8 to precipitate rhodium hydroxide on the basic compound to obtain a catalyst precursor; and (2) preparing a catalyst precursor. Heating.

In the step (1), under the condition of pH 2 to 8,
A basic compound is immersed in a rhodium compound solution, and rhodium hydroxide is precipitated on the basic compound to form a catalyst precursor (hereinafter, referred to as a rhodium hydroxide).
Simply referred to as “precursor”).

The rhodium compound used in the step (1) is not particularly limited as long as it can dissociate Rh ^{3+ in} an aqueous solution. Such compounds include, for example, rhodium nitrate, rhodium sulfate, rhodium chloride, rhodium acetate and the like.

The rhodium compound solution can be prepared by dissolving these compounds in a solvent such as water, methanol, acetone or a mixed solvent thereof. Of these, water is preferred.

When the pH of the prepared rhodium compound solution is not in the range of 2 to 8, the pH is adjusted so as to be 2 to 8.
The pH can be adjusted by a known method, for example, a method of adding an alkaline compound solution when the pH is lower than a desired value. The alkaline compound used is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonia. If the pH exceeds 8, rhodium hydroxide will precipitate, so it is preferable to adjust the pH so that the pH does not exceed 8.

The pH of the solution may be adjusted before the basic carrier is immersed in the rhodium compound solution, or may be adjusted after the basic carrier is immersed.

In the step (1), after rhodium hydroxide is precipitated on the basic compound, if necessary, the precipitated rhodium hydroxide may be aged in the solution for about 1 to 24 hours. The pH during ripening is usually about 8-11. The pH can be adjusted by a known method, for example, when the pH is lower than a desired value, a method of adding an alkaline compound solution, or the like. The alkaline compound used is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonia.

The temperature for aging is not particularly limited, but is usually about 20 to 60 ° C.

The obtained precursor can be isolated by a known method such as filtration. The precursor may be washed with water and dried if necessary.

Step (2) is a step of heating the precursor obtained in step (1).

Specifically, the precursor obtained in the step (1) is heated at about 200 to 500 ° C. for about 3 to 10 hours in an oxidizing atmosphere such as air.

The activity of the catalyst of the present invention can be further increased by further performing a reduction treatment, if necessary. Examples of such a reduction treatment include a gas phase reduction treatment in a reducing gas atmosphere such as hydrogen and carbon monoxide, and a liquid phase reduction treatment using a reducing agent such as methanol and formaldehyde. Specific examples of the hydrogen reduction treatment include a method in which a rhodium catalyst is heated under a hydrogen atmosphere at about 200 to 500 ° C. for about 3 to 10 hours.

After the catalyst of the present invention has been used once, it can be regenerated, if necessary, by subjecting it to a heat treatment in a reducing atmosphere such as hydrogen.

According to the method for producing a catalyst of the present invention, rhodium hydroxide is deposited on a basic carrier and deposited thereon, so that a catalyst carrying rhodium having a large specific surface area, that is, rhodium having a small particle diameter, is produced. be able to.

The catalyst of the present invention exhibits catalytic activity in a method of synthesizing methyl acetate and / or acetic acid by reacting methanol and carbon monoxide in a liquid phase, for example, under the following reaction conditions.

The amount of the catalyst of the present invention is not particularly limited as long as a predetermined effect is obtained, but is usually about 0.1 to 10% by weight, preferably about 0.1 to 10% by weight, based on methanol as a raw material.
It is about 0.5 to 5%.

A small amount of iodide is added as a reaction accelerator. Examples of such an iodide include methyl iodide, ethyl iodide, propyl iodide and the like. Of these, methyl iodide is preferred. The amount of iodide added
It is not particularly limited, and can be appropriately set depending on the type of the carrier to be used, the amount of the catalyst, and the like. is there.

In the case of synthesizing acetic acid using the catalyst of the present invention, it is preferable to further add water to the reaction system because the reaction efficiency is further increased. The amount of water to be added is not particularly limited, but is usually 1% by weight with respect to methanol as a raw material.
Or less, preferably about 0.2 to 0.6.

The reaction pressure is usually about 1 to 10 MPa, preferably about 3 to 7 MPa. Carbon monoxide partial pressure is usually 0.1-5M
It is about Pa, preferably about 0.5-1 MPa. Carbon monoxide may be diluted with a rare gas such as argon or an inert gas such as nitrogen. The reaction pressure without dilution with an inert gas is almost equal to the sum of the partial pressure of methanol and the partial pressure of carbon monoxide.

The reaction temperature is usually about 130-300 ° C., preferably about 150-250 ° C. If the reaction temperature is too low, the catalytic activity decreases, while if the reaction temperature is too high, the partial pressure of the raw material methanol increases and the reaction pressure becomes too high.

The reaction time can be appropriately set according to the type and composition of the raw materials used, the type of the target product, and the like. When obtaining methyl acetate, it is usually about 1 to 24 hours, preferably about 2 to 10 hours. If the reaction time is too long, acetic acid starts to be generated because water is by-produced. When acetic acid is obtained without adding water to the reaction system, the reaction time is usually about 24 to 72 hours, preferably about 30 to 50 hours. The reaction time when acetic acid is obtained by adding water to the reaction system is usually about 1 to 24 hours, preferably about 2 to 10 hours.

The catalyst of the present invention exhibits catalytic activity also in a method of synthesizing methyl acetate and / or acetic acid by reacting dimethyl ether with carbon monoxide. The catalyst of the present invention can be used in a synthesis method using dimethyl ether as a reaction raw material under the same reaction conditions as in a synthesis method using methanol as a reaction raw material.

When methyl acetate and / or acetic acid is synthesized from methanol in the presence of the catalyst of the present invention, dimethyl ether is by-produced. In the synthesis method of the present invention, methyl acetate and / or acetic acid can be synthesized by separating and recovering dimethyl ether produced as a by-product and unreacted methanol together, adding them to the raw materials and recycling them by recycling.

[0039]

The catalyst according to the invention can be very easily separated from the product. The catalyst of the present invention exhibits high catalytic activity in the liquid phase in the synthesis of methyl acetate and acetic acid. The catalyst of the present invention exhibits high catalytic activity even when water and acetic acid coexist in the reaction system.

The dimethyl ether by-produced when methyl acetate and / or acetic acid is synthesized from methanol in the presence of the catalyst of the present invention is useful as an alternative fuel to light oil.

[0041]

Embodiments of the present invention will be described below. The present invention is not limited to these examples.

[0042]Example 1 Rhodium nitrate (Rh (NO_Three)_Three0.13g dissolved in 200ml distilled water
To prepare a rhodium nitrate solution. The pH of this solution is 3
there were. Add hydrotalcite powder (Mg _FourAl_Two(O
H)₁₂CO_Three2g of rhodium hydroxide
Was precipitated on hydrotalcite.

After depositing rhodium hydroxide, the pH of the solution was adjusted to 10 by adding 0.5N sodium hydroxide.
This solution was stirred and aged for 5 hours to obtain a precursor. The obtained precursor was separated by filtration, sufficiently washed with water and dried. Furthermore,
The precursor was heated in air at 400 ° C. for 5 hours to obtain a catalyst. The catalyst was activated by reducing the obtained catalyst with hydrogen at 400 ° C. for 2 hours.

The obtained catalyst was one in which rhodium was highly dispersed and supported on hydrotalcite, and the amount of rhodium supported was 3.0% by weight. Since no peak derived from rhodium was observed in the X-ray diffraction pattern of the obtained catalyst, the average particle size of rhodium was 3 nm or less.

Example 2 A catalyst was produced in the same manner as in Example 1 except that the amount of rhodium nitrate was changed to 0.04 g.

The obtained catalyst had rhodium supported on hydrotalcite in a highly dispersed state, and the amount of rhodium supported was
0.8 wt%. Since no rhodium-derived peak was observed in the X-ray diffraction pattern of the sample, the average particle size of rhodium was 3 nm or less.

Example 3 A catalyst was produced in the same manner as in Example 1 except that the amount of rhodium nitrate was changed to 0.09 g.

The obtained catalyst was one in which rhodium was highly dispersed and supported on hydrotalcite, and the amount of rhodium supported was 1.7 wt%. Since no peak derived from rhodium was observed in the X-ray diffraction pattern of the sample, the average particle size of rhodium was 3 nm or less.

Example 4 The same procedure as in Example 1 was carried out except that the amount of rhodium nitrate was 0.05 g and the carrier used was 2 g of zinc oxide powder (ZnO, particle size: 40-60 mesh) instead of hydrotalcite. A catalyst was prepared using the method.

The obtained catalyst had rhodium highly dispersed and supported on zinc oxide, and the amount of rhodium supported was 0.9 wt%.
Met. Since no peak derived from rhodium was observed in the X-ray diffraction pattern of the sample, the average particle size of rhodium was 3 nm or less.

Example 5 The amount of rhodium nitrate was 0.01 g, and cerium oxide powder (CeO ₂ , particle size: 60) was used instead of hydrotalcite as a carrier.
A catalyst was produced in the same manner as in Example 1 except that 2 g of (-80 mesh) was used.

The obtained catalyst had rhodium supported in high dispersion on cerium oxide, and the supported amount of rhodium was 0.1.
It was 2 wt%. Since no peak derived from rhodium was observed in the X-ray diffraction pattern of the sample, the average particle size of rhodium was 3 nm or less.

Example 6 The catalyst obtained in Example 1 was reduced under a hydrogen atmosphere at 400 ° C. for 2 hours. 0.2 g of activated catalyst (rhodium content: 0.058 mm
ol) was placed in a 200 ml autoclave, to which 780 mmol of methanol and 35 mmol of methyl iodide were added, and the inside of the reaction vessel was replaced with carbon monoxide. Under carbon monoxide atmosphere (0.5
(MPa: 45 mmol), the mixture was heated at 200 ° C. for 4 hours.

As a result, methyl acetate (23 mmol) and dimethyl ether (35 mmol) were obtained. After the reaction, the catalyst settled at the lower portion of the reaction vessel, so that the reaction product could be easily separated from the catalyst.
After the reaction, methyl iodide was recovered almost quantitatively.

Example 7 The catalyst obtained in Example 2 was reduced under a hydrogen atmosphere at 400 ° C. for 2 hours. 0.2 g of activated catalyst (rhodium amount: 0.016 mm
ol) was placed in a 200 ml autoclave, to which 780 mmol of methanol and 35 mmol of methyl iodide were added, and the inside of the reaction vessel was replaced with carbon monoxide. Under carbon monoxide atmosphere (0.5MP
a: 45 mmol), the mixture was heated at 200 ° C. for 4 hours.

As a result, 21 mmol of methyl acetate and 29 mmol of dimethyl ether were obtained. After the reaction, methyl iodide was recovered almost quantitatively.

Example 8 The catalyst obtained in Example 3 was reduced under a hydrogen atmosphere at 400 ° C. for 2 hours. 0.2 g of activated catalyst (rhodium content: 0.033 mm
ol) was placed in a 200 ml autoclave, to which 780 mmol of methanol, 35 mmol of methyl iodide and 200 mmol of water were added, and the inside of the reaction vessel was replaced with carbon monoxide. The mixture was heated at 200 ° C. for 12 hours under an atmosphere of carbon monoxide (0.5 MPa: 45 mmol).

As a result, 13 mmol of methyl acetate, 22 mmol of acetic acid and 16 mmol of dimethyl ether were obtained. After the reaction, methyl iodide was recovered almost quantitatively.

Example 9 The catalyst obtained in Example 4 was reduced under a hydrogen atmosphere at 400 ° C. for 2 hours. 0.2 g of activated catalyst (rhodium content: 0.02 mmo
l) was placed in a 200 ml autoclave, to which 780 mmol of methanol and 35 mmol of methyl iodide were added, and the inside of the reaction vessel was replaced with carbon monoxide. Under carbon monoxide atmosphere (0.5MP
a: 45 mmol), the mixture was heated at 200 ° C. for 4 hours.

As a result, 21 mmol of methyl acetate and 50 mmol of dimethyl ether were obtained. After the reaction, methyl iodide was recovered almost quantitatively.

Example 10 The catalyst obtained in Example 5 was reduced under a hydrogen atmosphere at 400 ° C. for 2 hours. 0.2 g of activated catalyst (rhodium content: 0.004 mm
ol) was placed in a 200 ml autoclave, to which 780 mmol of methanol and 35 mmol of methyl iodide were added, and the inside of the reaction vessel was replaced with carbon monoxide. Under carbon monoxide atmosphere (0.5MP
a: 45 mmol), the mixture was heated at 200 ° C. for 4 hours.

As a result, 14 mmol of methyl acetate and 44 mmol of dimethyl ether were obtained. After the reaction, methyl iodide was recovered almost quantitatively.

Using a catalyst produced by the same method as in Example 1 except that zirconium oxide or alumina was used instead of hydrotalcite as a carrier, methyl acetate was used under the same conditions as the above reaction conditions. Good results are also obtained when synthesized.

Comparative Example 1 Rhodium chloride (RhCl ₃ ) 0.04 was placed in a 200 ml autoclave.
9 mmol, 780 mmol of methanol and 35 mmol of methyl iodide were added, and the inside of the reaction vessel was replaced with carbon monoxide. Under a carbon monoxide atmosphere (0.5 MPa: 45 mmol), the mixture was heated at 200 ° C for 4 hours.
Heated for hours.

As a result, 16 mmol of methyl acetate, 23 mmol of acetic acid and 32 mmol of dimethyl ether were obtained.

Since the catalyst, rhodium chloride, was dissolved in the reaction solution, the catalyst was separated from the reaction solution by distillation.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C07C 67/36 C07C 67/37 67/37 69/14 69/14 C07B 61/00 300 // C07B 61/00 300 B01J 23/56 301Z ( 56) References JP-A-7-188096 (JP, A) JP-B-52-41753 (JP, B2) JP-B-62-10969 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , (DB name) B01J 21/00-38/74 C07B 61/00 300

Claims (6)

(57) [Claims] 1. Methanol and / or dimethyl ether
Acetate, which reacts toluene and carbon monoxide in the liquid phase, and
/ Or a acid catalyst for synthesizing basic methyl acetate and / or acetic acid catalyst for synthesizing the rhodium carrier comprising a compound characterized by being carried. 2. The catalyst for synthesizing methyl acetate and / or acetic acid according to claim 1, wherein the basic compound is at least one selected from the group consisting of hydrotalcite, zinc oxide, cerium oxide, zirconium oxide and alumina. . 3. The supported rhodium has an average particle size of 5 nm.
The catalyst for synthesizing methyl acetate and / or acetic acid according to claim 1, wherein the catalyst is: 4. A process for producing a catalyst for synthesizing methyl acetate and / or acetic acid, which comprises: (1) under conditions of pH 2 to 8,
Acetic acid, comprising: a step of immersing a basic compound in a rhodium compound solution to precipitate rhodium hydroxide on the basic compound to obtain a catalyst precursor; and (2) a step of heating the obtained catalyst precursor. A method for producing a catalyst for synthesizing methyl and / or acetic acid. 5. A liquid phase reaction of methanol and / or dimethyl ether with carbon monoxide to produce methyl acetate and / or
Or a method for synthesizing acetic acid, wherein the synthesis reaction is performed in the presence of a catalyst in which rhodium is supported on a basic compound and iodide. 6. The method according to claim 5, wherein the by-produced dimethyl ether and unreacted methanol are separated and recovered and added to the raw material.