JPS6337092B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing acetaldehyde by reacting methyl acetate, carbon monoxide and hydrogen.

It is known to produce acetaldehyde by reacting methyl acetate, carbon monoxide and hydrogen in the liquid phase in the presence of a group metal of period 4 or 5 of the periodic table (Japanese Patent Publication No. 19286/1986). .
However, the method described in the above literature requires a high reaction pressure of 300 atmospheres or more, and when the product is distilled and separated from the reaction mixture after the reaction, the catalyst is partially reduced and the activity remains for a relatively short period of time. There are difficulties in carrying out the reaction industrially, such as a decrease in Also, recently, the yield of acetaldehyde has been improved by carrying out the reaction in a reaction zone containing a palladium catalyst and an iodine compound by keeping the reaction mixture at a boiling state and continuously distilling the reaction products out of the system. A method has been proposed (Japanese Unexamined Patent Publication No. 55-92335), but even with this method, the problem that the activity of the catalyst decreases in a short period of time remains unsolved.

The present inventors have conducted extensive research to develop a method for producing acetaldehyde that is industrially more advantageous than the conventional methods described above, and as a result, they have arrived at the present invention.

That is, according to the present invention, methyl acetate, carbon monoxide, and hydrogen are reacted in a gas phase in the presence of a catalyst in which (a) rhodium or a compound thereof and (b) palladium or a compound thereof is supported on a carrier and a halogen compound. By this, acetaldehyde can be produced with high yield and high selectivity. This method produces acetaldehyde in high yield and high selectivity even when the reaction is carried out at relatively low pressure, and because the reaction is carried out in the gas phase, the catalyst and product can be separated without reducing the activity of the catalyst. It has advantages not found in conventional methods, such as being able to maintain stable catalyst activity because the catalyst components do not elute into the reaction solution as in the case of liquid phase reactions. . In the method of the present invention, acetic acid is produced in addition to acetaldehyde, and the amount of acetic acid produced varies slightly depending on the reaction conditions used, such as the reaction temperature and pressure, but is usually in an amount of 1.0 to 2.0 moles relative to acetaldehyde.

In the method of the present invention, as described above, a catalyst in which rhodium or a compound thereof and palladium or a compound thereof are supported on a carrier is used. Specific examples of rhodium compounds and palladium compounds include rhodium chloride, rhodium bromide, rhodium iodide, rhodium carbonyl, palladium acetate, palladium chloride, palladium nitrate, palladium carbonyl, and the like. Examples of the carrier include activated carbon, alumina, silica, silica alumina, titania, and zirconia, and the use of activated carbon is particularly preferred in order to obtain high catalytic activity. The concentration of rhodium and palladium compounds relative to the support is not critical, but generally ranges from 0.01 to 5%, preferably from 0.1 to 2%, by weight of the metal. The ratio of rhodium or its compound to palladium or its compound is preferably selected from within the range of 0.001 to 10, particularly 0.1 to 1 in terms of the gram atomic ratio of rhodium metal to palladium metal. The catalyst can be prepared by known methods. For example, the desired catalyst can be obtained by impregnating a carrier with an aqueous solution containing a rhodium salt and a palladium salt and then drying the carrier. Furthermore, a catalyst in which rhodium and palladium are supported on a carrier can be obtained by impregnating a carrier with a rhodium salt and a palladium salt and then reducing the metal salt on the carrier with a reducing agent. In addition to rhodium or its compound and palladium or its compound, the above catalyst may further contain alkali metal salts, alkaline earth metal salts, manganese salts, lanthanum salts, cerium salts,
The yield of acetaldehyde can be further improved by supporting an appropriate amount of one or more selected from aluminum salts, iron salts, cobalt salts, nickel salts, and chromium salts.

Examples of the halogen compound used together with the above-mentioned catalyst in the present invention include chloride, bromide, and iodide. Specific examples include organic halogen compounds such as alkyl halides such as methyl iodide and methyl bromide, acid halides such as acetyl iodide and acetyl bromide, and hydrogen halides such as hydrogen iodide and hydrogen bromide. be able to. These halogen compounds can be used alone or in combination of two or more.

The reaction according to the invention is carried out by contacting the catalyst with a mixed gas containing methyl acetate, a halogen compound, hydrogen, carbon monoxide and optionally a diluent gas inert to the reaction such as nitrogen, methane, ethane, etc. In this case, the molar ratio of the halogen compound and methyl acetate contained in the mixed gas (halogen compound/methyl acetate) is 0.001 to 10, preferably 0.005.
~0.5, and the molar ratio of carbon monoxide to hydrogen (CO/
_H2 ) is preferably 0.01 to 10, preferably 0.1 to 5. Also, the molar ratio of methyl acetate to hydrogen and carbon monoxide in the mixed gas (methyl acetate/CO+
If _H2 ) is too small, it is impractical from an industrial point of view, and if it is too large, more ethylidene diacetate will be produced and the selectivity of acetaldehyde will be lower, so it is necessary to keep it in the range of 0.01 to 2. There is. The reaction is preferably carried out under pressurized conditions, and the reaction pressure is generally selected from within the range of 10 to 000 pressures (absolute pressure). Reaction temperature is generally 100-300℃
℃, especially selected from within the range of 150 to 250℃.

In carrying out the method of the present invention, either a fixed catalyst bed or a fluidized catalyst bed reaction format can be employed. Reactions with fixed catalyst beds can be carried out by passing the reactant gases over the catalyst at a space velocity (SV) of 500 to 10,000 (total gas/catalyst/time).

Hereinafter, the present invention will be explained in more detail with reference to Examples. Parts in the examples are parts by weight. Note that the selectivity of each product except acetic acid was calculated according to the following formula.

Selectivity of specific product (%) = Number of moles of specific product produced per unit time / A + 2B + 2C + D + E + F × 100 [However, A: Number of moles of acetaldehyde produced per unit time B: Number of moles of acetic acid produced per unit time Number of moles of ethyl C: Number of moles of ethylidene diacetate produced per unit time D: Number of moles of methane produced per unit time E: Number of moles of acetone produced per unit time F: Number of moles of acetone produced per unit time Number of moles of acetic anhydride] Example 1 Cylindrical activated carbon with a diameter of 4 mm and a height of 4 to 8 mm (manufactured by Kuraray Chemical Co., Ltd., product name "Kuraray Coal")
Add 50 parts of "4GS") to a solution of 1.14 parts of sodium palladium chloride, 0.83 parts of rhodium chloride trihydrate and 1.0 part of potassium acetate in 40 parts of water,
Evaporate to dryness on a steam bath. 10 c.c. (approximately 4 g) of the catalyst thus obtained was packed into a pressurized flow device equipped with a Hastelloy reaction tube having an inner diameter of 16 mm. The reaction tube is heated to 200℃ while nitrogen gas is passed through it, and then a mixed gas consisting of methyl acetate, methyl iodide, carbon monoxide, and hydrogen (methyl acetate: iodide Methyl: carbon monoxide: hydrogen = 20:1:30:49 (volume ratio)
The reaction was carried out at a reaction temperature of 200°C and 40 atmospheres by introducing 50% of the reaction mixture per hour (atmospheric pressure, 0°C). As a result, acetaldehyde was produced at a production rate of 100 g/l of catalyst per hour, and acetic acid was produced in an amount 1.5 times the mole of acetaldehyde. In addition, methane, ethyl acetate, acetone, ethanol,
A small amount of ethylidene diacetate was produced. The selectivity of each product was as follows.

Acetaldehyde 88.4% Methane 6.2% Ethyl acetate 2.8% Acetone 1.6% Ethanol 1.0% Ethylidene diacetate Very small amount Example 2 Dissolve 50 parts of the same activated carbon used in Example 1 and 0.48 parts of palladium acetate in 35 parts of acetic acid. solution and evaporated to dryness on a steam bath. Add this to 0.33 parts of rhodium chloride trihydrate and sodium acetate.
It was added to an aqueous solution in which 0.8 part was dissolved and evaporated to dryness on a steam bath in the same manner. The reaction conditions were the same as in Example 1, except that 10 c.c. (approximately 4 g) of the thus obtained catalyst was charged into the same reaction tube as used in Example 1, and the reaction temperature was changed to 210°C. The reaction was carried out below. As a result, acetaldehyde was produced at a production rate of 60 g/l of catalyst per hour, and about 1.6 times the mole of acetic acid was produced relative to acetaldehyde. In addition, products similar to those in Example 1 were produced, and their selectivities were as follows.

Acetaldehyde 86.0% Methane 8.7% Ethyl acetate 3.0% Acetone 1.5% Ethanol 0.8% Ethylidene diacetate Very small amount Example 3 Cylindrical activated carbon with a diameter of 4 mm and a height of 3 to 8 mm (manufactured by Takeda Pharmaceutical Co., Ltd., Shirasagi Charcoal 4GC) For,
The activated carbon was impregnated with an aqueous solution in which sodium palladium chloride and rhodium chloride were dissolved so that the supported amounts of sodium palladium chloride and rhodium chloride were 1.0% by weight and 0.5% by weight, respectively.
Dry at ℃. Catalyst 10 thus obtained
cc was charged into the same reaction tube as used in Example 1, and a mixed gas consisting of methyl acetate, methyl iodide, carbon monoxide, hydrogen and nitrogen (methyl acetate: methyl iodide: carbon monoxide) was charged into the reaction tube. :Hydrogen:Nitrogen=10:0.1:20:40:29.9 (capacity ratio)) at 20% per hour
The reaction temperature is 220℃ by introducing at a rate of
The reaction was carried out at 60 atm. As a result, acetaldehyde was produced at a production rate of 70 g/l·hour of catalyst, and the selectivity was 89%. Acetic acid was produced in a molar amount approximately 1.4 times that of acetaldehyde. In addition, small amounts of methane, ethyl acetate, acetone, ethanol, and ethylidene diacetate were produced.

Example 4 Palladium chloride was added to the same activated carbon as used in Example 3 so that the supported amounts of sodium palladium chloride, rhodium chloride, and chromium bromide were 0.8% by weight, 0.3% by weight, and 1.0% by weight, respectively. The activated carbon was impregnated with an aqueous solution in which sodium, rhodium chloride, and chromium bromide were dissolved, and dried at 100°C. 10 c.c. of the catalyst thus obtained was charged into the same reaction tube as used in Example 1, and the reaction tube was filled with a mixed gas (acetic acid The reaction was carried out at a reaction temperature of 200° C. and a pressure of 50 atm by introducing methyl: methyl iodide: carbon monoxide: hydrogen = 15:0.5:39.5:4.5 (volume ratio) at a rate of 60 per hour. As a result, acetaldehyde was produced at a production rate of 60 g/l·hour of catalyst, and the selectivity was 88%.
Acetic acid was produced in about 1.5 times the molar amount of acetaldehyde. In addition, small amounts of methane, ethyl acetate, ethylidene diacetate, acetone, and acetic anhydride were produced.

Example 5 10 c.c. of catalyst prepared in the same manner as in Example 1 was charged into the same reaction tube as used in Example 1, and methyl acetate, methyl iodide, carbon monoxide and hydrogen were added to the reaction tube. By introducing a mixed gas consisting of (methyl acetate: methyl iodide: carbon monoxide: hydrogen = 20:1:49:30 (volume ratio)) at a rate of 60% per hour, the reaction was carried out at a reaction temperature of 190°C and 50 atm. I did it. As a result, acetaldehyde was produced at a production rate of 68 g/l·hour of catalyst, and the selectivity was 91.6%. Acetic acid was produced in a molar amount 1.2 times that of acetaldehyde. In addition, small amounts of methane, acetic anhydride, ethyl acetate, acetone, ethanol, and ethylidene diacetate were produced.

Example 6 10 c.c. of catalyst prepared in the same manner as in Example 1 was charged into the same reaction tube used in Example 1. The reaction tube was heated to 150°C while nitrogen gas was passed through it, and then a mixed gas of hydrogen:nitrogen = 5:95 (volume ratio) was added at a rate of 200°C at a rate of 5/hour (atmospheric pressure 0°C).
The catalyst was reduced by flowing at 400°C for 2 hours and then at 400°C for 2 hours. Next, while maintaining the pressure inside the reaction tube at 40 atmospheres, methyl acetate, methyl iodide, carbon monoxide and hydrogen (25:1:30:44
The reaction was carried out at a reaction temperature of 180°C and 40 atmospheres by introducing (volume ratio) at a rate of 30°C (atmospheric pressure, 0°C) per hour. As a result, acetaldehyde was 83
The product was produced at a production rate of g/l of catalyst/hour, and the selectivity was 89%. Acetic acid was produced in a molar amount 1.3 times that of acetaldehyde. In addition, small amounts of methane, ethylidene diacetate, and acetic anhydride were produced. The selectivity of each product was as follows.

Acetaldehyde 89% Methane 4% Acetic anhydride 3% Ethylidene diacetate 2% Acetone <1% Ethyl acetate <1% Example 7 Rhodium nitrate and palladium nitrate were added to an aqueous solution prepared by adding 15 parts of water to 30 parts of 60% nitric acid. respectively
0.71 parts were dissolved. 50 parts of activated carbon similar to that used in Example 1 was added to this solution, and the mixture was evaporated to dryness on a steam bath. 10 c.c. of the catalyst thus obtained was packed into the same reaction tube as used in Example 1, and the catalyst was reduced in the same manner as in Example 6. Then, while maintaining the pressure in the reaction tube at 46 atm, methyl acetate, methyl iodide, carbon monoxide and hydrogen (25:1:25:49) were added.
(Volume ratio)) was introduced at a rate of 45% per hour (atmospheric pressure, 0°C) to carry out the reaction at a reaction temperature of 185°C and 46 atmospheres. As a result, acetaldehyde
It was produced at a production rate of 105 g/l of catalyst/hour, and the selectivity was 91%. In addition to this, 5% methane,
Ethylidene diacetate and acetic anhydride were produced in an amount of 2% each. The production of ethyl acetate and acetone was extremely small.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that 2.0 parts of rhodium chloride alone was used instead of using both sodium palladium chloride and rhodium chloride. As a result, acetaldehyde was produced at a production rate of only 6 g/l·hr of catalyst, and about 1.3 mol of acetic acid was produced relative to acetaldehyde. In addition, small amounts of ethylidene diacetate, acetic anhydride, and acetone were produced.
The selectivity of each product was as follows.

Acetaldehyde 77.1% Ethylidene diacetate 15.5% Acetic anhydride 6.1% Others 1.3% Comparative Example 2 Same as Example 1 except that only 2.5 parts of sodium palladium chloride was used instead of using both sodium palladium chloride and rhodium chloride in Example 1. The reaction was carried out in the same manner. the result,
Only small amounts of methane and acetic acid were produced, and almost no acetaldehyde or other products were produced.

Comparative Example 3 In an autoclave with a capacity of 1 equipped with a stirrer,
Instead of rhodium chloride trihydrate, use sodium palladium chloride and rhodium chloride trihydrate in a molar ratio of 2:
The reaction was carried out in the same manner as in Example 1 of JP-A-51-115409, except that the ratio of 1:1 was used. As a result, the selectivity of each product was as follows.

Ethylidene diacetate 76.3% Acetic anhydride 16.5% Acetaldehyde 6.2% Others 1.0% Comparative example 4 Mixed gas consisting of methyl acetate, methyl iodide, carbon monoxide, hydrogen and nitrogen (methyl acetate: methyl iodide: carbon monoxide: hydrogen: Nitrogen = 65:1:
Example 1 except that 9:13:12 (capacity ratio) is used.
The reaction was carried out in the same manner. As a result, the selectivity of each product was as follows.

Ethylidene diacetate 7.1% Methane 12.6% Acetaldehyde 75.8% Others 4.5% Example 8 Mixed gas consisting of methyl acetate, methyl iodide, carbon monoxide and nitrogen (methyl acetate: methyl iodide: carbon monoxide: hydrogen = 65:1 :13:21 (volume ratio)) The reaction was carried out in the same manner as in Example 1. As a result, the selectivity of each product was as follows.

Acetaldehyde 85.0% Methane 8.5% Ethylidene diacetate 1.3% Others 5.2% The effects of the present invention are clear from the above examples and comparative examples.

Claims (1)

[Claims] 1 Methyl acetate, carbon monoxide and hydrogen in the presence of a catalyst in which (a) rhodium or a rhodium compound and (b) palladium or a palladium compound are supported on a carrier and a halogen compound, and acetic acid against hydrogen and carbon monoxide in a mixed gas. molar ratio of methyl
A method for producing acetaldehyde, characterized in that the reaction is carried out in a gas phase while maintaining the concentration in the range of 0.01 to 2.