JP3058512B2 - Acetic acid production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing acetic acid, and more particularly, to a method for producing acetic acid using methanol and CO gas as raw materials.

[0002]

2. Description of the Related Art For example, Japanese Patent Publication No. Sho 60-4
No. 3767 discloses a method for carbonylating an alcohol obtained by supporting nickel, cobalt or a compound thereof on a carbonaceous carrier, and further, methanol and carbon monoxide in the presence of the catalyst and an iodine compound cocatalyst. Although a method of producing acetic acid by a phase catalytic reaction is disclosed, it is possible to reduce the by-product of methane by using a carbonaceous carrier rhodium metal catalyst and performing the reaction in the presence of water. There is no specific description or description suggesting it.

[0003] The Proceeding of Ninth International Catalysis Congress (Proc)
eating of 9th International
alCatalysis Congress), Vo
1, 3, P1051-1058 (1988) show that the activated carbon supported rhodium metal catalyst has excellent activity in the production of acetic acid by the carbonylation reaction of methanol and, for example, 523 ° K, 11 atm, w / F
= 5 g · h / mol (Rh: 1 g · h / mol), and C
O / MeOH / MeI / H ₂ = 50/9/1 / (19)
It is only taught that the coexistence of hydrogen under the condition of (mol) improves the activity of the acetic acid production reaction as compared with the case where no coexistence of hydrogen, and the reaction is carried out in the presence of water; There is no specific description or suggestion that the methane by-product rate is thereby reduced.

Japanese Patent Publication No. 47-3334 discloses a method for producing acetic acid in high yield by carbonylation of methanol in a liquid phase using a rhodium complex catalyst and methyl iodide or hydrogen iodide as an accelerator. However, there are disadvantages such as the fact that the reaction system is extremely corrosive and requires expensive corrosion-resistant materials, a special step is required for separating the product and the catalyst, and there are many by-products of methane.

[0005] JP-A-1-299248 discloses a method for producing acetic acid using carbon monoxide and methanol as raw materials, using a nickel-rhodium metal catalyst carrying activated carbon as a catalyst and methyl iodide as a promoter. Although disclosed, the conversion of methanol is low, the selectivity and yield of acetic acid are low, and there are many by-products such as methane, which is not a satisfactory condition.

According to the present invention, in producing acetic acid from CO gas and methanol as raw materials, the corrosiveness of a reaction system is remarkably reduced, by-products of methane are reduced, and a high selectivity is obtained in a simplified production process. And a method for producing acetic acid with high yield.

[0007]

The present invention relates to a method for producing acetic acid using methanol and CO gas as raw materials.
An object of the present invention is to provide a method for producing acetic acid, which comprises reacting O gas with methanol in a gas phase in the presence of a carbonaceous carrier rhodium metal catalyst, a methyl iodide promoter and water.

Examples of the carbonaceous carrier used for the rhodium metal catalyst in the method of the present invention include, in addition to activated carbon, carbon black, coke, etc., inorganic carriers such as silica, alumina and zeolite carrying carbonaceous materials. However, of these, activated carbon is preferred.

The amount of rhodium supported on the carbonaceous carrier rhodium metal catalyst is not particularly limited.
Usually, it is in the range of 0.01 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight.

The carbonaceous-supported rhodium metal catalyst used in the method of the present invention is preferably 50 to 200 ° C. after the Rh reagent is supported on the carbonaceous carrier by an impregnation method, a deposition method, an immersion method, a vapor deposition method, a kneading method or the like. Performs a drying operation for evaporating water at 80 to 120 ° C., and further performs 100 to 700
It is produced by a method in which a hydrogen-containing gas is passed at a temperature of preferably from 200 to 400 ° C. to carry out a hydrogen reduction treatment for reducing the catalyst. For the reduction, solution reduction with formalin and alkali can also be performed. As the Rh reagent used in the impregnation method or the like, rhodium chloride, sodium rhodate, ammonium rhodate, rhodium hydroxide and the like can be used. Particularly, rhodium chloride is preferred. Further, since the reduction of the catalyst is also performed during the production of acetic acid, the reduction treatment is not always necessary.

The amount of the methyl iodide promoter used in the method of the present invention is not particularly limited, but is usually 0.1 to 50 mol, preferably 1 to 20 mol, per 100 mol of methanol. . Instead of methyl iodide, an iodine compound which produces methyl iodide in the apparatus by reacting with methanol, such as iodine or hydrogen iodide, can be used as the promoter.

In the method of the present invention, by performing the reaction in the presence of water, the selectivity of acetic acid is improved, and the selectivity of by-product methane is reduced. As a result, the selectivity of acetic acid and the selectivity of methane are reduced. The ratio to the ratio (hereinafter abbreviated as selectivity ratio) is remarkably increased, the acetic acid yield is improved, and unnecessary consumption of methanol is reduced. Although the amount of water used in the method of the present invention can be suppressed as much as possible, the by-product of methane can be suppressed, but is preferably 3 to 50 mol% based on methanol used. If it is less than 3 mol%, the effect of suppressing methane by-product is insufficient, and
If it exceeds mol%, the partial pressures of carbon monoxide and methanol in the reaction system decrease, and the conversion of methanol and the yield of acetic acid decrease, which is not preferable.

[0013] The catalytic reaction in the method of the present invention is carried out in the presence of the above carbonaceous carrier rhodium metal catalyst, the above methyl iodide promoter and water in the presence of methanol and CO gas, the proportion of methanol and CO gas used, Molar ratio =
1: 100 to 100: 1, preferably 1:10 to 10:
1. Reaction temperature 100-400 ° C, preferably 150-3
00 ° C, reaction pressure -0.9 to 300 kg / cm ² · G,
Preferably 0 to 100 kg / cm ² · G, and w / F
(Catalyst weight / feed gas flow rate) The reaction is carried out in a gas phase under a condition of 0.1 to 500 g · h / mol, preferably 1 to 30 g · h / mol.

The presence of methane as an impurity in the CO gas does not hinder the catalytic action. If the reaction temperature exceeds 400 ° C., the amount of methane produced is undesirably increased. The reactor used for the catalytic reaction in the method of the present invention is not particularly limited, and may be any of a fixed bed, a fluidized bed and a moving bed.

[0015]

According to the present invention, (1) the consumption of methyl iodide as a promoter is reduced, the acetic acid production reaction is not inhibited, and there is no by-product of iodine and hydrogen iodide. (2) The amount of by-products of methane is reduced, so that when recovering unreacted CO gas from the product, the recovered gas contains only a small amount of methane,
A method for producing acetic acid with high selectivity and high yield is provided, which can be reused as a raw material without a methane separation operation, and (3) have the above advantages.

[0016]

The present invention will be described below in more detail with reference to Examples and Comparative Examples.

Example 1 Granular activated carbon (Shirasagi C2C manufactured by Takeda Pharmaceutical Co., Ltd.) was used in an amount of 20 to 42%.
After sizing to a mesh (particle size 0.35 to 0.84 mm),
5.2 Ig was weighed. Next, rhodium chloride was weighed so as to carry 2.5% by weight of rhodium metal as a metal, and dissolved in water to obtain a 100 cc aqueous solution. Activated carbon was immersed in this aqueous solution, evaporated on a hot water bath using a rotary evaporator, and further dried at 120 ° C. in a drier. This was reduced with hydrogen at 400 ° C. for 2 hours and used as a catalyst.

As the reactor, a fixed bed flow type reactor comprising a raw material gas and methanol supply equipment, an evaporator for methanol and water, a raw material preheater, a reactor (inner diameter 10 mm), a cooler and an acetic acid recovery device is used. Was. 9 in advance
High-purity CO gas purified to 9.95% purity was used as a raw material CO gas.

Methanol, methyl iodide and water are supplied to an evaporator at a constant flow rate to vaporize the mixture. Further, the raw material gas is mixed at a constant flow rate, and the mixed raw material is heated to 160 ° C. by a raw material preheater. It was introduced into a reactor filled with 6 g of the catalyst, and reacted under the conditions shown in Table 1. The product discharged from the reactor was cooled and acetic acid was recovered by gas-liquid separation. Table 2 shows the obtained results.

Comparative Example 1 An experiment similar to that of Example 1 was performed under the conditions shown in Table 1.
Table 2 shows the obtained results.

[0021]

[Table 1]

[0022]

[Table 2]

Continuation of front page (56) References JP-A-5-306254 (JP, A) JP-A-59-176228 (JP, A) JP-A-1-299248 (JP, A) JP-A-2-152937 (JP) , A) JP 60-43767 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 53/08 B01J 23/46 311 C07C 51/12 C07B 61/00 300

Claims (3)

(57) [Claims] 1. A method for producing acetic acid using methanol and CO gas as raw materials, wherein CO gas is contacted with methanol in a gas phase in the presence of a carbonaceous carrier rhodium metal catalyst, a methyl iodide promoter and water. A method for producing acetic acid, comprising: 2. The amount of water is 3 to 50 with respect to methanol.
The method of claim 1 in the mole% range. 3. The catalytic reaction according to claim 1, wherein the reaction temperature is 150 to 300.
° C, reaction pressure 0-100 kg / cm ² · G, and w /
The method according to claim 1, wherein the reaction is carried out under the condition of F (catalyst weight / feed gas flow rate) 1 to 30 g · h / mol.