KR920001987B1 - Process of the preparation for acetic acid used with by-product gas of iron making - Google Patents

Abstract

An acetic acid is produced by (A) separating and refining hydrogen and carbon monoxide from byproct gases, COG (Coke Oven Gas) and LDG (Lintz-Donawhitz Gas) from steelmaking plant, (B) reacting refined carbon monoxide and methanol to give methylformate, (C) storing methanol obtained by reacting a part of produced methylformate and refined hydrogen, (D) converting the rest of produced methylformate into acetic acid by catalytic isomerization, and (E) storing produced acetic acid in a storage tank.

Description

Acetic acid production process using steel off-gas

1 is an acetic acid manufacturing process diagram showing a process for producing acetic acid from the steelmaking by-product gas in accordance with the present invention.

2 is the mass balance of the process shown in FIG.

3 is the material balance of the whole process.

4 is the mass balance of the process in which a methyl formate decomposition reactor is installed.

The present invention relates to a method for producing acetic acid using COG (Coke Oven Gas) and LDG (Lintz-Donawhitz Gas) as a by-product steel mill. Conventional acetic acid manufacturing methods are mostly by carbonylation using methanol and carbon monoxide of high purity, and the Monsanto process is known as a representative method. However, no method of preparing acetic acid by using COG and LDG gas, which are steel by-products, has been proposed. When acetic acid is prepared using steel by-product gas, gaseous high-purity carbon monoxide and methanol are required. Due to the difficulties of the process, it is inefficient in terms of process and economic conditions, and because methanol is used as a raw material, methanol must be produced, purchased, and supplied separately. In particular, the separation of pure carbon monoxide from steel by-product gas is most frequently included as an impurity. Separation of nitrogen is a problem, which is due to nitrogen having the same molecular weight and similar adsorption characteristics as carbon monoxide. For this reason, separation of pure carbon monoxide is expensive and difficult to operate.

An object of the present invention is to prepare a methyl formate from a gas containing carbon monoxide, and react a portion of it with hydrogen separated from steelmaking by-product gas to produce methanol, thereby circulating methanol as a raw material of methyl formate. The remaining methyl formate must be made into acetic acid by isomerization, or the methyl formate must be decomposed into carbon monoxide and methanol and then converted into acetic acid in an acetic acid production reactor to separate pure carbon monoxide from the above-mentioned problems, i.e. It is to provide a method for producing acetic acid using iron and steel by-product gas that can solve the problem of having to import or methanol.

Hereinafter, the present invention will be described in detail.

The present invention, as shown in Figures 1 to 4, provides a method for producing acetic acid from the steelmaking by-product gas by using two methods, First, looking at the process shown in Figure 1, COG is a by-product steel mill (1) is dried and purified in a gas dryer and a purifier (2), and the purified COG is stored in the hydrogen storage tank (4) by increasing the concentration of hydrogen by the PSA method (Pressure Swing Adsorption Method) (3). In the same manner as the COG, LDG (5), a steelmaking by-product gas, is dried and purified in a gas drying and purifier (6), and carbon dioxide is removed from the carbon dioxide remover (7) by an amine method or a thermal carbonation method. Carbon monoxide and nitrogen at the same time or carbon monoxide alone, together with methanol stored in the methanol storage tank 12, is introduced into the methyl formate reactor 8 to synthesize methyl formate, and the synthesized methyl formate is methylforme. A part of the synthetic methyl formate stored and stored in the storage tank 9 is introduced into the hydrogenation reactor 10 together with the hydrogen stored in the hydrogen storage tank 4 to form methanol, and the remainder is acetic acid reactor 11. Is converted to acetic acid by isomerization reaction by a catalyst, and the converted acetic acid is configured to be stored in the acetic acid storage tank 13, and the methanol formed in the hydrogenation reactor 10 is stored in the methanol storage tank 12. It is reacted with carbon monoxide and sent to the methyl formate reactor (8).

FIG. 2 and FIG. 3 respectively show the substance balance map and the overall process substance map for each process unit of the acetic acid manufacturing process diagram shown in FIG. On the other hand, another method for the production of acetic acid using the iron and steel by-product gas is shown in Figure 4, this method is the same as the process of Figure 1, but the metal formate decomposition reactor (14) In the decomposition reactor 14, methyl formate is once decomposed and converted to carbon monoxide and methanol, and then the converted carbon monoxide and methanol react to produce acetic acid.

FIG. 4 shows only the transformed portion except for the portion overlapping with FIG. 2, which is the material balance of FIG. 1, to clarify the difference from the process shown in FIG.

This process is a case where one more methyl formate decomposition reactor 14 is installed as compared to the process shown in FIG. 1. In this case, methyl formate separates and recovers pure carbon monoxide from steelmaking by-product as well as a raw material for acetic acid production. The process can be liquefied and stored, stored and transported.

Each process of the present invention will be described in more detail as follows. The main raw materials that can supply carbon monoxide and hydrogen in steel by-product gas are COG (Coke Oven Gas) and LDG (Lintz-Donawhitz Gas).

Composition of seasonal by-product gas (volume%)

Impurities in COG are mainly contained in several tens of mg / Nm ³ units such as hydrogen sulfide, naphthalene and cyanic acid, and are present in several ppm units in LDG. These impurities, other sulfur compounds, carbon dioxide, water, and the like are removed through drying and gas purifiers 2 and 6 as shown in FIG. Gas purifiers can be purified using semi-permeable membranes or scrubbers. Any sulfur component can be recovered to prevent air pollution or treated with zinc oxide chemical reactions, and carbon dioxide is released into the atmosphere.

Purified gas is stored in the hydrogen storage tank (4) by increasing the concentration of hydrogen using the pressure swing adsorption method (PSA) in the case of COG. In the case of LDG, when carbon dioxide is removed from the carbon dioxide remover (7) using commercial processes such as the amine method or the thermal carbonation method, only carbon monoxide and nitrogen are introduced into the methyl formate reactor (8). Methanol stored in the methanol storage tank 12 is used via (10).

In this case, carbon monoxide and nitrogen present in the methyl formate reactor 8 do not need to be separated separately, and only carbon monoxide participates in the reaction to produce a liquid methyl format. In the methyl formate reactor 8, carbon monoxide and the methanol are subjected to a homogeneous reaction as in the following formula (1).

CO + CH ₃ OH → HCOOCH ₂ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ

At this time, the melted catalyst is a homogeneous sodium methoxide (NaOCH ₃ ) and the like shown in US Patent 4,316,880 and the like, the ratio with methanol is used in the ratio of 1: 100 and the temperature is operated in the range of 80-100 ℃. The resulting methyl formate is stored in the methyl formate storage tank (9) and the stored methyl formate is reacted with hydrogen in the hydrogenation reactor (10) to produce methanol or directly introduced into the acetic acid reactor (11) to produce acetic acid or Or as shown in FIG. 4, to decompose to produce acetic acid.

Methyl formate is prepared by the reaction of methanol and carbon monoxide, and can be prepared using an alkali catalyst of high temperature and high pressure, such as US Pat. Although any of the carbonylation process of methanol may be employ | adopted, the process of allowing the use of a low concentration of carbon monoxide is more preferable. In the hydrogen reactor 10 receives the methyl formate supplied from the methyl formate storage tank (9) and hydrogen from the hydrogen suit tank (4), the hydrocracking reaction of methyl formate occurs as shown in the following formula (2) The catalyst to be used is preferably a copper-based catalyst, and 2 mol of methanol is produced from 1 mol of methyl formate.

HCOOCH ₃ + 2H ₂ → 2CH ₃ OH ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ

The method for preparing methanol from methyl formate is prepared by hydrocracking methyl formate at 100-300 ° C. and 10-60 atm using a copper / chromium catalyst or a copper / chromium-zinc catalyst containing copper as the main catalyst. As illustrated in US Pat. No. 4,524,581, the operating conditions of the hydrogen reactor 10 vary according to the conditions of the reactants during operation, that is, liquid phase or gas phase. The produced methanol is separated from the unreacted methyl formate using a general distillation column and stored in the methanol storage tank 12, from which the methanol is supplied to the methyl formate reactor 8 by controlling the amount of methanol. The methyl formate is supplied to the acetic acid reactor 11 from the methyl formate storage tank 9, and the methyl formate supplied is converted into acetic acid as shown in the following formula (3) in the presence of a metal catalyst.

HCOOCH ₃ → CH ₃ COOH ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ (3)

The isomerization of acetic acid is described in British Patent No. 628,161, Japanese Patent Application Nos. 48-30613, 49-3513, 51-65703, and 48-29710, and these patents include iron, cobalt, and nickel. Methyl formate was reacted with acetic acid using a catalyst such as rhodium, rhenium, or activated carbon. Here, the reaction proceeds at a high pressure of 300 atm or higher, and low yield and generation of by-products other than acetic acid have been a problem.

In addition, acetic acid production using rhodium-promoters significantly alleviated the above severe reaction conditions, but because the price of rhodium is too expensive, the cost of preparing for separation and recycling after the reaction is excessively high. The use of the rhodium catalyst described in US Pat. No. 4,194,056 is also problematic.

In Japanese Patent Application No. 56-73040, using nickel metal, an oxo compound and an organic nitrogen group compound were added to obtain a high conversion rate of more than 95% under a maximum pressure of 30 atm. I have revealed the results. On the other hand, Japanese Patent Application No. 57-212135 describes the role of an iridium catalyst in the process of producing acetic acid in methyl formate without carbon monoxide. In the presence or absence of carbon monoxide, any efficient isomerization process may be employed regardless of the type of catalyst used, but a catalyst system that does not require carbon monoxide is more preferred.

The resulting acetic acid is separated using a general distillation method and then stored in the acetic acid storage tank 13. If pure carbon monoxide is required to maintain the pressure in this conversion reaction or if acetic acid is prepared after first decomposing methyl formate into methanol and carbon monoxide as described above, decomposition of methyl formate is This reaction is readily carried out below 200 ° C. using a supported caloric hydroxide catalyst, as in EP 57,090.

HCOOCH ₃ → CH ₃ OH + CO ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ (4)

Carbon monoxide and methanol produced at this time becomes carbon monoxide and methanol of more than 98% high purity without any by-products.

In order to produce acetic acid using carbon monoxide and methanol obtained at this time it is preferable to use the commercially available methanol carbonylation method of Monsanto process, the reaction formula is shown in the following formula (5).

CO + CH ₃ OH → CH ₃ COOH (5)

As a result, in both processes, 2 moles of carbon monoxide produce 1 mole of acetic acid with 2 moles of hydrogen, and no introduction of any reactants from the outside is necessary.

This will be described in more detail as follows. That is, as can be seen in FIG. 2 or FIG. 4, which shows the amount of raw materials and intermediates supplied to produce 1 mole of acetic acid, purified carbon monoxide and hydrogen or mixed gas containing them are stored in a reservoir. After the preparation is complete, when introduced into the reaction system and the conversion ratio of all the reactors is 100%, in the methyl formate reactor (8), 2 moles of carbon monoxide and 2 moles of methanol circulated react to form methyl formate and methyl One mole of methyl formate, which is stored in the formate storage tank 9 and part thereof, is reacted in the acetic acid reactor 11 or decomposed in the methyl formate reaction reactor 14 and converted to methanol and carbon monoxide to produce acetic acid. The acetic acid storage tank 13 is suited as one mole of acetic acid and the remaining one mole of methyl momate is mixed with two moles of hydrogen supplied from the hydrogen storage tank 4 in the hydrogenation reactor 10. Reaction to produce 2 moles of methanol.

Methanol produced at this time is stored in the methanol storage tank (12). 3 is the whole process which looked at the above process. In other words, 2 moles of carbon monoxide and 2 moles of hydrogen are introduced into the reaction system to produce 1 mole of acetic acid.

Reactions used in the present invention may be employed as a part of the overall process according to the present invention, as long as the catalysts are different from each other and the operating conditions are different but the efficiency of the reaction is high. Many other variable requirements can be made using existing techniques as described.

As described above, the present invention can easily prepare a methyl formate from iron and iron by-product gas using low-purity carbon monoxide and methanol in the presence of an alkali catalyst, so that a large part of the separation process required to obtain pure carbon monoxide can be omitted. In addition, the methyl formate is supplied with 2 moles of hydrogen and easily converted into 2 moles of methanol to produce methanol, which can supply methanol for the production of methyl formate itself. In this case, acetic acid production by isomerization of methyl formate or acetic acid production by ethanol carbonylation after decomposition of methyl formate may be used, and isomerization is considered in consideration of the reaction surface in comparison with carbonylation reaction. Driving conditions are much less relaxed So, if am may be used a small amount of pure carbon monoxide and methanol to decompose the stored methyl formate or have the time to use the carbonyl illustration, if necessary a pure carbon monoxide.

Accordingly, the present invention shows a process for producing 1 mole of acetic acid using 2 moles of carbon monoxide and 2 moles of hydrogen in steel by-product gas, and no introduction of any reactants from the outside is required. Since the operating conditions are much relaxed, there is an economically advantageous effect, and also pure carbon monoxide and methanol can be obtained by decomposing methyl formate, and the reaction can also produce acetic acid by carbonylation reaction. .

Claims (4)

Purifying and separating hydrogen and carbon monoxide from COG (1) and LDG (5), which are by-product gases generated in steel mills, respectively; Preparing a methyl formate by synthesizing the carbon monoxide purified and separated as described above in the methyl formate reactor (8) and methanol supplied from the methanol storage tank (12); Introducing a part of the synthesized methyl formate into the hydrogenation reactor (10) together with the hydrogen stored in the hydrogen storage tank (4) to synthesize methanol and store it in the methanol storage tank (12); The remainder of the methyl formate is transferred to the acetic acid reactor (11) and converted to acetic acid by isomerization with a catalyst; And the converted acetic acid is stored in the acetic acid storage tank 13; Acetic acid production method using the steel production by-product gas comprising a. The method according to claim 1, wherein nitrogen and carbon monoxide in the LDG (5), which is steel by-product gas, are supplied together to the methyl formate reactor (8) without being separated, and the carbon monoxide and methanol supplied from the methanol storage tank (12) react to form methyl methyl. Acetic acid production method using iron by-product gas, characterized in that to synthesize a mate. Purifying and separating hydrogen and carbon monoxide from COG (1) and LDG (5), which are by-product gases generated in steel mills, respectively; Preparing a methyl formate by synthesizing the carbon monoxide purified and separated as described above in the methyl formate reactor (8) and methanol supplied from the methanol storage tank (12); A part of the synthesized methyl formate is subjected to a hydrogenation reactor (10) to produce methanol and recycled back to the synthetic raw material of methyl formate; The other part of the methyl formate is produced by the production of carbon monoxide and methanol in a methyl formate decomposition reactor (14) connected to the methyl formate storage tank (9); And preparing acetic acid by adding carbon monoxide and methanol to the acetic acid reactor (11). Acetic acid production method using the steel production by-product gas comprising a. The method according to claim 3, wherein nitrogen and carbon monoxide in the LDG (5), which is steel by-product gas, are supplied together to the methyl formate reactor (8) without separation, and the methanol supplied from the methanol storage tank (12) reacts to form methyl methyl. Acetic acid production method using iron by-product gas, characterized in that to synthesize a mate.

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