JPS646812B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating carbon monoxide from a mixed gas containing carbon monoxide along with nitrogen, oxygen, methane, carbon dioxide, hydrogen, and the like.

Carbon monoxide is a basic raw material in synthetic chemistry, and is produced from coke and coal using generator furnaces, water gas furnaces, Winkler furnaces, Lurgi furnaces, Kotspers furnaces, etc. It is also produced from natural gas and petroleum hydrocarbons by steam reforming and partial oxidation methods. In these methods, the product is obtained as a mixture of gases such as carbon monoxide, hydrogen, carbon dioxide, methane and nitrogen. This mixed gas also contains a small amount of water. For example, in the case of water gas, carbon monoxide 35-40%, hydrogen 45-51%, carbon dioxide 4-5%, methane 0.5-1.0%, nitrogen 4-9%
% and contains 1,000 to 20,000 ppm of water. Carbon monoxide, a by-product of steel mills, oil refineries, and petrochemical plants, is similarly obtained as a mixed gas.

In order to use these carbon monoxides as raw materials for synthetic chemicals, it is necessary to separate them from the mixed gas.

Hydrogen is an important raw material in the chemical industry, and is separated from the various mixed gases mentioned above or from the waste gas of petrochemical plants, such as waste gas from hydrocarbon dehydrogenation processes, but it contains a small amount of carbon monoxide. There are many things to do. Since this carbon monoxide acts as a catalyst poison for the catalyst of reactions using hydrogen, it is necessary to separate and remove it. In addition, these waste gases contain
It usually contains a small amount of water.

To separate and remove carbon monoxide from mixed gas,
There is a copper solution cleaning method. This is applied to an ammoniacal aqueous solution of copper formate () or a hydrochloric acid suspension of copper chloride ().
The mixed gas is pressurized to 150 to 200 atm at room temperature and absorbed to separate and remove carbon monoxide.Next, this copper solution is heated under reduced pressure to release and separate carbon monoxide, and the copper solution is This is a method of reproducing
It has disadvantages such as difficulty in operational management to prevent equipment corrosion, solution loss, and precipitate formation, and high construction costs due to high pressure.

A cryogenic separation method is used to obtain large amounts of high-purity carbon monoxide. This cools the mixed gas and liquefies it to -165
This method involves fractional distillation at a low temperature of ~-210℃. but,
the need for complex refrigeration and heat recovery systems;
There are disadvantages such as expensive equipment due to the use of high-grade materials, high power consumption, and difficulty in separating carbon monoxide and nitrogen. Furthermore, if water and carbon dioxide are included in the mixed gas, a blockage accident will occur in the cryogenic tube system, so water and carbon dioxide are removed using pretreatment equipment.
It is necessary to remove it to below 1ppm.

According to British Patent No. 1318790, when a toluene solution of copper aluminum tetrachloride (Cu (AlCl ₄ )) is brought into contact with a mixed gas containing 30 mol% carbon monoxide at 25°C, it absorbs carbon monoxide. , this at 80℃
It is stated that 95% of carbon monoxide can be recovered when heated to This absorption liquid has the advantage of being unaffected by hydrogen, carbon dioxide, methane, nitrogen, and oxygen contained in the mixed gas, and has low absorption pressure, but it reacts irreversibly with water and reduces its absorption capacity. Causes deterioration and formation of precipitates and generates hydrochloric acid. For industrial implementation, DJ Haase and DG Walker et al.
Progress magazine, Volume 70, Issue 5, May 1974,
As stated on page 76, water in the gas mixture
Must be strictly controlled to 1ppm or less. Therefore, a strong dehydration treatment process for the mixed gas is required before the absorption process, and strict control is essential. Copper aluminum tetrachloride reacts strongly with water and irreversibly loses its ability to absorb carbon monoxide, so even with 1 ppm of water, the amount of deactivation will gradually increase as the amount of mixed gas processed increases. In addition, it has the disadvantage that equipment corrosion progresses due to the hydrochloric acid generated by the reaction.

Although various other methods have been proposed, no method for separating carbon monoxide from a mixed gas is yet completely satisfactory.

As a result of intensive research to solve these problems, the present inventors found that it is stable against water in the mixed gas,
Furthermore, they discovered an absorbent liquid that has the ability to absorb and release carbon monoxide under mild conditions, and completed the present invention.

The purpose of the present invention is to industrially advantageously separate and purify or separate and remove carbon monoxide from a mixed gas containing water. This is achieved by using a solution composed of a compound having a carbon monoxide, copper halide (2), aluminum halide (2), and an aromatic solvent as a carbon monoxide absorption liquid.

To explain the present invention in more detail, the carbon monoxide absorption liquid used in this method contains a compound having two aromatic rings bonded by a methylene carbon chain or a vinylidene group, a copper halide () and an aluminum halide. It can be prepared by dissolving the compound () in an aromatic solvent, keeping it at 20°C, usually 40-50°C, for several hours, and stirring.

Compounds having two aromatic rings linked by a methylene carbon chain or a vinylidene group described in the specification include, for example, 1,4-diphenylbutane, 1,3-diphenylpropane, 1,2-diphenylethane, diphenylmethane and 1,1-
Diphenylethylene, etc.

Examples of the copper halide used in the present invention include copper chloride (2), copper fluoride (1), and copper bromide (1). The aluminum halide ( ) used in the present invention includes, for example, aluminum chloride ( ), aluminum fluoride ( ), and aluminum bromide ( ). Aromatic solvents used in the present invention include, for example, benzene, toluene, and xylene.

Regarding the composition of the absorption liquid used in the present invention, the molar ratio of the compound having two aromatic rings bonded by a methylene carbon chain or vinylidene group to copper halide is 0.02 to 10, preferably
The molar ratio of copper halide (2) to aluminum halide (2) is 0.01 to 10, preferably 0.5 to 1. The molar ratio of the aromatic solvent to the copper halide (2) is from 0.5 to 30, preferably from 3 to 10.

The carbon monoxide absorption liquid according to the present invention is stable to water. For example, as seen in Examples 1, 2, and 3, the absorption liquid was first contacted with a nitrogen stream containing 8700 ppm water for 10 minutes at 20°C, and then
Even when carbon monoxide is absorbed by contacting with high-purity carbon monoxide, there is hardly any decrease in the carbon monoxide absorption capacity. In addition, the absorption of carbon monoxide is rapid, and the absorbed carbon monoxide leaves the absorption liquid at 80 ~
It is rapidly released when the temperature is raised to 100°C.

In contrast, as shown in Comparative Example 1, an absorption liquid that does not contain a compound having two aromatic rings bonded by a methylene carbon chain or a vinylidene group, that is, copper halide () and aluminum halide (), When an absorption liquid composed of an aromatic solvent is brought into contact with a water-containing gas, its ability to absorb carbon monoxide is significantly reduced. This clearly shows that the absorbent liquid of the present invention is superior.

Next, the present invention will be further explained with reference to Examples and Comparative Examples.

Example 1 Aluminum chloride () was obtained by dehydrating and purifying a special grade reagent manufactured by Kishida Chemical Industry Co., Ltd. by a vacuum sublimation method, and toluene was used by dehydrating a first grade reagent manufactured by Takahashi Fujiyoshi Shoten Co., Ltd. with metallic sodium and then distilling it. For diphenylmethane, a special grade reagent manufactured by Tokyo Kasei Co., Ltd. was used. For copper chloride (2008), a special grade reagent manufactured by Koso Chemical Co., Ltd. was used. For carbon monoxide gas and nitrogen gas, cylinder gases manufactured by Takachiho Chemical Co., Ltd. (99.95% purity) and Suzuki Shokan Co., Ltd. (99.999% purity) were added immediately before use. ) was passed through a packed column for drying and purification.

in a 200 ml two-necked eggplant flask under dry nitrogen.
2.4 g (18 mmol) aluminum chloride (), 1.8
g (18 mmol) of copper chloride () and 3.0 g (18
Add 20 mmol of diphenylmethane and add 20 mmol of toluene.
ml was added and dissolved, and heated and kept at 40°C for 4 hours while stirring using a magnetic stirrer to prepare an absorption liquid.

In a 200 ml two-necked eggplant flask, stir the absorption liquid at 20°C using a magnetic stirrer.
It was connected to a container containing 1 atm of a mixed gas of carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen partial pressure 0.2 atm) to absorb carbon monoxide. For the initial 10 minutes of absorption, use BA-106T manufactured by Iwaki Co., Ltd.
A type air pump was used to circulate the gas mixture over the absorption liquid. Carbon monoxide absorption gas was measured at 20°C by the gas billet method.

As shown by the solid line in Figure 1, absorption of carbon monoxide is rapid, with 11.7 mmol of carbon monoxide absorbed after 3 minutes, and 14.0 mmol of carbon monoxide absorbed after 10 hours.
This means that the absorption amount has almost reached equilibrium.

While cooling the corkscrew reflux device installed above the two-necked eggplant flask with tap water, the absorption liquid was heated to 1 atm.
The sample was heated to 90°C, and the amount of gas released was measured by the gas billet method. Carbon monoxide was rapidly released, reaching 14.0 mmol after 5 minutes.

Next, 1 atm nitrogen gas (water concentration 8700 ppm) 5 containing 32 mg (1.8 mmol) of water was prepared separately. Combine this container containing nitrogen gas with a 200ml two-necked eggplant flask, manufactured by Iwaki Co., Ltd.
The absorbent liquid was circulated using a BA-106T air pump and stirred with a magnetic stirrer at 20℃.
It was allowed to pass for 10 minutes.

Then, while stirring this absorption liquid at 20℃ using a magnetic stirrer, it is combined with a container containing 1 atm of a mixed gas of carbon monoxide and nitrogen (carbon monoxide partial pressure: 0.8 atm, nitrogen partial pressure: 0.2 atm). Then, an air pump was used to circulate the liquid over the absorption liquid to absorb carbon monoxide. As shown by the black circles in Figure 1, the absorption rate and amount of carbon monoxide are
The value before contact with gas containing 8700ppm water,
Almost no change was observed. This absorption liquid
Upon heating to 90° C. at 1 atm, carbon monoxide was rapidly released, reaching 13.8 mmol after 5 minutes.

Example 2 The same procedure as in Example 1 was carried out, except that 3.2 g (18 mmol) of 1,2-diphenylethane (special grade reagent manufactured by Tokyo Kasei Co., Ltd.) was used instead of 3.0 g of diphenylmethane described in Example 1. I did it.

Before contacting the absorption liquid with nitrogen gas containing 8700 ppm of water, a mixed gas of 1 atm carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen content pressure
0.2 atm) 1 was circulated at 20°C to absorb carbon monoxide. The absorption liquid quickly absorbed carbon monoxide, and the amount of carbon monoxide absorbed after 10 hours was 14.9 mmol, almost reaching the equilibrium absorption amount. This absorption liquid
When twisted at 1 atm and 90°C, carbon monoxide was rapidly released, and the released amount reached 14.7 mmol after 5 minutes.

Next, 1 atm nitrogen gas 5 containing 8700 ppm water was circulated using an air pump, and the mixture was stirred with a magnetic stirrer for 10 minutes at 20°C.
I let it pass for a minute.

Then, while stirring this absorption liquid at 20°C using a magnetic stirrer, a mixed gas of 1 atm carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen partial pressure 0.2 atm) 1 was circulated. Carbon oxide was absorbed. The absorption liquid quickly absorbs carbon monoxide,
The amount of carbon monoxide absorbed after 10 hours was 15.2 mmol, almost reaching the equilibrium absorption amount. This absorption liquid
Upon heating to 90° C. at 1 atm, carbon monoxide was rapidly released, reaching 15.2 mmol after 5 minutes.

Example 3 Same as Example 1 except that 2.1 g (11.8 mmol) of 1,1-diphenylethylene (special grade reagent manufactured by Tokyo Kasei Co., Ltd.) was used instead of 3.0 g of diphenylmethane described in Example 1. I performed the following operations.

Before contacting the absorption liquid with nitrogen gas containing 8700 ppm of water, a mixed gas of 1 atm carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen content pressure
0.2 atm) 1 was circulated at 20°C to absorb carbon monoxide. The absorption liquid quickly absorbed carbon monoxide, and the amount of carbon monoxide absorbed after 10 hours was 14.8 mmol, almost reaching the equilibrium absorption amount. This absorption liquid
Upon heating to 90° C. at 1 atm, carbon monoxide was rapidly released, reaching 14.7 mmol after 5 minutes.

Next, 1 atm nitrogen gas 5 containing 8700 ppm water was circulated using an air pump, and the mixture was stirred with a magnetic stirrer for 10 minutes at 20°C.
I let it pass for a minute.

Then, while stirring this absorption liquid at 20°C using a magnetic stirrer, a mixed gas of 1 atm carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen partial pressure 0.2 atm) 1 was circulated. Carbon oxide was absorbed. The absorption liquid quickly absorbs carbon monoxide,
The amount of carbon monoxide absorbed after 10 hours was 14.6 mmol, almost reaching the equilibrium absorption amount. This absorption liquid
Upon heating to 90° C. at 1 atm, carbon monoxide was rapidly released, reaching 14.5 mmol after 5 minutes.

Example 4 1,3-diphenylpropane was prepared from the literature (DG
Cram and H.Steinberg, J.Amer.Chem.Soc.
73, 5961 (1951)). That is, it was prepared by reducing 1,3-diphenylpropan-2one (special grade reagent manufactured by Tokyo Kasei Co., Ltd.) with hydrazine and then distilling it under reduced pressure, and then using it by further refluxing it over metallic sodium and distilling it under reduced pressure.

3.5 g (18 mmol) synthesized above in place of 3.0 g diphenylmethane described in Example 1
The same operation as in Example 1 was carried out except that 1,3-diphenylpropane was used.

Before contacting the absorption liquid with nitrogen gas containing 8700 ppm of water, a mixed gas of 1 atm carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen content pressure
0.2 atm) 1 was circulated at 20°C to absorb carbon monoxide. The absorption liquid quickly absorbed carbon monoxide, and the amount of carbon monoxide absorbed after 10 hours was 14.3 mmol, almost reaching the equilibrium absorption amount. This absorption liquid
Upon heating to 90° C. at 1 atm, carbon monoxide was rapidly released, reaching 14.1 mmol after 5 minutes.

Next, 1 atm nitrogen gas 5 containing 8700 ppm water was circulated using an air pump, and the mixture was heated with a magnetic stirrer for 10 minutes at 20°C.
I let it pass for a minute. After that, this absorption liquid was stirred at 20℃ using a magnetic stirrer and heated to 1atm.
Mixed gas of carbon monoxide and nitrogen (partial pressure of carbon monoxide
0.8 atm, nitrogen partial pressure 0.2 atm) 1 was circulated to absorb carbon monoxide. The absorption liquid quickly absorbs carbon monoxide, and the amount of carbon monoxide absorbed after 10 hours is
The amount was 14.2 mmol, which almost reached the equilibrium absorption amount. When this absorption liquid is heated to 90℃ at 1atm, carbon monoxide is rapidly released, and the amount released is 14.1m2 after 5 minutes.
reached mol.

Comparative Example 1 The same reagents as described in Example 1 were used.

In a 200ml two-necked eggplant flask under dry nitrogen,
2.4 g (18 mmol) of aluminum chloride () and
1.8 g (18 mmol) of copper chloride () was added and dissolved in 20 ml of toluene, and while stirring using a magnetic stirrer, the mixture was heated and kept at 40°C for 4 hours to prepare an absorption liquid. That is, this absorption liquid is the same as Example 1 except that it does not contain diphenylmethane.
It was prepared in the same manner as the absorption liquid described in Example 1, and the method for measuring the amount of carbon monoxide absorbed and the method for contacting the absorption liquid with water described below were also the same as in Example 1.

In a 200 ml two-neck eggplant flask, stir the absorption liquid at 20°C using a magnetic stirrer.
It was connected to a container containing 1 atm of a mixed gas of carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen partial pressure 0.2 atm) to absorb carbon monoxide. For the initial 10 minutes of absorption, use BA-106T manufactured by Iwaki Co., Ltd.
A type air pump was used to circulate the gas mixture over the absorbent liquid. The amount of carbon monoxide absorbed was measured at 20°C using the gas biuret method.

Carbon monoxide absorption is rapid, reaching 12.0 m after 3 minutes.
mol of carbon monoxide was absorbed, and the amount of carbon monoxide absorbed after 10 hours was 13.9 mmol, almost reaching the equilibrium absorption amount.

While cooling the corkscrew reflux device installed above the two-necked eggplant flask with tap water, the absorption liquid was heated to 1 atm.
The sample was heated to 90°C, and the amount of gas released was measured by the gas billet method. Carbon monoxide was rapidly released, reaching 13.9 mmol after 5 minutes.

Next, 1 atm nitrogen gas (water concentration 8700 ppm) 5 containing 32 mg (1.8 mmol) of water was prepared separately. Combine this container containing nitrogen gas with a 200ml two-necked eggplant flask, manufactured by Iwaki Co., Ltd.
Circulate using BA-106T type air pump,
Heat the absorbent solution stirred with a magnetic stirrer at 20℃.
It was allowed to pass for 10 minutes.

Then, while stirring this absorption liquid at 20℃ using a magnetic stirrer, a mixed gas of 1 ata of carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen partial pressure
0.2 atm) 1 to absorb carbon monoxide. Carbon monoxide absorption is rapid;
After a minute, 8.9 mmol of carbon monoxide was absorbed, and after 10 hours, the amount of carbon monoxide absorbed was 10.3 mmol, almost reaching the equilibrium absorption amount. Therefore, 10 minutes of contact with Gas 5 containing 8700 ppm water resulted in a 26% decrease in the carbon monoxide absorption capacity of the absorbent. When this absorption liquid was heated to 90° C. at 1 atm, carbon monoxide was rapidly released, and the amount released was 10.2 mmol after 5 minutes.

Next, 1 atm nitrogen gas 5 containing 8700 ppm water was prepared again, and this was circulated using an air pump and passed over the absorption liquid stirred by a magnetic stirrer for 10 minutes at 20 °C. .

Then, while stirring this absorption liquid at 20°C using a magnetic stirrer, a mixed gas of 1 atm carbon monoxide and nitrogen (carbon monoxide partial pressure 0.8 atm, nitrogen partial pressure 0.2 atm) 1 was circulated. Carbon oxide was absorbed. Carbon monoxide absorption is rapid; after 3 minutes,
4.9 mmol of carbon monoxide was absorbed, and the amount of carbon monoxide absorbed after 10 hours was 6.7 mmol, almost reaching the equilibrium absorption amount. Therefore, by contacting again for 10 minutes with Gas 5 containing 8700 ppm water, the carbon monoxide absorption capacity of the absorbent was further reduced by 26%.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the contact time with gas and the amount of carbon monoxide absorbed in Example 1.
The solid line shows the absorption curve of carbon monoxide gas before contacting the water-containing nitrogen gas with the absorption liquid,
The black circle corresponds to the carbon monoxide gas absorption curve after the absorption liquid was brought into contact with nitrogen gas 5 containing 8700 ppm water for 10 minutes.

Claims (1)

[Claims] 1. It is characterized by using an absorption liquid composed of copper halide (), aluminum halide (), an aromatic solvent, and a compound having two aromatic rings bonded by a methylene carbon chain or a vinylidene group. A method for separating carbon monoxide from a gas mixture containing 1 ppm or more of water.