JPH0545291B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an absorbent for carbon monoxide (hereinafter referred to as CO), and in particular to an absorbent for absorbing CO from a mixed gas containing CO.
The present invention relates to a solid absorbent that selectively absorbs gases and is less susceptible to deterioration due to toxic gases.

(Conventional technology) CO is a basic raw material in synthetic chemistry and is contained in steel mill byproduct gases, such as coke oven exhaust gas.
Research on the effective use of CO is underway in various fields.

Generally, methods for industrially separating and purifying CO from a mixed gas to produce high-purity CO include a copper liquid absorption method, a COSORB method, and a cryogenic separation method.
However, the copper liquid absorption method is not economical due to drawbacks such as operational complexity, equipment corrosion due to the use of corrosive solutions, solution loss, and high construction costs.
At present, it is hardly used industrially.

The COSORB method uses a liquid absorbent consisting of a toluene solution of copper aluminum tetrachloride (CuAlCl ₄ ) (COSORB solution) to separate and concentrate CO.
When this solution is used, despite its high absorption capacity, there are drawbacks such as significant deterioration due to toxic gases, especially water, and toluene as a solvent mixed in during CO recovery.

In addition, the cryogenic separation method is generally not economical for separating CO when nitrogen is included in the mixed gas because the boiling points of nitrogen and CO are close to each other.

In general, when synthesizing chemicals using CO as a raw material, impurities have a negative effect on the synthesis catalyst and are often highly dependent on the partial pressure of CO.
In many cases, the purity of CO in raw materials for chemical synthesis is strictly regulated.

(Problems to be Solved by the Invention) The present invention makes full use of the advantages of the COSORB solution, eliminates the above-mentioned disadvantages, has high selectivity absorption and separation performance for CO, and has a high resistance to water and other toxic gases. Solid CO with extremely low deterioration
This paper proposes an absorption/separation agent.

By the way, in general, when attempting to selectively and efficiently separate CO using a solid adsorbent, the following problems arise.

Solid adsorbents can be roughly divided into two types: one is physical adsorbents that utilize the molecular sieve effect of activated carbon, zeolite, molecular sieves, etc., and the other is JP-A-58-49436, JP-A-Sho 58−
There is a chemical absorbent using a copper-based complex as an absorbent, as disclosed in Japanese Patent No. 156517.

Physical adsorbents utilize the molecular sieving effect to separate adsorbed substances by taking them into pores, and as is well known, the selectivity of adsorption into the pores is similar to that of chemical absorbents. High-purity gas cannot be obtained because it is far inferior to the conventional method.

Chemical absorbents using copper () are known to have high selectivity for carbon monoxide, but if left as is, they are susceptible to disproportionation and oxidation, and become copper (), reducing absorption capacity. . Therefore, efforts have been made to keep copper monovalent by forming a double salt with a counter ion such as aluminum halide (2). In addition, supporting and dispersing copper () in porous materials is considered for efficient use of copper (), and by uniformly dispersing copper (), a chemical absorbent with high selectivity and high absorption capacity can be prepared. be done.

As a porous carrier for dispersing copper (),
Zeolite as shown in USP 4034065 and activated carbon as shown in Japanese Patent Application Laid-Open No. 156517/1987 are known. However, as described above, these carriers have poor selectivity, and therefore have some problems as carriers for chemical absorbents for purifying CO with higher purity.

In view of the above points, the present invention provides a chemical absorbent using copper () without reducing absorption capacity.
The aim is to find a carrier that can take advantage of the high selectivity that is the mixed gas separation property, and to provide a CO absorption and separation agent that is effective in producing high-purity CO.

(Means for Solving the Problems) As a result of repeated research to find the above-mentioned carrier, the present inventors discovered that alumina, which does not have molecular sieving ability, is suitable, and arrived at the present invention. It is something.

The present invention uses lower alcohols of cuprous chloride, aluminum chloride or tetrahydrofuran (THF).
This is a carbon monoxide absorbent made by bringing a solvent solution into sufficient contact with alumina, and then removing the solvent.

In the present invention, the reason why alumina is used as a carrier for the chemical absorbent is as follows. That is,
Those with zeolite pores such as zeolite, those with micro pores such as activated carbon,
Others that have molecular sieving ability exhibit sufficient high selectivity absorption of CO because it is difficult for lower alcohol or tetrahydrofuran (THF) solvent solutions of cuprous chloride and aluminum chloride to enter the inner surface of the pores. Can not do it.
On the other hand, the alumina of the present invention, which does not have molecular sieving ability, has large pore diameters, allows the above solution to easily enter, and can sufficiently support copper (), which exhibits highly selective absorption of CO. The chemical absorption ability of () is not reduced, and the high selectivity properties can be exhibited as they are.

The alumina used in the present invention preferably has a BET surface of 40 to 40 m ² /g.

In addition, the present inventors have previously proposed a solid absorbent using an aromatic compound as a solvent that forms a dinuclear complex with cuprous chloride and aluminum chloride (see Japanese Patent Application No. 1983-40292). ). However, as a result of subsequent research, it was discovered that organic solvents are not limited to aromatic compounds, and that even non-aromatic compounds can form dinuclear complexes with Cu() and Al().

The present invention is based on this knowledge, and uses a non-aromatic organic solvent that forms a dinuclear complex with lower alcohols such as methanol, ethanol, propanol, butanol, or cuprous chloride or aluminum chloride of THF.

In the present invention, a lower alcohol or THF solvent solution of cuprous chloride or aluminum chloride,
sufficiently contact with alumina, then remove the solvent,
The amount of cuprous chloride and aluminum chloride supported on alumina is 1 to 50 parts by weight, preferably 10 to 40 parts by weight as a total of cuprous chloride and aluminum chloride, based on 100 parts by weight of alumina. in this case,
It is preferable that cuprous chloride and aluminum chloride exist in equal mol.

(Effects of the Invention) According to the absorbent of the present invention, CO separation can be performed with a purity of 98% or more, and it can be used as is as a raw material for ordinary chemical synthesis. Therefore, the absorbent of the present invention is effective in efficiently and economically separating and purifying CO from a mixed gas and recovering high-purity CO.

(Example) Special grade reagents manufactured by Wako Pure Chemical Industries, Ltd. were used for copper chloride ( ), aluminum chloride ( ), and methyl alcohol. The alumina used was B type alumina manufactured by Catalysts Kasei Co., Ltd. (spherical shape: 1 mmψ, average pore diameter: 110 Å, BET surface area: 220 m ² /g) calcined at 550° C. for 3 hours.

CuCl in a 200ml two-necked eggplant flask under dry nitrogen.
0.6 g, AlCl ₃ 0.8 g, and 20 ml of methyl alcohol were added, and the mixture was stirred at room temperature for 2 hours. 10 g of the pretreated alumina carrier was added to this solution and immersed for 30 minutes. After this, reduce the pressure inside the eggplant flask (6 mmHg)
Then, methanol was evacuated at room temperature overnight to obtain an absorbent.

A mixed gas of 66% CO and 34% _N2 is added to this absorbent.
Aeration was performed for 10 minutes to allow CO to be absorbed. When the amount of CO absorbed was measured using a constant-pressure volumetric absorption measuring device, it was found that CO
had absorbed 64 c.c.

Next, the mixture was heated to 90° C. to remove CO, and then cooled, and nitrogen gas containing H ₂ O at a saturated vapor pressure was bubbled through (approximately 40 mmol of H ₂ O contact amount). After this, when the above CO mixed gas was aerated again, the absorbed amount was 62c.c.
No deterioration of absorption capacity due to H ₂ O was observed.

In addition, ethanol instead of methyl alcohol,
Similar results were obtained using lower alcohols such as propanol and butanol.

Example 2 The same CuCl and AlCl ₃ as in Example 1 were used.

CuCl in a 200ml two-necked eggplant flask under dry nitrogen.
Add 0.6g, 0.8g of AlCl ₃ and 20ml of THF, and heat at room temperature.
The mixture was stirred for hours and left overnight. A black transparent solution was obtained. 10 g of the same alumina carrier used in Example 1 was added to this solution and immersed for 30 minutes. After this, reduce the pressure inside the eggplant flask (6 mmHg)
The THF was then evacuated for 5 hours. The dried material remaining at the bottom of the flask was used as an absorbent.

A mixed gas of 66% CO and 34% N ₃ was passed through this absorbent, and the amount absorbed was measured. The CO absorption amount was 58 c.c. in a fresh state, and 60 c.c. after being brought into contact with H ₂ O as in Example 1, and no deterioration due to H ₂ O was observed.

Comparative Example 1 The same CuCl, AlCl ₃ and methyl alcohol as in Example 1 were used.

CuCl in a 200ml two-necked eggplant flask under dry nitrogen.
0.6 g of AlCl ₃ , 0.8 g of AlCl 3 and 20 ml of methanol were added thereto, and the mixture was stirred at room temperature for 2 hours to obtain a black transparent solution. To this solution, 10 g of Y-zeolite (manufactured by Linde Co., Ltd.), which had been calcined at 550° C. for 3 hours and cooled in a desiccator, was added and immersed for 30 minutes. Thereafter, the pressure inside the eggplant flask was reduced (6 mmHg), and methanol was evacuated at room temperature overnight to prepare an absorbent.

Add a mixed gas of 66% CO and 34% _N2 to this absorbent for 10 minutes.
It was vented for a minute to allow CO to be absorbed. When the amount of CO absorbed was measured using the same method as in Example 1, the amount absorbed was 16
cc, and the amount had almost no effect as a CO absorbent. When this was heated to 90℃ to desorb CO, it was cooled, and the above raw material gas was aerated again, the absorption amount was 14c.c., which revealed that it had almost no absorption capacity. .

Claims (1)

[Claims] 1. A carbon monoxide absorbent obtained by bringing a solution of cuprous chloride or aluminum chloride in a lower alcohol or tetrahydrofuran solvent into sufficient contact with alumina, and then removing the solvent.