JPS5922626A - Preparation of liquid absorbent for carbon monoxide - Google Patents

Abstract

PURPOSE:To prepare an absorbent liquid having high water resistance while maintaining absorption performance by using the adsorbent liquid of CuCl-tris (dimethylamino)phosphine oxide (HMPA)/toluene, and changing the amt. of HMPA and other solvents according to the moisture content in the gas to be treated. CONSTITUTION:It is preferred to maintain the concn. of CuCl in an absorbent liquid at 1.0-2.0mol/l, more preferably 1.5-2.0mol/l to maintain the amt. of CO to be absorbed in the absorbent liquid at a practicale value, and CuCl is dissolved in HMPA to form a CuCl-HmPA complex for said purpose. If the concn. is increased in order to improve water resistance, the viscosity increases and the absorption rate of CO decreases. Therefore, for example, toluene is further added as a low viscosity solvent to the soln. of CuCl-HMPA complex to adjust the viscosity. The parts shown by horizontal lines are the range where precipitate, that is, CuCl(S) is not formed, which covers a range where the water resistance is higher as the ratio of HMPA with respect to CuCl is higher.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preparing a carbon oxide absorption solution, and in particular, to improve the water resistance of a cuprous chloride-based absorption solution for separating, concentrating, and recovering carbon monoxide from process exhaust gas, etc. It's about how to improve.

In the chemical industry, steel industry, etc., separating, concentrating, and recovering carbon monoxide (CO) from process exhaust gas has become a major technical issue, for example, in order to produce raw material gas for synthetic chemicals or to save energy. .

At present, methods for separating and concentrating CO from a gas source containing CO include an absorption method that uses an absorption liquid such as a solution of cuprous salt, and a cryogenic separation method that is fundamentally different from that method. ing. The latter cryogenic separation method consists of a complex cooling and heat recovery system, and because the operating temperature is low, it is necessary to use expensive equipment materials. There is a drawback that consumption is high.

On the other hand, the former absorption method is practical because it requires a simple device, but the performance of the absorption liquid used poses a problem. In other words, when using the absorbent in an actual process, efficient C
It is necessary to be able to absorb and separate O, have no decrease in CO absorption capacity, and be able to use it continuously for a long period of time.

As conventional CO absorption liquids, ammoniacal cuprous aqueous solutions or hydrochloric acidic cuprous salt aqueous solutions have been used, but both have a problem in that the amount of Co absorbed per unit volume of the aqueous solution is small.

In response, the inventors developed an absorption liquid in which cuprous chloride (CuC1) was dissolved in tris(dimethylamino)phosphine oxide (also known as hexamethylphosphortriamide, hereinafter referred to as HMPA) (patent application). No. 55-92607). This absorption liquid has a very high Co absorption amount per unit volume compared to aqueous liquids, and has many advantages in actual process applications. A problem was found that when a heating operation for desorption is performed, the CtLCl/HMPA complex having absorption ability reacts with moisture, causing C1LC1l to become insolubilized. That is, when the C1LC1-HMPA complex contains a large amount of water, as shown in the following formula, C1LC1-HMPA complex undergoes a hydrolysis reaction to
uC, ect> is released.

CtbCl - HMPA (A') + Hzαl), =: C or CJ (J) + HgO・) (MPA (1) C, L (J! (
J) kZ, Cu, cl(
s) precipitates. In the formula, l represents a liquid and S represents a solid.

Cu, C6(1) d CμC1(8)↓For this reason, in the conventional process, when processing a gas to be processed with a large amount of water, there was a drawback that a pretreatment device for removing water was required.

In view of the above-mentioned prior art, the object of the present invention is to
C1! An object of the present invention is to provide a method for preparing a CO absorption liquid that exhibits stable and high absorption performance without being insolubilized by moisture.

In the present invention, according to the moisture concentration in the gas to be treated,
It is characterized by adjusting the amount of solvent in the copper tris(dimethylamino)phosphine oxyto solution.

In the present invention, in order to keep the Co absorption amount of the absorption liquid at a practical value, K is set to 1.0 to 2.0.
0m01/1. Preferably 1.5-2.0 mal/
It is desirable to keep CttCl at HM
When dissolved in PA, a CtLC-HMPA complex is formed, but when the concentration is increased to improve water resistance, the viscosity increases and the CO absorption rate decreases. Therefore, in the present invention, toluene is further added as a low viscosity solvent to the CuCl-HMPA complex solution to adjust the viscosity. In addition,
In the present invention, other solvents than toluene can also be used as the low viscosity solvent.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

Figure 1 shows the relationship between HMPA and CtL (CuC by changing the ratio of J).
1. 1.2 and 3 in Figure 0 show the experimental results of preparing a HMPA/toluene-based CO absorption liquid and adding water dropwise to it to determine the range in which no precipitate is generated. , the CtbC1 concentration in the absorption solution was 1.5 and 2, respectively.
The case of mOl/l is shown. The shaded area in FIG. 1 is the range in which no precipitate, ie, CwCl(1), is generated, and it can be seen that the higher the ratio of HMPA to CuCl, the more the water resistance improves.

From the results shown in Figure 1, depending on the Cu and CI concentrations of the absorption liquid,
The permissible water content (saturated water content) is different, and CtLC
It can be seen that the lower the concentration of HMPA, the higher the ratio of HMPA to C. It is often about 1%, but if the allowable moisture content is 1 inch, the Cucl concentration is 2 nt01/It, 1.5m01
/II and 1.0 mal/l, HMP A
/Cucl ratios are 1.6, 1.9 and 2, respectively.
．． It becomes 3.

Based on the above basic experimental results, the compositions shown in Table 1 are typical CO absorption liquid compositions that are water resistant and have a high absorption rate.

Table 1 It should be noted that, as a matter of course, if the moisture content in the gas to be treated is low, the allowable moisture content will decrease, so HMP
The amount of A used can be reduced.

As described above, according to the present invention, Cu, CI HMPA/)
By using a luene-based absorption liquid and changing the amount of HMPA and other solvents depending on the amount of water in the gas to be treated,
It is possible to obtain an absorbent liquid with excellent water resistance while maintaining absorption performance. Also, by using this absorption liquid, CO
In the separation and concentration process, exhaust gas can be treated without installing pre-treatment equipment to remove moisture.
It is also advantageous in terms of equipment and operating costs.

[Brief explanation of the drawing]

Figure 1 is a graph showing the allowable water content of the absorption liquid as a function of the ratio of HMPA/cILCII by changing the CtL (J concentration).

Claims (1)

[Claims] (1) Carbon monoxide absorption characterized by adjusting the amount of solvent in a solution of cuprous chloride in tris(dimethylamino)phosphine oxide according to the water concentration in the gas to be treated. How to prepare the liquid. (2. In Claim 1, the method for preparing a carbon monoxide absorption liquid is characterized in that the solvent contains toluene as a low viscosity solvent in addition to tris(dimethylamino)phosphine oxide. (3) ) In claim 2, the concentration of cuprous chloride in the absorption liquid is 1 to 2 m01/l, the concentration of tris(dimethylamino)phosphine oxide is about 2.3 to 3.2, and the amount of toluene is 40 m01/l. A method for preparing a carbon monoxide absorbent, characterized in that the carbon monoxide absorption liquid is ~60υo1%.