JPS5869710A - Absorbing liquid for carbon monoxide - Google Patents

Abstract

PURPOSE:To improve the water-resistance and heat stability of CO absorbing liquid composed of cuprous chloride dissolved in hexamethyl phosphoryl triamide, by adding proper amounts of hydrochloric acid and lanthanum chloride to the liquid. CONSTITUTION:A CO-absorbing liquid obtained by dissolving cuprous chloride (CuCl) in hexamethyl phosphoryl triamide (HMPA) is incorporated with the lowest possible amounts of hydrochloric acid (HCl) and lanthanum chloride (LaCl3) to maintain th CO absorption capacity. A stable absorbing liquid having high water resistance can be obtained by this process. When the liquid is used in the CO-separation and CO-concentration processes, the pretreatment such as the removal of water from the exhaust gas becomes unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon monoxide absorption liquid, and in particular to a CO absorption liquid for separating, concentrating and recovering carbon monoxide (hereinafter sometimes referred to as CO) from process exhaust gas. It is related to.

In the chemical industry, iron and steel industry, etc., separation, concentration, and recovery of CO from process exhaust gas, for example, has become a major technological focus, based on the idea of producing raw material gas for synthesis or recovering energy.

Conventionally, methods for separating and condensing CO from a gas source containing CO include the absorption liquid method, which uses an absorption liquid such as a solution of cuprous salt, and the cryogenic separation method, which is fundamentally different from this method. Are known. 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, and it also requires high power consumption to obtain low temperature. The disadvantage is that it becomes large.

On the other hand, as the CO absorption liquid used in the absorption liquid method, an ammoniacal cuprous salt aqueous solution or a hydrochloric acidic cuprous salt aqueous solution has been used;
There was a problem that the amount of O absorbed was small. In response to this, the inventors developed an absorption liquid in which cuprous chloride (CμC1) was dissolved in hexamethylphosphortriamide (HMPA, also known as tris(dimethylai)phosphine oxide) K, which had a poor CO absorption capacity. (Patent Application No. 55-21708),
This absorption liquid has a very high CO absorption amount per unit volume compared to aqueous solutions, and has many advantages in actual process application.
When further heated to desorb CO, the dissolved cuprous chloride (Cμcg> is partially hydrolyzed to produce cuprous oxide (CtLzQ) as shown in the following formula, and the amount of CO absorbed by the absorbent increases. This resulted in a problem of a decrease in

CLLCl-HMPA + HxO→CLL illusion ↓+1-
LCI-HMPA An object of the present invention is to provide a CO absorption liquid that has high CO absorption performance and is not affected by moisture in exhaust gas.

The absorption liquid of the present invention is a CO absorption liquid in which cuprous chloride (CμCI) is dissolved in hexamethylphosphortriamide (HMPA) (hereinafter referred to as CuC4/HMPA liquid), hydrochloric acid (HCI) and lanthanum chloride (LaC4mPA). )of,
By adding it in the minimum amount that maintains a practical amount of CO absorption, an absorbent liquid with high water resistance and thermal stability can be obtained.

In the present invention, the amount of HCj added is 0.1 to 0.2
The amount of painting for 凰01/lSLαCj3 is 0. O1 to 0.1 degrees o1/j is preferred.

Hereinafter, the present invention will be explained in more detail with reference to comparative examples and examples.

Comparative Example A test tube with a stopper (K) so as not to be affected by oxygen in the air.
C@LC1/HMPA (2mat
/l) solution containing water for 5 seconds was sealed and heated in a constant temperature bath kept at 90°C. As a result, as the mixture was heated, a dark-colored precipitate was formed. As mentioned above, part of the CμCI/HMPA complex is hydrolyzed, resulting in oxidized first
This is because copper (CMIO) was produced. When CbxO is generated, the amount of CO absorbed by the absorbent decreases, so that it may be unsuitable as an absorbent for separating and concentrating CO from a gas source containing water.

Example Absorbing liquid that is not affected by moisture in the gas, that is, C
In order to obtain a water-resistant absorbent solution that does not reduce the amount of O absorbed, various acid solutions or dead metal salts were added to the CμC4/HMPA-based solution, and the mixture was added to the CμC4/HMPA solution using a test tube in the same manner as in the comparative example above. We examined the effects. As a result, among the various additives, the ones that were most effective on liquid stability were hydrogen chloride (HCI) and lanthanum chloride (LaC1m).

FIG. 1 shows the results after heating at 90° C. for 4 hours while varying the amounts of MCI and LaCl3 added. In the figure, the ○ mark indicates that a precipitate was formed, and the X mark indicates a case that a precipitate was formed. From the figure, HCI is O, Lm01/
It can be seen that if LaCl3 is added in an amount of 0.01 61/1 or more, no precipitate is formed.

Next, FIG. 2 shows the results when the absorption liquid shown in FIG. 1 was further heated at 90° C. for a long time (20 hours).

By heating for a long time, what was stable for 4 hours tends to form a precipitate. Even under these conditions, LaC45 does not precipitate at 1 mol/l of HCjO.
This is when the amount added is 0.05 to 01/1 or more.
When HCj is added in an amount of more than 0.2*0171, the amount of CO absorbed is significantly reduced. It is predicted that the larger the amount of LaC15 added, the more desirable it is, but since the chemical itself is expensive, 0.05 to 0.1++ aO4/l is considered to be the optimum amount. Here, LaC15 is usually commercially available. LaCj s・7H20 is used, but since it does not dissolve HMPAK, which is the solvent for CμCt, LaCj s・7H20 is dissolved in water in advance and HMPAK is used.
Needs to be dissolved. Table 1 shows an example of the most desirable liquid composition for application in an actual CO absorption process.

As a result of continuous absorption experiments of CO-containing gas in an absorption/desorption experimental tower, the absorption liquid was stable for more than 100 hours without forming a precipitate.According to the present invention, as described above, according to the present invention,
By incorporating Hcj and LaC1m into the CbCl/HMP A-based CO absorption liquid, a stable absorption liquid with good water resistance can be obtained. When this absorption liquid is used in a CO separation/concentration process, there is no need for a pretreatment device to remove moisture from the exhaust gas, which is advantageous in terms of equipment and operating costs.

[Brief explanation of the drawing]

Figures 1 and 2 are CμCI/HMPA, respectively.
FIG. 2 is an explanatory diagram showing the presence or absence of precipitation when an absorption liquid of C2v*01/II) is impregnated with water and LaC15 and HCj are added thereto in various amounts. Daikonto Patent Attorney Takenaga Kawakita Figure 1 Figure 2 HCJl Noboru (moVL)

Claims (1)

[Claims] (1) Cuprous chloride (CucJ), hexamethylphosphortriamide (HMPA), lanthanum chloride (LaC1s)
), hydrogen chloride (HCI), and water.
Carbon monoxide absorption liquid for imaging.