JPS6247057B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a carbon monoxide (hereinafter referred to as CO) absorption liquid. In the chemical industry, steel industry, etc., separating, concentrating, and recovering CO from process exhaust gas has become a major technical challenge, with the aim of producing raw material gas for synthesis or saving energy. Currently, methods for separating and concentrating 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 is
It 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 has the disadvantage of increasing power consumption to obtain the low temperature. be. 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 conventionally been used, but in either case, the amount of CO absorbed per unit volume of the aqueous solution is The problem was that it was small. In these absorption liquids,
It is thought that a chloro complex or ammine complex is formed in order to solubilize monovalent copper, which is directly involved in CO absorption, in the solution. Recently, a CO absorbent solution in which a complex (CuAlCl ₄ ) of cuprous chloride (hereinafter referred to as CuCl) and anhydrous aluminum chloride (hereinafter referred to as AlCl ₃ ) is dissolved in toluene has been developed and is attracting attention. . This absorption liquid has a feature that the amount of CO absorbed per unit volume of solution is much higher than that of aqueous solutions. Therefore, when applied to actual CO separation and concentration processes, the absorption tower does not require high pressure or low temperature, and can be operated at room temperature and pressure, so the equipment does not require pressure-resistant materials, etc. Since the CO absorption load is large, it has the advantage of requiring only a small amount of solution circulation. However, the above absorption liquid has a problem in that its constituent AlCl ₃ comes into contact with water or steam and undergoes quantitative hydrolysis, resulting in a corresponding decrease in the amount of CO absorbed. An object of the present invention is to provide an absorption liquid that is resistant to hydrolysis even when it comes into contact with water or steam and maintains high carbon monoxide absorption performance. In order to achieve the above object, the absorption liquid of the present invention is
It is characterized by containing cuprous chloride and oxyacid derivatives of phosphorus. The above oxyacid derivative of phosphorus has a melting point of 20℃.
Hereinafter, phosphoric acid esters and/or phosphine oxides having a boiling point of 100°C or higher are suitable. The absorption liquid of the present invention can be used in either the form of a slurry or a homogeneous solution, but a homogeneous solution is preferable from the viewpoint of ease of operation. In order to improve the dispersibility of cuprous chloride and the like in the absorption liquid, it is desirable in the present invention to add a metal salt other than monovalent copper. Such metal salts include Li,
Alkali metals such as K and Na, alkaline earth metals such as Be, Mg and Ca, group a metals such as Al and Tl, and Ti, V, Cr, Mu, Fe, Co, Ni, Mo, Ru,
Chlorides and sulfates of transition metals such as Rh, Pd, La, etc.
Nitrates are suitable, and alkali metal chlorides and transition metal chlorides are particularly preferably used. The composition ratio of each component above is cuprous chloride:metal salt:
The molar ratio of phosphorus oxygen acid derivatives is 1:0 to 3:2.
A range of 20 is appropriate, especially 1:0 to 2:3 to 15
A range of is preferred. In the present invention, a suitable surfactant or the like may be added to improve the dispersibility of each component in the absorption liquid. When selecting the constituent components of the present invention, it is important to ensure that the absorption liquid has low viscosity and good stability;
Further, it is preferable that the constituent components do not volatilize out of the system when coming into contact with a CO-containing gas or when separating CO. Next, operating conditions for absorbing and separating CO in a CO-containing gas using the absorption liquid of the present invention and recovering it as concentrated CO will be described. FIG. 1 is a basic flow sheet of the CO separation and concentration process using the absorption liquid of the present invention. In the figure, CO-containing gas is pretreated in a pretreatment device 1 as necessary, and a raw material gas line 11
, enters the absorption tower 2, contacts the absorption liquid in the absorption tower, and CO is selectively absorbed. The absorption tower exhaust gas is discharged into the atmosphere through the exhaust gas line 21 after the entrained components are appropriately removed. on the other hand,
The liquid that has absorbed CO is sent from the absorption line 31 through the heat exchanger 4 to the separation column 3, where it is heated or depressurized to release CO. The exhaust gas from the separation tower contains a high concentration of CO, but after removing entrained components, it is recovered through the gas line 41 and becomes a product gas. The absorption liquid from which CO has been separated is returned to the absorption tower 2 through the line 51 and is used for circulation. The operating temperature and pressure when applying the absorption liquid of the present invention to the actual CO concentration and separation process are as follows:
It can be changed depending on the CO content rate in the CO-containing gas, the contact time, the composition of the absorption liquid, etc. In general, lowering the absorption temperature increases the amount of CO absorbed, but requires a cooling device for low-temperature production, increases the viscosity of the absorption liquid, and sometimes causes the absorption liquid to solidify. On the other hand, if the absorption temperature is too high,
The amount of CO absorbed becomes smaller. In view of the above, the absorption temperature is generally preferably 10 to 80°C. Furthermore, the higher the absorption pressure, the greater the amount of CO absorbed and the faster the absorption rate, but a gas compressor is required, and the equipment must also have a pressure-resistant structure, which increases construction costs. From this point of view, the absorption pressure is generally preferably 0 to 20 kg/cm ² in gauge pressure. The absorption liquid that has absorbed CO can be prepared by raising the temperature or lowering the pressure above the absorption temperature, or by contacting it with an inert medium (e.g. water vapor, benzene vapor, etc.), or depending on the use of CO. By contacting with hydrogen gas etc., CO is released and regenerated. The above-mentioned dispersion operations may be performed alone or in combination. dissipated
By collecting CO, concentrated CO gas can be obtained, and these gases are effectively used as fuel or raw material gas for chemical synthesis. Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that the volumes of gases in the examples are all values under standard conditions (0° C., 1 atm). Example 1 9.90 ml of CuCl was placed in a cylindrical glass container with a volume of 100 ml.
g (0.1 mol) and 0.77 g (0.005 mol) of _TiCl3
Tris(dimethylamino)phosphine oxide (also known as hexamethylphosphoramide)
After adding 51.5 g (0.29 mol), the mixture was heated at 80° C. for 5 hours to obtain a homogeneous solution. Add this solution to 30
After cooling to ℃, while maintaining the same temperature, CO20
%, N ₂ 80% (volume %) was continuously blown in at normal pressure, and the equilibrium absorption amount of CO under these conditions was determined. As a result, this absorption liquid absorbed 25.6 ml of CO per ml. For comparison,
When we calculated the equilibrium CO absorption amount under the same conditions for 9.9 g (0.1 mol) of CuCl dissolved in 50 ml of 8N HCl aqueous solution (conventional cuprous hydrochloric acid solution), we found that 4.5 ml of CO per 1 ml of absorption liquid. It was nothing more than absorbing. Example 2 When the liquid obtained in Example 1 that had absorbed an equilibrium amount of CO was heated to 100°C and reduced to 50 mmHg, 25.1 ml of CO was recovered per ml of the absorbed liquid. Example 3 An absorption liquid having the same composition as that shown in Example 1 was newly prepared, 2% (volume %) of water was added thereto, and the mixture was left at 30° C. for 24 hours. Thereafter, the CO equilibrium absorption amount was measured under the same conditions as in Example 1. As a result, 25.6ml of CO was absorbed per ml of absorption liquid,
It was shown that the addition of water did not change the performance at all. Example 4 CuCl was added at 9.90 ml in a cylindrical glass container with a volume of 100 ml.
g (0.1 mol) and 0.67 g of CrCl ₃ , 6H ₂ O
(0.0025 mol) was collected, and 51.5 g (0.29 mol) of tris(dimethylamino)phosphine oxide was added to obtain a homogeneous solution. When the equilibrium CO absorption amount of this absorption liquid was measured under the same conditions as in Example 1, it was found that 26.5 ml of CO was absorbed per ml of absorption liquid.
Absorbed CO. Example 5 CuCl was added at 9.90 ml in a cylindrical glass container with a volume of 100 ml.
When 51.5 g (0.29 mol) of tris(dimethylamino)phosphine oxide was added to the solution, a homogeneous solution was obtained. When the CO equilibrium absorption amount of this absorption liquid was measured under the same conditions as in Example 1, 8.6 ml of CO was absorbed per 1 ml of the absorption liquid. Example 6 4.45g of CuCl in a cylindrical glass container with a volume of 100ml
(0.05 mol) was collected and 51.5 g (0.29 mol) of tris(dimethylamino)phosphine oxide was added to obtain a slurry-like absorption liquid. When the CO equilibrium absorption amount of this absorption liquid was measured under the same conditions as in Example 1, it was found to be 11.2 per ml of absorption liquid.
ml of CO was absorbed. Examples 7 to 14 An absorbing liquid having the composition shown in Table 1 was placed in a cylindrical glass container with a volume of 100 ml and maintained at 30°C. Next, the CO equilibrium absorption amount of these absorption liquids was measured under the same conditions as in Example 1. Furthermore, the liquid that had absorbed the equilibrium amount of CO was heated to 100°C and reduced to 50 mmHg to determine the amount of CO recovered. These results are shown in Table 1.

[Table] As described above, according to the present invention, CO can be efficiently and stably absorbed from various gas sources containing CO. In other words, the absorption liquid of the present invention is stable against water and has a very high CO absorption amount, so there is no need for pretreatment to remove water as in the past, and the absorption tower can be operated at high pressure and low temperature. You can exercise at normal pressure and temperature without the need for Furthermore, since the CO absorption load can be increased, the amount of solution circulation can be small, making it possible to achieve a highly efficient and economical CO separation and concentration process.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an example of a carbon monoxide separation and concentration process using the absorption liquid of the present invention. 2... Absorption tower, 3... Separation tower, 4... Heat exchanger, 11... Gas supply line.

Claims (1)

[Scope of Claims] 1. A carbon monoxide absorption liquid characterized by containing cuprous chloride and an oxyacid derivative of phosphorus. 2. The carbon monoxide absorption liquid according to claim 1, wherein the absorption liquid further contains a metal salt other than monovalent copper. 3. The carbon monoxide absorption liquid according to claim 1 or 2, characterized in that the oxygen acid derivative of phosphorus is a phosphoric acid ester or (and) a phosphine oxide. 4. In claim 1 or 2, the monovalent metal salt other than copper is an alkali metal chloride, an alkaline earth chloride, copper dichloride, zinc chloride, lanthanum chloride, thallium monochloride, Titanium trichloride, tin dichloride, vanadium trichloride, iron dichloride,
A carbon monoxide absorption liquid characterized by being at least one compound selected from the group consisting of iron trichloride, cobalt dichloride, nickel dichloride, chromium trichloride, chromium sulfate, and chromium nitrate.