JPS6197121A - Method for recovering carbon monoxide - Google Patents

Abstract

PURPOSE:To separate economically high purity CO from a gaseous mixture contg. CO by bringing the gaseous mixture into contact with a porous CO absorbent to absorb selectively CO and by desorbing the absorbed CO by evacuation combined with heating. CONSTITUTION:A porous CO absorbent is manufactured by supporting univalent Cu or univalent Cu and tervalent Al on an inorg. porous body such as porous alumina. A gaseous mixture contg. CO such as exhaust gas from a blast furnace, a coke oven or a converter in an iron mill is brought into contact with the porous CO absorbent to absorb selectively CO. After unabsorbed gas is removed by evacuation, evacuation and heating or heating and evacuation are successively carried out to desorb the absorbed CO from the absorbent. Evacuation and heating may be carried out at the same time. Thus, CO is separated from the gaseous mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for selectively recovering carbon monoxide from a mixed gas containing carbon monoxide as a main component. A method for recovering carbon monoxide, characterized in that, when recovering carbon monoxide, desorption treatment is performed by reducing pressure and heating.

BACKGROUND TECHNOLOGY In general, industrial methods for separating and refining CO from a mixed gas to produce high-purity CO include liquid preparation absorption method, CO8O
There is the RB method or the cryogenic separation method. However, the liquid absorption method suffers from drawbacks such as operational complexity, equipment corrosion due to the use of corrosive solutions, solution loss, and high construction costs, making it uneconomical and currently hardly used industrially. Not adopted. In the CO8ORB method, the presence of moisture in the mixed gas causes solution deterioration, and in the cryogenic separation method, when nitrogen is contained in the mixed gas, nitrogen and CO are
Because of the close boiling point differences between the two, separation for CO is generally not economical.

Generally, when synthesizing chemicals using CO as a raw material,
Impurities have a negative effect on synthesis catalysts and are often highly dependent on the partial pressure of CO, so the Co purity of raw materials used in chemical synthesis is often strictly regulated.

The Co purity obtained by the method of the present invention is 95% or more, and it is characterized in that it can be used as it is as a raw material for ordinary chemical synthesis. Further, with the method of the present invention, products with a Co purity of 98% or higher can be easily produced.

The present invention provides a method for efficiently and economically separating and purifying carbon monoxide from a mixed gas and recovering high-purity CO using a porous carbon monoxide absorbent.

That is, the present invention provides a method for recovering carbon monoxide by desorbing carbon monoxide from an absorbent that has selectively absorbed carbon monoxide, in which the desorption treatment is performed by a combination of reduced pressure and heating. It is characterized by

Effect of the Invention The effect of the present invention is that by changing the heating or cooling temperature and changing the atmospheric pressure, the amount of CO pickup, that is, the amount of CO recovered by the absorption-desorption operation, can be reduced. , could be recovered in much larger quantities than if they were recovered by each individual change.

Operation Various embodiments are possible for combining temperature change and pressure change in the recovery of CO gas in the method of the present invention. That is, (1) heating and depressurization are performed simultaneously; (2) heating and depressurization are performed with a time difference; (3) initial suction treatment is performed;
For example, the unabsorbed residual gas is removed under reduced pressure and then heated under reduced pressure. Of these, heating and depressurizing at the same time is CO
In the case of continuous absorption and recovery from waste gas whose main component is It can be advantageously used, for example, when it is necessary to collect product residues of different purity.

Next, the effects of the present invention will be explained using figures. Figure 1 shows the case in which CO is recovered by changing temperature (TSA), Figure 2 shows the case in which CO is recovered by changing pressure (VS A), and Figure 3 shows the case in which the combination of temperature and pressure of the present invention is changed. In particular, by changing both at the same time, C
It is an explanatory diagram about the case of recovering O (TVSA). In the figure, the horizontal axis is 00 partial pressure (atml) and the vertical axis is absorption C
The amount (mmol/g-absorbent) is shown in each case. In addition, 1st to 3rd
The graph shown in the figure (three solid lines) is 25℃ from the top,
Absorbed CO amount at 90°C and 120°C (mmole/g
- Absorbent) and 00 partial pressure (atm).

Considering the state in which CO is separated by heating the absorbent at 25°C in Figure 1, the amount of CO generated when heated to 90°C is the graph between the line drawn perpendicularly from the point Δ and the graph at 90°C. The amount of CO up to the intersection B with the .

In addition, in Figure 2, if the pressure is reduced while keeping the temperature at 25°C, it will move from A to D along the absorption curve at 25°C.
During this time, an amount of Δ■3' of CO should be recovered. However, in reality, the amount of CO released by depressurization does not change along the absorption curve but is released along the bisteresis curve shown by the broken line, so the point where it should reach is point E.
ΔVz[, which is smaller than Δv2', cannot be recovered.

In contrast to the conventional method shown in Figs. 1 and 2 above, Fig. 3 shows CO2 reduction by combining the temperature change and pressure change of the present invention.
This figure shows the amount of adsorbed CO recovered when CO is recovered.

In FIG. 3, the co absorbed at point A is reduced in pressure while the temperature rises to 90° C., and the co is released along the storehouses from A to F, and the amount of CO shown by ΔV is recovered. As is clear from the above results, the combination of the present invention makes it possible to recover a larger amount of CO than in the case of single treatment.

The purpose of the present invention is to efficiently recover adsorbed CO, and there are no particular restrictions on the absorption method. However, in order to carry out continuous treatment by repeating CO absorption and recovery, it is effective to adopt an absorption method that matches the recovery in terms of combining processes.

The method of the present invention is characterized in that a porous absorbent is used, the absorbent being copper (Il) in combination with a porous inorganic carrier, such as copper(I) halide.
activated carbon, copper (Il zeolite or copper halide (1
), an absorbent supported on a porous inorganic oxide support such as porous alumina using aluminum(III) halide and an organic solvent; An absorbent supported on a porous inorganic oxide carrier such as porous alumina using a solvent can be effectively used. Among these absorbents, those in which copper halide (T) and fluorium halide are supported on a porous inorganic oxide using an organic solvent are particularly suitable for Co
It is extremely effective because it has excellent selective absorption and little deterioration due to water. Also, absorbents made of copper halide (1), aluminum halide (@), polystyrene, and alumina are also extremely effective. .

For example, as shown in Figs.
The amount of O absorption changes drastically between 25℃ and 120℃,
It is highly dependent on the 00 partial pressure, and both of these factors (
It is clear that the joint manipulation of temperature and CO pressure serves as a much more effective CO absorber than the manipulation of any single factor.

The present invention applies CO2 to temperature and partial pressure at room temperature to around 120°C and at pressures around reduced pressure and normal pressure.
This achievement was achieved by discovering a CO absorbent whose equilibrium absorption amount is significantly influenced. That is, by combining temperature and pressure, the same C
High-purity Co can be efficiently recovered and produced during operations that are much narrower than those required to obtain the O pickup amount (under temperature and pressure). For example, in the case of absorbents that require a longer time for CO desorption during temperature changes than pressure changes, the amount of CO can be reduced during the temperature change and compensated for by the pressure change in order to obtain the desired amount of CO. These changes are appropriately selected depending on the temperature and pressure dependence of the CO equilibrium absorption amount of the absorbent used, and the conditions of use. As mentioned above, the present invention relies on the use of a co absorbent having a temperature and pressure dependence of CO equilibrium absorption as shown in FIGS. 1-3. That is, the porous absorbent used in the present invention is effective as long as the C0 equilibrium absorption amount changes by a significant difference depending on changes in temperature and pressure.

Next, the present invention will be further explained in detail with reference to Examples.

Example 1 (continuous type) Cu[11,4j (ml, CuAlα4=JNz Os in which porous aluminum was formed from a complex salt consisting of an organic compound)
/i 0 (Wt/wt+ l group φ spherical absorbent is made of stainless steel (5US-30
4) Each group has 200. I filled it up one by one.

As the raw material gas, a specific gas adjusted to have the following components was used, which was once depressurized from a cylinder.

The composition was as follows.

H22vol CH C068#co, 12#N, 18# Each process of absorption, desorption, and cooling was repeated and continuous operation was performed. First, 580 cc of water was introduced into the first column at normal pressure of 40°C from the bottom of the column.
The raw material gas was passed through the reactor at a rate of Z for 8 minutes to absorb CO, and the upper and lower valves of the column were blocked. After that, the valve is switched and the raw material gas is vented into the second tower to start absorption, and the first tower
40 at a speed of 300 cc/i) with a vacuum pump.
The pressure was reduced to 2.5 torr, and silicone oil heated to 95°C was introduced into the outside of the double tube to heat the absorption layer to 90°C. This operation took 15 minutes. After the desorption operation was completed, the supply of silicone oil at 95°C was stopped, and the supply of silicone oil at 20°C was started to cool the absorption layer. It took 15 minutes to cool down to 40°C. After cooling, raw material gas was introduced again and absorption operation started. One cycle was completed in column 1 by cooling.

The above operation was carried out sequentially from the first column to the fifth column with a phase shift of 8 minutes.

The material balance for 8 minutes was as follows.

Raw material gas Recovery gas vo1% Nca vo1% NccH
z 2+ 93 0.1 3Co
6813155 97.0 2619Co,
121 557 1.2 32 Comparative Example 1° The same absorbent reactor used in the example was used. The filling amount is also 200.9. Raw material gases of the same composition were also used. Silicone oil heated to 40°C was circulated around the outside of the double tube, and the absorbent layer was previously heated to 40°C. After that, the raw material gas is introduced from the bottom of the reactor at normal pressure, 40℃, 580℃.
C15) for 10 minutes to absorb CO.

Thereafter, the supply of raw material gas was stopped and the absorption layer was heated to 90°C. The amount and composition of the gas recovered in this operation were measured.

Raw material gas Recovery gas vo1% Ncc vo1% NccH,
21160,45 Co 68 3944 93.6 1147
Co, 12 696 13 28 Comparative Example 2° The same absorbent and reactor as used in the example were used. Both the filling amount and the 200.9X source gas had the same composition. The raw material gas is fed from the bottom of the reactor at normal pressure, 20℃, 5
It was aerated for 10 minutes at a rate of 80 cc15) to absorb the cobalt.

After that, the supply of raw material gas was stopped, and the reactor was operated with a vacuum pump for 3
The pressure was reduced to 40 torr at a speed of 00cc15). The exhaust gas was collected and the amount and composition of the gas was measured.

Raw material gas Recovery gas vo1% Nac vo1% NccHz2
116 0.3 5Co 68 3
944 95.4 1686co, 12 69
6 1.6 29

[Brief explanation of drawings]

Figure 1 shows the case of collecting CO due to temperature changes (TSA)
, Fig. 2 shows the case where CO is recovered by pressure change (VS
A) and FIG. 3 show the CO for the case of changing the combination of temperature and pressure according to the present invention, particularly for the case of changing both at the same time and recovering CO from K ('l''VsA).
It is a graph showing the relationship between partial pressure (atom) and absorbed CO amount. Shiku J Unano Soil (atm)

Claims (1)

[Claims] 1. After bringing a mixed gas containing carbon monoxide as a main component into contact with a porous carbon monoxide absorbent to selectively absorb carbon monoxide, carbon monoxide is removed from the absorbent. 1. A method for recovering carbon monoxide by desorption of carbon monoxide, characterized in that the desorption treatment is performed by a combination of reduced pressure and heating. 2. The method according to claim 1, wherein the desorption treatment is carried out by reducing the pressure and then heating under reduced pressure. 3. The method according to claim 1, wherein the desorption treatment is carried out by heating and then reducing the pressure. 4. The method according to claim 1, wherein the desorption treatment is performed simultaneously by depressurization and heating. 5. The method according to claim 1, wherein the desorption treatment is carried out by removing residual unabsorbed gas under reduced pressure and then heating under reduced pressure. 6. The absorbent uses copper (I) as a carbon monoxide absorbing component,
Claim 1 in which this is supported on an inorganic porous body.
- Any method of item 5. 7. The method according to any one of claims 1 to 5, wherein the absorbent comprises copper (I) and aluminum (III) supported on an inorganic porous body. 8. The method according to any one of claims 1 to 7, wherein the mixed gas containing carbon monoxide as a main component is exhaust gas from a blast furnace, converter, or coke oven of a steelworks.