JPH0699127B2 - Adsorbent for CO separation and recovery, method for producing the same, and method for separating and recovering CO using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure swing adsorption separation method (hereinafter referred to as PSA method).
And / or a solid adsorbent used for the purpose of separating and recovering CO from a mixed gas containing CO by a temperature fluctuation type adsorption separation method (hereinafter referred to as TSA method), and further, a method for producing the adsorbent, and CO using the adsorbent
The present invention relates to a method for separating and recovering.

Conventional technology As a typical gas containing CO as a main component, a converter gas obtained from a converter of a steel mill, a blast furnace gas obtained from a blast furnace, an electric furnace gas obtained from an electric furnace, and coke are gasified. There is the generated reactor gas, etc. Most of these gases are usually used as fuels, but some of these gases contain CO, for example, around 70 vol% or more, so they are included in these gases. If CO can be separated and recovered with high purity, it can be used as a synthetic raw material for formic acid, acetic acid, etc., for reduction of organic compounds, etc., and is very useful in the chemical industry.

Conventionally, as a method for separating and recovering CO from a gas containing CO as a main component, a cryogenic separation method, a copper ammonia method, a COSORB (COSO
RB) method, etc. are known, but these methods have the problem that the facility cost is high and the cost required for thermal energy such as electric power and steam is large, and they are suitable for separation and recovery of large-capacity CO. However, it was not always suitable for separation and recovery of medium or small volume CO. Furthermore, CO obtained by separation by these methods has a drawback that it cannot be applied to organic synthesis as it is because gas components such as O ₂ and CO ₂ that interfere with the organic synthesis reaction are mixed. .

By the way, the PSA method and the TSA method are known as methods for selectively separating a specific gas from a medium volume or small volume source gas.

The PSA method is one of the methods for selectively separating a specific gas from a mixed gas, and the adsorbate is adsorbed on the adsorbent at a high pressure, and then adsorbed on the adsorbent by lowering the pressure of the adsorption system. A method of desorbing an adsorbate and separating an adsorbate and a non-adsorbate. Industrially, a plurality of adsorbent-filled towers are provided, and in each adsorption tower, pressurization → adsorption →
By repeating a series of operations from washing to degassing, the entire apparatus can be continuously separated and collected.

The TSA method is also one of the methods for selectively separating a specific gas from a mixed gas similarly to the PSA method, in which an adsorbate is adsorbed on an adsorbent at a low temperature, and then the temperature of the adsorption system is increased to adsorb the adsorbent. This is a method of desorbing the adsorbed substance adsorbed on the agent and separating the adsorbed substance and the non-adsorbed substance.

Conventionally, as a method of separating and recovering CO from a mixed gas containing CO by the PSA method, a method of using mordenite-based zeolite as an adsorbent has been proposed. (JP-A-59-226
No. 25, Japanese Patent Laid-Open No. 59-49818) In addition, the mixed gas containing CO is converted to CO by the PSA method or the TSA method.
As a method for separating and recovering copper, a method is proposed in which copper compounds such as copper (I) halide, copper (I) oxide, copper (II) salt, and copper (II) oxide are supported on activated carbon as an adsorbent. Has been done. (JP-A-58-156517, JP-A-59-69)
JP 414, JP 59-105841, JP 59-136134
Similarly, from a mixed gas containing CO by the PSA method or the TSA method,
As a method for producing a CO absorbing / separating agent used for separating and recovering CO, a solution of copper (I) halide and aluminum (III) halide in an organic solvent is converted into a porous inorganic oxide such as alumina, silica or silica / alumina. Methods have been proposed for contacting and then removing the free organic solvent. (See JP-A-60-90036 and JP-A-60-90037) In addition, the applicant of the present invention, as a method of separating and recovering CO from a mixed gas containing CO by PSA method or TSA method, silica or / A patent application has already been filed for a method of using an adsorbent for CO separation and recovery in which a carrier made of alumina and a copper (I) compound, a copper (II) compound or a reduced product thereof is carried. (Japanese Patent Application No. 60-82978) Problems to be Solved by the Invention The performance required for the quick-adhesive agent packed in the adsorption tower in carrying out the PSA method or the TSA method is selective adsorption of a target component to coexisting components. That there is a large difference in the adsorption amount of the target component at the time of pressurization or low temperature and at the time of reduced pressure or high temperature, that the adsorbed target component is easily desorbed,
Other than the target component, it is difficult to be adsorbed and desorbed, and the life of the adsorbent is long. These performances are important factors in the PSA method or the TSA method because they have a great influence on the purity and yield of the product gas.

However, in the method of using the mordenite-based zeolite utilizing the physical adsorption-desorption phenomenon of the adsorbent as the adsorbent, since the CO adsorption amount is relatively small, the switching frequency of the pressure swing must be increased. However, there is a disadvantage in terms of both operation and valve life.
₂ must be removed in advance, the product purity is low because co-adsorption of N ₂ is unavoidable, and in-column cleaning is performed using product CO gas to remove adsorbed N _2. There are problems such as a large amount of cleaning at this time and a low product CO recovery rate.

On the other hand, according to the method of using an adsorbent in which the above-described copper compound is supported on activated carbon, which utilizes the chemical adsorption / desorption phenomenon of the adsorbent, CO is produced from a mixed gas containing CO, N ₂ , CO _2, etc. When separating, there is a problem that it is difficult to separate and collect high-purity CO because CO _{2 and the} like tend to co-adsorb with CO, and the amount of CO adsorbed by the adsorbent is not necessarily large. Yes, it has not yet been adopted on an industrial scale.

Further, the method using an adsorbent in which copper (I) halide and aluminum (III) halide are supported on a porous inorganic oxide mainly utilizes the CO selective absorption of CuAlX ₄ (X is halogen). However, since the adsorbing power for CO is too strong, the adsorbed CO is difficult to desorb during degassing.
It is not suitable for the method, it is necessary to carry out the operation during the production of the adsorbent in a dry inert gas atmosphere, and it is difficult to recover the activity again in the adsorbent whose activity once decreased. Therefore, it is still necessary to improve industrially.

On the other hand, Japanese Patent Application No. 60-829 previously filed by the applicant
From the industrial point of view, the invention of No. 78 is superior to the conventional method described above.
It is excellent in CO adsorption / desorption performance and activity recovery,
The present inventors have arrived at the present invention as a result of earnest researches for further improving the invention of this earlier application.

Means for Solving the Problems The adsorbent for CO separation and recovery of the present invention has a most frequent pore size of 60 to 12
On a carrier consisting of 0Å silica or / and alumina,
A copper (II) compound is supported.

Further, the method for producing an adsorbent for CO separation and recovery of the present invention is a carrier or a separation liquid in which a copper (II) compound is dissolved or separated in a solvent, on a carrier made of silica or / and alumina having a most frequent pore size of 60 to 120Å. The method is characterized in that the solvent is removed after the contact with.

Further, the method for separating and recovering CO of the present invention is a CO 2 adsorption method by pressure fluctuation type adsorption separation method and / or temperature fluctuation type adsorption separation method.
When separating and recovering CO from a mixed gas containing CO, an adsorbent for CO separation and recovery is used, in which a copper (II) compound is supported on a carrier made of silica or / and alumina with a most frequent pore size of 60 to 120Å. It is characterized by being used.

Hereinafter, the present invention will be described in detail.

Adsorbent The adsorbent for CO separation of the present invention is one in which a copper (II) compound is supported on a carrier made of silica and / or alumina having a special pore size distribution.

That is, in the present invention, a carrier made of silica or / and alumina having a most frequent pore size of 60 to 120Å is used as the carrier. For loading with a most frequent pore size of less than 60Å
The physical adsorption amount of other component gas such as CO ₂ increases and the separation efficiency tends to decrease. Further, when the most frequent pore diameter is more than 120Å, the copper (II) compound is not evenly supported and the pore volume is also small, so that the supporting capacity tends to decrease and the CO adsorption / desorption capacity tends to decrease. . As a result, the silica or / and alumina carrier outside the above range is inferior in performance in terms of CO adsorption amount and CO release amount to those in the above range.

Wherein the pore size distribution, N ₂ in liquid N ₂ temperature of -196 ° C.
Is adsorbed and the pore volume of each pore diameter is calculated from the adsorption isotherm.

For silica, for example, an aqueous solution of sodium silicate is neutralized with an acid such as hydrochloric acid to form a precipitate, which is then washed with water and dried,
Further, if necessary, it is activated by heating under reduced pressure, and is obtained by forming it into a granular form. Alumina is obtained, for example, by precipitating aluminum hydroxide from an aqueous solution of a soluble aluminum salt, filtering it, and igniting it. When using silica and alumina together, in addition to a simple mechanical mixture of silica and alumina, a method of kneading silica gel and alumina gel in a wet state, a method of immersing an aluminum salt in silica gel, an aqueous solution of silica and alumina. And a method of depositing an alumina gel on the silica gel, and the like.

The particle size of silica, alumina and silica-alumina having the above specific pore size distribution is, for example, about 1 to 7 mm, and is selected in consideration of the pressure loss when packed in a tower. Dry if necessary before use.

As the copper (II) compound supported on the specific carrier,
Copper (II) halides such as copper (II) chloride, copper (II) fluoride, and copper (II) bromide; copper (II) oxide; copper (II) cyanide; copper (II) formate; copper acetate ( II), copper (II) oxalate, copper (II) sulfate, copper (II) nitrate, copper (II) phosphate, copper (II) carbonate
Copper (II) oxyacid salts or organic acid salts; such as copper hydroxide (I
I); Copper sulfide (II); Trifluorocuprate (II), tetrafluorocuprate (II), trichlorocuprate (II), tetrachlorocuprate (II), tetracyanocuprate (II) salt,
Examples thereof include tetrahydrooxocopper (II) salts, hexahydrooxocopper (II) salts, complex salts such as ammine complex salts, and the like.

The amount of the copper (II) compound supported on the carrier is usually 0.5 to 8
It is selected from the range of m-mol / g, preferably 1-5 m-mol / g. If the loading amount of the copper (II) compound is too small, the CO adsorption capacity will be insufficient, while if the loading amount of the copper (II) compound is too large, the separation efficiency will decrease.

Production Method of Adsorbent The above-mentioned adsorbent is produced by contacting the above-mentioned specific carrier with a solution or dispersion of a copper (II) compound dissolved or dispersed in a solvent, and then removing the solvent.

The contact with the solvent or the separation liquid is performed by impregnation, spraying or the like.

Examples of the catalyst include water, hydrochloric acid, acetic acid, formic acid, ammoniacal formic acid aqueous solution, ammonia water, halogen-containing solvents (chloroform, carbon tetrachloride, ethylene dichloride, trichloroethane, tetrachloroethane, tetrachloroethylene, methylene chloride, fluorine-based solvents, etc. ), Hydrocarbons (hexane, benzene, toluene, xylene, ethylbenzene, cyclohexane, decalin, etc.), alcohols (methanol, ethanol, propanol, butanol, amyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, etc.), ketones (acetone) , Methyl ethyl ketone, methyl isobutyl ketone, acetophenone, isophorone, cyclohexanone, etc., esters (methyl acetate, ethyl acetate, amyl acetate, methyl propionate, propionate Phosphate amyl), ethers (isopropyl ether, dioxane, etc.), cellosolves (Cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve Sol acetate), such as carbitol is used.

The contact between the carrier and the solution or dispersion of the copper (II) compound is
Usually, it is carried out by impregnation or spraying. In this case, in order to completely replace the gas existing in the carrier pores with the solution or dispersion liquid, contact the solution or separation liquid with the degassed carrier under vacuum, or contact the solution or dispersion liquid with the carrier, and then reduce the pressure. It may be degassed under the conditions.

After contacting the carrier with the solution or dispersion, the solvent is distilled off by heating and drying under an atmosphere of an inert gas such as nitrogen, argon or helium, preferably without lowering the temperature of the system. The removal of the solvent can be performed not only by heat drying but also by vacuum drying. By such a method, the copper (II) compound can be efficiently loaded on the carrier.

In this case, the CO adsorption capacity is often insufficient only by the above-mentioned drying. Therefore, it is preferable to further heat-treat the adsorbent after drying in an atmosphere of an inert gas such as N ₂ , argon or helium or a reducing gas such as CO or H ₂ . The heat treatment temperature is suitably 200 to 600 ° C. in the inert gas and 150 to 250 ° C. in the reducing gas,
The desired activation cannot be sufficiently achieved outside this temperature range.

Separation and recovery of CO The adsorbent obtained as described above is packed in an adsorption tower, and is mixed from a mixed gas containing CO by the PSA method or the TSA method.
Separation and capture of CO is carried out.

When CO is separated and collected by the PSA method, the adsorption pressure in the adsorption step is preferably atmospheric pressure or higher, for example, 0 to 6 kg / cm ² G, and the vacuum degree in the vacuum degassing step is atmospheric pressure or lower, for example 200 It is desirable to set it to ~ 10 Torr.

When CO is separated and recovered by the TSA method, the adsorption temperature in the adsorption step is preferably about 0 to 40 ° C, and the degassing temperature in the degassing step is preferably about 60 to 180 ° C.

It is also possible to use the PSA method and the TSA method in combination, to carry out adsorption under atmospheric pressure or above under low temperature conditions and degassing under atmospheric pressure or under high temperature conditions.

Since the TSA method is less advantageous than the PSA method in terms of energy consumption, either the PSA method should be industrially adopted, or the PSA-TS
It is desirable to use the A combination method.

As the applicable mixed gas containing CO, for example, a converter gas generated from a converter of an iron mill is used. The converter gas usually contains CO as a main component, as well as O ₂ , methane and other hydrocarbons, water and a small amount of H ₂ S, NH _{3 and the} like. In addition to the converter gas, blast furnace gas, electric furnace gas, generating furnace gas and the like can be used as the raw material gas.

In this case, prior to the CO separation and recovery step, components that may poison the adsorbent or shorten its life, i.e., adsorption removal step of impurities such as sulfur compounds and NH ₃ , water removal step and O ₂ removal step Is desirable.
However, the CO ₂ removal process and the N ₂ removal process need not be provided.

Action The CO adsorption / desorption phenomenon by the solid adsorbent obtained by the method of the present invention is mainly caused by the copper (II) compound supported on the carrier and the CO
It is based on a reversible chemical reaction (complex formation reaction and dissociation reaction) with (no chemical reaction with N ₂ and CO ₂ ) and as a side effect CO ₂ etc. on the pore surface of the carrier. Is considered to be based on the physical adsorption and desorption of the.

And silica used as a carrier in the present invention or /
And alumina, because it has a distribution of sizes of a particular pores, even raw material gas contains the CO ₂ and N _2, the physical adsorption of CO ₂ and N ₂ to the support pores in the adsorption step It is considered that these impurities, which are small in amount and physically adsorbed on the carrier pores, are easily desorbed by the cleaning gas.

EXAMPLES Next, the present invention will be further described with reference to examples.

FIG. 1 shows the pore size distribution curve of the carrier used in the examples, and FIG. 2 shows the pore size distribution curve of the carrier used in the comparative examples.

In the drawing, DV / DR on the vertical axis is a differential value of V / R (pore volume / pore radius, that is, an index showing how much pore volume is up to the pore radius), and is a unit value. It is an index showing the rate of increase or decrease in the pore volume in the pore radius.

Example 1 In a 200 cc Erlenmeyer flask, 6.7 g of copper (II) chloride was dissolved in 16 cc of ethanol, and the silica / alumina carrier D30 cc having the pore size distribution shown in FIG. 1 was added to this solution for 1 hour. After stirring, the solvent was distilled off in a N ₂ stream while heating at 100 ° C. with a mantle heater. After that, it was further heated to 400 ° C. in an N ₂ gas stream using an electric furnace, heat-treated at that temperature for 1 hour, and then cooled to room temperature to obtain a CO 2 separated and collected adsorbent.

The adsorbent obtained above is packed in an adsorption tower (15 mmφ × 300 mmH), and a mixed gas of 1 atm with a composition of CO: 71.4vol% N ₂ : 12.7vol% CO ₂ : 15.9vol% is supplied to this adsorption tower. Then, CO was adsorbed at 25 ° C to determine the initial adsorption amount.

After the adsorption operation, degassing was performed for 5 minutes at a pressure of 25 Torr using a vacuum pump to release the adsorbed gas. Then, the particles were adsorbed again under the same conditions as above, and the second adsorption amount was obtained. Further, even if the release-adsorption operation was repeated, the adsorption amount of each component gas did not change.

The results were as follows.

Initial adsorption _{CO: 17.4cc / cc CO 2:} 1.1cc / cc N 2: trace 2 subsequent adsorption _{CO: 9.3cc / cc CO 2:} 0.6cc / cc N 2: trace Comparative Examples 1 silica-alumina support An adsorbent was prepared in the same manner as in Example 1 except that silica / alumina carrier F (Comparative Example 1) and silica / alumina carrier G (Comparative Example 2) having the pore size distribution shown in FIG. 2 were used in place of D. Was performed and CO was separated and recovered.

The results are shown in Table 1.

Effect of the Invention In the present invention, since the silica or / and alumina carrier having the most frequent pore size of 60 to 120Å is used to support the copper II compound, the CO adsorption / desorption capacity is further increased, and the other components are further added. It is possible to reduce the adsorption / desorption amount of gas.

Therefore, the present invention has great significance in the chemical industry as a method for producing an adsorbent for separating and recovering high-purity CO from a converter gas and other gases containing CO on an industrial scale.

[Brief description of drawings]

FIG. 1 shows the pore size distribution curve of the carrier used in the examples, and FIG. 2 shows the pore size distribution curve of the carrier used in the comparative examples.

Claims (4)

[Claims] 1. An adsorbent for CO separation and recovery comprising a carrier of silica or / and alumina having a most frequent pore size of 60 to 120Å and a copper (II) compound supported on the carrier. 2. A solution or dispersion prepared by dissolving or dispersing a copper (II) compound in a solvent is brought into contact with a carrier made of silica or / and alumina having a most frequent pore size of 60 to 120Å, and then the solvent is removed. A method for producing an adsorbent for CO separation and recovery, comprising: 3. The production method according to claim 2, further comprising heat treatment in an atmosphere of an inert gas or a reducing gas after removing the solvent. 4. When the CO is separated and recovered from a mixed gas containing CO by the pressure fluctuation type adsorption separation method and / or the temperature fluctuation type adsorption separation method, the most frequent pore diameter is 60 to 60 as an adsorbent.
A method for separating and recovering CO, which comprises using an adsorbent for separating and recovering CO, which is obtained by supporting a copper (II) compound on a carrier made of 120 Å silica and / or alumina.