JPH0672005B2 - Method for adsorption and separation of carbon monoxide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for adsorbing and separating carbon monoxide contained in a gas containing carbon monoxide.

[Prior art]

Conventionally, as a method for separating and concentrating carbon monoxide (CO) from a mixed gas, a cryogenic separation method, a chemical absorption method, an adsorption method, etc. have been proposed and implemented.

The cryogenic separation method is a method that has been used for a long time in the field of gas purification, and its principle is the same as distillation using the difference in the boiling points of the components, but the separation between the components with a small difference in the boiling points, for example, It is difficult to accurately separate CO and nitrogen economically. It is clear that this technology is unsuitable for the production of high-purity CO, because the main component of the by-product gas of a steel mill, such as a converter gas, is nitrogen, other than CO. Further, this deep-cooling separation method has a problem that it requires a large amount of energy because it uses a low temperature, and the separation accuracy is low because it is a physical separation method. The chemical absorption method is a method of chemically selectively absorbing CO gas into a solution and removing or recovering it. For example, the copper-ammonia cleaning method was developed to remove CO from a raw material gas for ammonia, and uses an aqueous ammonia solution containing copper (I) ions and carbonic acid or formic acid as an absorbing liquid. Further, a copper aluminum tetrachloride toluene solution method, a hydrochloric acid-acidified copper (I) chloride aqueous solution method and the like are also known as chemical absorption methods. Other technologies related to the chemical absorption method are disclosed in JP-A-56-46890 and JP-A-57-1.
9013, 57-42521, 57-105230, 57-145018
No. 58, No. 58-32005, No. 58-69710, No. 58-208116, No. 5
8-219914, 59-36522, 56-161821, 59-3820
No. 8, No. 54-71788, No. 56-15936, No. 56-15937, No. 5
8-24321, 58-99110, 58-135118, etc.
An absorbing solution designed to stabilize Cu (I) in a monovalent state has been proposed. However, since this chemical absorption method uses an absorbing solution, it tends to cause a problem in stability of the solution, and conversely, in order to prevent it, a very complicated operation is required. For example, a part of the components may scatter out of the system, react irreversibly with water to form a precipitate, or generate a corrosive gas. In any case, the chemical absorption method depends on the temperature change in many cases because the basic operation is the solution absorption and desorption, so it is difficult to fundamentally solve the stability of the solution. .

The adsorption method uses a porous material such as zeolite or activated carbon, and mainly includes a method utilizing physical adsorption and a chemical adsorption method utilizing chemical bonding. Regarding the physical adsorption method, for example, a method using zeolite (Japanese Patent Laid-Open No. 59-22625).
No. 59-49818), a method of using activated carbon having a molecular sieving effect (JP-A-59-107916), and the like. Regarding the chemisorption method, zeolite is loaded with Cu ions. Then, a method using a reduced product (US Pat. Nos. 4019879 and 4034065, etc.) and Cu (I)
A method in which a complex is supported on an organic polymer or activated carbon to have water resistance (Japanese Patent Laid-Open Nos. 58-49436 and 58-104009).
No. 58-124516, No. 58-156517, No. 59-105841) and the like. However, the adsorption separator used in the conventional chemical adsorption method has drawbacks such as poor water resistance and poor carbon monoxide adsorption selectivity.

The present inventors have previously made a complex of copper (I) halide and aluminum (III) halide as a porous carrier as a chemisorption separating agent having improved water resistance and selective adsorption of carbon monoxide. A supported product was proposed (JP-A-60-90036).
No. 60-90037, No. 60-90041). However, these adsorption / separation agents need to use aluminum halide as an essential component in addition to copper halide, and an organic solvent must be used in the production thereof. Including the problem that

〔Purpose〕

An object of the present invention is to provide a method for adsorptive separation of carbon monoxide using an adsorptive separation agent that overcomes the above-mentioned drawbacks found in conventional carbon monoxide adsorption and separation agents.

〔Constitution〕

According to the present invention, a carbon monoxide-containing gas is contacted with a non-complexed cuprous halide-alumina complex to adsorb the carbon monoxide to the complex, and then the complex is formed. In the method for desorbing carbon monoxide adsorbed on the composite by maintaining the pressure under an elevated temperature condition or a pressure lower than that during the adsorption, the alumina comprises: a) an alumina hydrogel forming substance to an alumina hydrogel. B) Altering the pH of the alumina hydrogel alternately between the alumina hydrogel dissolution region and the boehmite gel precipitation region, and changing the pH to at least one of the alumina hydrogel dissolution region and the boehmite gel precipitation region, A step of adding an alumina hydrogel-forming substance to obtain a method-grown alumina hydrogel, and / or the alumina hydrogel is a boehmite gel. Alumina hydrogel-forming substance is added to a continuous flow or an intermittent flow while keeping it in the region to obtain a crystal-grown alumina hydrogel, c) The crystal-grown alumina hydrogel is washed and dried or calcined by a combined operation. To the step of obtaining alumina, the method of adsorption and separation of carbon monoxide is characterized in that it is alumina having a pore volume of 0.3 to 1.2 cc / g and an average pore diameter of 50 to 150Å.

The carbon monoxide adsorption separating agent used in the present invention (hereinafter, also simply referred to as a separating agent) is a non-complexed cuprous halide (hereinafter simply referred to as a cuprous halide) which does not form a complex with aluminum halide. According to the research conducted by the inventors of the present invention, as an alumina for complexing cuprous halide, a) a step of obtaining an alumina hydrogel from an alumina hydrogel-forming substance, b) Altering the pH of the alumina hydrogel alternately between the alumina hydrogel dissolution region and the boehmite gel precipitation region, and at the time of changing the pH to at least one of the alumina hydrogel dissolution region and the boehmite gel precipitation region, an alumina hydrogel forming substance. Is added to obtain a crystal-grown alumina hydrogel, and / or the alumina hydrogel is vaporized. A step of adding an alumina hydrogel-forming substance in a continuous flow or an intermittent flow while maintaining it in the gel precipitation region to obtain a crystal-grown alumina gel, c) combining the crystal-grown alumina hydrogel with washing and drying or calcination. It has been found that the use of alumina formed by a combination of xerogel or a process of obtaining alumina is preferred. This alumina has substantially no micropores having a diameter of several angstroms, and therefore has no molecular sieving ability and has either a Bressted acid point that is stable at low temperature or a Lewis acid point that is easily generated at high temperature. Since it has acid sites, large pore size, and high surface area, it has the ability to support cuprous halide in a highly concentrated and uniform manner.

Furthermore, this alumina has the property of retaining the cuprous halide without significantly changing the coordination state around the cuprous halide. As a result, the supported and dispersed cuprous halide is kept stable. Then, this stable alumina composite containing cuprous halide exhibits its high selectivity as it is without lowering the chemical absorption capacity of the cuprous halide. Those with zeolite-like pores such as zeolite, those with micropores such as activated carbon, and others with molecular sieving ability are
Since the solution of cuprous halide does not easily enter the inner surface of the pores, it is not possible to sufficiently exhibit high selective adsorption of carbon monoxide, and such fine pores tend to physically adsorb unnecessary components. Therefore, it is not suitable for separation by adsorption / desorption operation at room temperature.

According to the combination of the specific steps as described above, the pore volume is 0.3
~ 1.2 cc / g, especially 0.5-0.9 cc / g and average pore diameter (diameter) 50-150 angstroms, especially alumina having physical properties of 100-130 angstroms can be easily prepared. It is extremely suitable as a carrier for complexing cuprous halide. This alumina is usually used as a molded body. The shape of the molded body can be any shape such as a columnar shape or a spherical shape. Therefore, it can be appropriately selected according to the usage conditions. Generally, a cylindrical molded body having a diameter of 1/16 inch or 1/32 inch is used.

In the case of producing alumina by the above-mentioned steps, in order to obtain a raw material for a separating agent having excellent carbon monoxide adsorption performance,
It is important to define the pore volume and pore diameter of the obtained alumina within an appropriate range. That is, regarding the carbon monoxide separating agent, when the pore volume is too small, the contact efficiency between the copper (I) inside the pores and the raw material gas is lowered, and the adsorption ability is poor. Further, as the pore volume increases, the amount of unadsorbed raw material gas (low-concentration CO gas) remaining in the pores increases, and if it is too large, it causes the purity of the recovered product CO gas to decrease. On the other hand, regarding the pore size, as the pore size becomes smaller, the molecular sieving ability is expressed, and CO ₂ , H ₂
O, O _{2 and the} like are easily adsorbed, and the pores are easily collapsed by supporting the cuprous halide. for that reason,
The pore size after preparation is preferably 20 angstroms or more. Also, of course, the surface area is governed by the pore volume and pore diameter. It is preferable that the cuprous halide has a high surface area in order to be uniformly dispersed and supported. Such physical properties of the carbon monoxide adsorptive separating agent are almost completely controlled by the physical properties of the specific alumina. The specific method for producing alumina comprising the above-mentioned steps can regulate the physical properties of the separating agent within a range suitable for its carbon monoxide adsorption. That is, in the alumina production method comprising the above steps, the pore volume is 0.3 to 1.2 cc / g, especially 0.5 to
Alumina whose 0.9 cc / g and average pore diameter are adjusted to 50 to 150Å, particularly 100 to 130Å, can be easily obtained.

Further, when alumina is used as a carrier for complexing cuprous halide, its chemical properties are also important characteristics. This chemical property generally differs depending on the difference in the preparation method. For example, even when the same raw material is used, different production methods such as precipitation method, aging method, and sintering method are used. When it is produced by using it, the acidity, acid strength distribution, etc. of the obtained alumina are different. This property has a great influence on the preparation of the separating agent, and when the cuprous halide is supported, there is a difference in its supporting ability and dispersibility, so it is necessary to control it appropriately. Conventionally, a method for producing a porous alumina molded body is to produce an alumina hydrogel which is a seed from an alumina hydrogel-forming substance which is a precursor for producing an alumina hydrogel, grows the crystal particles thereof, and converts them into a sol or a gel-like substance. After that, the desired porous alumina molded body is generally manufactured by steps such as washing, dehydration molding, drying, and firing. In this manufacturing operation, an important step for controlling the chemical properties is to obtain a sol or gel substance. Conventionally, an alumina hydrogel that is a seed is produced from an alumina hydrogel-forming substance that is a precursor that produces a porous alumina molded body, and this alumina hydrogel is grown,
The method for producing the alumina hydrogel which becomes the seed in the gelation step for obtaining these gelled substances includes a precipitation method, a uniform precipitation method and a hydrolysis method. In the precipitation method, a compound containing aluminum is neutralized with an acid or an alkali to produce an alumina hydrogel which becomes seeds. Further, the homogeneous precipitation method is broadly included in the precipitation method, and overcomes the drawback of the precipitation method, that is, the point that the alumina hydrogel that becomes the seed is non-uniform because the neutralization operation is difficult to control. It is characterized in that an organic compound such as urea or hexamethylenetetramine is used as a solvating agent and the neutralization operation becomes slow. The hydrolysis method is a method of producing an alumina hydrogel by hydrolyzing an aluminum compound without using a neutralizing agent. Any of these methods can be used in the step a) of obtaining the alumina hydrogel from the alumina hydrogel-forming substance in the above-mentioned alumina production step, but an unnecessarily complicated method is used in combination with the following step b). Since it is not preferable to use it, it is sufficient to use the precipitation method by a simple neutralization operation. However, when the method of adding the alumina hydrogel-forming substance in a continuous flow or an intermittent flow while maintaining the alumina hydrogel in the alumina hydrogel precipitation region in step b) is used, in step a), the seeded alumina hydrogel is precipitated. When the method is used, it is necessary to adopt a method for uniform generation. Because in this way,
Since the effect of making the alumina hydrogel of non-uniform particles uniform is insufficient, the desired alumina cannot be obtained. Conventionally, the alumina hydrogel obtained from the step a) is supplied as it is or after being aged as a sol or a gel-like substance to the steps such as dehydration and drying. However, this method gives an alumina excellent in adsorption separation performance. Absent. In order to adjust alumina to the above properties,
It is necessary to adjust the basic particles, but regarding the method of controlling the pore structure such as the pore size, the pore volume and the pore size distribution of the alumina, the applicant has already disclosed in JP-A-56-12050.
No. 8 publication. That is, in a method for producing a porous inorganic oxide from a hydrogel-forming substance as a raw material, (1) a step of obtaining the seed hydrogel from the hydrogel-forming substance, and (2) a step of producing the hydrogel.
The pH is alternately changed between the hydrogel dissolution region and the hydrogel precipitation region, and when the pH is changed to at least one of the hydrogel dissolution region and the hydrogel precipitation region, a hydrogel-forming substance is added to finally obtain a target size. A method for obtaining a hydrogel in which crystals have grown in a form suitable for By this method, it is possible to obtain a gel in which the basic particles are relatively aligned in the target size. Further, the present applicant discloses an alumina hydrosol having fibrous basic particles in Japanese Patent Application Laid-Open No. 55-27830, and further, an alumina composed of boehmite particles which are extremely uniform fibrous basic particles. The hydrosol is disclosed in JP-A-58-213632. Further, the present inventors, while maintaining the alumina hydrogel in the boehmite gel precipitation region, the alumina hydrogel-forming substance is added in a continuous flow or an intermittent flow, and is related to a method for obtaining a crystal-grown alumina hydrogel. The technology is disclosed in each of JP-A-190823, JP-A-59-97526 and JP-A-60-54917. The inventors of the present invention have studied the preparation of porous alumina having properties suitable for the purpose of the present invention using such a technique, and found that the pH of the alumina hydrogel alternates between the alumina hydrogel dissolution region and the boehmite gel precipitation region. And a pH change to at least one of the alumina hydrogel dissolution region and the boehmite gel precipitation region, a step of adding an alumina hydrogel forming substance to obtain a crystal-grown alumina hydrogel and / or the alumina hydrogel is subjected to boehmite gel precipitation. By adding the alumina hydrogel-forming substance in a continuous flow or an intermittent flow while maintaining it in the region to obtain a crystal-grown alumina hydrogel in a size that gives the desired specific properties, by including it in the separating agent manufacturing step, I found that I could achieve my purpose. That is, the pore volume of alumina obtained by such a step is 0.3 to 1.2 cc / g, especially 0.5
To 0.9 cc / g, and the average pore size adjusted to 50 to 150 angstroms, particularly 100 to 130 angstroms, the resulting alumina surface area becomes very large and It has been found that a carbon monoxide adsorbing / separating agent having a very high capacity can be obtained by supporting. It is considered that this is because not only the pore structure of the alumina but also the chemical properties of the surface of the alumina play an important role in combination with the cuprous halide. In order to support the cuprous halide on the alumina, it is sufficient to bring the solution containing the cuprous halide into contact with the alumina and then remove the solvent. In this case, as the cuprous halide solution, one that keeps the copper ions of the cuprous halide stable at a monovalence is used. For example, an aqueous solution containing cuprous halide and hydrogen halide or water Examples thereof include a mixed aqueous solution of a cuprous halide and a salt that dissolves to dissociate protons and halogen ions, a solution of a cuprous halide in a lower alcohol having 1 to 4 carbon atoms, or a solvent of tetrahydrofuran.

Next, the manufacturing process of the alumina will be described in detail.

[Alumina hydrogel-forming substance]

The alumina hydrogel-forming substance used in the production of this alumina is a compound containing aluminum as an element. For example, metallic aluminum (Al), aluminum chloride (AlCl ₃ , AlCl ₃ .6H ₂ O), aluminum nitrate [Al (N
O _{3) 3} · 9H ₂ O], aluminum sulfate _{[Al 2 (SO 4) 3,} Al 2 (SO 4) 3
・ 18H ₂ O], polyaluminum chloride {[Al ₂ (OH) _n Cl _6-n ] _m
(1 <n <5, m <10)}, ammonium alum [(NH
₄ ) ₂ SO ₄・ Al (SO ₄ ) ₃・ 24H ₂ O], sodium aluminate (NaAl
O _2), aluminate potassium (Kalo _2), aluminum isopropoxide {Al [OCH (CH _{3) 2] 3},} ethoxide [Al (OC ₂ H _{5) 3],} aluminum · t-butoxide {Al
[OC (CH ₃ ) ₃ ] ₃ }, aluminum hydroxide [Al (OH) ₃ ] and the like. Preferably, aluminum salts such as aluminum chloride (AlCl ₃ , AlCl ₃ .6H ₂ O), aluminum nitrate (Al (N
O _{3) 3} · 9H ₂ O], aluminum sulfate _{[Al 2 (SO 4) 3,} Al 2 (SO 4) 3
.18H ₂ O], aluminates such as sodium aluminate (N
aAlO ₂ ), aluminum hydroxide [Al (OH) ₃ ] and the like.

[Production of Seed Alumina Hydrogel] (Step a)] The seed alumina hydrogel is formed using the above-mentioned alumina hydrogel-forming substance. The particles contained in the seed alumina hydrogel (alumina hydrogel particles) are used as seeds for adding the alumina hydrogel-forming substance to produce crystal-grown alumina hydrogel in the subsequent step [step b)] of obtaining crystal-grown alumina hydrogel. Therefore, in the alumina hydrogel,
Present in the form of hydroxide. This seed alumina hydrogel is generally manufactured according to a conventionally known method. That is, a common method such as a precipitation method, a uniform precipitation method, an ion exchange method, a hydrolysis method and a metal dissolution method can be adopted. In this case, the precipitation method is a method of neutralizing the alumina hydrogel-forming substance with an acidic or alkaline solution. For example, ammonia, sodium hydroxide or the like as a neutralizing agent is added as a solution to a solution of aluminum nitrate or aluminum sulfate, or hydrochloric acid, sulfuric acid or nitric acid is added as a neutralizing agent to a solution of an alkali metal salt or an ammonium salt. Neutralize and convert to ammonium hydroxide. Specifically, it includes a method by a neutralization reaction using a combination of a solution of aluminum nitrate and sodium aluminate and a solution of aluminum sulfate and sodium aluminate. The homogeneous precipitation method is the same as the above-mentioned precipitation method in principle, but is different in that the neutralizing agent concentration during neutralization is kept uniform and the precipitation is carried out uniformly. For example, when performing uniform precipitation from a solution containing an alumina hydrogel-forming substance in the form of an acid salt, an ammonia-releasing substance such as urea or hexamethylenetetramine is used as a neutralizing agent. Specifically, the required amount of urea is dissolved in a solution containing aluminum nitrate or aluminum sulfate, the mixed solution is gradually heated with stirring, the neutralizing agent is gradually decomposed to release ammonia, and this release A method of gradually neutralizing an aluminum salt with ammonia to convert it into an alumina hydrogel is included. The ion exchange method is a method in which cations or anions that coexist in a solution of an alumina hydrogel-forming substance are ion-exchanged by using an ion exchange resin to generate a colloidal gel. What is called commercially available colloidal alumina is usually manufactured by these methods. The hydrolysis method is a method in which a hydrolyzable alumina hydrogel-forming substance is added to water to cause a hydrolysis reaction to generate an alumina hydrogel. Specifically, the reaction of an alcohol solution of aluminum isopropoxide is included. As a metal dissolution method, there is a method in which basic aluminum hydroxide is generated by adding aluminum metal powder to boiling aluminum nitrate or an aluminum nitrate solution.

As described above, the alumina hydrogel to be the seed can be obtained by various methods familiar to those skilled in the art.
That is, step a) is well known to those skilled in the art, and is not limited by the above-mentioned matters. The kind of hydrogel-forming substance used as a starting material, etc. should be considered in consideration of factors such as economic efficiency. It can be selected appropriately. In some cases, a commercially available alumina hydrogel can be used as it is, or can be prepared by combining the alumina hydrogel-forming substance used in obtaining the crystal-grown alumina hydrogel in step b) with a pH fluctuation or regulator. is there. In this case, there is an advantage that step a) and step b) can be performed in a continuous operation without a complicated operation such as a separation operation in the middle. That is, step a) and step b) can be performed using the same reagent under the same conditions. The concentration of the alumina hydrogel to be the seeds is not particularly limited, but it may be within a range such that the whole is stirrable and does not hinder the execution of step b), and is usually 10% by weight or less, particularly 0.1 to 5% by weight. %.

[Step of Obtaining Crystal-Grown Alumina Hydrogel] [Step b)] In this step, the seed alumina alumina hydrogel obtained in the step a) is subjected to pH fluctuation and / or control,
The step of adding an alumina hydrogel-forming substance and growing crystals of the alumina hydrogel is included. In this step, the alumina hydrogel basic particles can be grown very uniformly and controlled to a target size. In this step, the pH of the seed alumina hydrogel obtained in the step a) is alternately changed between the alumina hydrogel dissolution region and the boehmite gel precipitation region, and at least one of the alumina hydrogel dissolution region and the boehmite precipitation region. When the pH changes to the region of, the alumina hydrogel-forming substance is added to obtain a crystal-grown alumina hydrogel, and / or the alumina hydrogel-forming substance is kept in the boehmite gel precipitation region to form a continuous flow or an intermittent flow. Added
Obtaining a crystal-grown alumina hydrogel is performed. In the case of operation under pH fluctuation, as one of preferred methods, only when changing to the boehmite gel precipitation region, the above-mentioned alumina hydrogel-forming substance or pH adjusting agent is added alone or in the form of a mixture, and a boehmite gel is prepared. Get a precipitate. In this case, the alumina hydrogel means not only boehmite but also general alumina hydrogel such as bayerite and amorphous alumina hydrogel. In addition, boehmite gel is composed of fine boehmite crystallites having a fibrous shape among alumina hydrogels, and when the crystallites aggregate, they form remarkably sparse aggregates as compared with other alumina hydrogels. Therefore, the alumina obtained by drying and calcining this has a remarkably high surface area and a metal species supporting ability. In the case of operation while maintaining the pH, one of the preferred methods is to obtain a boehmite gel precipitate by using one in which at least one of the alumina hydrogel-forming substance and the pH adjusting agent substantially contains a sulfate group. is there. As used herein, the alumina hydrogel dissolution region refers to a pH of 5 or less or 11 or more, and the boehmite gel precipitation region refers to a pH of 6 to 11. That is, the alumina hydrogel dissolution region is a pH region where the alumina hydrogel fine particles can be solubilized, and the boehmite gel precipitation region is a pH region under the condition where the growth of boehmite microcrystallites can be caused. Therefore, the crystal growth operation of alumina hydrogel under pH fluctuation and the crystal growth operation of alumina hydrogel under pH maintenance are completely different in principle, and conceptually, there is a completely opposite part. That is, when the pH is changed, in order to change the pH more effectively, the presence of polyvalent ions and a high concentration of the dissolved salt are likely to act as an inhibitor. However, it is believed that the presence of dissolved salts has a buffering effect and the presence of multiply charged ions has a positive effect on catalyzing crystal growth in order to maintain the pH within a certain range.

Under pH fluctuation, in the boehmite gel precipitation area, the fine alumina hydrogel particles dissolved in the alumina hydrogel dissolution area and the alumina hydrogel-forming substance added during pH fluctuation are rapidly occluded in large hydrogel particles, that is, boehmite microcrystallites. , The crystals grow to a larger alumina hydrogel, while the mixed fine alumina hydrogel particles are dissolved in the alumina hydrogel dissolution region, and the remaining particles of the alumina hydrogel are homogenized. On the other hand, under the condition that the pH is maintained, the uniform seed alumina hydrogel is subjected to the conditions controlled in the boehmite gel precipitation region, that is, the alumina hydrogel is uniformly occluded in the hydrogel particles. The homogenization of the particles of the crystal-grown alumina hydrogel produced by adding the forming substance is realized. That is, in step b), the pH of the hydrogel with respect to the seed alumina hydrogel.
By varying or / and maintaining the pH and adjusting the addition of the alumina hydrogel-forming material,
A precipitate of alumina hydrogel particles having a uniform particle size is obtained. In short, when the particles of alumina hydrogel are non-uniform, it is possible to repeatedly and alternately fluctuate the reaction system between dissolution conditions and growth conditions by utilizing the property that the particles are more likely to be dissolved and grow easily. , Or when the alumina hydrogel particles are uniform, it is difficult to generate secondary nuclei, and the conditions under which the particle growth is uniform, that is, the alumina hydrogel-forming substance is maintained while maintaining the pH at a preferable addition rate. By introducing into the system, a uniformly grown alumina hydrogel of seed alumina hydrogel is obtained. The change to the dissolution area of the alumina hydrogel or the precipitation area of the boehmite gel, or the retention thereof is performed using a pH adjusting agent. As the pH adjuster, an alumina hydrogel-forming substance itself or a non-alumina hydrogel-forming substance may be used.
However, in the case of fluctuation or retention in at least one region, the pH adjusting agent used is preferably the alumina hydrogel-forming substance itself. More preferably, under pH fluctuation, the alumina hydrogel-forming substance is used as a pH adjusting agent only when the pH changes to the boehmite gel precipitation region, and in the operation while maintaining the pH, at least one of the alumina hydrogel forming substance and the pH adjusting agent is used. Substantially contains sulfate radicals. That is, since most of the alumina hydrogel-forming substances show acidity or alkalinity in a state of being dissolved in water, they can be used as a pH adjusting agent. For example, those exhibiting acidity include aluminum chloride, aluminum nitrate, aluminum sulfate, etc., those exhibiting alkalinity include sodium aluminate, etc., and those containing sulfate include aluminum sulfate, Is also one of those exhibiting acidity. Examples of the pH adjusting agent composed of a non-alumina hydrogel-forming substance include acids such as hydrochloric acid, nitric acid and sulfuric acid, alkalis such as sodium hydroxide and aqueous ammonia, and sulfuric acid containing a sulfate group.

[Conversion of Alumina Hydrogel to Alumina] [Step c)] The crystal-grown alumina hydrogel is made into an alumina xerogel by a combined operation of washing and drying, followed by firing.
A porous alumina molded body having a desired shape and characteristics is obtained. To remove coexisting unwanted ions or impurities,
A washing operation is performed according to the state of the alumina hydrogel and / or the state of the alumina xerogel. Conversion from alumina hydrogel to alumina xerogel can be carried out by drying, and this drying method is generally carried out at a temperature of room temperature or higher and 200 ° C. or lower under conditions such that water in the alumina hydrogel is sufficiently evaporated. Firing is generally 300-1
200 ℃, preferably 400 ~ 800 ℃ γ-alumina is formed
Performed at the temperature of. In this step, the alumina molded body is molded in the state of alumina hydrogel or xerogel, or rarely in the state of a fired product.
The method may be a gel molding method by adjusting the humidity of alumina hydrogel or a molding method using alumina xerogel powder and a binder. Further, this step is a step of converting alumina hydrogel into alumina, and a conventionally known method can be adopted. The porous alumina molded body thus obtained is advantageously used as a raw material of the separating agent of the present invention, and in particular, by adopting the process b), an alumina molded body having the desired physical properties and chemical properties is obtained. Can be formed.

The target separating agent can be obtained by carrying out complexing with cuprous halide on the alumina molded body obtained as described above. In this case, the amount carried is such that the surface of alumina is evenly distributed. An amount sufficient to cover a single layer is preferred,
The amount depends on the surface area of the alumina, and usually the weight of copper is in the range of 0.2 to 0.4 with respect to the weight of alumina.

The separating agent obtained as described above has the property of adsorbing carbon monoxide with good selectivity, and the separating agent having adsorbed carbon monoxide is heated or kept under reduced pressure to absorb the adsorbed carbon monoxide. It has the property of desorbing carbon oxide.

When the carbon monoxide contained in the gaseous substance is separated and recovered using the above-mentioned separating agent, any of the temperature fluctuation method and the pressure fluctuation method can be adopted. When the temperature fluctuation method is used, it is preferable to contact the carbon monoxide-containing gas with the separating agent of the present invention at a temperature as low as possible.
In order to desorb the adsorbed carbon monoxide from the separating agent, the temperature is higher than the adsorption treatment temperature. The larger the temperature difference, the larger the desorption amount of the adsorbed gas. Therefore,
The temperature difference may be selected according to the desired recovery amount. adsorption·
The desorption treatment temperature can also be appropriately selected. Generally, adsorption treatment is performed at a temperature of 5 to 100 ° C, and desorption treatment is performed at a temperature of 90 to 150 ° C.

Further, in the pressure fluctuation method, adsorption and desorption are performed by treating the carbon monoxide-containing gas with the adsorbent of the present invention with a pressure difference.
Adsorption is performed on the high pressure side of pressure fluctuation, and desorption is performed on the low pressure side.
After pressurizing and adsorbing, desorption may be performed by returning to normal pressure, or desorption may be performed after adsorbing at normal pressure and depressurizing. In this case, the pressure difference is selected according to the amount of carbon monoxide recovered. The recovery amount increases as the pressure difference increases. Further, the temperature fluctuation method and the pressure fluctuation method can be combined.

〔effect〕

According to the present invention, carbon monoxide contained in various carbon monoxide-containing gases can be efficiently separated and recovered. Therefore, the present invention is applied as a production technology for producing high-purity carbon monoxide from low-purity carbon monoxide gas, and is also a technology for separating and recovering carbon monoxide from a carbon monoxide-containing gas, for example, a steel mill byproduct gas. And so on.

That is, in most cases, mixed gas containing a large amount of CO such as by-product gas of a steelworks contains acidic gas such as CO ₂ and SO ₂ and a physical adsorptive gas at the same time. CO ₂ or the like is simultaneously adsorbed when using a porous material having a base or having a basic property, and post-treatment was required to obtain highly pure CO. No such post-treatment is required when using the agent.
Therefore, the adsorbent of the present invention is particularly effective for selective adsorption separation of CO from a gas containing these CO ₂ , SO _{2, and the} like.

The separating agent used in the present invention uses alumina obtained by the above-described specific step as a carrier for complexing cuprous halide, so that the complexing of cuprous halide is easy, It can be performed using an aqueous solution containing a cuprous halide. Moreover, since the alumina obtained from the specific step has both the chemical properties as well as the physical properties required for the carbon monoxide separating agent as described above, it is possible to uniformly disperse the cuprous halide. It also provides a separating agent that is easy to disperse in a high concentration and has high selectivity and high adsorption to carbon monoxide.

〔Example〕

 Next, the present invention will be described in more detail with reference to Examples.

The pore size distribution shown below was determined by the so-called mercury porosimetry method using Mercury, Pressure, and Porosimeter Model 70 (manufactured by Carlo Erba Co., Milan, Italy). The mercury was set to 140 °, and the absolute mercury pressure was changed from 1 to 2000 kg / cm ² for measurement. Further, as cuprous chloride used below, a commercially available special grade reagent (manufactured by Wako Pure Chemical Industries) was used as it was, and as aluminum chloride, a PCB quantitative reagent (manufactured by Wako Pure Chemical Industries) was used as it was.

Example 1 0.15 l of a 11.6 wt% sulfuric acid aqueous solution and 10 l of deionized water were placed in a enamel jar and heated to 90 ° C., and 0.39 l of an aqueous sodium aluminate solution having an Al ₂ O ₃ concentration of 69 g / l was vigorously stirred. Immediately after the addition, an aqueous slurry of aluminum hydroxide having a pH of 10 was obtained. This was used as seed aluminum hydroxide, and stirring was continued. After 10 minutes, 0.15 l of the sulfuric acid aqueous solution was added as the first step operation, and the pH was 3.5. While stirring this solution at 90 ° C., and after 5 minutes, 0.3 l of the above aqueous solution of sodium aluminate was added,
showed that. This operation of alternately adding sulfuric acid and sodium aluminate after a fixed period of time was repeated 8 steps. Then, the slurry was filtered, re-dispersed in 10 l of deionized water, and filtered and washed three times to obtain a cake. Take out this cake,
Molded into 1.6 mmφ with an extrusion molding machine,
After drying at 20 ° C for 6 hours, it was baked at 500 ° C for 3 hours to obtain alumina A. The properties of this alumina A are shown in Table 1.

Table-1 Average pore size [Å]: 119 Pore volume [cm ³ / g]: 0.713 Surface area [m ² / g]: 240 Next, under nitrogen, in a 200 ml 2-neck round bottom flask, 0.6 g of cuprous chloride
(6 mmol) was added, 1N hydrochloric acid solution (40 l) was added, and the mixture was heated and kept at 70 ° C. for 2 hours to obtain a colorless transparent solution. In this solution, 12
10 g of the above alumina carrier A dried at 0 ° C. for 2 hours was added under a nitrogen stream. After soaking at 70 ° C for 30 minutes, the inside of the eggplant flask was depressurized by an aspirator and exhausted for 8 hours to sufficiently remove water to obtain a light gray adsorption separating agent.

A CO mixed gas of 1 atm (CO partial pressure: 0.8 atm, N ₂ partial pressure: 0.2 atm) was passed through this adsorption / separation agent at room temperature, and the adsorption amount was measured by the constant pressure volume method. Adsorption amount is 4.2 mmol (4.0 mmol / g)
Met. Next, decompress the system with a vacuum pump (0.1 atm)
And held for 10 minutes. At that time, when exhaust gas from the vacuum pump was collected and analyzed by gas chromatography, 2.4 mmol of CO was recovered.

Further, nitrogen gas containing water having a saturated water vapor pressure was blown to the adsorption separator (H ₂ O contact amount about 30 mmol). Then, the mixed gas was passed through the adsorption separator at room temperature, and the adsorption amount was measured. As a result, the adsorption amount was 2.3 mmol. Next, when this adsorption / separation agent was depressurized (0.1 atm) with a vacuum pump and kept for 10 minutes, 2.3 mmol of CO was recovered, and deterioration due to water was not observed.

Example 2 0.05 l of an aluminum sulfate aqueous solution having an Al ₂ O ₃ concentration of 80 g / l and 10 l of deionized water were placed in an enamel jar and heated to 90 ° C., and then vigorous stirring was performed to form an aluminate having an Al ₂ O ₃ concentration of 69 g / l. When 350 ml of an aqueous solution of soda was added instantaneously, a cloudy, slurried aqueous solution of aluminum hydroxide having a pH of 10 was obtained. Using this as seed aluminum hydroxide, Al ₂ O ₃ concentration of 8 g / l aluminum sulfate aqueous solution 0.29 / hr,
An aqueous solution of sodium aluminate having an Al ₂ O ₃ concentration of 69 g / l was added at a rate of 0.20 l / hr using a constant rate injector. The temperature was 90 ° C. and the pH was 9 to 10 for 6 hours after the addition operation was continued. Also,
3 hours after the start of injection, collect 0.3l sampling solution,
Filtration, redispersion in 2 liters of deionized water and washing by filtration were repeated 3 times to obtain a cake. This cake showed pseudo-boehmite on X-ray diffraction. The cake was molded into a columnar shape with an extrusion molding machine having a die having a hole of 1.6 mmφ with a solid content concentration of about 25%, and dried at a temperature of 120 ° C. for 6 hours. Then put it in an electric furnace and blow air, 500
Calcination was carried out for 3 hours. The properties of the obtained alumina B are shown in the table.
Shown in 2.

Table-2 Average Pore Diameter [Å]: 108 Pore Volume [cm ³ / g]: 0.722 Surface Area [m ² / g]: 266m ² / g Next, in the same manner as in Example 1, hydrochloric acid of cuprous chloride was used. A solution was prepared. To this, 10 g of the alumina carrier B dried at 120 ° C. for 2 hours was added under a nitrogen stream. After soaking at 70 ° C for 30 minutes, the inside of the eggplant flask was depressurized by an aspirator and exhausted for 8 hours to sufficiently remove water to obtain a light gray adsorption separating agent. When the CO mixed gas used in Example 1 was passed through this adsorption separator and its adsorption performance was confirmed, it was 4.6 mmo.
The adsorption amount of l was shown. Next, when the pressure inside the system was reduced by a vacuum pump (0.1 atm) and kept for 10 minutes, 2.6 mmol of CO
Was recovered. Further, nitrogen gas containing water having a saturated vapor pressure was sprayed onto this adsorption separator (contact amount of H ₂ O was about 30 mmo.
l). Then, when the CO mixed gas was ventilated at room temperature, the adsorption / desorption amount was 2.6 mmol, and deterioration due to water was not observed.

Example 3 2.28 N hydrochloric acid solution (0.13 L) and deionized water (10 L) were placed in a enamel jar and heated to 90 ° C., and then vigorously stirred.
0.28 l of an aqueous solution of sodium aluminate having an Al ₂ O ₃ concentration of 69 g / l was added instantaneously, and after stirring for 15 minutes, this was used as an aqueous solution of seed aluminum hydroxide.
When added, it showed a pH of 3.5. After maintaining this at 90 ° C. and stirring for 5 minutes, the above sodium aluminate aqueous solution was added.
When 35 l was added, the pH became 9. The operation of adding hydrochloric acid and sodium aluminate alternately after a certain period of time was continued in the second and subsequent steps, and after the 10th step was completed, the mixture was held for 15 minutes to obtain alumina C in the same manner as in Example 1. It was This alumina C
The properties of are shown in Table-3.

Table-3 Average supplementary pore diameter [Å]: 114 Pore volume [cm ³ / g]: 0.650 Surface-attached [m ² / g]: 228 Next, an adsorption / separation agent was obtained by the same operation as in Example 1 and When the adsorption capacity was examined, the adsorption amount was 4.2 mmol. When this was depressurized (0.1 atm) with a vacuum pump and kept for 10 minutes, 2.3 mmol of CO was recovered. Further, nitrogen gas containing water having a saturated water vapor pressure was blown to the adsorption separator (H ₂ O contact amount about 30 mmol). After that, when the amount of adsorption / desorption was measured at room temperature in the same manner as above, it was 2.3 mmol, and deterioration due to water was not observed.

Comparative Example Al ₂ O ₃ concentration 80 g / l aluminum sulfate aqueous solution 0.224 l and deionized water 10 l were placed in a porcelain jar and heated to 90 ° C., and then Al ₂ O ₃ concentration 69 g / l aluminate was stirred vigorously. 1.55 l of a soda aqueous solution was added instantaneously to obtain a slurry white liquid having a pH of 10. This was kept at 90 ° C for 6 hours. At that point the solution had a pH of 10. The liquor was filtered and washed with deionized water to remove most of the Na ⁺ and SO ₄ ²⁻ ions. 1.6 m of the obtained filter cake is extruded
It was molded into mφ, dried at 120 ° C. for 6 hours, and then baked at 500 ° C. for 3 hours to obtain an alumina molded body E. The physical properties of this molded product were as follows.

Table-4 Surface area [m ² / g]: 159 Pore volume [cc / g]: 0.31 Average pore diameter [Å]: 78 Using 10 g of this alumina molded body, the adsorption separator was prepared by the method of Example 1. Prepared. When the amount of adsorption was measured by the same operation as in Example 1, it was 2.9 mmol at room temperature. When this is kept under reduced pressure (0.1 atm) for 10 minutes with a vacuum pump, 1.2 mmol
CO was captured. The desorption capacity of the adsorption separation agent in this case was smaller than that of the example, but it is considered that this is due to the difference in the production of the alumina used.

Claims (1)

[Claims] 1. A carbon monoxide-containing gas is brought into contact with a non-complexed cuprous halide-alumina complex to adsorb the carbon monoxide to the complex, and then the complex is removed. In the method of desorbing carbon monoxide adsorbed on the composite by maintaining the pressure under an elevated temperature condition or a pressure lower than that during adsorption, the alumina comprises: a) removing alumina hydrogel from an alumina hydrogel-forming substance; Step b): Altering the pH of the alumina hydrogel alternately between the alumina hydrogel dissolution region and the boehmite gel precipitation region, and at the time of changing the pH to at least one of the alumina hydrogel dissolution region and the boehmite gel precipitation region. A step of adding a hydrogel-forming substance to obtain a crystal-grown alumina hydrogel, and / or boehmite gel precipitation of the alumina hydrogel A step of adding an alumina hydrogel-forming substance in a continuous flow or an intermittent flow while maintaining the temperature in the region to obtain a crystal-grown alumina hydrogel, c) A crystal-grown alumina hydrogel is washed and dried or fired in combination to form an alumina gel or alumina. The method for adsorbing and separating carbon monoxide, which is alumina having a pore volume of 0.3 to 1.2 cc / g and an average pore diameter of 50 to 150Å, which is formed by a combination of the steps of: