JPH0250770B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is a pressure fluctuation adsorption separation method (hereinafter referred to as PSA
This technology relates to adsorbents used for the purpose of separating and recovering high-purity CO from a mixed gas containing CO by the temperature fluctuation adsorption separation method (hereinafter referred to as the TSA method) and/or the temperature fluctuation adsorption separation method (hereinafter referred to as the TSA method). method and its adsorbent to achieve high purity
This relates to a method for separating and recovering CO. Conventional technology As a typical gas whose main component is CO,
Examples include converter gas obtained from a converter in a steel mill, blast furnace gas obtained from a blast furnace, electric furnace gas obtained from an electric furnace, and generator gas obtained by gasifying coke. Most of these gases are normally used as fuel, but some of these gases contain around 70 vol% or more of CO, so the CO contained in these gases is If it can be separated and recovered with high purity, it can be used as a raw material for the synthesis of formic acid, acetic acid, etc., and for the reduction of organic compounds, and is extremely useful in the chemical industry. Conventionally, cryogenic separation methods, copper ammonia methods, and COSORB methods are known as methods for separating and recovering CO from a gas whose main component is CO, but these methods require high equipment costs and electricity,
There is a problem in that the cost of thermal energy such as steam is high, and although it is suitable for separating and recovering large volumes of CO, it is not necessarily suitable for separating and recovering medium or small volumes of CO. Furthermore, the CO obtained by separation by these methods contains O ₂ and CO ₂
It has the disadvantage that it cannot be used as it is for organic synthesis because it contains gas components that can be a hindrance to organic synthesis reactions. Incidentally, the PSA method and the TSA method are known as methods for selectively separating a specific gas from a medium or small volume of source gas. The PSA method is a method for selectively separating specific gases from a mixed gas.The adsorbent is adsorbed onto an adsorbent under high pressure, and then the adsorbent is adsorbed onto the adsorbent by lowering the pressure of the adsorption system. This method desorbs adsorbed substances and separates adsorbed substances and non-adsorbed substances.Industrially, multiple towers filled with adsorbent are installed, and in each adsorption tower, pressure increase → adsorption → washing → desorption is performed. By repeating a series of air operations, the entire device can perform continuous separation and recovery. Similarly to the PSA method, the TSA method is also a method for selectively separating a specific gas from a mixed gas, by adsorbing the adsorbent onto an adsorbent at a low temperature and then raising the temperature of the adsorption system. In this method, the adsorbed substances adsorbed on the adsorbent are desorbed, and the adsorbed substances and non-adsorbed substances are separated. Conventionally, a method using mordenite-based zeolite as an adsorbent has been proposed as a method for separating and recovering CO from a mixed gas containing CO using the PSA method. (JP-A-59-22625, JP-A-59-22625, JP-A-59-22625,
(Refer to Publication No. 49818) In addition, as a method for separating and recovering CO from a mixed gas containing CO using the PSA method or TSA method, copper halides (), copper oxides (), copper () salts, copper oxides (), etc. A method has been proposed in which a compound supported on activated carbon is used as an attachment agent.
(JP-A-58-156517, JP-A-59-69414, JP-A-59-105841, JP-A-59-136134)
(Refer to the publication) In addition, as a method for removing CO from a mixed gas containing CO, there is a method in which the molar ratio of SiO ₂ /Al ₂ O ₃ is 20 to 200.
There is also a known method of using an adsorbent produced by directly introducing valent copper ions into zeolite by an ion exchange method, or by introducing valence copper ions into the zeolite by an ion exchange method and then reducing the valent copper ions to valent copper ions. It is being (Refer to US Pat. No. 4,019,879) Problems to be Solved by the Invention When carrying out the PSA method or the TSA method, the performance required of the adsorbent packed in the adsorption tower is as follows.
There is selective adsorption of the target component over coexisting components, there is a large difference in the adsorption amount of the target component during processing or low temperature and under reduced pressure or high temperature, the adsorbed target component is easily desorbed, and components other than the target component is difficult to adsorb and desorb,
etc. These performances have a significant impact on product gas purity and yield, so
This is an important element in the PSA or TSA Act. However, in the method of using mordenite-based zeolite as an adsorbent, which utilizes the physical adsorption/desorption phenomenon of the adsorbent, the pressure swing must be changed more frequently because the amount of CO adsorbed is relatively small. , there are disadvantages in terms of operation and valve life, CO ₂ must be removed before adsorption operation, and co-adsorption of N ₂ is inevitable, resulting in low product purity. In addition, when cleaning the inside of the tower using product CO gas to remove adsorbed N ₂ , the amount of cleaning required is large, resulting in a low recovery rate of product CO. On the other hand, in the case of a method using an adsorbent in which the above-mentioned copper compound is supported on activated carbon, which utilizes the chemical adsorption/desorption phenomenon of the adsorbent, CO is separated from a mixed gas containing CO, N ₂ , CO ₂ , etc. However, when trying to separate and recover high-purity CO because it tends to co-adsorb _CO2 and other substances at the same time, it is also difficult to separate and recover CO2 with high purity.
There are problems such as the amount of CO adsorption is not necessarily large, and it has not yet reached the point where it can be adopted on an industrial scale. Furthermore, a method using an adsorbent in which valent copper ions are introduced into zeolite with a SiO ₂ /Al ₂ O ₃ molar ratio of 20 to 200 by an ion exchange method removes CO from a mixed gas with a relatively low CO content. Although it can be used for the purpose of removing CO, for the purpose of selectively separating CO from a mixed gas containing, for example, around 70 vol% or more, it is difficult to adsorb CO and the purity and yield of the product CO gas is insufficient. Because the rate is inferior,
Difficult to adopt industrially. In view of this situation, the present invention was achieved as a result of intensive research aimed at finding an industrially advantageous adsorbent that can efficiently separate and recover high-purity CO from a mixed gas containing CO. Means for Solving the Problems The adsorbent for CO separation and recovery of the present invention has a copper compound supported on a carrier made of silica and/or alumina. In addition, the method for manufacturing the adsorbent for CO separation and recovery of the present invention includes contacting a carrier made of silica and/or alumina with a solution or dispersion in which a copper compound is dissolved or dispersed in a solvent, and then removing the solvent. It is characterized by: Furthermore, the method of separating and recovering high-purity CO of the present invention uses the PSA method or/and TSA method.
In separating and recovering high-purity CO from a mixed gas containing CO, this system is characterized by using an adsorbent for CO separation and recovery, which is made by supporting a copper compound on a carrier made of silica and/or alumina. be. The present invention will be explained in detail below. Adsorbent The adsorbent for CO separation and recovery of the present invention is made by supporting a copper compound on a carrier made of silica and/or alumina. The precipitate is precipitated, washed with water, dried, and if necessary activated by heating under reduced pressure to form a powder. 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, methods include kneading silica gel and alumina gel together in a wet state, soaking silica gel in aluminum salt, and mixing silica and alumina in an aqueous solution. A method of simultaneously gelling the silica gel, a method of depositing alumina gel on silica gel, etc. are adopted. These silica, alumina, and silica-alumina are all commercially available, and in the present invention, granular materials with a particle size of, for example, about 1 to 7 mm are selected in consideration of pressure loss when packed into a column, Dry this if necessary before using. When comparing silica and alumina, silica tends to be superior in terms of CO adsorption amount, while alumina tends to be superior in terms of CO purity. Copper compounds supported on silica and/or alumina carriers include copper() compounds, copper()
A compound or a reduced product of a copper() compound is used. Here, copper () compounds include copper chloride (),
Copper halides () such as copper fluoride () and copper bromide (); copper oxide (); copper cyanide (); copper formate (), copper acetate (), copper oxalate (), copper sulfate () , copper sulfite (), oxyacid or organic acid salt of copper (); copper sulfide (); dichlorocopper ()
Examples include complex salts such as acid salts, tetrachlorocopper()ates, dicyanocopper()ates, and tetracyanocopper()ates. Copper chloride () is particularly suitable. Copper () compounds include copper halides () such as copper chloride (), copper fluoride (), copper bromide (); copper oxide (); copper cyanide (); copper formate (), copper acetate (); ), copper oxalate (), copper sulfate (), copper nitrate (), copper phosphate (), copper carbonate (), and other oxy- or organic acid salts of copper ();
Copper hydroxide (); Copper sulfide (): trifluorocopper()ate, tetrafluorocopper()ate, trichlorocopper()ate, tetrachlorocopper()ate, tetracyanocopper()ate, tetrahydrocopper()ate Oxocopper() salt, hexahydroxocopper()
Examples include acid salts and complex salts such as ammine complex salts. When a copper () compound is supported on a carrier, a reduced product of the copper compound may also be used. This reduced product is estimated to be a mixture of a copper() compound and a copper() compound, or a compound having an intermediate valence. The amount of copper compound supported on the silica or/and alumina support is not particularly limited, but is usually 0.5
~10 m-mol/g, preferably 1-5 m-mol/
Select from the range of g. If the supported amount is too small
If the CO adsorption capacity is insufficient, and on the other hand, the amount supported is too large, the separation efficiency will decrease. Method for producing adsorbent The above-mentioned adsorbent is produced by contacting a carrier made of silica or/and alumina with a solution or dispersion in which a copper compound is dissolved or dispersed in a solvent, and then removing the solvent. . The solution or dispersion is brought into contact by impregnation, spraying, or the like. At this time, in addition to simply contacting silica or/and alumina with a solution or dispersion of a copper compound by means such as impregnation or spraying, the solution or dispersion of a copper compound is brought into contact with vacuum-degassed silica or/and alumina. Alternatively, a solution or dispersion of a copper compound may be brought into contact with silica and/or alumina, and then degassed under reduced pressure conditions. Examples of solvents include water, hydrochloric acid, acetic acid, formic acid, ammoniacal formic acid aqueous solution, aqueous ammonia, halogen-containing solvents (chloroform, carbon tetrachloride, ethylene dichloride, trichloroethane, tetrachloroethane, tetrachloroethylene, methylene chloride, fluorinated solvents). etc.), sulfur-containing solvents (carbon disulfide, dimethyl sulfoxide, etc.), nitrogen-containing solvents (propionitrile, acetonitrile, diethylamine, dimethylformamide, N-methylpyrrolidone, 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, itophorone, cyclohexanone, etc.), esters (methyl acetate, ethyl acetate, amyl acetate, methyl propionate, amyl propionate, etc.) ), ethers (isopropyl ether,
dioxane, etc.), cellosolves (cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc.), and carbitols. After contacting a solution or dispersion of a copper compound with a carrier made of silica or/and alumina,
The solvent is removed by appropriate means under an air atmosphere or an inert gas atmosphere such as nitrogen or argon. The solvent can be removed not only by heat drying but also by vacuum drying. When a copper() compound is used, an adsorbent with sufficient CO adsorption ability can be obtained through this drying process, but
Furthermore, heat treatment may be performed under an inert gas or reducing gas atmosphere. On the other hand, when a copper() compound is used, the CO adsorption capacity is often insufficient just by the above-mentioned drying.
Therefore, when a copper() compound is used, it is desirable to activate the adsorbent after drying by further heat-treating it in an inert gas or reducing gas atmosphere. The appropriate heating temperature is 200 to 600°C, preferably 400 to 550°C in an inert gas such as nitrogen or argon, and 100 to 230°C in a reducing gas such as CO or _H2 . . Through this heat treatment, the copper () compound supported on the carrier is partially reduced, resulting in a mixture of copper () compounds and copper () compounds, or a compound with a valence between two valences. It is estimated to be. Separation and recovery of CO The adsorbent obtained as described above is packed into an adsorption tower, and separation and recovery of CO from a mixed gas containing CO is performed by the PSA method or the TSA method. When separating and recovering CO by the PSA method, it is desirable that the adsorption pressure in the adsorption step is at least atmospheric pressure, for example 0 to 6 kg/cm ² G, and the degree of vacuum in the vacuum degassing step is below atmospheric pressure, for example 200 kg/cm 2 G.
It is desirable to set it to ~10Torr. When separating and recovering CO by the TSA method, the adsorption temperature in the adsorption step is, for example, about 0 to 40°C, and the degassing temperature in the degassing step is, for example, 60 to 40°C.
It is desirable to set the temperature to about 180℃. It is also possible to use the PSA method and the TSA method in combination, performing adsorption at atmospheric pressure or higher under low temperature conditions and degassing at atmospheric pressure or lower under high temperature conditions. In addition, since the TSA method is disadvantageous compared to the PSA method in terms of energy consumption, it is desirable to adopt the PSA method or a combined PSA-TSA method from an industrial perspective. As the mixed gas containing CO that can be applied to the method of the present invention, for example, converter gas generated from a converter in a steel mill is used. Converter gas usually contains CO as a main component, as well as O ₂ , methane and other hydrocarbons, water, and small amounts of H ₂ S, NH ₃ and the like. In addition to converter gas, blast furnace gas, electric furnace gas, generator gas, etc. can also be used as raw material gas. In addition, in the present invention, prior to the CO separation and recovery step, a step of adsorbing and removing impurities such as sulfur compounds and NH ₃ , a step of removing water, and a step of removing impurities that may poison the adsorbent or shorten its lifespan are performed. It is desirable to provide an O ₂ removal step.
However, it is not enough to provide a CO ₂ removal process or a N ₂ removal process. Industrially, the operation when using the PSA method is as follows:
Using a plurality of adsorption towers filled with the above adsorbent, the following operations are carried out in each adsorption tower: (1) A step in which the raw material gas is passed through the adsorption tower to adsorb CO, and a step in which the CO concentration in the exhaust gas is Shortly before the CO concentration in the gas becomes equal, the exhaust gas is used to boost the pressure of another column (2) After the adsorption step is completed, the adsorption column is connected to the adsorption column that has completed vacuum deaeration; A depressurization step in which the pressure in the former adsorption tower is reduced to near atmospheric pressure in parallel flow, and a corresponding step in which the pressure in the latter adsorption tower is increased (); (3) A part of the product gas is flowed in parallel flow into the depressurized adsorption tower. (4) A cleaning process in which CO is introduced into the column to clean residual impurity gas inside the column, and a process in which the gas discharged at this time is used to boost the pressure of other columns (4) The CO adsorbed by the adsorbent is
(5) The adsorption tower where product recovery has been completed and the adsorption tower where the adsorption process has been completed are connected, and the former adsorption tower is operated in parallel flow. (6) Pressure raising () step in which the pressure is raised in parallel flow using the washed exhaust gas from other adsorption towers; (7) Pressure raising () step in which the pressure is raised by the exhaust gas from other adsorption towers near the end of the adsorption process. , may be repeated in sequence. By sequentially repeating the above operations in each adsorption tower in this manner, highly pure CO gas can be continuously separated and recovered at a high recovery rate. Effect The adsorption/desorption phenomenon by the solid adsorbent of the present invention is mainly based on the reversible chemical reaction (complex formation reaction and dissociation reaction) between the copper compound supported on the carrier and CO (N ₂ , CO (No chemical reaction with ₂ occurs), and is thought to be based on secondary physical adsorption onto the pore surface of the silica or/and alumina support and desorption therefrom. Examples Next, the present invention will be further explained with reference to Examples. Example 1 14g of copper chloride () was added in a 200ml Erlenmeyer flask.
Copper chloride () by dissolving in 40ml hydrochloric acid
A solution was prepared. To this solution, 40 g of alumina (AH-S11 manufactured by Fujimi Abrasives Industry Co., Ltd.) with an average particle size of 3 mm was previously dried at 110 ° C. for about 4 hours, and
After degassing with an aspirator for 1 minute, it was left standing for 4 hours. Next, while heating to 200° C. with a mantle heater, the solvent was distilled off in a N ₂ stream, and then cooled to room temperature to obtain an adsorbent for CO separation and recovery. Transfer the adsorbent obtained above to an adsorption tower (15mmφ x 300mmH)
A mixed gas of 1 atm with a composition of CO: 71.4 vol% N ₂ : 12.7 vol% CO ₂ : 15.9 vol% was supplied to the adsorption tower at 20°C.
CO was adsorbed. The amount of CO adsorption at this time is 16.2
It was cc/cc. After the adsorption operation, the inside of the column was washed with 180 ml of CO, and then degassing was performed for 5 minutes at a pressure of 50 Torr using a vacuum pump to release the adsorbed gas. The amount of CO released at this time was 8.9 cc/cc, and the composition of the recovered gas was CO: 99.9 vol% CO ₂ : 0.1 vol % N ₂ : trace. When adsorbed again under the same conditions as above, the released
The same amount of CO was adsorbed. Comparative Example 1 An experiment was conducted in the same manner as in Example 1, except that an adsorption tower filled with mordenite zeolite (particle size 3 mm) was used as an adsorbent. Comparative Example 2 An adsorbent was produced in the same manner as in Example 1, except that commercially available activated carbon (particle size: 3 mm) was used in place of alumina, and the same experiment as in Example 1 was conducted using this adsorbent. The results of Example 1 and Comparative Examples 1 and 2 are shown in Table 1.

[Table] Example 2 In Example 1, the mixed gas adsorption operation was carried out in two steps.
It was carried out under a pressure of Kg/cm ² G, and after the adsorption operation, the pressure was reduced to atmospheric pressure and the inside of the column was washed with 180 ml of CO. Then, degassing was performed for 5 minutes at a pressure of 50 Torr using a vacuum pump.
The adsorbed gas was released. The results were as follows. CO adsorption amount 17.4cc/cc CO release amount 10.1cc/cc Recovered gas composition CO: 99.95vol% CO ₂ : 0.05vol% N ₂ : trace Example 3 10g of copper chloride () was added in a 200ml Erlenmeyer flask.
Copper chloride () solution was prepared by dissolving in 60 ml of water. 40 g of the alumina used in Example 1 was added to this solution, degassed with an aspirator for 1 minute, and then allowed to stand for 4 hours. Next, while heating to 200°C with a mantle heater, the solvent was distilled off in a N ₂ stream, and then heat treatment was performed at 500°C in a N ₂ stream for about 1 hour. Thereafter, it was cooled to room temperature to obtain an adsorbent for CO separation and recovery. An adsorption experiment was conducted using this adsorbent under the same conditions as in Example 1. The results were as follows. CO adsorption amount 6.2 cc/cc Washing CO amount 180 ml CO release amount 3.2 cc/cc Recovered gas composition CO: 98.7 vol% CO ₂ : 1.2 vol% N ₂ : 0.1 vol% Example 4 Silica-alumina with particle size of 3 mm as carrier Example 2 except that 33g of (N631L manufactured by JGC Chemical Co., Ltd.) was used, the heat treatment temperature was 450℃, and the amount of washing was 360ml.
The experiment was conducted under the same conditions. The results were as follows. CO adsorption amount 13.7cc/cc CO release amount 9.9cc/cc Recovered gas composition CO: 99.7vol% CO ₂ : 0.3vol% N ₂ :trace Example 5 Using 11 g of copper oxide () instead of copper chloride (), The experiment was conducted under the same conditions as in Example 1 except that the heat treatment temperature was 500°C. The results were as follows. CO adsorption amount 13.5cc/cc CO release amount 6.4cc/cc Recovered gas composition CO: 99.6vol% CO ₂ : 0.4vol% N ₂ :trace Example 6 In Example 1, the adsorption operation was performed at 1 atm and 20°C. The discharge operation was carried out at 1 atm and 120°C. The results were as follows. CO adsorption amount 16.2cc/cc CO release amount 9.6cc/cc Recovered gas composition CO: 96.3vol% CO ₂ : 3.4vol% N ₂ : 0.2vol% Example 7 In Example 3, the average particle size was 3 mm instead of alumina. Silica (DCS, manufactured by Rhone-Poulenc) was added to a copper chloride solution, degassed with an aspirator for 1 minute, and then allowed to stand for 4 hours. Next, while heating it to 200℃ with a mantle heater,
After the solvent was distilled off in a N ₂ stream, heat treatment was subsequently performed at 450°C for about 1 hour in a CO stream. Thereafter, it was cooled to room temperature to obtain an adsorbent for CO separation and recovery. An adsorption experiment was conducted using this adsorbent under the same conditions as in Example 1. The results were as follows. CO adsorption amount 5.9cc/cc Washing CO amount 360ml CO release amount 3.0cc/cc Recovered gas composition CO: 98.8vol% CO ₂ : 1.1vol% N ₂ : 0.1vol% Effects of the invention The CO adsorbent of the present invention is inexpensive It is easy to manufacture using raw materials, is stable against heat, is hard, and has long-term durability when packed in an adsorption tower, and has low adsorption of gases other than CO in the mixed gas. Extremely pure
It has excellent advantages such as the ability to separate and recover CO. Therefore, the present invention makes it possible to separate and recover high-purity CO from converter gas and other CO-containing gases on an industrial scale, which is of great significance in the chemical industry.

Claims (1)

[Claims] 1. An adsorbent for CO separation and recovery, comprising a carrier made of silica and/or alumina supporting a copper compound. 2. The adsorbent according to claim 1, wherein the copper compound is a copper() compound. 3. The adsorbent according to claim 1, wherein the copper compound is a copper() compound or a reduced product thereof. 4. A method for producing an adsorbent for CO separation and recovery, which comprises contacting a carrier made of silica or/and alumina with a solution or dispersion in which a copper compound is dissolved or dispersed in a solvent, and then removing the solvent. 5. After contacting a carrier made of silica and/or alumina with a solution or dispersion in which a copper compound is dissolved or dispersed in a solvent, the solvent is removed and further heat treatment is performed under an inert gas or reducing gas atmosphere. The manufacturing method according to claim 4, characterized in that: 6. When separating and recovering high-purity CO from a mixed gas containing CO by pressure fluctuation type adsorption separation method and/or temperature fluctuation type adsorption separation method, as an adsorbent,
A method for separating and recovering high-purity CO, characterized by using an adsorbent for separating and recovering CO, which is made by supporting a copper compound on a carrier made of silica and/or alumina.