JP2000005559A - Method for removing specified gas component in waste combustion gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for separating carbon dioxide at high temps. using hydrosodalite. SOLUTION: When a specified gas component (carbon dioxide) is separated and recovered from a high-temp. waste combustion gas, the high-temp. waste combustion gas as such or controlled to a fixed temp. is passed through hydrosodalite to adsorb or react the component on and with the hydrosodalite, then the specified component is selectively separated by the difference between the adsorption temp. and/or reaction temp. of the specified component and the adsorption temp. and recovered. The specified component is separated and recovered in this way at high temps. without cooling the waste gas. Further, since the sensible heat of the separated and recovered specified component such as carbon dioxide is utilized in the catalytic reaction, the specified component is efficiently converted to resources at a low cost, the heat energy to be fed to the catalytic reaction is reduced, and further generation of carbon dioxide is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and recovering carbon dioxide from a high-temperature exhaust gas discharged as a combustion gas without cooling the exhaust gas while keeping the temperature high. The carbon dioxide separated and recovered at a high temperature can be subjected to a chemical conversion reaction without loss of heat energy by utilizing the sensible heat of the carbon dioxide as it is for a catalytic reaction or the like. Thereby, the carbon dioxide can be efficiently converted into various useful organic substances and the like, and the carbon dioxide in the combustion exhaust gas can be recycled at low cost.

[0002]

2. Description of the Related Art Recently, extreme weather has occurred on a global scale, and a typical phenomenon, global warming, is a correct global environmental problem that jeopardizes the survival of mankind.
Many experts have pointed out that carbon dioxide is attracting the most attention as a causative agent of global warming, and that if carbon dioxide is continuously emitted as it is, it will be a serious problem for the survival of humanity in the future .

That is, in recent years, with the advance of science and technology, the population of the world has increased, and the standard of living has significantly improved. The amount of energy consumed to satisfy people's demands is enormous, causing various global environmental problems. One of the major problems is global warming. Carbon dioxide is attracting attention as a major causative substance of global warming. Assuming that fossil fuel consumption will continue to increase as it is, the average temperature of the earth will increase in the future only by the effect of emitted carbon dioxide.
It is predicted that the temperature will rise by 1 to 5 ° C over the next 60 years.
993). Due to this rise in temperature, abnormal weather such as the ice sheet in Antarctica and Greenland and the glaciers in the Alps may occur, and it has been pointed out that there is a possibility that the survival of all living things including humans will be seriously threatened.

[0004] Therefore, control of carbon dioxide emission is a very serious and urgent problem for mankind. Increasing the use of alternative energy sources that do not emit carbon dioxide, such as nuclear energy, solar energy, geothermal energy, wind energy, hydrogen fuel, etc., can be an important solution in the long term, but are of little help in emergency situations Absent. Future 50-6
The only urgent solution for zero years is to separate and capture the carbon dioxide generated by the use of fossil fuels. Also,
A major issue is how to treat the large amount of carbon dioxide recovered.

To solve the problem, it is important to regulate the amount of carbon dioxide emitted. However, as long as fossil fuel is used as an energy source, generation of carbon dioxide cannot be eliminated. Therefore, it is important to separate and recover carbon dioxide generated by burning fossil fuel and then to recycle it. Recycling considered today is the reduction of carbon dioxide to carbon monoxide, which is subsequently converted to methanol, acetic acid, ethylene glycol, and the like.

Conventionally, methods for separating and recovering carbon dioxide from a mixed gas include a gas absorption method, a cryogenic separation method (distillation method), a membrane separation method, and a gas adsorption method (pressure swing adsorption method and temperature swing adsorption method). ), Etc. (edited by Toshinaga Kawai, "Carbon dioxide recovery technology" p.22, N
TS, 1991, edited by Yuji Shindo, "The atmosphere surrounding the earth"
p. 115, Ohmsha, 1993). Of these, the gas absorption method involves selectively contacting a mixed gas at a low temperature with an absorbing solution such as an amine capable of selectively absorbing carbon dioxide to absorb carbon dioxide, and then heating the solution to emit carbon dioxide. This is a method of separating and separating carbon. The cryogenic separation method (distillation method) is a method of compressing and cooling a mixed gas to liquefy it, and then separating and distilling the liquid mixture to separate carbon dioxide. The membrane separation method is a method of separating a carbon dioxide by passing a mixed gas by applying a pressure difference before and after a polymer membrane through which carbon dioxide is selectively permeable. Among the gas adsorption methods, the pressure swing adsorption method (PSA method) is a method in which a mixed gas is brought into contact with an adsorbent such as activated carbon or a molecular sieve having fine pores under pressure to cause carbon dioxide to flow through the fine pores. This is a method of selectively adsorbing carbon dioxide and then reducing the pressure to desorb and separate the adsorbed carbon dioxide. On the other hand, in a temperature swing adsorption method (TSA method), a mixed gas is brought into contact with a similar adsorbent at a room temperature or a low temperature to selectively adsorb carbon dioxide, and then the temperature is raised to increase the adsorbed carbon dioxide. It is a method of desorbing and separating carbon.
The above separation and recovery methods are applied today in the temperature range of room temperature or lower, and are not applied to separation and recovery in the high temperature range.

Conventionally, various techniques have been developed as a method of recovering a specific gas component from exhaust gas. For example,
As a method of recovering valuable components in the exhaust gas, in the treatment of the exhaust gas after removing the carbon black of the furnace pump rack manufacturing equipment, the exhaust gas is cooled and pressurized.
After absorbing and recovering carbon dioxide and carbon monoxide in the exhaust gas with a suitable solvent (absorbent), hydrogen gas in the exhaust gas is separated and recovered by an adsorption method or a cryogenic separation method. Method for recovering valuable components (Japanese Unexamined Patent Publication No.
27902). However, this method involves absorbing and recovering carbon dioxide and carbon monoxide in the exhaust gas with an absorbing solution. In particular, an aqueous solution of ethanolamine or potassium carbonate generally used as a method of absorbing carbon dioxide is used. The method utilizes an alkaline solution circulation type decarbonation method using an aqueous solution of the above as an absorbing solution.

Further, as a method for producing carbon dioxide, argon and nitrogen from flue gas, there is provided a method for producing a first pressure swing adsorbent from a substantially flue-free flue gas discharged from a low air ratio burner. In the (pressure swing adsorption) step, carbon dioxide is selectively adsorbed and separated, and a second pressure swing adso-
A process for producing carbon dioxide, argon and nitrogen from combustion exhaust gas, characterized in that nitrogen or argon is selectively adsorbed and separated in an optional (pressure swing adsorption) step, and the remaining argon or nitrogen is recovered. 63-1
No. 47805). However, the method is characterized in that carbon dioxide is selectively adsorbed and separated by cryogenic pressure swing adsorption method and recovered.

Further, as a method of recovering a specific gas component from a mixed gas, a method of recovering a specific exhaust gas component such as carbon dioxide from combustion exhaust gas by a pressure fluctuation adsorption separation method (pressure swing adsorption method, PSA method) (particularly, 1-1802 Kaihei
No. 18) has been proposed. However, the method supplies a gas having an increased partial pressure of a specific gas component at low temperature and normal pressure, and desorbs the specific gas component adsorbed by a clinoptilolite-based adsorbent under reduced pressure, It is characterized in that it is collected and each step is performed cyclically.

As described above, various methods for separating and recovering a specific gas component from exhaust gas have been conventionally proposed. However, in any of these separation methods, high-temperature exhaust gas is once cooled and then separated. The method for performing the separation operation at a high temperature has not been known so far. That is, high-temperature separation of a specific gas component such as carbon dioxide has been considered impossible with today's technical level using any of the above methods.

However, as for the treatment of a large amount of separated and recovered carbon dioxide, underground sequestration and storage in the sea are being studied with a view to urgently treating a large amount of carbon dioxide. However, separately from this, a method for converting C1 compounds such as carbon dioxide, carbon monoxide, and methane into useful methanol, acetic acid, ethylene glycol, and the like has been studied from the viewpoint of effective use of unused resources. I have. In addition, conversion to an organic compound having a higher utility value and a higher carbon number is also being studied, and if these technologies are established, large-scale recycling of carbon dioxide will be possible. Moreover, these conversion reactions are carried out by catalytic reactions that require the reduction of carbon dioxide to carbon monoxide, which requires thermal energy. If the operation of separating and recovering carbon dioxide from exhaust gas can be performed at a high temperature, the thermal energy of carbon dioxide can be used as it is as the thermal energy of the reduction reaction of carbon dioxide, which is also desirable from the viewpoint of energy saving. .

As described above, the recycling of carbon dioxide is performed by a catalytic reaction requiring heat energy. If the carbon dioxide can be separated and recovered at a high temperature, the sensible heat of the carbon dioxide can be used for the catalytic reaction to reduce the heat energy to be supplied during the catalytic reaction.
This prevents further generation of carbon dioxide. For the above reasons, there has been a demand for a material and a system capable of separating and recovering carbon dioxide at a high temperature without cooling it.

[0013]

Under such circumstances, based on the above-described concept, the present inventors have determined that a specific gas component such as carbon dioxide is extracted from a high-temperature exhaust gas discharged as a combustion gas. As a result of various studies on methods for separating and recovering high temperature exhaust gas, high temperature exhaust gas (preferably 10
(0 to 500 ° C.), the specific gas component such as carbon dioxide is adsorbed and / or reacted by passing over a hydrosodalite powder or a molded body held at 0 to 500 ° C., and then the specific gas component such as carbon dioxide is adsorbed and / or reacted. Alternatively, it has been found that carbon dioxide is desorbed when the reacted hydrosodalite is heated to a temperature higher than the adsorption temperature and / or reaction temperature, and the present invention has been completed.

That is, an object of the present invention is to provide a method for separating and recovering a specific gas component from a high-temperature combustion exhaust gas discharged as a combustion gas at a high temperature.

Further, according to the present invention, a specific gas component such as carbon dioxide in a high temperature combustion exhaust gas is separated and recovered at a high temperature, and the sensible heat of the specific gas component is directly used for a catalytic reaction or the like. It is an object of the present invention to provide a method for separating and recovering a high-temperature specific gas component that can be subjected to a chemical conversion reaction without loss of heat energy to efficiently recycle the specific gas component. Things.

[0016]

A first aspect of the present invention for achieving the above object is to separate and recover a specific gas component from a high temperature combustion exhaust gas discharged as a combustion gas. The exhaust gas is heated to a predetermined temperature (preferably 100
(500 ° C.), passed through a hydrosodalite to adsorb and / or react the specific gas component with the hydrosodalite, and then adsorbed and / or reacted the specific gas component. Raise the temperature of the hydrosodalite to above the adsorption temperature and / or reaction temperature,
A method for recovering a specific gas component in combustion exhaust gas, wherein the specific gas component is selectively separated and recovered based on a temperature difference between an adsorption temperature and / or a reaction temperature and a desorption temperature of the specific gas component. .

According to another aspect of the present invention, there is provided a method for recovering the above specific gas component, wherein the adsorption temperature and / or the reaction temperature is preferably 100 to 500 ° C., and the desorption temperature is 800 ° C. or less. ,.

Another aspect of the present invention is the above-mentioned method for recovering a specific gas component, wherein the specific gas component is carbon dioxide and / or nitrogen gas.

Further, another aspect of the present invention is characterized in that the high temperature combustion exhaust gas is exhaust gas from a lime factory or a cement factory for heating calcium carbonate or dolomite, a factory for burning fossil fuel, or an internal combustion engine. The above-mentioned method of recovering the specific gas component.

Further, another embodiment of the present invention is the above-mentioned method for recovering a specific gas component, wherein the specific gas component is recovered using hydrosodalite.

Next, the present invention will be described in more detail. The present invention has found hydrosodalite as a material that can be separated and recovered at a high temperature (preferably 100 to 500 ° C.) without cooling carbon dioxide in combustion exhaust gas. Carbon dioxide is known as an acid gas and has a basic point as a surface active point,
Alternatively, ceramics having strong affinity or reactivity with carbon dioxide have been demanded.

The basic principle of the present invention is to use hydrosodalite as a carbon dioxide adsorbent and / or a reactant. Carbon dioxide is an acidic substance, selectively adsorbed on the surface of hydrosodalite showing basicity,
Next, it is desorbed by raising the temperature. Hydrosodalite reacts with carbon dioxide at a high temperature and changes to sodium carbonate. Thereafter, the sodium carbonate emits carbon dioxide by raising the temperature and returns to the hydrosodalite before the reaction. These phenomena indicate that the carbon dioxide adsorption / desorption phenomenon and / or the reaction / decomposition are selectively exerted at a high temperature.

The hydrosodalite used in the present invention will be described. Hydrosodalite is a kind of alkaline rock-forming mineral, and its composition formula is Na ₈ (AlSiO ₄ ) ₆ (O
H) ₂ . The crystal structure is equiaxed and has cages of about 9 Å in size in the structure. Cages can contain cations and anions, which result in carbon dioxide adsorption. Hydrosodalite reacts with carbon dioxide at a high temperature and changes to sodium carbonate (Na ₈ (AlSiO ₄ ) ₆ CO ₃ ). The heating change of hydrosodalite shows the dehydration of zeolite water and a complicated thermal effect up to 400 ° C. That is, the phase changes to the second phase at 300 ° C., and the X-ray diffraction pattern of this phase is not much different from that of the original phase.
Splitting of the diffraction lines and changes in the relative intensity distribution occur. This indicates that heating produces a phase with reduced symmetry of the original crystal lattice. As the temperature increases, one of the split diffraction lines gradually decreases, and at 700 ° C., an equiaxed phase is formed again. At 800 to 900 ° C., another stage of dehydration is seen, and the dehydration is completed. At this stage, it changes to nepheline (NaAlSiO ₄ ) through formation of cane gearite (NaAlSiO ₄ ). Since nepheline no longer reacts with carbon dioxide, the working temperature of hydrosodalite is up to 900 ° C., where it changes to nepheline.

Hydrosodalite is rarely found in nature because the hydroxyl groups in the structure are easily replaced by, for example, chloride ions or sulfate ions and are unstable. Therefore, it is desirable that hydrosodalite is mainly artificially synthesized. There are two methods of synthesizing hydrosodalite by hydrothermal treatment or heat treatment. FIG. 1 shows an example of the mixing amounts of the raw materials and the heat treatment conditions for each synthesis method, but this does not limit the synthesis conditions at all. Further, in FIG. 1, the alumina source and the silica source are based on kaolin, but they are not only kaolin but also industrial raw materials such as sodium silicate and sodium aluminate, natural raw materials such as diatomaceous earth and silica sand, coal ash, steel slag and the like. Can also be obtained from industrial waste.

The conditions for synthesizing the hydrosodalite shown in FIG. 1 will be described below. (A) Synthesis by hydrothermal treatment Kaolin (Jodiakaolin, Al ₂ Si ₂ O ₅ (O
H) A powder mixture of ₄ ) and Na ₂ CO ₃ was calcined at 700 ° C. for 1 hour, and an NaOH aqueous solution was added in an amount equivalent to a 1/3 molar ratio with respect to kaolin, and kneaded well. -Prepare the strike. The paste obtained is autoclaved.
Hydrosodalite is synthesized by performing a hydrothermal treatment at 120 ° C. for 24 hours.

(B) Synthesis by heat treatment Kaolin and NaOH aqueous solution are mixed at a 3:10 molar ratio,
Hydrosodalite is synthesized by heating the obtained paste in a thermostat at 100 ° C. for 25 hours.

The high-temperature flue gas discharged as the combustion gas targeted in the present invention is a flue gas from a lime factory or a cement factory for heating calcium carbonate or dolomite, a factory using fossil fuel, or an internal combustion engine. However, the present invention is not limited thereto, and may be any type of high-temperature exhaust gas containing at least carbon dioxide, or any equivalent type of exhaust gas. Specifically, for example, gases obtained from electric furnaces, converters, blast furnaces, generating furnaces, coke ovens, etc., combustion gases, various reaction gases or gases produced as by-products, gases naturally present or produced, etc. Are typical examples.

The average composition of the exhaust gas is, for example, from a petroleum-fired power plant, CO ₂ : 10%, N ₂ : 75%, O ₂ : 3
%, H ₂ O: 12% (edited by Yuji Shindo, “Atmosphere Enclosing the Earth”, p.109, Ohmsha, 1993). For the separation and recovery of carbon dioxide from exhaust gas, Basically, it is sufficient to examine whether carbon dioxide and nitrogen gas can be separated.

The high-temperature combustion exhaust gas discharged in a high-temperature state can be sent directly to the adsorption step without any temperature adjustment as long as it is within a predetermined temperature range (preferably 100 to 500 ° C.). However, if the temperature is outside the predetermined temperature range, the temperature is adjusted in advance and set to the predetermined temperature. In addition, even when the temperature is 600 ° C. or higher, the present invention can be implemented although the amount of adsorption and / or the amount of reaction decreases. However, at 900 ° C. or higher, hydrosodalite cannot be used because it is thermally decomposed and changes to nepheline.

Next, in order to separate a specific exhaust gas component such as carbon dioxide from the high-temperature combustion exhaust gas, the high-temperature combustion exhaust gas is brought into contact with hydrosodalite to adsorb and / or react with the above-mentioned specific gas component. The specific gas components are separated by heating the hydrosodalite that has adsorbed and / or reacted the gas components to a temperature higher than the adsorption temperature and / or the reaction temperature to desorb the specific gas components. The flue gas treatment system may be of any type, whether it is a fixed bed system or a fluidized bed system, as long as the temperature of the hydrosodalite can be changed. Examples of the shape of the hydrosodalite include powder, fine particles, granules, and molded bodies, but the shape is not particularly limited.

According to the findings of the present inventors, for example, in the case of carbon dioxide and nitrogen gas, the hydrosodalite used in the present invention in a temperature range of 100 to 800 ° C., as shown in Examples described later. Does not adsorb or react with nitrogen gas at all. On the other hand, it was found that carbon dioxide was well adsorbed and / or reacted with hydrosodalite used in the present invention. Further, the adsorption amount and / or reaction amount of the specific component in the high-temperature combustion exhaust gas in the adsorption and / or reaction step varies depending on the adsorption temperature and / or the reaction temperature.

The specific component gas amount (V) that is adsorbed and / or reacted with hydrosodalite and then desorbed by raising the temperature is determined by the adsorption amount and / or reaction amount at the specific component gas adsorption temperature and / or reaction temperature. It is determined using the difference between (V1) and the adsorption amount and / or reaction amount (V2) at the desorption temperature.
Alternatively, by setting temperature conditions for the reaction and desorption, etc., the specific component gas can be easily separated. Note that the relationship of V = V1−V2 is established.

The separation apparatus is operated according to individual emission gas sources such as a large-capacity fixed source such as a lime factory or a cement factory, a thermal power plant or a steel mill for heating calcium carbonate or dolomite, and a small-scale dispersed source such as a car or a household. size,
It can take various forms such as the shape, the material of the heat-resistant container, the form of the temperature holding device, etc. The basic method is to separate carbon dioxide and nitrogen gas at high temperature (preferably 100 to 500 ° C.) using hydrosodalite. The separation and recovery method of the present invention
It goes without saying that the present invention can be carried out irrespective of the above embodiment.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail. The combustion exhaust gas is passed through the hydrosodalite of the present invention at a high temperature (preferably 100 to 500 ° C.) to selectively adsorb and / or react with carbon dioxide. Next, the temperature of the hydrosodalite is raised by heating, and the temperature is raised to a temperature higher than the adsorption temperature and / or the reaction temperature, so that carbon dioxide adsorbed and / or reacted on the hydrosodalite is desorbed. The desorption temperature of carbon dioxide is desirably 800 ° C. or less for practical use. Next, after lowering the temperature of the hydrosodalite,
Through the flue gas, carbon dioxide is selectively adsorbed and / or reacted again. Then, the temperature of the hydrosodalite is increased, and the desorption temperature is set to a temperature higher than the adsorption temperature and / or the reaction temperature, thereby desorbing carbon dioxide adsorbed and / or reacted on the hydrosodalite.
By repeating the above operations, carbon dioxide is separated and recovered from the flue gas. It is necessary that the temperature of the hydrosodalite be changed up and down or cyclically.The method for that can be fixed bed system or fluidized bed system, if the temperature of the hydrosodalite can be changed cyclically, Either method may be used.

[0035]

Next, the present invention will be specifically described based on examples. The following examples show that carbon dioxide and nitrogen gas can be separated at a high temperature using hydrosodalite. It is not intended to limit the invention.

Example 1 Evaluation Method of High-Temperature Separation of Carbon Dioxide FIG. A sample tube made of quartz glass having an inner diameter of 10 mmφ and a length of 300 mm is filled with 1 g of powdered hydrosodalite (the particle size does not need to be specified; there is no problem as long as the gas flows), and helium is used as a carrier gas. While flowing at a flow rate of 30 ml / min, the tube was heated to a predetermined temperature (arbitrary temperature of 700 ° C. or lower) in a tubular furnace and maintained for 1 hour. Thereafter, the temperature was reset to a predetermined adsorption temperature and held. Carbon dioxide or nitrogen gas was flowed together with the carrier gas, and the respective gases were adsorbed and / or reacted with hydrosodalite. After sufficient adsorption and / or reaction of carbon dioxide or nitrogen until the equilibrium was reached, carbon dioxide or nitrogen was stopped and only the carrier gas was flowed for one hour. Next, the temperature of the tubular furnace was gradually increased at a rate of 10 ° C./min using a temperature controller, and the gas desorbed up to 700 ° C. was measured by a detector and recorded by a recorder. Repeat the above operation,
The reproducibility was confirmed.

Example 2 (2-1) Measurement was performed using the apparatus shown in FIG. 1 g of hydrosodalite was packed in a quartz glass sample tube and placed in a tube furnace. 30 ml of helium as carrier gas
/ Min while flowing at 700 ° C. for 1 hour. After the heating, the sample temperature was set to 100 ° C., and then a sufficient amount of carbon dioxide or nitrogen was introduced. Thereafter, only the carrier gas was allowed to flow for one hour, and then the temperature was gradually increased to 700 ° C. at a rate of 10 ° C./min, and the desorbed carbon dioxide or nitrogen was measured. Desorption of carbon dioxide is about 150
Starting at 0 ° C. and observed up to 700 ° C., the total amount of desorption was 5.7 ml. On the other hand, for nitrogen, 100-
No desorption was observed at 700 ° C. That is, it is understood that nitrogen does not adsorb and / or react with hydrosodalite in the same temperature range. Upon repeated measurement, good reproducibility was obtained. From the above results, carbon dioxide is adsorbed and / or reacted on hydrosodalite at 100 ° C,
It has been found that the adsorbed and / or reacted carbon dioxide is gradually desorbed as the temperature rises. If carbon dioxide is adsorbed and / or reacted and desorbed cyclically between 100 ° C. and 700 ° C., carbon dioxide can be separated and recovered. The desorption temperature is 100 times the adsorption and / or reaction temperature.
The temperature can be appropriately selected within a range of higher than 700 ° C. to 700 ° C.

(2-2) The same experiment as in the above (2-1) was performed using 1 g of hydrosodalite. However,
After heating at 700 ° C. for 1 hour, setting the sample temperature at 200 ° C., introducing a sufficient amount of carbon dioxide or nitrogen,
Carbon dioxide or nitrogen desorbed by heating to 0 ° C. was measured. Desorption of carbon dioxide begins at about 250 ° C.
It was observed up to 0 ° C, and the total amount of desorption was 5.9 ml.
On the other hand, desorption of nitrogen was not observed at 200 to 700 ° C. That is, it is understood that nitrogen does not adsorb and / or react with hydrosodalite in the same temperature range. Upon repeated measurement, good reproducibility was obtained.
From the above results, it was found that carbon dioxide was adsorbed and / or reacted with hydrosodalite at 200 ° C., and the adsorbed and / or reacted carbon dioxide was gradually desorbed due to a rise in temperature. If the adsorption and / or reaction and desorption of carbon dioxide are performed cyclically between 200 ° C. and 700 ° C., carbon dioxide can be separated and recovered. The desorption temperature is higher than the adsorption and / or reaction temperature of 200 ° C. and 700 ° C.
If it is in the range up to, it can be selected appropriately.

(2-3) The same experiment as in the above (2-1) was performed using 1 g of hydrosodalite. However,
After heating at 700 ° C. for 1 hour, setting the sample temperature to 300 ° C., introducing a sufficient amount of carbon dioxide or nitrogen,
Carbon dioxide or nitrogen desorbed by heating to 0 ° C. was measured. Desorption of carbon dioxide begins at about 350 ° C.
It was observed up to 0 ° C. and the total amount of desorption was 5.2 ml.
On the other hand, desorption of nitrogen was not observed at 300 to 700 ° C. That is, it is understood that nitrogen does not adsorb and / or react with hydrosodalite in the same temperature range. Upon repeated measurement, good reproducibility was obtained.
From the above results, it was found that carbon dioxide was adsorbed and / or reacted on hydrosodalite at 300 ° C., and the adsorbed and / or reacted carbon dioxide was gradually desorbed as the temperature rose. If carbon dioxide is adsorbed and / or reacted and desorbed cyclically between 300 ° C. and 700 ° C., carbon dioxide can be separated and recovered. The desorption temperature is higher than the adsorption and / or reaction temperature of 300 ° C., and is 700 ° C.
If it is in the range up to, it can be selected appropriately.

(2-4) The same experiment as in the above (2-1) was conducted using 1 g of hydrosodalite. However,
After heating at 700 ° C. for 1 hour, setting the sample temperature to 400 ° C., introducing a sufficient amount of carbon dioxide or nitrogen,
Carbon dioxide or nitrogen desorbed by heating to 0 ° C. was measured. Desorption of carbon dioxide begins at about 450 ° C.
It was observed up to 0 ° C and the total amount of desorption was 2.3 ml.
On the other hand, desorption of nitrogen was not observed at 400 to 700 ° C. That is, it is understood that nitrogen does not adsorb and / or react with hydrosodalite in the same temperature range. Upon repeated measurement, good reproducibility was obtained.
From the above results, it was found that carbon dioxide was adsorbed and / or reacted on hydrosodalite at 400 ° C., and the adsorbed and / or reacted carbon dioxide was gradually desorbed due to a rise in temperature. If carbon dioxide is adsorbed and / or reacted and desorbed cyclically between 400 ° C. and 700 ° C., carbon dioxide can be separated and recovered. The desorption temperature is higher than the adsorption and / or reaction temperature of 400 ° C., and is 700 ° C.
If it is in the range up to, it can be selected appropriately.

(2-5) The same experiment as in the above (2-1) was conducted using 1 g of hydrosodalite. However,
After heating at 700 ° C. for 1 hour, setting the sample temperature at 500 ° C., introducing a sufficient amount of carbon dioxide or nitrogen,
Carbon dioxide or nitrogen desorbed by heating to 0 ° C. was measured. Desorption of carbon dioxide starts at 500 ° C. and 700
° C, and the total amount of desorption was 4.5 ml. On the other hand, with respect to nitrogen, no desorption was observed at 500 to 700 ° C. That is, it is understood that nitrogen does not adsorb and / or react with hydrosodalite in the same temperature range.
Upon repeated measurement, good reproducibility was obtained. From the above results, 50% of carbon dioxide was added to hydrosodalite.
It was found that the carbon dioxide was adsorbed and / or reacted at 0 ° C., and the adsorbed and / or reacted carbon dioxide was gradually desorbed as the temperature rose. 50 adsorption and / or reaction and desorption of carbon dioxide
If cyclically performed between 0 ° C. and 700 ° C., carbon dioxide can be separated and recovered. The desorption temperature is higher than the adsorption and / or reaction temperature of 500 ° C. and can be appropriately selected within a range up to 700 ° C.

(2-6) The same experiment as in the above (2-1) was performed using 1 g of hydrosodalite. However,
After heating at 700 ° C. for 1 hour, setting the sample temperature to 600 ° C., introducing a sufficient amount of carbon dioxide or nitrogen,
Carbon dioxide or nitrogen desorbed by heating to 0 ° C. was measured. Desorption of carbon dioxide starts at 600 ° C. and 700
° C, and the total amount of desorption was 0.8 ml. On the other hand, desorption of nitrogen was not observed at 600 to 700 ° C. That is, it is understood that nitrogen does not adsorb and / or react with hydrosodalite in the same temperature range.
Upon repeated measurement, good reproducibility was obtained. From the above results, carbon dioxide was converted to hydrosodalite by 60%.
It was found that the carbon dioxide was adsorbed and / or reacted at 0 ° C., and the adsorbed and / or reacted carbon dioxide was gradually desorbed as the temperature rose. 60 times the adsorption and / or reaction and desorption of carbon dioxide
If cyclically performed between 0 ° C. and 700 ° C., carbon dioxide can be separated and recovered. The desorption temperature is higher than the adsorption and / or reaction temperature of 600 ° C. and can be appropriately selected within a range up to 700 ° C.

Comparative Example As in the case of the example, the measurement was carried out using silica gel as a sample and using the apparatus shown in FIG. 5 g of silica gel was packed in a quartz glass sample tube and placed in a tube furnace. Heating was performed at 600 ° C. for 2 hours while flowing helium at 30 ml / min as a carrier gas. After heating, the sample temperature was set to 200, 300, 400,
After each setting at 500 ° C., a sufficient amount of carbon dioxide or nitrogen was introduced. Thereafter, only the carrier gas was allowed to flow for one hour, and then the sample temperature was lowered to room temperature. Then, the temperature was gradually increased to 700 ° C. at a rate of 10 ° C./min, and the desorbed gas was measured. No desorption was observed between room temperature and 700 ° C. at adsorption temperatures of 200, 300, 400 and 500 ° C. for both carbon dioxide and nitrogen gas. That is, it was found that neither carbon dioxide nor nitrogen was adsorbed on silica gel at the above adsorption temperature. From the above results, high-temperature separation and recovery of carbon dioxide using silica gel was impossible.

[0044]

As described in detail above, the present invention provides a method for separating and recovering a specific gas component from high-temperature flue gas.
The high-temperature flue gas is passed through hydrosodalite as it is or after it is set at a predetermined temperature, and the specific gas component is adsorbed and / or reacted with hydrosodalite, and then higher than the adsorption temperature and / or reaction temperature. The present invention relates to a method for separating and recovering a specific gas component in flue gas, comprising heating to a temperature and selectively desorbing and recovering the specific gas component. The specific gas components such as carbon dioxide in the exhaust gas discharged as the exhaust gas are not cooled and are kept at a high temperature (preferably 10
(0-500 ° C.).
Further, by utilizing the sensible heat of the separated and recovered specific gas component such as carbon dioxide for the catalytic reaction, the specific gas component can be efficiently recycled at low cost. Further, since the heat energy to be supplied at the time of the catalytic reaction can be reduced, the generation of further carbon dioxide can be prevented.

[Brief description of the drawings]

FIG. 1 shows an example of a hydrosodalite synthesis method.

FIG. 2 is a schematic diagram of an apparatus for evaluating high-temperature separation of carbon dioxide and nitrogen gas.

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[Procedure amendment]

[Submission Date] May 13, 1999 (1999.5.1
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C01B 31/20 (72) Inventor Toshihiko Ozaki 91, Minamiyogo, Kumagami-cho, Nishio-shi, Aichi Prefecture (72) Inventor Yasuo Shibazaki 2-4 Daiba, Atsuta-ku, Nagoya-shi, Aichi Pref. 4D020 AA03 BA08 BC01 CA01 DB02 4G046 JB08 JB11 JB18

Claims (3)

[Claims] When separating and recovering a specific gas component from a high-temperature flue gas discharged as a combustion gas, the high-temperature flue gas is brought into contact with hydrosodalite,
Adsorbing the specific gas component on the hydrosodalite and / or
Or reacting, and then heating the hydrosodalite to a temperature higher than the adsorption temperature and / or reaction temperature to selectively desorb and recover the specific gas component, and the specific gas in the combustion exhaust gas. Component recovery method. 2. The method for recovering a specific gas component according to claim 1, wherein the high-temperature combustion exhaust gas is an exhaust gas from a lime factory, a cement factory, a factory burning fossil fuel, or an internal combustion engine. . 3. The method for recovering a specific gas component according to claim 1, wherein the specific gas component is carbon dioxide.