Method for separating and recovering carbon dioxide and method for producing methanol

Abstract

Provided is a method for separating and recovering carbon dioxide, the method making it possible to separate and recover carbon dioxide obtained by removing hydrogen sulfide and carbonyl sulfide from a raw-material gas containing the carbon dioxide, the hydrogen sulfide, and the carbonyl sulfide. This method for separating and recovering carbon dioxide from a raw-material gas G01 containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by using a pressure swing adsorption method includes a dehumidification step for removing moisture in the raw-material gas G01 to form a dehumidified raw-material gas, and a carbon dioxide recovery step for separating and recovering the carbon dioxide gas from the dehumidified raw-material gas by using a pressure swing adsorption method, wherein the method also includes a carbonyl sulfide hydrolysis step for reacting the carbonyl sulfide with the moisture to hydrolyze the carbonyl sulfide into hydrogen sulfide and carbon dioxide, and a desulfurization step for separating the hydrogen sulfide.

Description

Carbon dioxide separation and capture method and methanol production method

[0001] The present invention relates to a method for separating and capturing carbon dioxide and a method for producing methanol.

[0002] In recent years, carbon dioxide (CO ２ Steelworks are required to reduce emissions of CO2. Steelworks emit large amounts of by-product gases, including blast furnace gas, which is a by-product of blast furnaces, coke oven gas, which is generated from coke ovens, and converter gas, which is generated from converters. Of these, blast furnace gas, which has particularly high emissions, is used as an energy source within steelworks, but blast furnace gas also contains a large amount of CO2. ２ Therefore, CO is released from the blast furnace gas. ２ Separating and effectively utilizing these is an important issue.

[0003] CO ２ As an effective method of utilizing CO ２ For example, Patent Document 1 discloses a method for converting CO into valuable products such as methanol and methane using a catalyst. ２ and hydrogen (H ２ A method for synthesizing methanol from a raw material gas containing methyl methyl ether has been proposed.

[0004] The catalyst used to synthesize the above-mentioned methanol and methane is hydrogen sulfide (H ２ It deteriorates due to sulfur compounds such as CO2 (carbonyl sulfide) and carbonyl sulfide (COS). ２ In order to effectively utilize CO from blast furnace gas, ２ Separation and desulfurization are required.

[0005] CO ２ As a method for separating CO, there is a pressure swing adsorption (PSA) method that utilizes the pressure dependency of the adsorption amount in an adsorbent such as zeolite. For example, Patent Document 2 discloses a method for separating CO using a PSA method. ２ from a raw material gas containing CO ２ A method for separating and recovering these substances has been proposed.

[0006] Reducing furnace gas such as blast furnace gas (CO２ , carbon monoxide (CO), H ２ , nitrogen (N ２ ), water (H ２ O), H ２ CO is extracted from a gas containing S and COS by the PSA method described in Patent Document 2. ２ The process for separating the above and synthesizing methanol using a catalyst can be carried out using a flow chart shown in Figure 1.

[0007] First, a raw material gas G01 such as a reduction furnace gas is converted into CO by a PSA apparatus 2. ２ The raw material gas G01 is introduced into a dehumidification facility 1 installed in the upstream stage of the separation to dehumidify the raw material gas G01. ２ This is because in the PSA method, the H concentration in the raw material gas is reduced. ２ When the O concentration is high, CO ２ This is because the resolution is significantly reduced.

[0008] Next, H ２ The dehumidified feed gas G01 with a reduced O concentration is introduced into the PSA apparatus 2. In the PSA apparatus 2, first, in the adsorption step, the dehumidified feed gas G01 is introduced into the adsorption tower of the PSA apparatus 2, and CO ２ The gas is adsorbed by the adsorbent packed in the adsorption tower, and a non-adsorbed gas G02 containing non-adsorbed gas components that were not adsorbed by the adsorbent is discharged.

[0009] Subsequently, in the desorption step, the pressure inside the adsorption tower is reduced by the pump 3A to remove the CO adsorbed by the adsorbent. ２ Desorb CO ２ The gas containing the above is discharged from the adsorption tower as a desorbed gas G03.

[0010] The discharged desorbed gas G03 is compressed by the compressor 3B and then ２ The gas is mixed with gas G04 and sent to a methanol synthesis facility 4, where methanol G05 is synthesized by the reaction of the following formula (1): ２ + 3H ２ → CH ３ OH + H ２ O (1)

[0011] Patent No. 7049075 Patent No. 6677181

[0012] As mentioned above, blast furnace gas contains CO ２ , CO, H ２ In addition to the main gas components such as ２ It also contains gas components containing sulfur (S) derived from iron ore and coke, such as S and COS. ２ S and COS are CO ２ Therefore, when blast furnace gas is used as the raw material gas G01, H ２ S and COS are obtained by mixing the raw material gas G01 with CO ２ It is separated and recovered together with CO ２ There was a problem that these H ２ If the desorbed gas G03 containing S and COS is introduced into the methanol synthesis equipment 4 to carry out the methanol synthesis reaction, the catalyst used in the methanol synthesis reaction will be deteriorated.

[0013] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to propose a method for separating and recovering carbon dioxide, which can separate and recover carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide, with hydrogen sulfide and carbonyl sulfide removed.

[0014] [1] A method for separating and recovering carbon dioxide from a feed gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by a pressure swing adsorption method, the method comprising: a dehumidification step of removing moisture from the feed gas to obtain a dehumidified feed gas; and a carbon dioxide recovery step of separating and recovering carbon dioxide gas from the dehumidified feed gas by a pressure swing adsorption method, the method further comprising: a carbonyl sulfide hydrolysis step of reacting the carbonyl sulfide with moisture to hydrolyze it into hydrogen sulfide and carbon dioxide; and a desulfurization step of separating the hydrogen sulfide.

[0015] [2] The carbon dioxide separation and capture method according to [1], wherein the carbonyl sulfide hydrolysis step is performed before the dehumidification step.

[0016] [3] The carbon dioxide separation and capture method according to [2], wherein the desulfurization step is performed after the carbon dioxide capture step.

[0017] [4] The carbon dioxide separation and capture method according to [2], wherein the desulfurization step is performed after the carbonyl sulfide hydrolysis step and before the carbon dioxide capture step.

[0018] [5] The carbon dioxide separation and capture method according to [1], wherein the carbonyl sulfide hydrolysis step is performed after the carbon dioxide capture step.

[0019] [6] The carbon dioxide separation and capture method according to [5], further comprising a humidity control step of adjusting the moisture content of the carbon dioxide gas after the carbon dioxide capture step and before the carbonyl sulfide hydrolysis step.

[0020] [7] The carbon dioxide separation and capture method according to [6], wherein the humidity adjustment step is a water washing step of washing the carbon dioxide gas with water.

[0021] [8] The carbon dioxide separation and capture method according to [6], wherein the humidity adjustment step is a steam addition step of adding steam to the carbon dioxide gas.

[0022] [9] The carbon dioxide separation and recovery method according to any one of [1] to [8], wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing an oxide of aluminum.

[0023]

[10] The method for separating and recovering carbon dioxide according to any one of [1] to [8], wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing either or both of a cobalt oxide or sulfide, and a molybdenum oxide or sulfide.

[0024]

[11] The carbon dioxide separation and capture method according to any one of [1] to

[10] , wherein the desulfurization agent used in the desulfurization step is a dry desulfurization agent, and the dry desulfurization agent contains at least one selected from the group consisting of iron oxide, copper oxide, and zinc oxide.

[0025]

[12] The carbon dioxide separation and capture method according to

[11] , wherein at least two types of dry desulfurization agents are used in the desulfurization step, at least one type of dry desulfurization agent contains an oxide of iron, and at least one type of dry desulfurization agent contains an oxide of copper.

[0026]

[13] The carbon dioxide separation and capture method according to any one of [1] to

[12] , further comprising a compression step of pressurizing the carbon dioxide gas to form a compressed gas, and subjecting the compressed gas to the desulfurization step.

[0027]

[14] The carbon dioxide separation and recovery method according to any one of [1] to

[13] , wherein the raw material gas is a reduction furnace gas.

[0028]

[15] The carbon dioxide separation and capture method according to

[14] , wherein the reduction furnace gas is a blast furnace gas.

[0029]

[16] A method for producing methanol, comprising synthesizing hydrocarbons or methanol from carbon dioxide obtained by using the carbon dioxide separation and capture method according to any one of [1] to

[15] above.

[0030] According to the present invention, it is possible to separate and recover carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide, from which hydrogen sulfide and carbonyl sulfide have been removed.

[0031] Fig. 1 is a diagram showing the flow of an example of a conventional carbon dioxide separation and capture method. Fig. 2 is a diagram showing the flow of a preferred example of a carbon dioxide separation and capture method according to the present invention. Fig. 3 is a diagram showing the flow of a preferred example of a method for producing methanol according to the present invention.

[0032] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A carbon dioxide separation and capture method according to the present invention is a method for separating and capturing carbon dioxide from a feed gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by pressure swing adsorption, and includes a dehumidification step of removing moisture from the feed gas to obtain a dehumidified feed gas, and a carbon dioxide capture step of separating and capturing carbon dioxide gas from the dehumidified feed gas by pressure swing adsorption. Here, the method is characterized by including a carbonyl sulfide hydrolysis step of reacting carbonyl sulfide with moisture to hydrolyze it into hydrogen sulfide and carbon dioxide, and a desulfurization step of separating the hydrogen sulfide.

[0033] The present inventors have ２ , H ２ H from a source gas containing S and COS ２ CO with S and COS removed ２As a result, we have found that COS, which is relatively difficult to remove, can be separated and recovered by pre-hydrolysis as shown in the following formula (2). ２ Converted to S and the resulting H ２ S is replaced with H originally contained in the raw material gas. ２ This resulted in the desulfurization of H from the raw gas. ２ CO with S and COS removed ２ Therefore, the obtained CO ２ When the gas is introduced into the methanol synthesis facility 4 to synthesize methanol, deterioration of the catalyst used in the methanol synthesis reaction can be suppressed. ２ O → CO ２ + H ２ S (2)

[0034] Figure 2 shows a flow chart of a preferred example of the carbon dioxide separation and capture method according to the present invention. In Figure 2, the same components as those shown in Figure 1 are denoted by the same reference numerals. Hereinafter, the carbon dioxide separation and capture method according to the present invention will be specifically described using the flow chart shown in Figure 2, but the present invention is not limited thereto.

[0035] First, the raw material gas G01 is introduced into the humidity control equipment 5, and the H ２ The O concentration is adjusted (humidity adjustment process). ２ , H ２ The gas contains S and COS. Examples of such gases include by-product gases emitted from steel mills. Examples of by-product gases include CO, CO₂, and CO₂, such as blast furnace gas, coke oven gas, and converter gas. ２ , CO, N ２ , H ２ , H ２ The present invention is directed to the reduction furnace gas containing COS and H from the blast furnace gas among the above gases. ２ S is removed well, and CO ２ Separating and recovering gas, ２ Emissions can be reduced.

[0036] The humidity control equipment 5 controls the H ２The humidity control equipment 5 can be configured as a water washing equipment that washes the raw material gas G01 with water. In this case, the humidity control step is configured as a water washing step. In the water washing step, the H concentration of the raw material gas G01 is adjusted by adjusting the water washing temperature. ２ In addition, the water washing process can adjust the O concentration. ３ When the water contains water-soluble gas components such as the above, these water-soluble gas components can be removed.

[0037] The humidity control equipment 5 can be configured as a steam addition equipment that adds steam to the raw material gas G01. In this case, the humidity control step is configured as a steam addition step. In the steam addition equipment, the H ２ The O concentration can be controlled.

[0038] Next, in the humidity adjustment step, H ２ The raw material gas G01 with the adjusted O concentration is introduced into the COS hydrolysis equipment 6, and the COS contained in the raw material gas G01 is converted into H according to the above formula (2). ２ React with O and H ２ S and CO ２ and hydrolyzed to form carbonyl sulfide (carbonyl sulfide hydrolysis step).

[0039] The COS hydrolysis equipment 6 can be configured as a catalyst-packed column packed with a catalyst that promotes the reaction of the above formula (2). The packed catalyst can be a catalyst containing an oxide of aluminum (Al). The catalyst can also contain either or both of an oxide or sulfide of cobalt (Co) and an oxide or sulfide of molybdenum (Mo).

[0040] In this carbonyl sulfide hydrolysis step, COS and H ２ By passing the raw material gas G01 containing O, the COS contained in the raw material gas G01 can be hydrolyzed. The temperature of the COS hydrolysis equipment 6 such as a catalyst packed tower (i.e., the temperature of the catalyst in the packed tower) is ２ From the viewpoint of preventing condensation of O, it is preferable to set the temperature at 100°C or higher. ２S is often more reactive with dry desulfurization agents than COS, and H ２ By converting it to S, the efficiency of the dry desulfurization agent is improved.

[0041] Next, COS is H ２ The raw material gas G01 converted into S is introduced into a dehumidification facility 1, where moisture is removed from the raw material gas G01 to produce a dehumidified raw material gas (dehumidification step).

[0042] The dehumidification equipment 1 cools the raw material gas G01, for example, to ２ The dehumidifying equipment 1 can be configured as a dehumidifying device that condenses and dehumidifies H O such as Al oxide, silicon (Si) oxide, and zeolite. ２ The desiccant-type equipment can be configured as a packed adsorption tower filled with an adsorbent that adsorbs O.

[0043] The dehumidification step is preferably carried out until the dew point of the raw material gas G01 becomes 0° C. or less, and more preferably until it becomes −20° C. or less. This allows for the CO 2 to be absorbed into the adsorbent in the subsequent carbon dioxide recovery step. ２ A decrease in the amount of adsorption can be suppressed.

[0044] Thereafter, the dehumidified raw material gas G01 obtained in the dehumidification step is introduced into the PSA device 2, and CO is extracted from the dehumidified raw material gas G01 by the PSA method. ２ The gas is separated and recovered (carbon dioxide recovery process).

[0045] The PSA device 2 is a CO ２ In the adsorption step, the dehumidified raw gas G01 is passed through the adsorption tower, whereby the CO ２ The gas components that are not adsorbed by the adsorbent are discharged from the adsorption tower as non-adsorbed gas G02. Then, in the desorption step, the pressure inside the adsorption tower is reduced using a pump 3, thereby removing CO from the adsorbent. ２ The desorbed CO ２In this carbon dioxide recovery process, when the raw material gas G01 is a blast furnace gas, the desorbed gas G03 containing CO, N is separated and recovered. At this time, the pressure of the gas on the inlet side of the pump 3 is, for example, 1 kPa or more and 20 kPa or less, and the pressure of the gas on the outlet side of the pump 3 is, for example, 100 kPa or more. ２ , and H ２ is mainly non-adsorbed gas G02, CO ２ , H ２ S, COS, and H ２ O is mainly separated into the desorbed gas G03.

[0046] The pressure in the adsorption tower during decompression in the desorption step is preferably 1 kPa or more and 20 kPa or less, and more preferably 5 kPa or more and 10 kPa or less.

[0047] Next, the desorbed gas G03 is introduced into the desulfurization equipment 7, and the H contained in the desorbed gas G03 is ２ S is separated (desulfurization process).

[0048] The desulfurization equipment 7 is H ２ The desorption gas 03 can be configured as a desulfurization agent packed tower filled with a dry desulfurization agent that adsorbs S. By passing the desorption gas 03 through the desulfurization agent packed tower, H ２ S can be desulfurized by adsorbing it onto a desulfurizing agent.

[0049] Examples of dry desulfurizing agents include oxides of iron (Fe), oxides of copper (Cu), and oxides of zinc (Zn), and a desulfurizing agent containing one or more selected from the group consisting of these oxides can be used.

[0050] It is also preferable to use at least two types of dry desulfurization agents, at least one of which contains an oxide of Fe, and at least one of which contains an oxide of Cu. Various combinations of desulfurization agents and the order in which they are used are conceivable. First, an inexpensive dry desulfurization agent containing an oxide of Fe is used to remove H contained in the desorbed gas G03. ２ After removing S, the remaining H ２ It is preferable to remove S and COS with a dry desulfurizing agent containing Cu oxide.

[0051] In the desulfurization step using at least two types of desulfurization agents, the number of desulfurization agent packed towers is equal to or greater than the number of types of desulfurization agents, each desulfurization agent packed tower is filled with a desulfurization agent, and the desorption gas G03 is sequentially circulated through each desulfurization agent packed tower, thereby desulfurizing the desorbed gas G03. For example, when two types of dry desulfurization agents are used, two desulfurization agent packed towers 7A and 7B are installed as shown in FIG. 2, the desulfurization agent packed tower 7A is filled with a dry desulfurization agent containing Fe oxide, and the desulfurization agent packed tower 7B is filled with a dry desulfurization agent containing Cu oxide. Then, the desorption gas G03 is sequentially circulated through the desulfurization agent packed towers 7A and 7B, whereby the desorption gas G03 is desulfurized to produce H ２ CO, which is a desorbed gas G03 with reduced S and COS concentrations ２ Gas G06 can be obtained.

[0052] In the above description, the COS hydrolysis equipment 6 is provided upstream of the dehumidification equipment 1, and the carbonyl sulfide hydrolysis step is performed upstream of the dehumidification step. However, the present invention is not limited to this. The COS hydrolysis equipment 6 may be provided downstream of the PSA unit 2, and the carbonyl hydrolysis step may be performed downstream of the carbon dioxide recovery step.

[0053] However, in the COS hydrolysis step, H ２ It is preferable to use a raw material gas G01 in which the O concentration is increased to 1% or more. However, in order to maintain the performance of the PSA apparatus 2, a dehumidification facility 1 is installed, and H ２ There is no facility to increase the O concentration. ２ If the O concentration is low and COS cannot be sufficiently hydrolyzed, COS that does not easily react with the desulfurization agent remains in the gas, and may flow into the catalyst in the desulfurization equipment 7 in the subsequent stage, causing deterioration of the catalyst. On the other hand, the raw material gas G01 after the water washing step has a H vapor pressure close to that at the temperature. ２ For example, when the water washing step is performed at 25° C., the H ２The O concentration can be easily increased to 1% or more. Therefore, the raw material gas G01 after the water-washing step is suitable for COS hydrolysis. Therefore, as shown in Figure 2, it is preferable to provide the COS hydrolysis equipment 6 in the upstream stage of the dehumidification equipment 1 and to perform the carbonyl sulfide hydrolysis step in the upstream stage of the dehumidification step.

[0054] When the COS hydrolysis equipment 6 is provided downstream of the PSA unit 2 and the carbonyl hydrolysis step is performed downstream of the carbon dioxide recovery step, it is preferable to further provide a humidity control equipment 5 downstream of the PSA unit 2 and upstream of the COS hydrolysis equipment 6, and to further perform a humidity control step for adjusting the moisture content of the carbon dioxide gas downstream of the carbon dioxide recovery step and upstream of the carbonyl sulfide hydrolysis step. This allows the COS contained in the desorbed gas G03 to be sufficiently hydrolyzed.

[0055] In addition, in FIG. 2, the desulfurization equipment 7 is provided at the rear of the PSA unit 2, and the desulfurization process is carried out at the rear of the carbon dioxide recovery process. This is because the performance of the adsorbent such as zeolite used in the carbon dioxide recovery process is ２ This is because the desulfurization equipment 7 does not deteriorate due to S and COS, so there is no need to provide the desulfurization equipment 7 upstream of the PSA unit 2. However, it is also possible to provide the desulfurization equipment 7 upstream of the PSA unit 2, and perform the desulfurization step upstream of the carbon dioxide capture step. Furthermore, it is also possible to provide the desulfurization equipment 7 upstream of the PSA unit 2 and downstream of the COS hydrolysis equipment 6, and perform the desulfurization step downstream of the carbonyl sulfide hydrolysis step and upstream of the carbon dioxide capture step.

[0056] However, from the viewpoint of suppressing carbon deposition (coking) resulting from CO in the gas, a gas with a low CO concentration is preferable, and therefore it is preferable to provide the desulfurization equipment 7 at a stage downstream of the PSA unit 2 and perform the desulfurization step at a stage downstream of the carbon dioxide recovery step. ２ Therefore, by providing a desulfurization facility 7 at the downstream of the PSA unit 2, it is possible to adsorb sulfur and carbon monoxide. ２ S and COS are CO2 emitted from the PSA device 2 ２ The desorbed gas G03 is concentrated in the desorbed gas G03 containing H. ２Since the concentration of S and COS is high and the flow rate is reduced, the desulfurization capacity is increased and the amount of H slipping from the outlet of the desulfurization equipment 7 is reduced. ２ It also has the effect of reducing the amount of S and COS.

[0057] FIG. 3 shows a flow chart of a preferred example of the method for producing methanol according to the present invention. In FIG. 3, the same components as those shown in FIG. 2 are denoted by the same reference numerals. The difference between the flow chart shown in FIG. 3 and the flow chart shown in FIG. 2 is that the COS hydrolysis equipment 16 is configured to perform a water-gas shift reaction step in addition to the COS hydrolysis step. The flow chart shown in FIG. 3 also includes a compression step in which the desorbed gas G03 is introduced into a compressor 3B and pressurized to a pressure of 1000 kPa or more to produce a compressed gas. Furthermore, the flow chart shown in FIG. 3 also includes a desulfurization step in which H ２ CO from which S and COS have been removed ２ The gas G06 is introduced into a methanol synthesis facility 4 to produce methanol G05. The differences will be described below.

[0058] First, in order to perform the water-gas shift reaction step in the COS hydrolysis equipment 16, the humidity control equipment 5 is composed of a humidity control equipment 5A that performs a water washing step and a humidity control equipment 5B that performs a steam addition step of adding steam G07 to the raw material gas G01. First, the raw material gas G01 is introduced into the humidity control equipment 5A and the water washing step is performed to remove H ２ Adjust the O concentration. ２ The raw material gas G01 with the adjusted O concentration is introduced into the humidity control equipment 5B, and water vapor is added to the raw material gas G01 to produce H ２ Increase the O concentration. ２ The raw material gas G01 with an increased O concentration is introduced into the COS hydrolysis equipment 16, where the carbonyl sulfide hydrolysis step and the water gas shift reaction step are carried out. ２ The processing efficiency can be improved.

[0059] In the humidity control equipment 5B, water vapor G07 is added to the raw material gas G01. From the viewpoint of preventing carbon deposition on the catalyst in the COS hydrolysis equipment 16, the H in the raw material gas G01 after the addition of water vapor G07 is ２ The O / CO molar ratio is preferably 1.0 or higher, and more preferably 2.0 or higher. Furthermore, since the water-gas shift reaction is an exothermic reaction and a lower temperature is more advantageous in terms of chemical equilibrium, the temperature of the catalyst in the COS hydrolysis equipment 16 is preferably 200°C or higher and 500°C or lower, and more preferably 200°C or higher and 400°C or lower. Furthermore, the temperature of the raw material gas G01 after the addition of water vapor G07 is also preferably 200°C or higher and 500°C or lower, and more preferably 200°C or higher and 400°C or lower.

[0060] Following the COS hydrolysis step and the water gas shift reaction step, the raw material gas G01 is dehumidified in the dehumidification equipment 1. ２ A dehumidification step is performed to remove O from the raw gas G01 to obtain a dehumidified raw gas G01. The dehumidification step is preferably performed so that the dew point of the raw gas G01 becomes 0°C or less, and more preferably -20°C or less. Thereafter, in the adsorption step, the dehumidified raw gas G01 is passed through a PSA apparatus 2 equipped with an adsorbent-packed column packed with zeolite as an adsorbent, and CO ２ In the desorption step, the pressure inside the adsorption tower is reduced by the pump 3A, and the CO ２ is desorbed from the adsorbent, and CO ２ The gas containing the above is discharged from the adsorption tower as a desorbed gas G03.

[0061] Next, the desorption gas G03 discharged from the adsorption tower is introduced into the compressor 3B and pressurized. The pressure of the desorption gas G03 may be set to an appropriate value depending on the reaction in the subsequent stage. In the PSA unit 2 in the previous stage, when methanol is synthesized, the pressure of the desorption gas G03 is preferably set to 1 MPa or more and 10 MPa or less via the compressor 3B.

[0062] The desorbed gas G03 is then passed through a desulfurization agent packed tower 7A filled with a dry desulfurization agent containing Fe oxide, and then passed through a desulfurization agent packed tower 7B filled with a dry desulfurization agent containing Cu oxide, thereby reducing the H ２ Reduces S and COS concentrations. ２ The desorption gas G03 with reduced S and COS concentrations is CO ２ The desorbed gas G03 is recovered as a gas G06. The use of the pressurized desorption gas G03 is preferable because it is expected to increase the desulfurization capacity and accelerate the desulfurization reaction. In order to improve the desulfurization performance of the desulfurization agent packed tower 7B, a dehumidification step may be performed by installing a dehumidification equipment 1 in the upstream stage.

[0063] And CO ２ Gas G06 to H ２ After mixing with the gas G04, the mixture is introduced into the methanol synthesis equipment 4, where methanol G05 is synthesized by the reaction of the above formula (1). ２ Gas G06 is H ２ Since S and COS are removed, deterioration of the catalyst used in the synthesis reaction of methanol G05 can be suppressed.

[0064] In the above explanation, methanol G05 is produced in the methanol synthesis equipment 4, but it may also be configured to produce hydrocarbons. In that case, a hydrocarbon synthesis equipment filled with a hydrocarbon synthesis catalyst may be used instead of the methanol synthesis equipment 4. For example, when the hydrocarbon to be synthesized is methane, a reaction vessel filled with a catalyst containing Ni is kept at a temperature of 200°C to 400°C, and CO ２ Gases G06 and H ２ The hydrocarbon synthesis facility is configured to allow gas G04 to flow.

[0065] According to the present invention, it is possible to separate and recover carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide, from which hydrogen sulfide and carbonyl sulfide have been removed.

[0066] 1 Dehumidification equipment 2 Pressure swing device 3, 3A Pump 3B Compressor 4 Methanol synthesis equipment 5, 5A, 5B Humidity control equipment 6, 16 Carbonyl sulfide hydrolysis equipment 7 Desulfurization equipment G01 Raw material gas G02 Non-adsorbed gas G03 Desorbed gas G04 Hydrogen gas G05 Methanol G06 Carbon dioxide gas G07 Water vapor

Claims

1. A method for separating and recovering carbon dioxide from a feed gas containing carbon dioxide, hydrogen sulfide and carbonyl sulfide by pressure swing adsorption, comprising: a dehumidification step of removing moisture from the feed gas to obtain a dehumidified feed gas; and a carbon dioxide recovery step of separating and recovering carbon dioxide gas from the dehumidified feed gas by pressure swing adsorption, the carbonyl sulfide hydrolysis step of reacting the carbonyl sulfide with moisture to hydrolyze it into hydrogen sulfide and carbon dioxide; and a desulfurization step of separating the hydrogen sulfide.

2. The carbon dioxide separation and capture method according to claim 1, wherein the carbonyl sulfide hydrolysis step is performed prior to the dehumidification step.

3. The carbon dioxide separation and capture method according to claim 2, wherein the desulfurization step is performed after the carbon dioxide capture step.

4. The carbon dioxide separation and capture method according to claim 2, wherein the desulfurization step is performed after the carbonyl sulfide hydrolysis step and before the carbon dioxide capture step.

5. The carbon dioxide separation and capture method according to claim 1, wherein the carbonyl sulfide hydrolysis step is performed after the carbon dioxide capture step.

6. The carbon dioxide separation and capture method according to claim 5, further comprising a moisture adjustment step for adjusting the moisture content of the carbon dioxide gas, subsequent to the carbon dioxide capture step and prior to the carbonyl sulfide hydrolysis step.

7. The carbon dioxide separation and capture method according to claim 6, wherein the humidity adjustment step is a water washing step in which the carbon dioxide gas is washed with water.

8. The carbon dioxide separation and capture method according to claim 6, wherein the humidity adjustment step is a water vapor addition step of adding water vapor to the carbon dioxide gas.

9. The method for separating and capturing carbon dioxide according to any one of claims 1 to 8, wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing an oxide of aluminum.

10. A method for separating and recovering carbon dioxide according to any one of claims 1 to 8, wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing either or both of a cobalt oxide or sulfide and a molybdenum oxide or sulfide.

11. A carbon dioxide separation and capture method according to any one of claims 1 to 10, wherein the desulfurization agent used in the desulfurization step is a dry desulfurization agent, and the dry desulfurization agent contains at least one selected from the group consisting of iron oxide, copper oxide, and zinc oxide.

12. The carbon dioxide separation and capture method according to claim 11, wherein at least two types of dry desulfurization agents are used in the desulfurization step, at least one type of dry desulfurization agent containing an oxide of iron and at least one type of dry desulfurization agent containing an oxide of copper.

13. A method for separating and capturing carbon dioxide according to any one of claims 1 to 12, further comprising a compression step of compressing the carbon dioxide gas to form a compressed gas, and supplying the compressed gas to the desulfurization step.

14. A method for separating and capturing carbon dioxide according to any one of claims 1 to 13, wherein the feed gas is a reduction furnace gas.

15. The carbon dioxide separation and capture method according to claim 14, wherein the reduction furnace gas is a blast furnace gas.

16. A method for producing methanol, comprising synthesizing hydrocarbons or methanol from carbon dioxide obtained by using the carbon dioxide separation and capture method according to any one of claims 1 to 15.

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