Gas treatment method and carbon dioxide treatment method

Abstract

This gas treatment method comprises: (a) a step for reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) a step for transporting the formic acid ester from a first place to a second place; (c) a step for hydrolyzing the transported formic acid ester to obtain a mixture containing formic acid, the hydrocarbon compound having a hydroxy group, and water; (d) a step for decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (e) a step for fixing the carbon dioxide.

Description

Gas treatment method and carbon dioxide treatment method

[0001] The present invention relates to a gas treatment method and a carbon dioxide treatment method.

[0002] Formic acid (HCOOH) has a carbon dioxide (CO ２ ) has a very high density of about 96% by mass, and is therefore attracting attention as a carbon dioxide carrier when transporting carbon dioxide to a site where it is stored (carbon dioxide storage site).

[0003] For example, carbon monoxide emitted from a steel mill or the like is sometimes reacted with methanol and water to produce formic acid, which is then transported to a carbon dioxide storage site using the formic acid as a carbon dioxide carrier. Carbon dioxide capture and storage (CCS; Carbon Dioxide Capture and Storage) is being considered, which involves decomposing formic acid into hydrogen and carbon dioxide and capturing and storing the carbon dioxide produced by the decomposition underground to prevent an increase in the carbon dioxide concentration in the atmosphere. In CCS, for example, carbon dioxide is absorbed into an alkaline aqueous solution such as an amine, and the aqueous solution is heated to capture a gas containing a high concentration of carbon dioxide, which is then stored underground. For example, Patent Document 1 discloses a carbon dioxide capture method and capture device.

[0004] JP 2012-110805 A

[0005] As mentioned above, formic acid has attracted attention as a carbon dioxide carrier. However, because formic acid is highly toxic and corrosive, it is necessary to select an appropriate container for transporting formic acid and to handle it with care.

[0006] The reaction of carbon monoxide with water to obtain formic acid is carried out in the following two steps. While the conversion rate of carbon monoxide in Step 1 is high, the conversion rate of methyl formate in Step 2 is generally low, and a large amount of water, about 2 to 10 times the reaction equivalent, is required to promote the reaction in Step 2. However, since the formic acid produced by the reaction in Step 2 forms an azeotrope with water, a huge amount of energy is required to concentrate formic acid from a mixture of formic acid and water. (Step 1) CO + CH ３ OH⇔HCOOCH３ (Step 2) HCOOCH ３ +H ２ O⇔HCOOH+CH ３ OH

[0007] In view of the above circumstances, one aspect of the present invention aims to provide a gas treatment method that is easy to handle during transportation and has excellent energy efficiency. Another aspect of the present invention aims to provide a gas treatment method and a carbon dioxide treatment method that constitute part of the above method.

[0008] A gas processing method according to one aspect of the present invention includes the following steps: (a) reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) transporting the formic acid ester from a first location to a second location; (c) hydrolyzing the transported formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water; (d) decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (e) fixing the carbon dioxide.

[0009] Another aspect of the present invention provides a gas processing method comprising the following steps: (a) reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) transporting the formic acid ester from a first location to a second location; (c) hydrolyzing the transported formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water; (d) decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (e) generating valuable resources using the carbon dioxide.

[0010] According to the gas treatment method of one aspect of the present invention, a formate ester, which is less toxic and corrosive than formic acid, is transported, and therefore handling during transportation is easy. Furthermore, according to the gas treatment method of one aspect of the present invention, the formate ester is hydrolyzed to obtain formic acid, and then the formic acid in a mixture containing formic acid and water is decomposed, thereby eliminating the need to concentrate the formic acid and achieving excellent energy efficiency.

[0011] According to one aspect of the present invention, there is provided a gas treatment method that is easy to handle during transportation and has excellent energy efficiency. Also, according to another aspect of the present invention, there is provided a gas treatment method and a carbon dioxide treatment method that constitute part of the above-mentioned method.

[0012] FIG. 1 is a configuration diagram showing an example of a gas processing facility according to the present invention.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or corresponding parts will be designated by the same reference numerals, and duplicated explanations will be omitted.

[0014] [Gas Processing Facility] Fig. 1 is a configuration diagram showing an example of a gas processing facility according to the present invention. Gas processing facility 100 shown in Fig. 1 is divided into a first location side and a second location side.

[0015] The processing equipment 10 is located at the first location side. The processing equipment 10 includes a reaction device 11, a separation device 12, and a separation device 13.

[0016] The gas containing carbon monoxide is transferred to the reactor 11 through the transfer pipe L11. The reactor 11 is a device that produces a formate ester from the carbon monoxide contained in the gas by bringing carbon monoxide into contact with a hydrocarbon compound having a hydroxy group in the presence of a catalyst. Examples of hydrocarbon compounds having a hydroxy group include monohydric alcohols such as methanol, ethanol, and propanol, and dihydric alcohols such as methanediol and ethylene glycol. Examples of formate esters include methyl formate, ethyl formate, and propyl formate. Methyl formate is preferred as the formate ester because it is an excellent carbon dioxide carrier. When the hydrocarbon compound having a hydroxy group is methanol, methyl formate is produced in the reactor 11 by the following reaction (A): CO + CH ３ OH⇔HCOOCH ３ …(A)

[0017] The gas may be, for example, an exhaust gas emitted from an ironworks or the like. The gas contains at least carbon monoxide. The gas may contain components other than carbon monoxide (for example, sulfur oxides (SO Ｘ), nitrogen oxides (NO Ｘ If the gas contains sulfur oxides and / or nitrogen oxides, a device (e.g., an adsorption device) for absorbing the sulfur oxides and / or nitrogen oxides in the gas may be provided before the reaction device 11.

[0018] The reaction in the reaction device 11 may be carried out under conditions of heat and pressure. For example, the reaction may be carried out under conditions of a reaction temperature of 70 to 90° C. and a pressure of 3 to 6 GPa.

[0019] A transfer pipe L12 and a transfer pipe L13 are connected to the reaction apparatus 11. The transfer pipe L12 transfers a hydrocarbon compound having a hydroxy group, and the transfer pipe L13 transfers a catalyst. An example of the catalyst transferred through the transfer pipe L13 is sodium methoxide.

[0020] The formic ester produced in the reaction device 11 is transferred to the separation device 12 through the transfer pipe L14. The formic ester transferred through the transfer pipe L14 may be in the form of a liquid or gas. In the reaction device 11, the unreacted hydrocarbon compound having a hydroxy group is also transferred to the separation device 12 through the transfer pipe L14.

[0021] The separation device 12 is a device that separates the formate ester produced in the reaction device 11 from components other than the formate ester (for example, a hydrocarbon compound having a hydroxy group, a catalyst). The separation device 12 may be, for example, a gas-liquid distillation device. A transfer pipe L15 is connected to the separation device 12. Furthermore, a device (not shown) that separates the unreacted carbon monoxide and the formate ester may be provided before or after the separation device 12. For example, when the formate ester is methyl formate, a separation device may be provided before the T1 line of the separation device 12.

[0022] The formate ester separated in the separation device 12 is transported from the first location to the second location by transportation means T1. The transported formate ester may consist essentially of formate ester, or may be a mixture containing components other than formate ester (e.g., a hydrocarbon compound having a hydroxy group). Examples of transportation means T1 include a ship, a diesel locomotive, a train, and a truck. The formate ester may be transported at room temperature and atmospheric pressure, at room temperature and elevated pressure, at low temperature and atmospheric pressure, or at low temperature and elevated pressure. The first location may be, for example, a carbon dioxide capture location. The second location may be a carbon dioxide fixation location or a location where valuable materials generated from carbon dioxide are used or consumed. The first location may be a region, country, etc. with a higher carbon dioxide emission rate than the second location, or a region, country, etc. with a lower carbon dioxide emission rate. The second location may be a region, country, etc. with a larger carbon dioxide fixation capacity than the first location.

[0023] The hydrocarbon compound having a hydroxy group, catalyst, etc. separated in the separation device 12 are transferred through a transfer pipe L15 to a separation device 13. The hydrocarbon compound having a hydroxy group transferred through the transfer pipe L15 may be a liquid.

[0024] The separation device 13 is a device that separates the hydrocarbon compounds having hydroxy groups transferred through the transfer pipe L15 from components other than the hydrocarbon compounds having hydroxy groups (e.g., catalyst). The separation device 13 may be, for example, a membrane separation device. The separation device 13 is connected to a transfer pipe L16 and a transfer pipe L17. The transfer pipe L16 mainly transfers the hydrocarbon compounds having hydroxy groups, and the transfer pipe L17 mainly transfers the components other than the hydrocarbon compounds having hydroxy groups.

[0025] The hydrocarbon compound having a hydroxy group transported through the transfer pipe L16 is mixed with a hydrocarbon compound having a hydroxy group supplied through the transfer pipe L18 and a hydrocarbon compound having a hydroxy group transported by the transport means T2 described below, and then transported to the reaction device 11 through the transfer pipe L12 and recycled.

[0026] The formic ester transported by transport means T1 is transported, for example, to treatment equipment 20 at a second location. Treatment equipment 20 includes a reaction device 21 and separation devices 22 to 26. After being transported to treatment equipment 20, the formic ester transported by transport means T1 is mixed with a catalyst transported through a transfer pipe L19 and water transported through a transfer pipe L20. The mixture of the formic ester, catalyst, and water is transported to the reaction equipment 21 through a transfer pipe L21. The amount of catalyst transported through the transfer pipe L19 may be adjusted depending on the amount of catalyst to be recycled.

[0027] The reactor 21 is an apparatus for hydrolyzing a formic acid ester to produce formic acid and a hydrocarbon compound having a hydroxy group, and simultaneously decomposing the formic acid into carbon dioxide and hydrogen in the presence of a catalyst. When the formic acid ester is methyl formate, the reactor 21 produces methanol, carbon dioxide, and hydrogen from the methyl formate through the following reactions (B) and (C): HCOOCH ３ +H ２ O⇔CH ３ OH+HCOOH…(B) HCOOH→H ２ +CO ２ …(C)

[0028] In the reaction device 21, reaction (C) progresses as formic acid is produced by hydrolysis of the formic ester. In particular, the use of a catalyst promotes reaction (C), shifting the equilibrium toward the side where the formic ester is consumed and formic acid is produced (the right side in reaction (B)), thereby promoting the hydrolysis reaction of the formic ester. Furthermore, promotion of the hydrolysis reaction of the formic ester makes it easier for the hydrolysis reaction to proceed without the need for an excessive supply of water.

[0029] The reaction in the reactor 21 may be carried out under normal temperature and pressure conditions, normal temperature and pressurized conditions, heated and normal pressure conditions, or heated and pressurized conditions. For example, the reaction may be carried out under conditions of a reaction temperature of normal temperature (20°C) to 100°C and pressurized conditions. Furthermore, when the reactor is sealed, hydrogen and carbon dioxide are produced as the decomposition reaction of formic acid proceeds, and the pressure inside the reactor increases. However, the hydrolysis of the formate ester and the decomposition of formic acid may be carried out in a reactor pressurized by hydrogen and carbon dioxide (i.e., under pressurized conditions).

[0030] In the reaction device 21, the hydrolysis of the formate ester and the decomposition of formic acid proceed, thereby generating carbon dioxide and hydrogen, and the pressure inside the reaction device 21 increases. In particular, the use of a catalyst promotes the reaction (C), which makes it easier to increase the pressure inside the reaction device 21. For this reason, the reaction device 21 may be a pressure-resistant container. The pressure generated by the increase in pressure inside the reaction device 21 may be used when fixing carbon dioxide.

[0031] As the catalyst, for example, the catalysts described in Japanese Patent No. 5390389, Japanese Patent No. 4572393, International Publication No. 2012-070620, and Japanese Patent No. 6502091 can be used.

[0032] A transfer pipe L22 is connected to the reaction device 21. The transfer pipe L22 transfers, for example, the formic acid ester, the hydrocarbon compound having a hydroxyl group, carbon dioxide, hydrogen, water, and the catalyst to the separation device 22.

[0033] The separator 22 separates the carbon dioxide and hydrogen produced in the reactor 21 from components other than carbon dioxide and hydrogen (e.g., formate esters, etc.). The separator 22 may be, for example, a gas-liquid distillation apparatus. The separator 22 is connected to a transfer pipe L23 and a transfer pipe L24.

[0034] The transfer pipe L23 is a transfer pipe that transfers carbon dioxide and hydrogen to the separation device 23. The separation device 23 is a device that separates carbon dioxide and hydrogen. The separation device 23 may be, for example, a membrane separation device. The separation device 23 is connected to a transfer pipe L25 and a transfer pipe L26. The transfer pipe L25 is a transfer pipe that mainly transfers carbon dioxide, and the transfer pipe L26 is a transfer pipe that mainly transfers hydrogen.

[0035] The carbon dioxide transferred through the transfer pipe L25 is transported, for example, by a pipeline (not shown) or the like and processed appropriately. The carbon dioxide transferred through the transfer pipe L25 may be fixed, for example, underground or in minerals. Furthermore, the carbon dioxide transferred through the transfer pipe L25 may be used to generate valuable materials such as carbon and carbonates.

[0036] Known methods can be applied to fix carbon dioxide and to generate valuable resources using carbon dioxide. In these methods, the carbon dioxide transferred through the transfer pipe L26 may be supplied to a separator (not shown) or the like in order to increase the purity of the carbon dioxide before fixation.

[0037] The transfer pipe L24 is a transfer pipe that transfers the formate ester, the hydrocarbon compound having a hydroxy group, water, and the catalyst to the separation device 24. The separation device 24 is a device that separates the formate ester, the hydrocarbon compound having a hydroxy group, and water from the water and the catalyst. The separation device 24 may be, for example, a gas-liquid distillation device. The separation device 24 is connected to a transfer pipe L27 and a transfer pipe L28. The transfer pipe L27 is a transfer pipe that mainly transfers the formate ester, the hydrocarbon compound having a hydroxy group, and water, and the transfer pipe L28 is a transfer pipe that mainly transfers the water and the catalyst.

[0038] Transfer pipe L27 is a transfer pipe that transfers the formate ester, the hydrocarbon compound having a hydroxy group, and water to separation device 25. Separation device 25 is a device that separates the formate ester, the hydrocarbon compound having a hydroxy group, and water. Separation device 25 may be, for example, a membrane separation device. Transfer pipe L29 and transfer pipe L30 are connected to separation device 25. Transfer pipe L29 is a transfer pipe that mainly transfers the formate ester and the hydrocarbon compound having a hydroxy group, and transfer pipe L30 is a transfer pipe that mainly transfers water.

[0039] The transfer pipe L29 transfers the formate ester and the hydrocarbon compound having a hydroxy group to the separation apparatus 26. The separation apparatus 26 separates the formate ester and the hydrocarbon compound having a hydroxy group. The separation apparatus 26 may be, for example, a gas-liquid distillation apparatus. The separation apparatus 26 is connected to the transfer pipe L31. The transfer pipe L31 mainly transfers the formate ester. The formate ester transferred through the transfer pipe L31 is mixed with the water and catalyst transferred through the transfer pipe L28 and the water transferred through the transfer pipe L30. The mixture containing the formate ester, water, and catalyst is then transferred through the transfer pipe L20, mixed with the water transferred through the transfer pipe L32, and recycled. The amount of water transferred through the transfer pipe L32 may be adjusted depending on the amount of recycled water.

[0040] The hydrocarbon compounds having a hydroxy group separated in the separation device 26 are transported from the second location to the first location by transportation means T2. The transported hydrocarbon compounds having a hydroxy group may consist essentially of hydrocarbon compounds having a hydroxy group, or may be a mixture containing components other than hydrocarbon compounds having a hydroxy group (e.g., formate esters). Examples of transportation means T2 include ships, diesel locomotives, railways, and trucks. The hydrocarbon compounds having a hydroxy group may be transported at room temperature and pressure. The first location may be, for example, a carbon dioxide recovery location. The second location may be a carbon dioxide fixation location or a location where valuable materials generated from carbon dioxide are used or consumed. The first location may be a region, country, etc. that emits more carbon dioxide than the second location, or may be a region, country, etc. that emits less carbon dioxide. The second location may be a region, country, etc. that has a greater potential for carbon dioxide fixation than the first location.

[0041] According to gas processing equipment 100, since formic acid esters, which are less toxic and corrosive than formic acid, are transported, handling during transportation is easy. Furthermore, according to gas processing equipment 100, since formic acid is obtained by hydrolyzing formic acid esters and then the formic acid in a mixture containing formic acid and water is decomposed, there is no need to concentrate the formic acid, and energy efficiency is excellent.

[0042] [Gas Processing Method] A method for recovering carbon monoxide in a gas and fixing carbon dioxide using gas processing equipment 100 will be described. That is, one embodiment of the present invention is a gas processing method including at least the following steps: (a) a step of reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) a step of transporting the formic acid ester obtained in step (a) from a first location to a second location; (c) a step of hydrolyzing the formic acid ester transported in step (b) to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water; (d) a step of decomposing the formic acid in the mixture obtained in step (c) to obtain carbon dioxide and hydrogen; and (e) a step of fixing the carbon dioxide obtained in step (d).

[0043] Gas processing facility 100 may also be used to recover carbon monoxide in the gas and produce valuable materials using carbon dioxide. That is, another embodiment of the present invention is a gas processing method including at least the following steps. For these gas processing methods, reference may be made to the description of the gas processing facility described above. (a) A step of reacting a carbon monoxide-containing gas with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester. (b) A step of transporting the formic acid ester obtained in step (a) from a first location to a second location. (c) A step of hydrolyzing the formic acid ester transported in step (b) to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water. (d) A step of decomposing the formic acid in the mixture obtained in step (c) to obtain carbon dioxide and hydrogen. (e) A step of producing valuable materials using the carbon dioxide obtained in step (d).

[0044] According to the gas treatment method of this embodiment, since a formic acid ester, which is less toxic and corrosive than formic acid, is transported, handling during transportation is easy. Furthermore, according to the gas treatment method of this embodiment, since formic acid is obtained by hydrolyzing a formic acid ester and then the formic acid in a mixture containing formic acid and water is decomposed, there is no need to concentrate the formic acid, and thus energy efficiency is excellent.

[0045] <Step (a)> Step (a) is a step of reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic ester. Step (a) can also be said to be a step of removing carbon monoxide from the gas. Step (a) may include the following steps: (a1) a step of reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a mixture of a formic ester and a hydrocarbon compound having a hydroxy group; and (a2) a step of separating the mixture obtained in step (a1) into a formic ester and a hydrocarbon compound having a hydroxy group and recovering the formic ester.

[0046] Step (a1) is a step in which carbon monoxide is brought into contact with a hydrocarbon compound having a hydroxy group in a reaction device 11, and the carbon monoxide in the gas is reacted with the hydrocarbon compound having a hydroxy group to obtain a mixture of a formate ester and a hydrocarbon compound having a hydroxy group. In step (a1), a catalyst may be added to promote the reaction between carbon monoxide and the hydrocarbon compound having a hydroxy group. The mixture may be in the form of a liquid or gas. When the hydrocarbon compound having a hydroxy group is methanol, the following reaction (A) proceeds in step (a1): CO + CH ３ OH⇔HCOOCH ３ …(A)

[0047] Step (a2) is a step of separating the mixture into the formate ester and the hydrocarbon compound having a hydroxy group in a separation device 12, and recovering the formate ester. The separation method may be, for example, gas-liquid distillation.

[0048] <Step (b)> Step (b) is a step of transporting the formic acid ester from a first location to a second location. The first location may be a carbon dioxide recovery location, and the second location may be a carbon dioxide fixation location. The first location may be a region, country, etc. that emits more carbon dioxide than the second location. The second location may be a carbon dioxide fixation location, or may be a location where valuable materials generated from carbon dioxide are used or consumed. The second location may be a region, country, etc. that can fix a larger amount of carbon dioxide than the first location. The formic acid ester may be transported by ship, diesel locomotive, railroad, truck, etc. Because formic acid esters are less corrosive and less toxic than formic acid, the gas treatment method of the present invention is safer than transporting formic acid and can reduce the management burden during transportation.

[0049] <Step (c)> Step (c) is a step in which the transported formate ester is brought into contact with water in a reaction apparatus 21 for hydrolysis to obtain formic acid and a hydrocarbon compound having a hydroxy group. When the formate ester is methyl formate, step (c) obtains formic acid and methanol from the transported methyl formate. When the formate ester is methyl formate, the following reaction (B) proceeds in step (c): HCOOCH ３ +H ２ O⇔CH ３ OH+HCOOH…(B)

[0050] <Step (d)> Step (d) is a step of obtaining carbon dioxide and hydrogen by decomposing the formic acid obtained in step (c) in a reaction device 21. In step (d), the following reaction (C) proceeds: HCOOH → H ２ +CO ２ …(C)

[0051] In step (d), a catalyst may be used from the viewpoint of promoting reaction (C). Examples of the catalyst that can be used include those described in Japanese Patent Nos. 5,390,389, 4,572,393, WO 2012-070620, and 6,502,091. When formic acid is produced by hydrolysis of the formate ester in step (c), reaction (C) proceeds. In particular, the use of a catalyst promotes reaction (C), shifting the equilibrium toward the side where the formate ester is consumed and formic acid is produced (to the right in reaction (B)), thereby promoting the hydrolysis reaction in step (c). Furthermore, promotion of the hydrolysis reaction in step (c) facilitates the hydrolysis reaction without the need for excessive water supply. Because reactions (B) and (C) proceed in a chain reaction, it is preferable to carry out steps (c) and (d) in the same reactor.

[0052] <Step (e)> In one embodiment, the step (e) is a step of fixing the carbon dioxide obtained in the step (d). In another embodiment, the step (e) is a step of producing valuable materials using the carbon dioxide obtained in the step (d). Known methods can be applied to fix carbon dioxide and produce valuable materials using carbon dioxide.

[0053] The gas processing method according to this embodiment may further include the following steps: (f) transporting the hydrocarbon compound having a hydroxy group obtained in step (c), and (g) reacting the hydrocarbon compound having a hydroxy group transported in step (f) with a gas containing carbon monoxide to obtain a formic acid ester.

[0054] <Step (f)> Step (f) is a step of transporting the hydrocarbon compound having a hydroxy group obtained in step (c) above. The hydrocarbon compound having a hydroxy group may be transported, for example, from the second location to the first location, or from the second location to a third location different from the first location. The hydrocarbon compound having a hydroxy group may be transported by ship, diesel locomotive, railroad, truck, etc.

[0055] <Step (g)> Step (g) is a step of obtaining a formate ester by reacting the hydrocarbon compound having a hydroxy group, which has been transported in step (f), with a gas containing carbon monoxide. For example, the transported hydrocarbon compound having a hydroxy group may be used in step (a), or the transported hydrocarbon compound having a hydroxy group may be transferred to reactor 11 and reacted with a gas containing carbon monoxide to obtain a formate ester. That is, a gas processing method according to another embodiment of the present invention is a gas processing method comprising: a step of reacting a hydrocarbon compound having a hydroxy group, which has been transported from a second location to a first location, with a gas containing carbon monoxide to obtain a formate ester; and a step of transporting the formate ester from the first location to the second location.

[0056] [Method for Treating Carbon Dioxide] Another embodiment of the present invention is the following method for treating carbon dioxide, which includes at least the following steps: (x) hydrolyzing a formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water, (y) decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen, and (z1) fixing carbon dioxide.

[0057] Another embodiment of the present invention is the following method for treating carbon dioxide, which includes at least the following steps. For these carbon dioxide treatment methods, reference may be made to the descriptions of the gas treatment facility and gas treatment method described above. (x) A step of hydrolyzing a formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water. (y) A step of decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen. (z2) A step of producing valuable materials using carbon dioxide.

[0058] <Step (x)> Step (x) is a step in which the formate ester after transportation is brought into contact with water in a reaction apparatus 21 to hydrolyze the formate ester, thereby obtaining formic acid and a hydrocarbon compound having a hydroxy group. When the formate ester is methyl formate, step (x) obtains formic acid and methanol from the methyl formate after transportation. When the formate ester is methyl formate, the following reaction (B) proceeds in step (x): HCOOCH ３ +H ２ O⇔CH ３ OH+HCOOH…(B)

[0059] <Step (y)> Step (y) is a step of obtaining carbon dioxide and hydrogen by decomposing formic acid in the mixture obtained in step (x) in the reaction device 21. In step (y), the following reaction (C) proceeds: HCOOH → H ２ +CO ２ …(C)

[0060] In step (y), a catalyst may be used from the viewpoint of promoting reaction (C). Examples of the catalyst that can be used include those described in Japanese Patent No. 5390389, Japanese Patent No. 4572393, International Publication No. 2012-070620, and Japanese Patent No. 6502091. When formic acid is produced by hydrolysis of the formate ester in step (x), reaction (C) proceeds. In particular, the use of a catalyst promotes reaction (C), shifting the equilibrium toward the side where the formate ester is consumed and formic acid is produced (to the right in reaction (B)), thereby promoting the hydrolysis reaction in step (x). Furthermore, promotion of the hydrolysis reaction in step (x) facilitates the hydrolysis reaction without the need for excessive water supply. Because reactions (B) and (C) proceed in a chain reaction, it is preferable to carry out steps (x) and (y) in the same reactor.

[0061] <Step (z1) and Step (z2)> In one embodiment, step (z1) is a step of fixing the carbon dioxide obtained in step (y). In another embodiment, step (z2) is a step of producing valuable materials using the carbon dioxide obtained in step (y). Known methods can be applied to fix carbon dioxide and produce valuable materials using carbon dioxide.

[0062] The present invention includes, for example, the following inventions [1] to

[11] : [1] A gas treatment method comprising: (a) a step of reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester, (b) a step of transporting the formic acid ester from a first location to a second location, (c) a step of hydrolyzing the formic acid ester after transportation to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water, (d) a step of decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen, and (e) a step of fixing the carbon dioxide. [2] A gas processing method comprising: (a) reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) transporting the formic acid ester from a first location to a second location; (c) hydrolyzing the transported formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water; (d) decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (e) producing a valuable resource using the carbon dioxide. [3] The gas processing method according to [1] or [2], wherein steps (c) and (d) are carried out in the same reactor. [4] The gas processing method according to any one of [1] to [3], wherein step (d) is a step of decomposing the formic acid using a catalyst. [5] The gas processing method according to any one of [1] to [4], further comprising transporting the hydrocarbon compound having a hydroxy group obtained in step (c) from the second location to the first location. [6] The gas processing method according to [5], wherein the hydrocarbon compound having a hydroxy group transported from the second location to the first location is used in the reaction of step (a). [7] A gas processing method comprising: a step of reacting the hydrocarbon compound having a hydroxy group transported from the second location to the first location with a gas containing carbon monoxide to obtain a formate ester; and a step of transporting the formate ester from the first location to the second location.[8] A method for treating carbon dioxide, comprising: (x) hydrolyzing a formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water, (y) decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen, and (z1) fixing the carbon dioxide. [9] A method for treating carbon dioxide, comprising: (x) hydrolyzing a formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water, (y) decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen, and (z2) producing a valuable resource using the carbon dioxide.

[10] The method for treating carbon dioxide according to [8] or [9], wherein the step (x) and the step (y) are carried out in the same reactor.

[11] The method for treating carbon dioxide according to [8] or [9], wherein the step (y) is a step of decomposing the formic acid using a catalyst.

[0063] 10, 20... treatment equipment, 11, 21... reactor, 12, 13, 22, 23, 24, 25, 26... separation equipment, T1, T2... transportation means, 100... gas treatment equipment.

Claims

1. A gas treatment method comprising: (a) a step of reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) a step of transporting the formic acid ester from a first location to a second location; (c) a step of hydrolyzing the formic acid ester after transportation to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water; (d) a step of decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (e) a step of fixing the carbon dioxide.

2. A gas processing method comprising: (a) a step of reacting a gas containing carbon monoxide with a hydrocarbon compound having a hydroxy group to obtain a formic acid ester; (b) a step of transporting the formic acid ester from a first location to a second location; (c) a step of hydrolyzing the formic acid ester after transportation to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxy group, and water; (d) a step of decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (e) a step of generating valuable materials using the carbon dioxide.

3. The gas processing method according to claim 1 or 2, wherein the steps (c) and (d) are carried out in the same reactor.

4. The gas treatment method according to claim 1 or 2, wherein the step (d) is a step of decomposing the formic acid using a catalyst.

5. The gas processing method according to claim 1 or 2, further comprising the step of transporting the hydroxyl group-containing hydrocarbon compound obtained in step (c) from the second location to the first location.

6. The gas processing method according to claim 5, wherein the hydrocarbon compound having a hydroxy group transported from the second place to the first place is used in the reaction in step (a).

7. A gas processing method comprising: a step of reacting a hydrocarbon compound having a hydroxyl group, which has been transported from a second location to a first location, with a gas containing carbon monoxide to obtain a formic acid ester; and a step of transporting the formic acid ester from the first location to the second location.

8. A method for treating carbon dioxide, comprising: (x) a step of hydrolyzing a formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxyl group, and water; (y) a step of decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (z1) a step of fixing the carbon dioxide.

9. A method for treating carbon dioxide, comprising: (x) a step of hydrolyzing a formic acid ester to obtain a mixture containing formic acid, a hydrocarbon compound having a hydroxyl group, and water; (y) a step of decomposing the formic acid in the mixture to obtain carbon dioxide and hydrogen; and (z2) a step of producing valuable materials using the carbon dioxide.

10. The method for treating carbon dioxide according to claim 8 or 9, wherein the step (x) and the step (y) are carried out in the same reactor.

11. The method for treating carbon dioxide according to claim 8 or 9, wherein the step (y) is a step of decomposing the formic acid using a catalyst.

Images