Carbon dioxide reforming method and carbon dioxide reforming system

Abstract

A carbon dioxide reforming method according to the present disclosure comprises: a carbon dioxide acquisition step for acquiring carbon dioxide; a carbon material acquisition step for acquiring a carbon material used in water or gas treatment; and a plasma treatment step for reforming the carbon dioxide into carbon monoxide by subjecting the carbon dioxide to plasma treatment in the presence of the carbon material. A carbon dioxide reforming system (200) comprises: a carbon dioxide acquisition unit (5) for acquiring carbon dioxide; a carbon material acquisition unit (6) for acquiring a carbon material used in water or gas treatment; and a plasma reforming control unit (7) for reforming the carbon dioxide into carbon monoxide by subjecting the carbon dioxide to plasma treatment in the presence of the carbon material.

Description

Carbon dioxide reforming method and carbon dioxide reforming system

[0001] This disclosure relates to a carbon dioxide reforming method and a carbon dioxide reforming system.

[0002] To achieve carbon neutrality, carbon dioxide (CO2) is recovered from exhaust gases and the atmosphere. ２ There is a growing demand for gas reforming technologies that can transform carbon dioxide into high-value-added substances, and research is underway on technologies that reduce carbon dioxide to carbon monoxide (CO) using discharge plasma.

[0003] In Patent Document 1, CO ２ A method for converting CO to a plasma jet generator ２ Supplying gas, CO ２ By igniting a plasma in a gas, a plasma jet containing CO and O is generated. The plasma jet is then introduced into a carbon reaction chamber containing carbon donor particles, where O and C combine to produce CO. From the carbon reaction chamber, CO and CO are released. ２ A method is disclosed for extracting a generated gas consisting of CO, recycling at least a portion of the generated gas, and supplying it to the plasma jet generator or a second plasma jet generator. ２ To efficiently convert carbon into CO, it is necessary to supply a carbon source from an external source, which presented challenges in terms of increased processing costs and the consumption of the carbon source.

[0004] On the other hand, with the strengthening of PFAS regulations, the increase in waste activated carbon used for adsorption and removal of PFAS from water and exhaust gases, and the methods for treating it, have become a challenge. Among organofluorine compounds, perfluoroalkyl compounds and polyfluoroalkyl compounds are collectively called PFAS.

[0005] International Patent Publication WO2023 / 222708

[0006] Carbon materials such as waste activated carbon used in water treatment and exhaust gas treatment, including PFAS removal, are rendered harmless by decomposing the adsorbed substances through incineration at high temperatures. However, this process burns carbon and CO2. ２ There was a problem with it being released into the atmosphere.

[0007] This disclosure was made to solve the above-mentioned problems and aims to provide a carbon dioxide reforming method and carbon dioxide reforming system that efficiently reforms carbon dioxide into carbon monoxide, reforms adsorbed substances on carbon materials used in water treatment and exhaust gas treatment to reduce their harmfulness, and further recycles the carbon materials.

[0008] The carbon dioxide reforming method according to this disclosure is characterized by comprising: a carbon dioxide acquisition step of acquiring carbon dioxide; a carbon material acquisition step of acquiring carbon material used in the treatment of water or gas; and a plasma treatment step of reforming the carbon dioxide into carbon monoxide by subjecting it to plasma treatment in the presence of the carbon material.

[0009] The carbon dioxide reforming system according to this disclosure is characterized by comprising: a carbon dioxide acquisition unit that acquires carbon dioxide; a carbon material acquisition unit that acquires carbon material used in the treatment of water or gas; and a plasma reforming control unit that reforms the carbon dioxide into carbon monoxide by applying plasma treatment in the presence of the carbon material.

[0010] According to this disclosure, not only can carbon dioxide be efficiently converted into carbon monoxide, but the adsorbed substances on carbon materials used in water treatment and exhaust gas treatment can be modified to reduce their harmfulness, and the carbon materials can be recycled.

[0011] It is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus using the carbon dioxide reforming method according to Embodiment 1. It is a flowchart showing the reforming step of the carbon dioxide reforming method according to Embodiment 1. It is a cross-sectional view for explaining a carbon dioxide reforming apparatus using the carbon dioxide reforming method according to Embodiment 2. It is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus using the carbon dioxide reforming method according to Embodiment 3. It is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus using the carbon dioxide reforming method according to Embodiment 4. It is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus using the carbon dioxide reforming method according to Embodiment 5. It is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus using the carbon dioxide reforming method according to Embodiment 6. It is a block diagram showing the configuration of a carbon dioxide reforming system using the carbon dioxide reforming method according to Embodiment 7.

[0012] Embodiment 1. FIG. 1 is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 1.

[0013] As shown in FIG. 1, the carbon dioxide reforming apparatus 100 of Embodiment 1 includes a processing container 1 provided with a carbon material supply port 1a and a carbon monoxide discharge port 1b, and a plasma generation unit 2 that generates a discharge plasma P provided with a carbon dioxide inlet 2a and electrodes 2b and 2c.

[0014] In the processing container 1, a carbon material C is supplied from the carbon material supply port 1a, and CO ２ is reduced in the presence of the carbon material C, and the reformed CO is discharged from the carbon monoxide discharge port 1b. In the processing container 1, the plasma generation unit 2 is arranged so that the generated discharge plasma P contacts the supplied carbon material C.

[0015] The plasma generation unit 2 is provided in a housing 2d made of an insulating material with electrodes 2b and 2c so that the generated discharge plasma P contacts the carbon material C supplied to the processing container 1, and a voltage is supplied between the electrodes 2b and 2c by a power source 2e.

[0016] The plasma generation unit 2 is provided with a carbon dioxide inlet 2a for introducing CO ２ In FIG. 1, the introduced CO ２The carbon dioxide inlet 2a is provided so that a spiral, or circumferentially swirling, plasma flow is formed, but this is not the only option. ２ When the carbon dioxide inlet 2a is provided so as to form a spiral plasma flow, the plasma flow is stably maintained away from the inner wall of the plasma generation unit housing, ２ By increasing the contact efficiency between gas and plasma, CO ２ This has the effect of improving the conversion rate from CO to CO.

[0017] Next, the carbon dioxide reforming method according to Embodiment 1 will be described using Figure 2. Figure 2 is a flowchart showing the reforming steps of the carbon dioxide reforming method according to Embodiment 1.

[0018] First, CO ２ In the acquisition step (S201 in Figure 2), CO2 is used for reforming. ２ Obtain gas containing CO. ２ There are no restrictions on the source, but examples include exhaust gases from steel and chemical plants, boiler exhaust gases, exhaust gases from thermal power plants, and CO2 recovered from the atmosphere. ２ You can use it.

[0019] CO ２ A higher concentration is desirable, with 80% or higher being preferred. ２ If the concentration is low, the coexisting gas (for example, O ２ , N ２ ) comes into contact with the plasma and CO ２ It inhibits the reforming reaction and reduces its efficiency. Also, NO Ｘ It produces undesirable by-products such as the following.

[0020] Next, in the carbon material acquisition step (S202 in Figure 2), carbon material C used in treatment facilities that treat water or gas is acquired. For example, activated carbon used in water treatment plants to adsorb and remove harmful substances (PFAS, pharmaceuticals, organic halogen compounds, etc.) from water is included. Also included is activated carbon used to adsorb and remove VOCs (Volatile Organic Compounds) from factory exhaust gas.

[0021] Carbon material C can be any carbon-containing material that can be used for treating water or gas, such as granular activated carbon, powdered activated carbon, graphite, charcoal, coal, or biochar.

[0022] Finally, in the plasma treatment step (S203 in Figure 2), CO is used in the presence of the carbon material C. ２ A discharge plasma is formed in a gas. Examples of discharge plasmas include, but are not limited to, DC arc, AC arc, gliding arc discharge, inductively coupled plasma, and microwave plasma. ２ The goal is to induce ionization in a gas.

[0023] CO ２ CO is converted to CO by a discharge plasma in the reaction shown in equation (1) below, where e is an electron. ２　 + e → CO + O + e...(1)

[0024] Note that the CO2 listed in formula (1) ２ CO is not necessarily in the ground state, but can be in electronically excited, vibrationally excited, or rotationally excited states. ２ It also exists. Therefore, equation (1) is the ground state CO ２ This includes not only direct dissociation reactions but also stepwise dissociation reactions that proceed through excited states.

[0025] The oxygen atom (O) produced in equation (1) is converted to CO by the reaction shown in equation (2) below upon contact with a carbon material: O + C → CO ... (2)

[0026] Furthermore, some of the oxygen produced in equation (1) becomes oxygen molecules in the reaction shown in equation (3): O + O → O ２ ... (3)

[0027] O generated by equation (3) ２ It reacts with carbon materials at high temperatures to produce CO in the reaction shown in equation (4) below. ２ + 2C → 2CO...(4)

[0028] Furthermore, at high temperatures, the Boodor reaction occurs, resulting in CO ２The carbon material reacts with the CO material, and CO is produced by the reaction shown in equation (5) below. ２ + C → 2CO...(5)

[0029] These reactions, from equation (1) to equation (5), produce CO in the presence of a carbon material. ２ By forming a plasma, CO can be efficiently produced. ２ It can be reduced to CO.

[0030] "Plasma treatment in the presence of carbon materials" refers to a state where the carbon material is in direct contact with the plasma, or where active species (oxygen atoms, excited oxygen molecules, excited CO) are generated by the plasma. ２ This refers to a state in which the carbon material comes into contact with the discharge plasma. The former involves placing the carbon material between electrodes that generate the discharge plasma. The latter involves forming the discharge plasma into a torch shape and positioning the carbon material so that it comes into contact with the torch.

[0031] There are no restrictions on the type of power used to generate the plasma, but it is preferable to use power derived from natural energy sources such as solar and wind power. When surplus power is generated depending on weather conditions, CO2 is released. ２ It can be operated in a way that reduces CO to CO.

[0032] The generated CO can be used as a raw material for methanol, SAF (Sustainable Aviation Fuel), resin materials, etc., or as a reducing agent in steelmaking. Its uses are not limited to these.

[0033] Substances adsorbed onto carbon materials are modified upon contact with plasma through reactions involving charged particles, reactive species (radicals), heat, and light. This results in the formation of CO, CO ２ It is converted into inorganic substances, reducing or neutralizing its harmfulness.

[0034] Thus, through the reforming steps S201 to S203, CO ２ CO can be converted to CO ２ By performing plasma modification in the presence of carbon material, not only can the conversion rate to CO be improved, but used carbon material (C+O) that is normally incinerated can also be utilized. ２ →CO２ ) is used as a resource (C+O → CO, C+CO ２ →2CO) and CO ２ This reduces emissions and allows for the recycling of carbon materials as CO. Furthermore, the harmful effects of adsorbed substances on carbon materials are reduced through plasma modification.

[0035] As described above, the carbon dioxide reforming method according to this embodiment 1 includes a carbon dioxide acquisition step of acquiring carbon dioxide, a carbon material acquisition step of acquiring carbon material C used in the treatment of water or gas, and a plasma treatment step of reforming the carbon dioxide into carbon monoxide by applying plasma treatment in the presence of carbon material C, so CO ２ CO can be converted to CO ２ By performing plasma modification in the presence of carbon material, not only can the conversion rate to CO be improved, but used carbon material (C+O) that is normally incinerated can also be utilized. ２ →CO ２ ) is used as a resource (C+O → CO, C+CO ２ →2CO) and CO ２ This reduces emissions and allows for the recycling of carbon materials as CO. Furthermore, the harmful effects of adsorbed substances on carbon materials are reduced through plasma modification.

[0036] Embodiment 2. Embodiment 2 describes a case in which activated carbon, on which an organofluorine compound containing PFAS is adsorbed, is used as the carbon material C.

[0037] Figure 3 is a cross-sectional view illustrating a carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 2.

[0038] As shown in Figure 3, in the carbon dioxide reforming method according to Embodiment 2, when activated carbon on which an organofluorine compound including PFAS has been adsorbed is obtained in the carbon material acquisition step (S202 in Figure 2), in the plasma treatment step (S203 in Figure 2), the supplied CO ２ water vapor (H ２ Mix in (O) and subject to plasma treatment.

[0039] The other methods of the carbon dioxide reforming method according to Embodiment 2 and the basic configuration of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method are the same as those of the carbon dioxide reforming method and carbon dioxide reforming apparatus 100 using Embodiment 1, and corresponding parts are denoted by the same reference numerals and their descriptions are omitted.

[0040] As a result, if the adsorbed material contains fluorine (F), such as PFAS, it is recovered as hydrogen fluoride (HF) through decomposition. The water vapor concentration can be arbitrarily determined according to the amount of adsorbed material and the power of plasma generation. If the water vapor concentration is too low, the conversion rate to HF decreases, while if the water vapor concentration is too high, CO ２ The conversion efficiency from CO decreases. Generally, CO ２ It is preferable to add 1-20% water vapor to the gas.

[0041] As described above, according to the carbon dioxide reforming method of this embodiment 2, in the carbon material acquisition step, if the acquired carbon material is activated carbon on which an organofluorine compound has been adsorbed, in the plasma treatment step, the carbon dioxide is subjected to plasma treatment in the presence of water, so that the adsorbed organofluorine compound can be recovered as HF by decomposition.

[0042] When the adsorbed substance, such as PFAS, contains fluorine (F), it comes into contact with the discharge plasma (P) and, after decomposition, forms HF in the presence of water vapor. This prevents the C-F bond from reforming and leaking to the outside. HF can be easily recovered by dissolving it in water or reacting it with calcium.

[0043] In the above embodiment 2, the supplied CO ２ Although water vapor was mixed with the carbon material C to be treated and subjected to plasma treatment, if the carbon material C to be treated is wet and contains moisture (for example, activated carbon used in water treatment), the same effect can be obtained without mixing in water vapor by treating it in an undried state.

[0044] Embodiment 3. Embodiment 3 describes a case in which F is recovered using a fluorine trap section.

[0045] Figure 4 is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 3.

[0046] As shown in Figure 4, the carbon dioxide reformer 100 of Embodiment 3 is equipped with a fluorine trap section 3 at the carbon monoxide outlet 1b. The fluorine trap section 3 contains at least calcium (Ca), for example, calcium hydroxide (Ca(OH) ２ ) is used, and F is calcium fluoride (CaF ２ They are captured as such.

[0047] The other configurations of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 3 are the same as those of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 1, and corresponding parts are denoted by the same reference numerals and their descriptions are omitted.

[0048] In this way, the gas reformed to CO passes through the fluorine trap section 3, which contains at least Ca, thereby capturing the F contained in the adsorbed material and suppressing its leakage to the outside. CaF ２ CO is a valuable material used in optical lenses and the like, and in this embodiment, ２ In addition to the conversion and recycling of carbon materials, it also involves the detoxification of harmful perfluorinated compounds and CaF ２ This results in the generation and recovery of valuable materials.

[0049] Furthermore, a gas containing at least water vapor can be mixed upstream of the fluorine trap section 3. In this case, the fluorine compounds produced by the decomposition of the adsorbed substance are converted to HF, and Ca(OH) ２ The reactivity with the fluorine is improved, allowing for more reliable removal in the fluorine trap section 3.

[0050] As described above, according to the carbon dioxide reforming method of this embodiment 3, in the plasma treatment step, carbon monoxide is discharged through the fluorine trap section 3 containing Ca, so that F contained in the adsorbed substance can be captured and leakage to the outside can be suppressed. In addition, harmful organofluorine compounds and CaF can be removed. ２ This results in the generation and recovery of valuable materials.

[0051] Embodiment 4. Embodiment 4 describes a case in which the carbon material C is preheated using the heat generated in the reforming reaction.

[0052] Figure 5 is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 4.

[0053] As shown in Figure 5, the carbon dioxide reformer 100 of Embodiment 4 includes a heat exchange unit 4 that preheats the supplied carbon material C using waste heat from the reforming reaction to CO.

[0054] The other configurations of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 4 are the same as those of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 1, and corresponding parts are denoted by the same reference numerals, and their descriptions are omitted.

[0055] This reduces the amount of electricity required to supply power to the plasma. Furthermore, in the case of activated carbon used in water treatment, preheating can lower the moisture content, adjusting it to a moisture level suitable for modification.

[0056] As described above, according to the carbon dioxide reforming method of this embodiment 4, in the plasma treatment step, the carbon material to be obtained in the carbon material acquisition step is preheated by the waste heat from the reforming reaction to carbon monoxide, thereby reducing the power input to the plasma. Furthermore, in the case of activated carbon used in water treatment, the moisture content can be reduced by preheating, adjusting it to a moisture content suitable for reforming.

[0057] Embodiment 5. In Embodiment 5, the waste heat from the reforming reaction is used to convert CO ２ This section explains how to preheat the device.

[0058] Figure 6 is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 5.

[0059] As shown in Figure 6, the carbon dioxide reformer 100 of Embodiment 5 uses the waste heat from the reforming reaction to CO to supply CO ２ It is equipped with a heat exchange section 4 for preheating.

[0060] The other configurations of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 5 are the same as those of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 1, and corresponding parts are denoted by the same reference numerals, and their descriptions are omitted.

[0061] This allows for a reduction in the amount of power supplied to the plasma.

[0062] As described above, according to the carbon dioxide reforming method of this embodiment 5, the carbon dioxide to be acquired in the carbon dioxide acquisition step is preheated by the waste heat from the reforming reaction to carbon monoxide in the plasma treatment step, thereby reducing the power input to the plasma.

[0063] Embodiment 6. Embodiment 6 describes a case in which only a portion (surface layer) of the carbon material C is reacted with a discharge plasma P, and the carbon material in which only a portion (surface layer) has reacted is recovered.

[0064] Figure 7 is a cross-sectional view showing the configuration of a carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 6.

[0065] As shown in Figure 7, the carbon dioxide reformer 100 of Embodiment 5 is equipped with a carbon material outlet 1c. The carbon material outlet 1c is provided with a carbon monoxide outlet 1b and a carbon material discharge control unit 9. The carbon material discharge control unit 9 adjusts the discharge rate of the carbon material so that the carbon material C remains in the processing container for a predetermined time.

[0066] The other configurations of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 6 are the same as those of the carbon dioxide reforming apparatus 100 using the carbon dioxide reforming method according to Embodiment 1, and corresponding parts are denoted by the same reference numerals, and their descriptions are omitted.

[0067] It is not necessary to react the entire carbon material C with the discharge plasma P; it is also possible to react only a portion of it. Specifically, by appropriately setting the contact time with the discharge plasma P, a recycled carbon material C in which only a portion (surface layer) has reacted can be obtained. ＲThis allows for the recovery of substances adsorbed near the surface of the carbon material C. As a result, the amount of activated carbon decreases, but its adsorption performance is restored, allowing for reuse.

[0068] In many cases, during water or gas treatment, the adsorbed substance is adsorbed near the surface of the carbon material. Therefore, by treating the area near the surface of the carbon material with plasma, the adsorbed substance can be modified. In this case, the carbon material excluding the surface layer can be reused for water or gas treatment. In this embodiment 6, by controlling the time the carbon material stays in the treatment container, i.e., the time it is treated in contact with the plasma, it becomes possible to treat only the necessary amount of the area near the surface of the carbon material, thereby suppressing the consumption of more carbon material than necessary and modifying the adsorbed substance.

[0069] Furthermore, by closing the carbon material emission control unit 9, the waste activated carbon can be completely recycled. Therefore, the regeneration and recycling of waste activated carbon can be performed arbitrarily using the same device.

[0070] As described above, according to the carbon dioxide reforming method of this embodiment 6, in the plasma treatment step, the residence time of the carbon material C is controlled by the carbon material emission control unit 9, and the surface layer of the carbon material C is reacted by plasma treatment. Ｒ By discharging only the necessary amount of material near the surface of the carbon material, it becomes possible to suppress the consumption of more carbon material than necessary and to modify the adsorbed substance.

[0071] Embodiment 7. Embodiment 7 describes a carbon dioxide reforming system using a carbon dioxide reforming method.

[0072] Figure 8 is a block diagram showing the configuration of a carbon dioxide reforming system 200 using the carbon dioxide reforming method according to Embodiment 7.

[0073] As shown in Figure 8, the carbon dioxide reforming system 200 of Embodiment 7 consists of a carbon dioxide acquisition unit 5, a carbon material acquisition unit 6, and a plasma reforming control unit 7.

[0074] The carbon dioxide acquisition unit 5, for example, in an alkaline solution such as an amine-based solution, generates CO2.２ Materials that absorb CO, such as polymer membranes or porous membranes. ２ CO2 is separated using solid adsorbents such as zeolites or MOFs (Metal Organic Frameworks). ２ Using a substance that adsorbs CO ２ Obtain it.

[0075] The carbon material acquisition unit 6 acquires carbon material used in the treatment of the gas or water to be treated at a water or gas treatment facility. The carbon material acquisition unit 6 may also have functions such as sorting the carbon material by size or adjusting the amount of adsorbed water.

[0076] The plasma reforming control unit 7 consists of a carbon dioxide supply unit 71, a carbon material supply unit 72, a processing monitoring unit 73, a plasma processing unit 74, and a gas measurement unit 75. The plasma reforming control unit 7 is, for example, CO ２ The carbon dioxide supply unit 71 and the carbon material supply unit 72 are controlled so that the supply amount and the carbon material supply amount are in an optimal ratio.

[0077] The carbon dioxide supply unit 71 receives CO2 obtained from the carbon dioxide acquisition unit 5. ２ The CO2 supplied to the plasma processing unit 74 at a predetermined supply rate. The carbon material supply unit 72 supplies the required amount of carbon material to the plasma processing unit 74. The processing monitoring unit 73 monitors, for example, the gas temperature and carbon material temperature of the plasma processing unit 74. It may also monitor the remaining amount of carbon material in the plasma processing unit 74. The plasma processing unit 74 receives CO2 supplied from the carbon dioxide supply unit 71. ２ The carbon material supplied from the carbon material supply unit 72 is reacted with the carbon material to generate CO. The gas measurement unit 75 measures the CO concentration of the gas emitted from the plasma processing unit 74. ２ Concentration, O ２ At least one concentration is measured. In addition, the concentration of trace components in the gas emitted from the plasma processing unit 74 is measured. The carbon monoxide utilization unit 8 utilizes the CO generated in the plasma processing unit 74.

[0078] Under ideal conditions, the plasma processing unit 74 is CO ２ And C is consumed in equimolar amounts (CO ２+C → 2CO...(5)). In this case, CO ２ The carbon dioxide supply unit 71 and the carbon material supply unit 72 are controlled so that CO and C are supplied in equimolar amounts.

[0079] On the other hand, in the plasma treatment unit 74, not all CO is necessarily converted to CO, and there may be cases where CO flows out as it is. In this case, the consumption amount of the carbon material is calculated from the concentration of at least one of CO, CO, and O measured by the gas measurement unit 75, and at least one of the CO supply amount and the carbon material supply amount is controlled to supply the CO supply amount and the carbon material supply amount at an optimal ratio. ２ is converted to CO, and there may be cases where CO flows out as it is. In this case, the consumption amount of the carbon material is calculated from the concentration of at least one of CO, CO, and O measured by the gas measurement unit 75, and at least one of the CO supply amount and the carbon material supply amount is controlled to supply the CO supply amount and the carbon material supply amount at an optimal ratio. ２ is converted to CO, and there may be cases where CO flows out as it is. In this case, the consumption amount of the carbon material is calculated from the concentration of at least one of CO, CO, and O measured by the gas measurement unit 75, and at least one of the CO supply amount and the carbon material supply amount is controlled to supply the CO supply amount and the carbon material supply amount at an optimal ratio. ２ and O ２ is converted to CO, and there may be cases where CO flows out as it is. In this case, the consumption amount of the carbon material is calculated from the concentration of at least one of CO, CO, and O measured by the gas measurement unit 75, and at least one of the CO supply amount and the carbon material supply amount is controlled to supply the CO supply amount and the carbon material supply amount at an optimal ratio. ２ supply amount and the carbon material supply amount is controlled to supply the CO supply amount and the carbon material supply amount at an optimal ratio. ２ supply amount and the carbon material supply amount is controlled to supply the CO supply amount and the carbon material supply amount at an optimal ratio.

[0080] Specifically, in addition to the above formula (5), the reaction of the following formula (6) also occurs. 2CO ２ → 2CO + O ２ ...(6)

[0081] Therefore, the ratio of CO consumed in formula (6) is estimated from the O concentration, and the consumption amount of C can be estimated by measuring the decrease in the CO concentration passing through the plasma treatment unit 74. Based on this estimation, the carbon material supply unit 72 can supply the required amount of carbon material to the plasma treatment unit 74. ２ concentration, and the consumption amount of C can be estimated by measuring the decrease in the CO concentration passing through the plasma treatment unit 74. Based on this estimation, the carbon material supply unit 72 can supply the required amount of carbon material to the plasma treatment unit 74. ２ concentration, and the consumption amount of C can be estimated by measuring the decrease in the CO concentration passing through the plasma treatment unit 74. Based on this estimation, the carbon material supply unit 72 can supply the required amount of carbon material to the plasma treatment unit 74. ２ concentration, and the consumption amount of C can be estimated by measuring the decrease in the CO concentration passing through the plasma treatment unit 74. Based on this estimation, the carbon material supply unit 72 can supply the required amount of carbon material to the plasma treatment unit 74.

[0082] In addition, the process monitoring unit 73 can monitor the remaining amount of the carbon material in the plasma treatment unit 74, and when the remaining amount becomes less than or equal to a predetermined value, it can also be controlled to supply the carbon material from the carbon material supply unit 72. Alternatively, the decrease rate of the carbon material in the plasma treatment unit 74 is monitored, and the supply rate of the carbon material from the carbon material supply unit 72 is adjusted so that the carbon material is not insufficient. The remaining amount and the decrease rate of the carbon material can be measured using optical methods such as image analysis, light transmission, and reflection.

[0083] The processing monitoring unit 73 measures the gas temperature or carbon material temperature of the plasma processing unit 74, and the plasma modification control unit 7 controls these temperatures to stay within a predetermined temperature range. For example, the plasma modification control unit 7 adjusts the power supplied to the plasma of the plasma processing unit 74. Alternatively, the plasma modification control unit 7 controls the CO supplied to the plasma processing unit 74. ２ The temperature is controlled by adjusting the quantity of carbon material.

[0084] The gas temperature and carbon material temperature are preferably 850°C or higher, and more preferably 1000°C or higher. This corresponds to the temperature at which PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid), representative substances of PFAS, decompose. Also, most organic compounds decompose at this temperature. ２ The reaction shown in equation (5), which directly reacts with carbon materials to produce CO (the Boudoar reaction), occurs significantly at temperatures above approximately 1000°C. Therefore, by raising the temperature above 1000°C, in addition to the decomposition of PFAS, CO is produced. ２ This allows for effective conversion from CO to CO.

[0085] On the other hand, excessively raising the temperature can lead to wasted power consumption, material degradation of the plasma processing unit 74, and increased cooling costs for the components. For this reason, the gas temperature and carbon material temperature are preferably 3000°C or lower, and more preferably 2000°C or lower.

[0086] Examples of temperature measurement methods include estimating the temperature from the emission spectrum of the plasma processing unit 74, measuring the temperature of the carbon material with a radiation thermometer, or estimating the temperature of the reaction field from the ambient temperature. However, the method is not limited to these as long as the gas temperature or carbon material temperature can be measured.

[0087] Incidentally, it is not necessary to react all of the carbon materials in the plasma treatment unit 74, and only a part of them can be reacted. Specifically, by appropriately setting the residence time in the plasma treatment unit 74, carbon materials in which only a part (surface layer) has reacted can be recovered. Thereby, substances adsorbed near the surface of the carbon material are decomposed and removed. As a result, the amount of activated carbon decreases, but the adsorption performance is restored and can be reused.

[0088] Further, a wet scrubber can be installed downstream of the plasma treatment unit 74 to treat the gas flowing out from the plasma treatment unit 74. Fluorine in the PFAS decomposed in the plasma treatment unit 74 can be dissolved in the liquid by the wet scrubber and recovered as HF. Also, CO supplied to the plasma treatment unit 74 ２ and nitrogen oxides and sulfur oxides derived from impurities (nitrogen components and sulfur components) contained in the carbon material can be removed.

[0089] As described above, according to the carbon dioxide reforming system according to the seventh embodiment, a carbon dioxide acquisition unit 5 that acquires carbon dioxide, a carbon material acquisition unit 6 that acquires a carbon material used for treating water or gas, and the carbon dioxide are provided. Since it has a plasma reforming control unit 7 that reforms carbon monoxide by performing plasma treatment in the presence of the carbon material, ２ CO can be reformed into CO, and by performing plasma reforming of CO in the presence of a carbon material, not only can the conversion rate to CO be improved, but also used carbon materials (C + O ２ → CO ２ → CO ２ ), which are usually incinerated, can be recycled (C + O → CO, C + CO ２ → 2CO), reducing the CO ２ emission amount and recycling the carbon material as CO. Further, the adsorbed substances adsorbed on the carbon material are reformed by plasma, reducing their harmful properties.

[0090] While this application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are envisioned within the scope of the art disclosed herein. For example, these include modifying, adding or omitting at least one component, or even extracting at least one component and combining it with a component from another embodiment.

[0091] 5 Carbon dioxide acquisition unit, 6 Carbon material acquisition unit, 7 Plasma modification control unit, 200 Carbon dioxide modification system.

Claims

1. A carbon dioxide reforming method characterized by comprising: a carbon dioxide acquisition step of acquiring carbon dioxide; a carbon material acquisition step of acquiring carbon material used in the treatment of water or gas; and a plasma treatment step of reforming the carbon dioxide into carbon monoxide by applying plasma treatment in the presence of the carbon material.

2. The carbon material is activated carbon that has adsorbed the adsorbed substance in the above treatment, characterized in that the carbon material is the carbon material according to claim 1.

3. The carbon dioxide reforming method according to claim 2, characterized in that the adsorbed substance is an organofluorine compound.

4. The carbon dioxide reforming method according to claim 3, characterized in that the plasma treatment step involves applying plasma treatment to the carbon dioxide in the presence of water.

5. The carbon dioxide reforming method according to claim 3 or 4, characterized in that the plasma treatment step is performed such that the carbon monoxide is discharged through the fluorine trap section.

6. The carbon dioxide reforming method according to claim 5, characterized in that the fluorine trap section captures fluorine of the organofluorine compound with calcium.

7. The carbon dioxide reforming method according to claim 1, characterized in that the plasma treatment step controls the residence time of the carbon material by a carbon material discharge control unit and discharges the carbon material whose surface layer has been reacted by the plasma treatment.

8. The carbon dioxide reforming method according to any one of claims 1 to 7, characterized in that the carbon material to be obtained in the carbon material acquisition step is preheated by the waste heat from the carbon monoxide reforming reaction in the plasma treatment step.

9. The carbon dioxide reforming method according to any one of claims 1 to 8, characterized in that the carbon dioxide to be obtained in the carbon dioxide acquisition step is preheated by the waste heat from the carbon monoxide reforming reaction in the plasma treatment step.

10. A carbon dioxide reforming system characterized by comprising: a carbon dioxide acquisition unit for acquiring carbon dioxide; a carbon material acquisition unit for acquiring carbon material used in the treatment of water or gas; and a plasma reforming control unit for reforming the carbon dioxide into carbon monoxide by applying plasma treatment in the presence of the carbon material.

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