Method and system for capturing and utilizing carbon dioxide

Abstract

The present invention provides a method and system for capturing and utilizing carbon dioxide. The method for capturing and utilizing carbon dioxide comprises: capturing carbon dioxide in a target component using an alkaline solution to obtain a carbonate-containing aqueous solution; electrolytically reducing the carbonate-containing aqueous solution to obtain a hydroxide aqueous solution, carbon dioxide electrolysis gas, oxygen and hydrogen, and adjusting the output ratio of carbon dioxide electrolysis gas and hydrogen by controlling the concentration of the carbonate-containing aqueous solution and the electrolysis voltage of the electrolytic reduction process; optionally catalytically reacting the carbon dioxide electrolysis gas and hydrogen to obtain hydrocarbons, which can be used as industrial by-products. The method for capturing and utilizing carbon dioxide provided by the present application can achieve carbon dioxide emission reduction, optionally solve the problem of transportation and utilization of carbon dioxide and hydrogen, and also obtain process by-products, so that the process has a lower investment cost and is convenient for industrial application.

Description

Technical Field

[0001] The present invention relates to the field of carbon dioxide capture and application, and in particular to a method and system for capturing and utilizing carbon dioxide. Background Art

[0002] Existing carbon capture technologies are divided into two paths: capturing from combustion exhaust and capturing from the air.

[0003] The methods for capturing carbon dioxide from combustion exhaust gas are mainly divided into liquid amine adsorption method and solid membrane adsorption method. Both technologies for capturing carbon dioxide from combustion exhaust gas can reach the pilot level at home and abroad, but they cannot solve the following problems: (1) Since the concentration of carbon dioxide in the air is only 400ppm, the existing methods for capturing carbon dioxide from flue gas cannot simultaneously capture carbon dioxide from the air; (2) The reduction of liquid amine adsorbent requires a large amount of steam, and therefore requires a large amount of low-temperature heat. The heat generation will increase carbon dioxide emissions and increase the cost and operation cost of the system; (3) The captured carbon dioxide cannot be used on-site and needs to be transported and a solution for the utilization or storage of carbon dioxide needs to be found.

[0004] The technologies for capturing carbon dioxide from the air are mainly divided into liquid alkaline solution adsorption and solid amine membrane adsorption routes. The technologies of the two routes are currently in the pilot stage, but the existing technologies for capturing carbon dioxide from the air cannot solve the following problems:

[0005] (1) As existing technologies can only capture carbon dioxide from the air and there is no industrial by-product to generate profits, the capture cost of existing technologies is too high.

[0006] (2) Existing technologies cannot solve the problem of transportation and utilization of carbon dioxide. The collected carbon dioxide needs to be matched with other technologies to solve the problem of carbon dioxide utilization.

[0007] (3) In solid amine membrane adsorption technology, a large amount of low-temperature steam is required for the reduction of the amine adsorbent, which consumes a lot of energy. If the steam heat source comes from the combustion of fossil energy, it will increase carbon dioxide emissions.

[0008] (4) In the existing alkaline solution adsorption technology, the reduction of gas adsorbent needs to be achieved through two chemical loops, K2CO3+Ca(OH)2=CaCO3+2KOH, CaCO3=CaO+CO2, CaO+H2O=Ca(OH)2. The defects of this method are: first, the system design is complex, the cost is high, and the control system is difficult to implement. Second, the chemical loop of carbon dioxide and calcium carbonate requires combustion at 900°C, which greatly increases its energy loss and carbon emissions. The calcium oxide adsorbent is easily deactivated and requires a large amount of calcium carbonate to be supplemented.

[0009] (5) In the alkaline solution adsorption technology reported in the existing literature, alkaline solution reduction is achieved by reacting chlorine with sodium carbonate solution, and chlorine and sodium hydroxide are obtained by electrolyzing brine (chlor-alkali industry). On the one hand, this route has the problems of high investment cost, complex system, and difficulty in achieving precise control. On the other hand, chlorine is toxic, corrosive and difficult to transport, which will cause the investment cost of system safety protection to be too high, which is not conducive to the commercialization of the technology.

[0010] In view of the existence of the above problems, it is necessary to develop a method and system for capturing and utilizing carbon dioxide that can solve the problem of transportation and utilization of carbon dioxide and achieve higher economic value. Summary of the invention

[0011] The main purpose of the present invention is to provide a method and system for capturing and utilizing carbon dioxide, so as to solve the problem that the existing carbon dioxide capture device method cannot solve the problem of transportation and utilization of carbon dioxide, and at the same time has the problem of high operating cost of the system.

[0012] In the chlorine hydrogen industry, the storage and transportation costs of hydrogen are very high in the process of using renewable energy to electrolyze water to produce hydrogen. Using carbon dioxide as an industrial raw material to achieve liquid organic hydrogen storage has attracted widespread attention as a technical route that can reduce the cost of hydrogen storage in the future. However, carbon dioxide cannot be produced in the process of electrolyzing water to produce hydrogen, and needs to be transported to the hydrogen production site, which greatly increases the transportation cost. Therefore, the key to achieving low-cost liquid organic hydrogen storage is to simultaneously produce carbon dioxide during the hydrogen production process.

[0013] In order to achieve the above-mentioned purpose, the present invention provides a method for capturing and utilizing carbon dioxide on the one hand, and the method for capturing and utilizing carbon dioxide comprises: using an alkaline solution to capture carbon dioxide in a target component to obtain a carbonate-containing aqueous solution; electrolytically reducing the carbonate-containing aqueous solution to obtain a hydroxide aqueous solution, carbon dioxide electrolytic gas, oxygen and hydrogen, and adjusting the output ratio of carbon dioxide electrolytic gas and hydrogen by controlling the concentration of the carbonate-containing aqueous solution and the electrolytic voltage of the electrolytic reduction process; optionally, catalytically reacting the carbon dioxide electrolytic gas and hydrogen to obtain hydrocarbons, which can be used as industrial by-products.

[0014] Furthermore, the electrolytic reduction process includes: electrolytically reducing the carbonate-containing aqueous solution to obtain a mixed gas of carbon dioxide electrolytic gas and oxygen, hydrogen and a hydroxide aqueous solution; and separating the carbon dioxide electrolytic gas and oxygen in the mixed gas.

[0015] Furthermore, the separation process is carried out by one or more selected from cryogenic liquefaction, catalytic oxidation, membrane separation and adsorption devices.

[0016] Furthermore, the electrolytic reduction process is a staged electrolytic process.

[0017] Furthermore, during the electrolytic reduction process, the electrolytic cell voltage is 2 to 3 V and the current density is 1000 to 10000 A / m 2 The pH of the carbonate-containing aqueous solution is 7 to 10, and the concentration of carbonate in the carbonate-containing aqueous solution is 1 to 10 mol / L.

[0018] Furthermore, the current density is 1500 to 10000 A / m 2 ; The pH of the carbonate-containing aqueous solution is 7 to 8; In the carbonate-containing aqueous solution, the concentration of carbonate is 1 to 5 mol / L.

[0019] Furthermore, the current density is 2000-4000A / m 2 .

[0020] Furthermore, before the electrolytic reduction process is performed, the method for capturing and utilizing carbon dioxide also includes: removing impurities from the carbonate-containing aqueous solution.

[0021] Furthermore, after the impurity removal process, the content of alkaline earth metal ions in the carbonate-containing aqueous solution is ≤10ppm.

[0022] Furthermore, alkaline earth metal ions include Ca 2+ and / or Mg 2+ .

[0023] Furthermore, the method of the impurity removal process is selected from filtration, chemical precipitation or adsorption.

[0024] Furthermore, the electrolytic reduction process is carried out under normal pressure or 2 to 40 bar.

[0025] Furthermore, between the impurity removal process and the electrolytic reduction process, the method for capturing and utilizing carbon dioxide also includes: adjusting the concentration of the carbonate-containing aqueous solution, wherein the adjustment process includes diluting with water or concentrating by heating.

[0026] Furthermore, the method for capturing and utilizing carbon dioxide also includes: extracting a portion of the carbonate-containing aqueous solution to obtain carbonates, which can be used as an industrial by-product.

[0027] Furthermore, the extraction treatment process is carried out by a recrystallization method.

[0028] Furthermore, the alkaline solution is an aqueous solution of alkali metal hydroxide.

[0029] Furthermore, the alkaline solution is a sodium hydroxide aqueous solution and / or a potassium hydroxide aqueous solution.

[0030] Furthermore, the pH of the alkaline solution is greater than 7 and less than or equal to 10.

[0031] Furthermore, the products of the electrolytic reduction process also include bicarbonate.

[0032] Furthermore, the electrolytic reduction process is carried out in an electrolytic cell, and the method for capturing and utilizing carbon dioxide also includes: preheating the carbonate-containing aqueous solution entering the electrolytic cell with a portion of the hydroxide aqueous solution leaving the electrolytic cell.

[0033] Furthermore, the method for capturing and utilizing carbon dioxide also includes: using a portion of the hydroxide aqueous solution leaving the electrolytic cell as an alkaline solution.

[0034] Furthermore, the electrolytic reduction process is carried out in an electrolytic cell, and the method for capturing and utilizing carbon dioxide also includes: using the heat released by the catalytic reaction to preheat the carbonate-containing aqueous solution entering the electrolytic cell.

[0035] Furthermore, the method for capturing and utilizing carbon dioxide also includes: preheating the carbonate-containing aqueous solution to 60-90°C.

[0036] Furthermore, the hydrocarbon is selected from one or more of methane, methanol, gasoline and aviation fuel.

[0037] Furthermore, when the hydrocarbon is methanol, the temperature of the catalytic reaction process is 200-400° C., the pressure is 10-50 bar, and the molar ratio of carbon dioxide electrolysis gas to hydrogen is 1:1-1:5.

[0038] Further, the target component is selected from air and / or combustion exhaust gas.

[0039] Furthermore, when the target component is air, before the capture process, the method for capturing and utilizing carbon dioxide also includes: concentrating the target component to obtain concentrated gas to increase the concentration of carbon dioxide; and then subjecting the concentrated gas to a capture process.

[0040] Furthermore, the concentration process includes: using an adsorbent to adsorb carbon dioxide in the target component, and then desorbing it to obtain concentrated gas, wherein the concentration of carbon dioxide in the concentrated gas is 0.4-5%.

[0041] Furthermore, between the concentration process and the capture process, the method for capturing and utilizing carbon dioxide also includes: compressing the concentrated gas.

[0042] Furthermore, the pressure of the compression process is 5 to 500 bar.

[0043] Furthermore, when the target component is combustion exhaust gas, before the capture process is performed, the method for capturing and utilizing carbon dioxide further includes: performing denitrification, desulfurization and / or dust removal treatment on the combustion exhaust gas.

[0044] Furthermore, the catalytic reaction is a thermal catalytic reaction, a photocatalytic reaction or a biocatalytic reaction; the hydrogen used in the catalytic reaction is generated by an electrolytic reduction process, or is partially generated by the electrolytic reduction process and the rest is input from the outside, or is entirely input from the outside.

[0045] Another aspect of the present application also provides a system for capturing and utilizing carbon dioxide, the system for capturing and utilizing carbon dioxide comprising: a carbon dioxide capture device, an electrolytic reduction unit, a voltage regulating device and an optional catalytic device, the carbon dioxide capture device being provided with an alkaline solution inlet, a target component inlet and a carbonate aqueous solution discharge port; the electrolytic reduction unit being provided with a first carbonate aqueous solution inlet, a carbon dioxide electrolytic gas outlet, an oxygen outlet, a hydrogen outlet and a hydroxide aqueous solution discharge port, the first carbonate aqueous solution inlet being connected to the carbonate aqueous solution discharge port via a carbonate aqueous solution delivery pipeline; the voltage regulating device being used to adjust the voltage during the electrolytic reduction process to adjust the output ratio of carbon dioxide electrolytic gas and hydrogen; the catalytic device being provided with a catalytic inlet and a hydrocarbon outlet, and the catalytic inlet being respectively connected to the carbon dioxide electrolytic gas outlet and the hydrogen outlet.

[0046] Further, when the electrolytic reduction unit can perform graded electrolysis through the voltage regulating device, the electrolytic reduction unit is an electrolytic reduction device, and the electrolytic reduction device is provided with a first carbonate aqueous solution inlet, a hydrogen outlet, a carbon dioxide electrolysis gas outlet, an oxygen outlet and a hydroxide aqueous solution discharge port; or when the electrolytic reduction unit does not perform graded electrolysis, the electrolytic reduction unit includes an electrolytic reduction device and a separation device, and the electrolytic reduction device is provided with a first carbonate aqueous solution inlet, a hydrogen outlet, an anode gas discharge port and a hydroxide aqueous solution discharge port, wherein the anode gas includes carbon dioxide electrolysis gas and oxygen; the separation device is provided with a to-be-separated gas inlet, a carbon dioxide electrolysis gas outlet and an oxygen outlet, and the to-be-separated gas inlet is connected to the anode gas discharge port.

[0047] Furthermore, the separation device is selected from one or more of a cryogenic device, a catalytic oxidation device, an adsorption device and a membrane separation device.

[0048] Furthermore, the system for capturing and utilizing carbon dioxide also includes an impurity removal device, which is arranged on the carbonate-containing aqueous solution conveying pipeline.

[0049] Furthermore, the impurity removal device is selected from a filtering device, a precipitation device or an adsorption device.

[0050] Furthermore, the system for capturing and utilizing carbon dioxide also includes a first heat exchange device, which is disposed on a carbonate-containing aqueous solution transport pipeline.

[0051] Furthermore, the heat medium inlet of the first heat exchange device is connected to the hydroxide aqueous solution discharge port, so that the hydroxide aqueous solution discharged from the hydroxide aqueous solution discharge port exchanges heat with the carbonate aqueous solution in the carbonate aqueous solution conveying pipeline.

[0052] Furthermore, the system for capturing and utilizing carbon dioxide includes a catalytic device and a second heat exchange device, and the second heat exchange device is arranged on a carbonate-containing aqueous solution conveying pipeline.

[0053] Furthermore, the heat medium inlet of the second heat exchange device is connected to the hydrocarbon outlet, so that the heat in the hydrocarbon discharged from the hydrocarbon outlet is exchanged with the carbonate-containing aqueous solution in the carbonate-containing aqueous solution transmission pipeline.

[0054] Furthermore, the system for capturing and utilizing carbon dioxide also includes: a carbonate aqueous solution concentration regulating device and a voltage regulating device. The carbonate aqueous solution concentration regulating device is arranged on the carbonate aqueous solution conveying pipeline and is used to regulate the concentration and pH of the carbonate aqueous solution; the voltage regulating device is used to regulate the electrolysis voltage of the electrolytic reduction device.

[0055] Furthermore, the carbonate-containing aqueous solution concentration regulating device is a diluting device or a concentrating device.

[0056] Furthermore, the system for capturing and utilizing carbon dioxide also includes a carbonate extraction device, which is provided with a second carbonate-containing aqueous solution inlet, and the second carbonate-containing aqueous solution inlet is connected to the carbonate-containing aqueous solution discharge port.

[0057] Furthermore, the extraction device is a crystallization device or a recrystallization device.

[0058] Further, the hydroxide aqueous solution discharge port is communicated with the alkaline solution inlet.

[0059] Furthermore, when the target component is air, the system for capturing and utilizing carbon dioxide also includes a concentration unit, which is provided with an inlet for gas to be concentrated and an outlet for concentrated gas. The outlet for concentrated gas is connected to the inlet for the target component through a concentrated gas delivery pipeline. The concentration unit is used to increase the content of carbon dioxide in the target component.

[0060] Furthermore, the concentration unit includes: a carbon dioxide adsorption device and a desorption device, the carbon dioxide adsorption device is provided with an inlet for gas to be concentrated, for adsorbing carbon dioxide in the target component; the desorption device is arranged downstream of the carbon dioxide adsorption device and is provided with a concentrated gas outlet, for desorbing the carbon dioxide adsorbed in the carbon dioxide adsorption device.

[0061] Furthermore, the system for capturing and utilizing carbon dioxide also includes a first compression device, which is disposed on the concentrated gas transmission pipeline.

[0062] Furthermore, when the target component is combustion exhaust gas, the system for capturing and utilizing carbon dioxide also includes a dust removal device, a desulfurization device and a denitrification device, and a target component transport pipeline connected to the target component inlet, and the dust removal device, the desulfurization device and the denitrification device are arranged on the target component transport pipeline.

[0063] Furthermore, the system for capturing and utilizing carbon dioxide also includes a collecting device, which is provided with a collecting port, and the collecting port is connected to the oxygen outlet for collecting oxygen.

[0064] Furthermore, the system for capturing and utilizing carbon dioxide also includes: a carbon dioxide compression device and a hydrogen compression device, the carbon dioxide compression device is provided with a carbon dioxide electrolysis gas inlet and a carbon dioxide electrolysis gas outlet, the carbon dioxide electrolysis gas inlet is connected to the carbon dioxide electrolysis gas outlet of the electrolytic reduction unit, and the carbon dioxide compressed gas outlet is connected to the catalytic inlet; the hydrogen compression device is provided with a hydrogen inlet and a hydrogen compressed gas outlet, the hydrogen inlet is connected to the hydrogen outlet of the electrolytic reduction unit, and the hydrogen compressed gas outlet is connected to the catalytic inlet.

[0065] By applying the technical solution of the present invention, the method for capturing and utilizing carbon dioxide provided in the present application can not only achieve carbon dioxide emission reduction, but can also optionally solve the problem of transportation and utilization of carbon dioxide and hydrogen, while also obtaining process by-products, thereby making the process have a lower investment cost and convenient for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0067] Figure 1 A schematic diagram of a process flow for capturing and utilizing carbon dioxide provided according to a first preferred embodiment of the present invention is shown.

[0068] Figure 2 A schematic diagram of a process flow for capturing and utilizing carbon dioxide according to a second preferred embodiment of the present invention is shown. In this embodiment, a portion of the sodium carbonate crystals produced by the system are directly utilized as an industrial by-product.

[0069] Figure 3 A schematic diagram of a process flow for capturing and utilizing carbon dioxide according to a fourth preferred embodiment of the present invention is shown. In this embodiment, carbon dioxide in the air is first concentrated, and the system is combined with compressed air energy storage.

[0070] Figure 4A schematic diagram of the process flow for capturing and utilizing carbon dioxide provided in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0071] It should be noted that, in the absence of conflict, the various embodiments and the various features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0072] As described in the background technology, the existing carbon dioxide capture method cannot solve the problem of carbon dioxide transportation and utilization, and has the problem of high operating costs. In order to solve the above technical problems, Figure 1 As shown, the present application provides a method for capturing and utilizing carbon dioxide, comprising: capturing carbon dioxide in a target component using an alkaline solution to obtain a carbonate-containing aqueous solution; electrolytically reducing the carbonate-containing aqueous solution to obtain a hydroxide aqueous solution, carbon dioxide electrolytic gas, oxygen and hydrogen, and preferably adjusting the output ratio of carbon dioxide electrolytic gas and hydrogen by controlling the concentration of the carbonate-containing aqueous solution and the electrolytic voltage of the electrolytic reduction process; optionally, catalytically reacting the carbon dioxide electrolytic gas and hydrogen to obtain hydrocarbons, which can be produced as industrial by-products.

[0073] Through the above method, carbon dioxide can be captured from the target component (such as air or combustion exhaust) to achieve the purpose of reducing carbon dioxide emissions. At the same time, the carbonate-containing aqueous solution is converted into carbon dioxide, oxygen, hydrogen and hydroxide aqueous solution (such as sodium hydroxide aqueous solution) by electrolytic reduction process, and the formed hydroxide aqueous solution can be returned to the capture process of carbon dioxide for reuse. Optionally, carbon dioxide and hydrogen are catalytically reacted to synthesize hydrocarbons, which can well solve the problems of transportation and utilization of carbon dioxide and hydrogen. The produced hydrocarbons can be sold as by-products, thereby greatly reducing the investment cost of carbon dioxide capture and utilization process, facilitating industrial promotion, and improving the overall production profit. In summary, the method for capturing and utilizing carbon dioxide provided by the present application can not only achieve carbon dioxide emission reduction, but also can solve the problems of transportation and utilization of carbon dioxide and hydrogen, and can also obtain process by-products, so that the process has a lower investment cost, is convenient for industrial application, and improves the overall production profit.

[0074] It should be noted that the hydrogen used in the catalytic reaction process can come entirely from the electrolytic reduction process, or can be partially generated by the electrolytic reduction process and the remainder from external input, or can be entirely from external input.

[0075] In some embodiments, Figure 1As shown, the electrolytic reduction process includes: electrolytic reduction of carbonate-containing aqueous solution to obtain a mixed gas of carbon dioxide electrolytic gas and oxygen, hydrogen and hydroxide aqueous solution; and separation of carbon dioxide electrolytic gas and oxygen in the mixed gas. Carbon dioxide and hydrogen can be electrolyzed and produced simultaneously through the electrolytic reduction process, which can greatly increase the concentration of carbon dioxide, and make carbon dioxide sustainable and improve its utilization rate.

[0076] The reaction principle of the electrolytic reduction process is as follows: CO3 2- +3H2O→2OH - +CO2↑+O2↑+2H2↑. During the electrolytic reduction process, oxygen and carbon dioxide are produced from the anode, and hydrogen and sodium hydroxide are produced from the cathode. In order to improve the utilization rate of carbon dioxide, it is necessary to separate the oxygen and carbon dioxide in the mixed gas. In some embodiments, the method of the above separation process includes but is not limited to one or more of deep cold liquefaction, catalytic oxidation and membrane separation. Compared with other methods, the use of the above separation method can greatly reduce the investment cost of the entire process while improving the separation efficiency of carbon dioxide and oxygen.

[0077] In other embodiments, the electrolysis process is a staged electrolysis process. In the staged electrolysis process, oxygen is produced at the first electrolysis anode, and carbon dioxide and residual oxygen are produced at the second electrolysis anode, i.e., two-stage series electrolysis. The staged electrolysis process enables the electrolytic reduction process and the process of separating carbon dioxide from the mixture of carbon dioxide and oxygen to be completed in the electrolytic cell, which greatly shortens the process flow and process time and improves the economic efficiency of the process.

[0078] In order to further improve the yield of carbon dioxide and hydrogen during the electrolytic reduction process and adjust the output ratio of carbon dioxide and hydrogen, various process parameters can be optimized. In some embodiments, during the electrolytic reduction process, the electrolytic cell voltage is 2 to 3 V, and the current density is 1000 to 10000 A / m 2 , the pH of the carbonate-containing aqueous solution is 7 to 10, and the concentration of carbonate in the carbonate-containing aqueous solution is 1 to 10 mol / L. In order to adjust the output ratio and output rate of carbon dioxide and hydrogen, the process parameters during the electrolysis process can be adjusted. In some embodiments, the current density is 1500 to 10000 A / m 2 , preferably 2000~4000A / m 2 ; In some embodiments, the pH of the carbonate-containing aqueous solution is 7 to 8; preferably, the concentration of carbonate in the carbonate-containing aqueous solution is 1 to 5 mol / L.

[0079] During the electrolytic reduction process, electrical energy is converted into the required chemical energy to stimulate the reaction activity of the carbonate-containing aqueous solution, thereby producing new carbon dioxide (carbon dioxide electrolysis gas), hydrogen, oxygen, etc. In order to further improve the effect of the electrolytic reduction process, such as Figure 1 As shown, the carbonate-containing aqueous solution may be pretreated (e.g., adjusting the concentration, removing impurities, and preheating). In some embodiments, before the electrolytic reduction process is performed, the method for capturing and utilizing carbon dioxide further includes: removing impurities from the carbonate-containing aqueous solution. Since the target components for carbon dioxide capture may contain other impurity components (e.g., sulfides, nitrides, alkaline earth metal ions such as calcium and magnesium, etc.) in addition to carbon dioxide, the above impurity components may affect the effect of the electrolytic reduction process. Therefore, in order to reduce the risk in this regard, the carbonate-containing aqueous solution needs to be removed before the electrolytic reduction process is performed.

[0080] When the content of alkaline earth metal ions is high, they are easily precipitated during the electrolysis process. This part of the precipitate will affect the effect of the electrolytic reduction process and the output of carbon dioxide and hydrogen. In some embodiments, after the impurity removal process, the content of alkaline earth metal ions in the carbonate-containing aqueous solution is ≤10ppm. In some embodiments, alkaline earth metal ions include but are not limited to Ca 2+ and Mg 2+ .

[0081] The specific process of impurity removal can be selected according to the composition of the impurities. In some embodiments, the above impurity removal methods include but are not limited to filtration, chemical precipitation or adsorption.

[0082] The electrolytic reduction process can be carried out under normal pressure or under pressure (2-40 bar). Since carbon dioxide, oxygen and hydrogen are produced during the electrolytic reduction process, carrying out the process under a higher pressure is not only convenient for collecting the above gas components, but also conducive to reducing the energy consumption of subsequent gas component compression.

[0083] In some embodiments, between the process of removing impurities from the carbonate-containing aqueous solution and the process of electrolytic reduction, a process of adjusting the concentration of the carbonate-containing aqueous solution is also included, wherein the adjustment process includes diluting with water or concentrating by heating.

[0084] In some embodiments, Figure 2As shown, the above-mentioned method for capturing and utilizing carbon dioxide also includes: extracting and treating part of the carbonate-containing aqueous solution to obtain carbonate, wherein the carbonate can be directly produced as an industrial by-product. The methods of the above-mentioned extraction process include but are not limited to crystallization, recrystallization, etc. The carbonate-containing aqueous solution can be supersaturated by temperature difference, so that carbonate or bicarbonate is crystallized and separated from the solution. The separated sodium carbonate crystals can be sold as a by-product, for example, as a raw material for the glass industry, thereby further improving the economic benefits of the entire process and reducing process costs.

[0085] Since the catalytic reaction of carbon dioxide and hydrogen will release a large amount of heat, this part of the heat can also be used to preheat the carbonate-containing aqueous solution entering the electrolyzer. The heat of the catalytic reaction can also be used to generate high-temperature water or steam for waste heat utilization. In addition, since the sodium hydroxide aqueous solution generated by the electrolytic reduction process also has a certain amount of heat, the sodium hydroxide aqueous solution separated from the electrolytic reduction process can also be used as a preheating heat source for the sodium carbonate aqueous solution to be entered into the electrolyzer. The above preheating method can make more full use of the thermal energy in the entire process and improve the utilization rate of energy.

[0086] In some embodiments, before the electrolytic reduction process, the method for capturing and utilizing carbon dioxide further includes: preheating the carbonate-containing aqueous solution to 60-90° C. After the carbonate-containing aqueous solution is preheated to the above-mentioned specific temperature and then the electrolytic reduction process is performed, the heat generated by electrolysis can generate high-temperature water for heat cogeneration, which can not only maintain a constant temperature of the electrolytic cell but also greatly reduce the power consumption of electrolysis, thereby achieving the purpose of energy saving and environmental protection.

[0087] Since the catalytic reaction of carbon dioxide and hydrogen releases a large amount of heat, this part of heat can also be used to preheat the carbonate-containing aqueous solution entering the electrolyzer. The heat of the catalytic reaction can also be used to generate high-temperature water or steam for waste heat utilization. In addition, since the sodium hydroxide aqueous solution generated by the electrolytic reduction process also has a certain amount of heat, the sodium hydroxide aqueous solution separated from the electrolytic reduction process can also be used as a preheating heat source for the sodium carbonate aqueous solution entering the electrolyzer. The above preheating method can make more full use of the thermal energy in the entire process and improve the utilization rate of energy.

[0088] In some embodiments, before the electrolytic reduction process, the method for capturing and utilizing carbon dioxide further includes: preheating the carbonate-containing aqueous solution to 60-90° C. After the carbonate-containing aqueous solution is preheated to the above-mentioned specific temperature and then the electrolytic reduction process is performed, the heat generated by electrolysis can generate high-temperature water for heat cogeneration, and maintaining a constant temperature of the electrolytic cell greatly reduces the power consumption of electrolysis, thereby achieving the purpose of energy saving and environmental protection.

[0089] It should be noted that during the pretreatment process, the impurity removal, concentration adjustment and preheating processes can be optionally performed in sequence.

[0090] In some embodiments, the alkaline solution is an alkali metal hydroxide aqueous solution. Compared with other alkaline solutions, the alkali metal hydroxide aqueous solution has a stronger alkalinity and a better effect on capturing carbon dioxide. The alkali metal hydroxide aqueous solution includes but is not limited to sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution.

[0091] Taking sodium hydroxide aqueous solution as the capture agent for illustration, the reaction principle of the carbon dioxide capture process is as follows: 2NaOH+CO2=H2O+Na2CO3. The above capture process can efficiently and continuously achieve the effect of reducing carbon dioxide emissions. At the same time, the raw materials used in the process are widely available and low in cost, which is conducive to further reducing the capture cost of carbon dioxide. The capture device used in the carbon dioxide capture process includes but is not limited to a countercurrent cooling tower or a crossflow cooling tower.

[0092] The hydroxide aqueous solution produced in the electrolytic reduction process can also be used as a collector in the capture process, which can realize the recycling of the collector, which is beneficial to greatly reduce the investment cost of the process. In addition, the equipment involved in the whole process is simple, which is convenient for precise control and industrial application.

[0093] In order to further improve the capture effect of carbon dioxide, in some embodiments, during the carbon dioxide capture process, the pH of the alkaline solution is greater than 7 and less than or equal to 10.

[0094] In some embodiments, when the electrolytic reduction process is incomplete, part of the carbon dioxide will dissolve in the aqueous solution, so that the product of the electrolytic reduction process is bicarbonate (such as NaHCO3, KHCO3). Therefore, when it is necessary to increase the yield of carbon dioxide, the electrolytic reduction process should be made as complete as possible.

[0095] The carbon dioxide, oxygen, and hydrogen produced by the electrolytic reduction process can have a variety of uses, such as using carbon dioxide in the medical field, refrigeration field, and refrigerant; hydrogen can be used as fuel, food field, cleaning product field, and electronic microchip device field; oxygen can be used in the medical field, combustion support, and ore mining field. In order to make full use of the above raw materials and produce products with more economic added value, in some embodiments, carbon dioxide and hydrogen are synthesized into hydrocarbons through catalytic reactions. In some embodiments, the above hydrocarbons include but are not limited to one or more of methane, methanol, gasoline, and aviation fuel.

[0096] Depending on the final product, the temperature and pressure of the catalytic reaction process are also different. In some embodiments, when the above-mentioned hydrocarbon is methanol, the temperature of the catalytic reaction process is 200-400°C, the pressure is 10-50 bar, and the molar ratio of carbon dioxide electrolysis gas to hydrogen is 1:1-1:5. The reaction principle of the catalytic reaction of methanol is as follows: CO2+3H2→CH3OH+H2O. Limiting the temperature, pressure and molar ratio of carbon dioxide electrolysis gas to hydrogen of the catalytic reaction within the above range is conducive to further improving the yield of methanol, thereby further reducing the capture cost of carbon dioxide.

[0097] Since the catalytic reaction is an exothermic reaction, the heat of the reaction can be used to heat and generate hot water or steam as an industrial byproduct. The unreacted carbon dioxide and hydrogen from the catalytic reaction can be recycled back to the catalytic reaction device to increase the yield of the final product and the conversion rate of carbon dioxide and hydrogen. Since the optimal amount ratio of hydrogen and carbon dioxide required for methanol production is 3:1, the chemical composition of the inlet electrolyte of the electrolyzer can be adjusted, and the output ratio of different electrolytic gases (carbon dioxide, hydrogen) can be controlled by controlling the voltage of the electrolyzer. Different molar ratios of hydrogen and carbon dioxide can be used for different downstream catalytic reactions.

[0098] In some optional embodiments, such as Figure 3 As shown, when the target component is air, before the capture process, the method for capturing and utilizing carbon dioxide also includes: concentrating the target component to obtain concentrated gas to increase the concentration of carbon dioxide; and then capturing the concentrated gas. The concentration of carbon dioxide in the target component can be increased through the above-mentioned concentration process, which is conducive to greatly improving the capture efficiency of carbon dioxide in the capture process. Preferably, the concentration process includes: using an adsorbent to adsorb carbon dioxide in the target component, and then desorbing it to obtain concentrated gas, wherein the concentration of carbon dioxide in the concentrated gas is 0.4-5% (vol).

[0099] In some optional embodiments, such as Figure 3 As shown, between the concentration process and the capture process, the above method for capturing and utilizing carbon dioxide also includes: compressing the concentrated carbon dioxide in an air compression device. The compression process is beneficial to improving the solubility of carbon dioxide in the alkaline solution during the capture process, thereby facilitating further improving the capture rate of carbon dioxide. Preferably, the pressure of the compression process is 5 to 500 bar. In some embodiments, the compression device used in the above compression process is connected to the power grid, and the concentrated gas is compressed using the surplus electricity when the power grid is at a low load, and stored in a high-pressure sealing device, and then released to generate electricity during peak power consumption. This can make full use of the power resources in the power grid through the compression energy storage process and obtain higher economic benefits.

[0100] The combustion exhaust gas usually contains sulfur oxides, nitrogen oxides and / or dust, which will affect the subsequent capture process, especially corrode the electrodes of the electrolytic cell or may cause catalyst poisoning for the subsequent catalytic reaction. Therefore, in order to reduce the impact of the above components. In some optional embodiments, when the target component is the combustion exhaust gas, before the capture process, the above method for capturing and utilizing carbon dioxide also includes: denitrification, desulfurization and / or dust removal of the combustion exhaust gas.

[0101] In some embodiments, the above-mentioned method for capturing and utilizing carbon dioxide further includes: compressing the carbon dioxide and hydrogen generated in the electrolytic reduction process respectively before catalytic reaction, which is beneficial to improving the reaction rate of the catalytic reaction and the conversion rate of hydrocarbon fuels.

[0102] It should be noted that carbon dioxide electrolysis gas refers to carbon dioxide gas produced through the electrolytic reduction process.

[0103] Another aspect of the present application also provides a system for capturing and utilizing carbon dioxide, which includes: a carbon dioxide capture device, an electrolytic reduction unit, a voltage regulating device, and an optional catalytic device. The carbon dioxide capture device is provided with an alkaline solution inlet, a target component inlet, and a carbonate aqueous solution discharge port; the electrolytic reduction unit is provided with a first carbonate aqueous solution inlet, a carbon dioxide electrolytic gas outlet, an oxygen outlet, a hydrogen outlet, and a hydroxide aqueous solution discharge port, and the first carbonate aqueous solution inlet is connected to the carbonate aqueous solution discharge port through a carbonate aqueous solution delivery pipeline; the voltage regulating device is used to adjust the voltage during the electrolytic reduction process to adjust the output ratio of carbon dioxide electrolytic gas and hydrogen; the catalytic device is provided with a catalytic inlet and a hydrocarbon outlet, and the catalytic inlet is connected to the carbon dioxide electrolytic gas outlet and the hydrogen outlet, respectively.

[0104] Through the above-mentioned system for capturing and utilizing carbon dioxide, carbon dioxide can be captured from the target component (such as air or combustion exhaust gas) to achieve the purpose of reducing carbon dioxide emissions. At the same time, the carbonate-containing aqueous solution is converted into carbon dioxide, oxygen, hydrogen and hydroxide aqueous solution (such as sodium hydroxide aqueous solution) by an electrolytic reduction unit, and the hydroxide aqueous solution formed can be considered to be returned to the capture process of carbon dioxide for reuse. Optionally, carbon dioxide and hydrogen are catalytically reacted in a catalytic device to synthesize hydrocarbons, which can well solve the problems of transportation and utilization of carbon dioxide and hydrogen. The produced hydrocarbons can be sold as by-products, thereby greatly reducing the investment cost of the carbon dioxide capture and utilization process, facilitating industrial promotion, and improving the overall production profit. In summary, the method for capturing and utilizing carbon dioxide provided by the present application can not only achieve carbon dioxide emission reduction, but also optionally solve the problems of transportation and utilization of carbon dioxide and hydrogen, and can also obtain process by-products, such as direct output of sodium carbonate or output of hydrocarbons, so that the process has a lower investment cost, is convenient for industrial application, and improves the overall production profit.

[0105] In some embodiments, when the electrolysis voltage is adjusted by a voltage regulating device so that the electrolytic reduction device can perform graded electrolysis, carbon dioxide and oxygen can be produced in stages. At this time, there is no need to set up a separation device. The electrolytic reduction unit only includes the electrolytic reduction device, and the carbon dioxide electrolysis gas outlet, oxygen outlet, hydrogen outlet and hydroxide aqueous solution discharge outlet are all set on the electrolytic reduction device.

[0106] In some embodiments, when the electrolytic reduction device cannot perform graded electrolysis, the electrolytic reduction unit includes an electrolytic reduction device and a separation device, the electrolytic reduction device is provided with a first carbonate aqueous solution inlet, a hydrogen outlet, an anode gas discharge port and a hydroxide aqueous solution discharge port, wherein the anode gas includes carbon dioxide electrolysis gas and oxygen; the separation device is provided with a gas inlet to be separated, a carbon dioxide electrolysis gas outlet and an oxygen outlet, and the gas inlet to be separated is connected to the anode gas discharge port. Carbon dioxide and hydrogen can be electrolyzed simultaneously by the electrolytic reduction device, which can greatly increase the concentration of carbon dioxide, and make carbon dioxide sustainable. Output, improve its utilization rate. In some embodiments, the separation device includes but is not limited to one or more of a cryogenic device, a catalytic oxidation device, an adsorption device and a membrane separation device. Compared with other separation devices, the use of the above separation device can greatly reduce the investment cost of the entire process, while improving the separation efficiency of carbon dioxide and oxygen.

[0107] Since the target components for carbon dioxide capture may contain other impurity components (such as sulfides, nitrides, alkaline earth metal ions such as calcium and magnesium, etc.) in addition to carbon dioxide, the above impurity components may affect the effect of electrolytic reduction in the electrolytic reduction process. Therefore, in order to reduce the risk in this regard, in some embodiments, the system for capturing and utilizing carbon dioxide also includes an impurity removal device, which is arranged on the carbonate-containing aqueous solution delivery pipeline. The specific process of impurity removal can be selected according to the composition of impurities. In some embodiments, the impurity removal device includes but is not limited to a filtering device, a precipitation device or an adsorption device.

[0108] Since the electrolytic reduction process and the catalytic reaction process will release a large amount of heat, in order to further improve the heat utilization rate of the entire process, in some embodiments, the above-mentioned system for capturing and utilizing carbon dioxide also includes a first heat exchange device, which is arranged on the carbonate-containing aqueous solution delivery pipeline. The first heat exchange device is used to recover the heat in the carbonate-containing aqueous solution to improve energy utilization. In some embodiments, the heat medium inlet of the first heat exchange device is connected to the hydroxide aqueous solution discharge port so that the hydroxide aqueous solution discharged from the hydroxide aqueous solution discharge port is heat-exchanged with the carbonate-containing aqueous solution in the carbonate-containing aqueous solution delivery pipeline. In other embodiments, the system for capturing and utilizing carbon dioxide includes a catalytic device and a second heat exchange device, which is arranged on the carbonate-containing aqueous solution delivery pipeline. In some embodiments, the heat medium inlet of the second heat exchange device is connected to the hydrocarbon outlet so that the heat in the hydrocarbons discharged from the hydrocarbon outlet is heat-exchanged with the carbonate-containing aqueous solution in the carbonate-containing aqueous solution delivery pipeline.

[0109] During the electrolytic reduction process, the concentration, pH and electrolytic voltage of the carbonate-containing aqueous solution will affect the effect of the electrolytic reduction process. Therefore, in order to improve the yield of carbon dioxide and hydrogen in the electrolytic reduction process and adjust the ratio of the two, it is necessary to adjust the carbonate concentration, pH and electrolytic voltage as needed. In some embodiments, the system for capturing and utilizing carbon dioxide also includes: a carbonate-containing aqueous solution concentration regulating device and a pressure regulating device. The carbonate-containing aqueous solution concentration regulating device is arranged on the carbonate-containing aqueous solution conveying pipeline to adjust the concentration and pH of the carbonate-containing aqueous solution. The above-mentioned pressure regulating device is used to adjust the electrolytic voltage in the electrolytic device. In some embodiments, the carbonate-containing aqueous solution concentration regulating device is a diluting device or a concentrating device.

[0110] In some embodiments, the system for capturing and utilizing carbon dioxide further comprises a carbonate extraction device, wherein the carbonate extraction device is provided with a second carbonate-containing aqueous solution inlet, and the second carbonate-containing aqueous solution inlet is connected to the carbonate-containing aqueous solution discharge port. By providing the carbonate extraction device, the excess carbonate can be separated and directly produced as an industrial by-product, thereby facilitating further reduction of the capture cost of carbon dioxide. The above-mentioned extraction device includes but is not limited to a crystallization device or a recrystallization device. In the crystallization device or the recrystallization device, the carbonate can be crystallized by a temperature difference, so that the carbonate is precipitated, and / or further purified. In addition, since the carbonate-containing aqueous solution discharged from the capture device contains part of the hydroxide aqueous solution, it can also be returned to the absorption tower as a capture agent again.

[0111] Since the product of the electrolytic reduction process includes an aqueous hydroxide solution, this raw material can also be used in the carbon dioxide capture process, so in order to further improve the utilization rate of the aqueous hydroxide solution, while improving the utilization rate of the raw material and the recyclability of the carbon dioxide capture process. In some embodiments, the aqueous hydroxide solution discharge port is connected to the alkaline solution inlet.

[0112] In some embodiments, when the target component is air, the system for capturing and utilizing carbon dioxide also includes a concentration unit, the concentration unit is provided with an inlet for gas to be concentrated and an outlet for concentrated gas, the outlet for concentrated gas is connected to the inlet of the target component through a concentrated gas delivery pipeline, and the concentration unit is used to increase the content of the target component. The above-mentioned concentration unit can increase the concentration of carbon dioxide in the target component, which is conducive to greatly improving the capture efficiency of carbon dioxide during the capture process. In order to further improve the concentration efficiency of carbon dioxide, in some embodiments, the concentration unit includes: a carbon dioxide adsorption device and a desorption device, the carbon dioxide adsorption device is provided with an inlet for gas to be concentrated, which is used to adsorb carbon dioxide in the target component; the desorption device is arranged downstream of the carbon dioxide adsorption device, and is provided with a concentrated gas outlet, which is used to desorb the carbon dioxide adsorbed in the carbon dioxide adsorption device.

[0113] In some embodiments, the system for capturing and utilizing carbon dioxide further includes a first compression device, which is disposed on a concentrated gas transmission pipeline. The first compression device is advantageously used to improve the solubility of carbon dioxide in an alkaline solution during the capture process, thereby facilitating further improvement of the capture rate of carbon dioxide. In some embodiments, the first compression device is connected to a power grid, and the concentrated gas is compressed using the surplus power during low load periods of the power grid, and is stored in a high-pressure sealing device, and then released to generate electricity during peak power consumption periods. This can fully utilize the power resources in the power grid through the compression energy storage process, thereby achieving higher economic benefits.

[0114] In some embodiments, when the target component is combustion exhaust gas, the system for capturing and utilizing carbon dioxide further includes a dust removal device, a desulfurization device, a denitrification device, and a target component delivery pipeline connected to the target component inlet, and the dust removal device, the desulfurization device, and the denitrification device are arranged on the target component delivery pipeline. It should be noted that the dust removal device, the desulfurization device, and the denitrification device are all arranged on the target component delivery pipeline, and the order of the three devices can be arranged as needed.

[0115] In some embodiments, the system for capturing and utilizing carbon dioxide further comprises a collecting device, wherein the collecting device is provided with a collecting port, and the collecting port is connected to the oxygen outlet for collecting oxygen. The oxygen is collected by the collecting device for subsequent utilization, thereby further improving the economic value of the entire process.

[0116] In some embodiments, the system for capturing and utilizing carbon dioxide further includes: a carbon dioxide compression device and a hydrogen compression device, the carbon dioxide compression device is provided with a carbon dioxide electrolysis gas inlet and a carbon dioxide compressed gas outlet, the carbon dioxide electrolysis gas inlet is connected to the carbon dioxide electrolysis gas outlet of the electrolytic reduction unit, and the carbon dioxide compressed gas outlet is connected to the catalytic inlet; the hydrogen compression device is provided with a hydrogen inlet and a hydrogen compressed gas outlet, the hydrogen inlet is connected to the hydrogen outlet of the electrolytic reduction unit, and the hydrogen compressed gas outlet is connected to the catalytic inlet. Compressing carbon dioxide and hydrogen and then transporting them to the catalytic device is conducive to further improving the reaction rate of the catalytic reaction and the conversion rate of hydrocarbon fuels.

[0117] A preferred capture and utilization process provided by the present application is as follows Figure 1 As shown (the target component is air). The above method can be used to build a system for producing negative carbon fuel that can capture 100,000 tons of carbon dioxide from the air every year, which is equivalent to the total amount of carbon dioxide absorbed by 5 million adult trees each year. This process can reduce the carbon dioxide content in the atmosphere, capture carbon dioxide produced by power plants, chemical plants, cement, steel and other industries, and simultaneously produce hydrogen to synthesize negative carbon energy, solving the carbon emission problems in aviation, automobile, shipbuilding and other transportation industries. The application scenarios of this process include but are not limited to: (1) Using renewable energy or nuclear energy to capture carbon dioxide from the air to produce negative carbon energy, thereby reducing carbon dioxide emissions from transportation such as aircraft, ships, and automobiles. (2) Using this device to capture carbon dioxide in power plants or industrial systems and convert it into zero-carbon fuel, solving the problems of capturing, transporting and utilizing industrial carbon dioxide. (3) Since carbon dioxide and hydrogen are produced simultaneously, this invention can also solve the problems of hydrogen storage, transportation and utilization in the electrolysis of water to produce hydrogen. (4) This technology can be used to solve the problem of long-term storage and transportation of renewable energy.

[0118] Example

[0119] like Figure 4A schematic diagram of a process for capturing and utilizing carbon dioxide is shown in the figure. The temperature, pressure, flow rate and composition of each process in the process are shown in Table 1.

[0120] Capture process:

[0121] After the air is compressed by the compressor, compressed air is obtained and transported to the absorption tower; in the absorption tower, the compressed air reacts with the alkaline solution (sodium hydroxide / potassium hydroxide aqueous solution) to be converted into a carbonate-containing aqueous solution (sodium carbonate or potassium carbonate aqueous solution). A portion of the carbonate-containing aqueous solution obtained through the capture process is pumped into the filtration device for filtration, and after filtration, it is transported to the electrolytic cell, and the other portion returns to the absorption tower and is used as a circulating capture agent again.

[0122] Electrolytic reduction process:

[0123] A carbonate-containing aqueous solution (e.g., sodium carbonate or potassium carbonate aqueous solution) is electrolytically reduced in an electrolytic cell to produce a mixed gas of carbon dioxide and oxygen at the cathode and hydrogen at the anode. The mixed gas of carbon dioxide and oxygen is separated in a separator (e.g., by a cryogenic device) to obtain carbon dioxide and a mixed gas of oxygen and a small amount of carbon dioxide. Part of the sodium hydroxide or potassium hydroxide aqueous solution produced by the electrolytic reduction process is pumped into an absorption tower as a capture agent.

[0124] Synthesis of hydrocarbons:

[0125] The relatively pure carbon dioxide obtained by separation is transported to a compressor for compression, and the hydrogen generated in the electrolytic reduction process is compressed, and then the two are subjected to a catalytic reaction (the catalyst for catalytic hydrogenation is ZnZrO / ZSM-5, the pressure is 25-35 bar, and the temperature is 200-300°C) to obtain product gas; the above product gas is cooled in a condenser to obtain methanol.

[0126] Table 1

[0127]

[0128]

[0129] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0130] (1) using an alkaline solution to absorb carbon dioxide in air and combustion exhaust gas to produce a carbonate solution, generating carbon dioxide by electrolyzing the carbonate solution, reducing the alkaline solution adsorbent and generating hydrogen at the same time;

[0131] (2) The device or system can adjust the chemical composition of the inlet electrolyte of the electrolyzer, and control the output ratio of different electrolytic gases (carbon dioxide, hydrogen) by controlling the voltage of the electrolyzer. Different molar ratios of hydrogen and carbon dioxide can be used for different downstream catalytic reactions. The CO2 and O2 generated by the alkaline electrolyzer need to be separated, and CO2 and H2 are synthesized to produce hydrocarbon fuels, such as methane, methanol, gasoline, aviation fuel, etc.;

[0132] (3) The catalytic reaction of CO2 and H2 synthesis is an exothermic reaction, and its heat can be reasonably recycled to produce hot water or steam to preheat the carbonate solution electrolyzer, so that the carbonate solution electrolyzer operates at the optimal temperature and achieves the highest efficiency;

[0133] (4) This carbon dioxide capture and utilization technology realizes capture and utilization simultaneously. The carbon dioxide captured from the air or flue gas can be directly output as an industrial by-product in the form of solid soda ash, or directly output in the form of liquid hydrocarbon fuel, thereby improving the production profit of the overall device or system and achieving the diversity of the output of the overall device or system; at the same time, it solves the problems of transportation and utilization of carbon dioxide, and also solves the problems of transportation and utilization of hydrogen in the field of hydrogen production by water electrolysis.

[0134] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for capturing and utilizing carbon dioxide, characterized in that: The method for capturing and utilizing carbon dioxide comprises: The carbon dioxide in the target component is captured by using an alkaline solution to obtain a carbonate-containing aqueous solution; Electrolytically reducing the carbonate-containing aqueous solution to obtain a hydroxide aqueous solution, carbon dioxide electrolytic gas, oxygen and hydrogen, and adjusting the output ratio of the carbon dioxide electrolytic gas and the hydrogen by controlling the concentration of the carbonate-containing aqueous solution and the electrolytic voltage of the electrolytic reduction process; During the electrolytic reduction process, the electrolytic cell voltage is 2-3V and the current density is 2000-4000A / m 2 , the concentration of carbonate in the carbonate-containing aqueous solution is 1 to 5 mol / L; Catalytically reacting the carbon dioxide electrolysis gas with hydrogen to obtain hydrocarbons, which can be used as industrial by-products; The electrolytic reduction process is carried out in an electrolytic cell, and part of the hydroxide aqueous solution leaving the electrolytic cell and / or the heat released by the catalytic reaction is used to preheat the carbonate-containing aqueous solution entering the electrolytic cell, and the carbonate-containing aqueous solution is preheated to 60-90°C.

2. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The electrolytic reduction process comprises: Electrolytically reducing the carbonate-containing aqueous solution to obtain a mixed gas of the carbon dioxide electrolytic gas and the oxygen, the hydrogen gas and the hydroxide aqueous solution; and The carbon dioxide electrolytic gas and the oxygen in the mixed gas are separated.

3. The method for capturing and utilizing carbon dioxide according to claim 2, characterized in that: The separation process is carried out by one or more methods selected from cryogenic liquefaction, catalytic oxidation, membrane separation and adsorption devices.

4. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The electrolytic reduction process is a staged electrolytic process.

5. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 4, characterized in that: The pH of the carbonate-containing aqueous solution is 7-10.

6. The method for capturing and utilizing carbon dioxide according to claim 5, characterized in that: The pH of the carbonate-containing aqueous solution is 7-8.

7. The method for capturing and utilizing carbon dioxide according to claim 5, characterized in that: Before performing the electrolytic reduction process, the method for capturing and utilizing carbon dioxide further includes: removing impurities from the carbonate-containing aqueous solution.

8. The method for capturing and utilizing carbon dioxide according to claim 7, characterized in that: After the impurity removal process, the content of alkaline earth metal ions in the carbonate-containing aqueous solution is ≤10 ppm.

9. The method for capturing and utilizing carbon dioxide according to claim 8, characterized in that: The alkaline earth metal ions include Ca 2+ and / or Mg 2+ .

10. The method for capturing and utilizing carbon dioxide according to claim 7, characterized in that: The method of the impurity removal process is selected from filtration, chemical precipitation or adsorption.

11. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The electrolytic reduction process is carried out under normal pressure or 2-40 bar.

12. The method for capturing and utilizing carbon dioxide according to claim 7, characterized in that: Between the impurity removal process and the electrolytic reduction process, the method for capturing and utilizing carbon dioxide further includes: adjusting the concentration of the carbonate-containing aqueous solution, wherein the adjustment process includes diluting with water or concentrating by heating.

13. The method for capturing and utilizing carbon dioxide according to claim 12, characterized in that: The method for capturing and utilizing carbon dioxide further comprises: extracting a portion of the carbonate-containing aqueous solution to obtain carbonate, which can be used as an industrial by-product.

14. The method for capturing and utilizing carbon dioxide according to claim 13, characterized in that: The extraction treatment process is carried out by a recrystallization method.

15. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The alkaline solution is an alkali metal hydroxide aqueous solution.

16. The method for capturing and utilizing carbon dioxide according to claim 15, characterized in that: The alkaline solution is a sodium hydroxide aqueous solution and / or a potassium hydroxide aqueous solution.

17. The method for capturing and utilizing carbon dioxide according to claim 15, characterized in that: The pH of the alkaline solution is greater than 7 and less than or equal to 10.

18. The method for capturing and utilizing carbon dioxide according to claim 15, characterized in that: The product of the electrolytic reduction process also includes bicarbonate.

19. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The method for capturing and utilizing carbon dioxide further includes: using a portion of the hydroxide aqueous solution leaving the electrolytic cell as the alkaline solution.

20. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The hydrocarbon is selected from one or more of methane, methanol, gasoline and aviation fuel.

21. The method for capturing and utilizing carbon dioxide according to claim 20, characterized in that: When the hydrocarbon is methanol, the temperature of the catalytic reaction process is 200-400° C., the pressure is 10-50 bar, and the molar ratio of the carbon dioxide electrolysis gas to the hydrogen is 1:1-1:

5.

22. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The target component is selected from air and / or combustion exhaust gas.

23. The method for capturing and utilizing carbon dioxide according to claim 22, characterized in that: When the target component is air, before the capture process, the method for capturing and utilizing carbon dioxide further includes: concentrating the target component to obtain concentrated gas to increase the concentration of carbon dioxide; and then subjecting the concentrated gas to the capture process.

24. The method for capturing and utilizing carbon dioxide according to claim 23, characterized in that: The concentration process comprises: using an adsorbent to adsorb carbon dioxide in the target component, and then desorbing it to obtain the concentrated gas, wherein the concentration of carbon dioxide in the concentrated gas is 0.4-5%.

25. The method for capturing and utilizing carbon dioxide according to claim 23 or 24, characterized in that: Between the concentration process and the capture process, the method for capturing and utilizing carbon dioxide further includes: compressing the concentrated gas.

26. The method for capturing and utilizing carbon dioxide according to claim 25, characterized in that: The pressure of the compression process is 5 to 500 bar.

27. The method for capturing and utilizing carbon dioxide according to claim 22, characterized in that: When the target component is combustion tail gas, before the capture process is performed, the method for capturing and utilizing carbon dioxide further comprises: performing denitrification, desulfurization and / or dust removal treatment on the combustion tail gas.

28. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The catalytic reaction is a thermal catalytic reaction, a photocatalytic reaction or a biocatalytic reaction; the hydrogen used in the catalytic reaction is generated by the electrolytic reduction process, or is partially generated by the electrolytic reduction process and the rest is input from the outside, or is entirely input from the outside.

29. A system for capturing and utilizing carbon dioxide, characterized in that: The system for capturing and utilizing carbon dioxide comprises: A carbon dioxide capture device, wherein the carbon dioxide capture device is provided with an alkaline solution inlet, a target component inlet and a carbonate-containing aqueous solution discharge port; An electrolytic reduction unit, wherein the electrolytic reduction unit is provided with a first carbonate-containing aqueous solution inlet, a carbon dioxide electrolytic gas outlet, an oxygen outlet, a hydrogen outlet and a hydroxide aqueous solution discharge port, wherein the first carbonate-containing aqueous solution inlet is connected to the carbonate-containing aqueous solution discharge port through a carbonate-containing aqueous solution delivery pipeline; a first heat exchange device, wherein the first heat exchange device is disposed on the carbonate-containing aqueous solution conveying pipeline, and a heat medium inlet of the first heat exchange device is connected to the hydroxide aqueous solution discharge port, so that the hydroxide aqueous solution discharged from the hydroxide aqueous solution discharge port is heat-exchanged with the carbonate-containing aqueous solution in the carbonate-containing aqueous solution conveying pipeline; A voltage regulating device, the voltage regulating device is used to adjust the voltage during the electrolytic reduction process to adjust the output ratio of the carbon dioxide electrolytic gas and the hydrogen; A catalytic device, wherein the catalytic device is provided with a catalytic inlet and a hydrocarbon outlet, and the catalytic inlet is connected to the carbon dioxide electrolysis gas outlet and the hydrogen outlet respectively; A second heat exchange device, wherein the second heat exchange device is arranged on the carbonate-containing aqueous solution conveying pipeline, and a heat medium inlet of the second heat exchange device is connected to the hydrocarbon outlet, so that the heat in the hydrocarbon discharged from the hydrocarbon outlet is exchanged with the carbonate-containing aqueous solution in the carbonate-containing aqueous solution conveying pipeline.

30. The system for capturing and utilizing carbon dioxide according to claim 29, characterized in that When the voltage regulating device enables the electrolytic reduction unit to perform graded electrolysis, the electrolytic reduction unit is an electrolytic reduction device, and the electrolytic reduction device is provided with the first carbonate-containing aqueous solution inlet, the hydrogen outlet, the carbon dioxide electrolytic gas outlet, the oxygen outlet and the hydroxide aqueous solution discharge port; or When the electrolytic reduction unit does not perform graded electrolysis, the electrolytic reduction unit comprises: An electrolytic reduction device, the electrolytic reduction device being provided with the first carbonate-containing aqueous solution inlet, the hydrogen outlet, an anode gas discharge port and the hydroxide aqueous solution discharge port, wherein the anode gas comprises carbon dioxide electrolytic gas and oxygen; The separation device is provided with a gas inlet for separation, the carbon dioxide electrolysis gas outlet and the oxygen outlet, and the gas inlet for separation is connected with the anode gas exhaust port.

31. The system for capturing and utilizing carbon dioxide according to claim 30, characterized in that The separation device is selected from one or more of a cryogenic device, a catalytic oxidation device, an adsorption device and a membrane separation device.

32. The system for capturing and utilizing carbon dioxide according to claim 29, wherein: The system for capturing and utilizing carbon dioxide further comprises an impurity removal device, which is arranged on the carbonate-containing aqueous solution conveying pipeline.

33. The system for capturing and utilizing carbon dioxide according to claim 32, characterized in that The impurity removal device is selected from a filtering device, a precipitation device or an adsorption device.

34. The system for capturing and utilizing carbon dioxide according to claim 30, wherein: The system for capturing and utilizing carbon dioxide also includes: The carbonate-containing aqueous solution concentration regulating device is arranged on the carbonate-containing aqueous solution conveying pipeline, and the carbonate-containing aqueous solution concentration regulating device is used to regulate the concentration and pH of the carbonate-containing aqueous solution.

35. The system for capturing and utilizing carbon dioxide according to claim 34, characterized in that The carbonate-containing aqueous solution concentration regulating device is a diluting device or a concentrating device.

36. The system for capturing and utilizing carbon dioxide according to claim 29, wherein: The system for capturing and utilizing carbon dioxide further comprises a carbonate extraction device, wherein the carbonate extraction device is provided with a second carbonate-containing aqueous solution inlet, and the second carbonate-containing aqueous solution inlet is connected to the carbonate-containing aqueous solution discharge port.

37. The system for capturing and utilizing carbon dioxide according to claim 36, characterized in that The extraction device is a crystallization device or a recrystallization device.

38. The system for capturing and utilizing carbon dioxide according to claim 29, wherein: The hydroxide aqueous solution discharge port is communicated with the alkaline solution inlet.

39. The system for capturing and utilizing carbon dioxide according to claim 29, wherein: When the target component is air, the system for capturing and utilizing carbon dioxide also includes a concentration unit, which is provided with an inlet for gas to be concentrated and an outlet for concentrated gas. The concentrated gas outlet is connected to the inlet of the target component through a concentrated gas delivery pipeline. The concentration unit is used to increase the content of carbon dioxide in the target component.

40. The system for capturing and utilizing carbon dioxide according to claim 39, wherein: The concentration unit comprises: A carbon dioxide adsorption device, provided with an inlet for the gas to be concentrated, for adsorbing carbon dioxide in the target component; The desorption device is arranged downstream of the carbon dioxide absorption device and is provided with the concentrated gas outlet, and is used for desorption of carbon dioxide absorbed in the carbon dioxide absorption device.

41. The system for capturing and utilizing carbon dioxide according to claim 39, wherein: The system for capturing and utilizing carbon dioxide further comprises a first compression device, which is disposed on the concentrated gas transmission pipeline.

42. The system for capturing and utilizing carbon dioxide according to claim 35, wherein: When the target component is combustion exhaust gas, the system for capturing and utilizing carbon dioxide also includes a dust removal device, a desulfurization device and a denitrification device, and a target component transport pipeline connected to the target component inlet, and the dust removal device, the desulfurization device and the denitrification device are arranged on the target component transport pipeline.

43. The system for capturing and utilizing carbon dioxide according to claim 30, wherein: The system for capturing and utilizing carbon dioxide further comprises a collecting device, wherein the collecting device is provided with a collecting port, and the collecting port is communicated with the oxygen outlet for collecting oxygen.

44. The system for capturing and utilizing carbon dioxide according to claim 30, wherein: The system for capturing and utilizing carbon dioxide also includes: A carbon dioxide compression device, wherein the carbon dioxide compression device is provided with a carbon dioxide electrolysis gas inlet and a carbon dioxide compressed gas outlet, the carbon dioxide electrolysis gas inlet is connected to the carbon dioxide electrolysis gas outlet of the electrolytic reduction unit, and the carbon dioxide compressed gas outlet is connected to the catalytic inlet; A hydrogen compression device is provided with a hydrogen inlet and a hydrogen compressed gas outlet, wherein the hydrogen inlet is communicated with the hydrogen outlet of the electrolytic reduction unit, and the hydrogen compressed gas outlet is communicated with the catalytic inlet.

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