System and process for electrochemical capture of co2

Abstract

The application provides a system and a process for electrochemically capturing CO2, the system comprising an acid battery, an alkali battery, an electrolyte storage device and a vacuum stripper; the acid battery comprises a PbCl2 positive electrode and a Sb negative electrode, the alkali battery comprises a SbOCl positive electrode and a Pb negative electrode, the electrolyte storage device comprises a CO2 gas inlet, and the vacuum stripper comprises a CO2 gas outlet; the electrolyte storage device is filled with an electrolyte comprising sodium metaborate and choline chloride, and the electrolyte storage device, the acid battery, the vacuum stripper and the alkali battery are connected in series to form a circulation loop; after the electrolyte flows out of the electrolyte storage device, it flows back to the electrolyte storage device after passing through the acid battery, the vacuum stripper and the alkali battery. The application is based on the principle of a primary battery, and can capture CO2 in the atmosphere by using a small potential difference without the need for expensive membranes or chemical addition, is easy to implement, does not cause the formation of by-products, has low energy consumption, high electronic efficiency, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of removing CO2 in the atmosphere, and particularly relates to a system and process for electrochemically capturing CO2. BACKGROUND

[0002] The theory that the emission of greenhouse gas CO2 leads to climate warming is gradually accepted by the world scientific community, and CO2 has been proven to be the main factor causing global greenhouse effect. In the past decades, the global CO2 emission has significantly increased, and the CO2 emission in 2014 has exceeded 35 Gt. The concentration of CO2 in the atmosphere is also increasing year by year, and the concentration of CO2 in the atmosphere in February 2015 exceeded 400 ppm, and the greenhouse effect is more and more obvious. Therefore, how to take appropriate strategies to slow down the increasing rate of CO2 concentration in the atmosphere, or stabilize it in a certain acceptable concentration range, is an important issue that mankind must face.

[0003] At present, the feasible coping strategies include improving the conversion and use efficiency of energy, replacing the existing energy with low-carbon content or carbon-free energy, and CO2 capture and storage technology. In order to alleviate the excessive emission of CO2, people have developed various CO2 capture technologies, mainly including solvent absorption method, adsorption method, membrane absorption separation method, low-temperature distillation method and various coupling technologies. However, in the feasible emission reduction scheme, such as CO2 geological storage and CO2 ocean storage, low-concentration CO2 needs to be captured first. However, the cost of CO2 capture accounts for about 75% of the total cost of CO2 emission reduction, which is the main reason for the economic feasibility of CO2 emission reduction. In fact, the main reason for the high cost of CO2 capture is due to the high energy consumption, so it is very important to develop an efficient and energy-saving carbon capture method to reduce the energy consumption of CO2 emission reduction. SUMMARY

[0004] Based on the technical problems existing in the background art, the present application provides a system and process for electrochemically capturing CO2. The system and process are based on the principle of primary battery, and can capture CO2 in the atmosphere by using a small potential difference without the need for expensive membranes or chemical addition, are easy to implement, do not cause the formation of by-products, have low energy consumption, high electron efficiency, and have good application prospect.

[0005] The system for electrochemically capturing CO2 provided by the present application comprises an acid battery, an alkali battery, an electrolyte storage device and a vacuum stripper.

[0006] The acid battery comprises a PbCl2 positive electrode and a Sb negative electrode, the alkali battery comprises a SbOCl positive electrode and a Pb negative electrode, the electrolyte storage device comprises a CO2 gas inlet, and the vacuum stripper comprises a CO2 gas outlet.

[0007] The electrolyte storage device is filled with electrolyte containing sodium metaborate and choline chloride, and the electrolyte storage device, the acid battery, the vacuum stripper and the alkali battery are connected in series to form a circulation loop, and the electrolyte flows out from the electrolyte storage device, passes through the acid battery, the vacuum stripper and the alkali battery, and then flows back to the electrolyte storage device.

[0008] Preferably, the acid battery, the alkali battery, the electrolyte storage device and the vacuum stripper are all provided with electrolyte inlets and electrolyte outlets.

[0009] Preferably, the electrolyte outlet of the electrolyte storage tank is connected with the electrolyte inlet of the acid battery, the electrolyte outlet of the acid battery is connected with the electrolyte inlet of the vacuum stripper, the electrolyte outlet of the vacuum stripper is connected with the electrolyte inlet of the alkali battery, and the electrolyte outlet of the alkali battery is connected with the electrolyte inlet of the electrolyte storage tank.

[0010] Preferably, the system further comprises an electrolyte circulating pump, which is located on the circulation loop and is used to provide power for electrolyte circulation.

[0011] Preferably, the system further comprises a CO2 gas collection tank, which is connected with the vacuum stripper and is used to collect CO2 stripped by the vacuum stripper.

[0012] Preferably, in the electrolyte, the concentration of sodium metaborate is 0.1-0.2 mol / L, and the concentration of choline chloride is 0.4-0.6 mol / L.

[0013] The application provides an electrochemical CO2 trapping system.

[0014] In the working process, the gas containing CO2 is introduced into the electrolyte storage device through the CO2 gas inlet on the electrolyte storage device, the electrolyte in the electrolyte storage device adsorbs CO2 to form CO3 2- , and then the electrolyte containing CO3 2- flows into the acid battery, H+ generated by the electrochemical reaction of the acid battery reacts with CO3 2- in the electrolyte to form H2CO3, then the electrolyte containing H2CO3 flows into the vacuum stripper, CO2 decomposed from H2CO3 is stripped by the vacuum stripper and discharged from the CO2 gas outlet and trapped, and then the electrolyte flows into the alkali battery and recycles back to the electrolyte storage device.

[0015] In the application, the electrochemical reaction of the acid battery is as follows:

[0016] Sb+C l -+H2O-3e→SbOCl+2H +

[0017] PbCl2+2e→Pb+2Cl -

[0018] CO3 2- +H + →HCO3 - +H + →CO 2(aq) +H2O

[0019] The electrochemical reaction of the alkaline battery is as follows:

[0020] SbOCl+2H + +3e→Sb+Cl - +H2O

[0021] Pb+2Cl - -2e→PbCl2

[0022] Preferably, the flow rate of the electrolyte is 1-3 mL / min, and the temperature is 25-40℃.

[0023] Preferably, the flow direction of the electrolyte is switched after the pH value of the electrolyte does not change.

[0024] The system and process for electrochemically capturing CO2 provided by the present application adopt two Sb / Pb electrode systems in series, and realize pH swing in the electrolyte through Faraday reaction under appropriate battery voltage, so that the two Sb / Pb batteries are connected in series in the cycle process, and the pH value in the electrolyte is adjusted through reversible electrochemical reaction, wherein the acid battery (PbCl2 / Sb as positive and negative electrodes) provides H + + in the electrolyte, and then the CO2 dissolved in the electrolyte is acidified, and then stripped by a vacuum stripper and collected by a CO2 gas collection tank, and the alkaline battery (SbOCl / Pb as positive and negative electrodes) realizes electrode regeneration by alkalizing the decarburized electrolyte (providing OH-), and after one cycle (i.e. no significant change in the pH value of the electrolyte), the flow direction of the electrolyte is switched by using an electrolyte circulating pump, and the electrolyte flows in the opposite direction, so that the two batteries exchange roles to realize continuous removal of CO2 from the atmosphere.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1. The present application can be effectively used for capturing CO2 in the atmosphere, and the electrolyte solution can be recycled without three waste emissions, which is a green process and has potential for industrial application.

[0027] 2. The capture technology of the present application has a simple process, mild conditions, easy process control, compact equipment, low energy consumption and high electronic efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the electrochemical CO2 capture system described in this invention;

[0029] Among them, 1-acid battery pack, 2-alkali battery pack, 3-electrolyte storage device, 4-vacuum stripper, 5-electrolyte circulation pump, 6-CO2 gas collection tank, 11-thermostat bath, 12-Sb electrode, 13-PbCl2 electrode, 14-pH meter, 21-thermostat bath, 22-SbOCl electrode, 23-Pb electrode, 24-pH meter. Detailed Implementation

[0030] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0031] Example 1

[0032] Reference Figure 1 This embodiment proposes an electrochemical CO2 capture battery system, including an acid battery pack 1, an alkaline battery pack 2, an electrolyte storage device 3, a vacuum stripper 4, an electrolyte circulation pump 5, and a CO2 gas collection tank 6.

[0033] The acid battery pack 1 includes a thermostatic bath 11, an Sb electrode 12, a PbCl2 electrode 13, and a pH meter 14. The Sb electrode 12 and the PbCl2 electrode 13 are arranged opposite each other in the thermostatic bath 11, with a gap of 1.5 mm between them. The electrode area is 9 cm². 2 The pH meter 14 is placed in the gap between the two electrodes; at the same time, the acid battery pack 1 is also equipped with an electrolyte inlet and an electrolyte outlet that are connected to the gap between the two electrodes.

[0034] The alkaline battery pack 2 includes a thermostatic bath 21, an SbOCl electrode 22, a Pb electrode 23, and a pH meter 24. The SbOCl electrode 22 and the Pb electrode 23 are also arranged opposite each other in the thermostatic bath 21, with a gap of 1.5 mm between them. The electrode area is 9 cm². 2 The pH meter 24 is placed in the gap between the two electrodes. At the same time, the alkaline battery pack 2 is also equipped with an electrolyte inlet and an electrolyte outlet that are connected to the gap between the two electrodes.

[0035] The electrolyte storage device 3 is equipped with a CO2 gas inlet and a gas outlet, as well as an electrolyte inlet and an electrolyte outlet;

[0036] The vacuum stripper 4 is provided with a CO2 gas outlet, and also provided with an electrolyte inlet and an electrolyte outlet; the vacuum stripper 4 in the embodiment is a hollow fiber membrane contactor;

[0037] The electrolyte storage device is filled with electrolyte, and the electrolyte is a deionized water solution containing 0.15 mol / L sodium metaborate and 0.4 mol / L choline chloride; the electrolyte storage device 3, the acid battery group 1, the vacuum stripper 4 and the alkali battery group 2 are connected in series to form a circulation loop, and the electrolyte flows out from the electrolyte storage device 3, passes through the acid battery group 1, the vacuum stripper 4 and the alkali battery group 2, and then flows back to the electrolyte storage device; in actual setting, the electrolyte outlet of the electrolyte storage device 3 is connected with the electrolyte inlet of the acid battery group 1 through a circulation pipeline, and in the embodiment, an electrolyte circulation pump 5 is further arranged on the circulation pipeline; the electrolyte outlet of the acid battery group 1 is connected with the electrolyte inlet of the vacuum stripper 4 through a circulation pipeline, the electrolyte outlet of the vacuum stripper 4 is connected with the electrolyte inlet of the alkali battery group 2 through a circulation pipeline, and the electrolyte outlet of the alkali battery group 2 is connected with the electrolyte storage device 3 through a circulation pipeline; in the embodiment, the CO2 gas outlet of the vacuum stripper 4 is further connected with the CO2 gas collection tank 6 through a gas pipeline.

[0038] The embodiment also proposes an electrochemical CO2 capture process, which is realized by using the above system, that is, 1500 mL of electrolyte is poured into the electrolyte storage device 3 in advance, and then the electrolyte circulation pump 5 and the vacuum stripper 4 are turned on, the electrolyte is powered to circulate through the electrolyte storage device 3, the acid battery group 1, the alkali battery group 2 and the vacuum stripper 4, and the temperature of the electrolyte is controlled to be 30℃, and the flow rate is 2 mL / min; in the specific working process, the atmosphere containing CO2 is introduced into the electrolyte storage device 3 through the CO2 gas inlet thereof, the electrolyte in the electrolyte storage device 3 adsorbs CO2 to form CO3 2- , and the unabsorbed gas is discharged through the gas outlet thereof; then the electrolyte containing CO3 2- flows into the acid battery group 1, and H + generated by the electrochemical reaction of the acid battery group 1 reacts with CO3 2-The reaction forms H2CO3; then the electrolyte containing H2CO3 flows into the vacuum stripper 4, CO2 decomposed from H2CO3 is stripped by the vacuum stripper 4, is discharged from the CO2 gas outlet on the vacuum stripper 4, and is continuously collected in the CO2 gas collection tank 6 through the gas pipeline, and then the electrolyte flows into the alkaline battery group 2 and is recycled back to the electrolyte storage device 3; after 0.5 h according to the above working cycle, the electrolyte is switched to flow in the opposite direction, at this time the roles of the acid battery group 1 and the alkaline battery group 2 are interchanged, CO2 in the atmosphere can be continuously removed and captured, and the above working cycle is continuously repeated until 12 h of operation, and the electronic efficiency (i.e. the relative Faraday efficiency, which is the relative efficiency obtained by dividing the actually calculated Faraday efficiency by the theoretical maximum Faraday efficiency of the electrochemical reaction: η 相对 = η / η max , η = (m x n x F) / (I x t), wherein m is the actual molar number of the product, n is the number of reaction electrons, F is the Faraday constant, i.e. the electric quantity contained in one mole of electrons, I is the current, and t is the time) can reach 90%.

[0039] Example 2

[0040] With reference to Figure 1 , this embodiment also proposes a system and process for electrochemically capturing CO2, which has the same settings as in Example 1, except that the distance between the two electrodes is set to 2 mm, the electrolyte is a deionized water solution containing 0.1 mol / L sodium metaborate and 0.5 mol / L choline chloride, and the electrolyte temperature is controlled to be 40℃, the working cycle is 1 h, then the electrolyte is switched to flow in the opposite direction, and the above working cycle is continuously repeated until 12 h of operation, and the electronic efficiency can reach 86%.

[0041] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A system for electrochemically capturing CO2, characterized in that, Includes acid battery packs, alkaline battery packs, electrolyte storage devices, and vacuum strippers; The acid battery pack includes a PbCl2 positive electrode and an Sb negative electrode, the alkaline battery pack includes an SbOCl positive electrode and a Pb negative electrode, the electrolyte storage device includes a CO2 gas inlet, and the vacuum stripper includes a CO2 gas outlet. The electrolyte storage device is filled with an electrolyte containing sodium metaborate and choline chloride. The electrolyte storage device, acid battery pack, vacuum stripper and alkaline battery pack are connected in series to form a circulation loop. After the electrolyte flows out of the electrolyte storage device, it flows through the acid battery pack, vacuum stripper and alkaline battery pack and then flows back to the electrolyte storage device.

2. The electrochemical CO2 capture system according to claim 1, characterized in that, The acid battery pack, alkaline battery pack, electrolyte storage device, and vacuum stripper are all equipped with electrolyte inlet and electrolyte outlet; The electrolyte outlet of the electrolyte storage device is connected to the electrolyte inlet of the acid battery pack, the electrolyte outlet of the acid battery pack is connected to the electrolyte inlet of the vacuum stripper, the electrolyte outlet of the vacuum stripper is connected to the electrolyte inlet of the alkaline battery pack, and the electrolyte outlet of the alkaline battery pack is connected to the electrolyte inlet of the electrolyte storage device.

3. The electrochemical CO2 capture system according to claim 1 or 2, characterized in that, The system also includes an electrolyte circulation pump, which is located on the circulation loop and is used to provide power for electrolyte circulation.

4. The electrochemical CO2 capture system according to claim 1 or 2, characterized in that, The system also includes a CO2 gas collection tank, which is connected to a vacuum stripper and is used to collect the CO2 stripped off by the vacuum stripper.

5. The electrochemical CO2 capture system according to claim 1 or 2, characterized in that, The electrolyte contains sodium metaborate at a concentration of 0.1-0.2 mol / L and choline chloride at a concentration of 0.4-0.6 mol / L.

6. A process for electrochemically capturing CO2, characterized in that, Includes a system for electrochemically capturing CO2 as described in any one of claims 1-5; During operation, CO2-containing gas is introduced into the electrolyte storage device through the CO2 gas inlet. The electrolyte in the storage device adsorbs the CO2 to form CO3. 2- ; followed by CO3 2- The electrolyte flows into the acid battery pack, and the H2 produced by the electrochemical reaction in the acid battery pack... + With CO3 in the electrolyte 2- The reaction forms H2CO3; then the electrolyte containing H2CO3 flows into the vacuum stripper, and the CO2 decomposed from H2CO3 is stripped by the vacuum stripper and discharged from the CO2 gas outlet on it and captured. After that, the electrolyte flows into the alkaline battery pack and then flows back to the electrolyte storage device.

7. The electrochemical CO2 capture process according to claim 6, characterized in that, The electrolyte flow rate is 1-3 mL / min, and the temperature is 25-40℃.

8. The electrochemical CO2 capture process according to claim 6 or 7, characterized in that, Once the pH value in the electrolyte remains unchanged, switch the electrolyte flow to reverse.

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