CN115400550A - Ultralow-energy-consumption carbon dioxide electrochemical capture method and system - Google Patents
Ultralow-energy-consumption carbon dioxide electrochemical capture method and system Download PDFInfo
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Abstract
The invention belongs to the technical field of electrochemistry, and particularly relates to CO with ultralow energy consumption 2 An electrochemical capture system. The system comprises an anode region, a cathode region and an anion exchange membrane arranged in the middle, wherein the cathode region is filled with alkali liquor; and a water-soluble organic Proton Coupled Electron Transfer (PCET) reactant is added into the anode region, and an external power supply is communicated between the anode region and the cathode region. The external power supply provides electric energy for the electrolytic cell. The cathode side is a hydrogen evolution electrode which generates electrochemical reduction reaction to decompose water to generate H 2 And OH ‑ (ii) a Electrochemically generated H on the anode side + With HCO in the anolyte 3 ‑ In CO 2 Reaction in a desorber to produce high purity CO 2 And produce water to realizeCO 2 The substance Q rich in the oxidation state of the organic PCET enters a reduction regeneration tower to carry out non-electrochemical reduction regeneration. The system can stably operate under low energy consumption, and can realize CO in flue gas 2 Can also be applied to CO in factory waste gas, transportation tail gas, atmosphere and other environments 2 And (4) trapping.
Description
Technical Field
The invention belongs to the technical field of electrochemistry, and relates to novel electrochemical CO based on a solution pH change driven by electrochemical oxidation-reduction reaction and a coupling non-electrochemical reduction reaction regenerated solvent 2 A capture and purification system, in particular to ultra-low energy consumption CO 2 An electrochemical trapping system.
Background
CO 2 The capture is to capture low-concentration CO 2 Absorbing and separating to high purity for subsequent sealing or utilization. At present, CO 2 Chemical absorption method for trapping CO by using amine absorbent mostly 2 The thermal desorption is adopted, and the desorption energy consumption is high (2-4.5 GJ/ton CO) 2 ) Is a technical bottleneck.
Existing electrochemical CO 2 The trapping technology utilizes electrochemical Proton Coupled Electron Transfer (PCET) reaction to change the pH environment of the solution and break CO 2 Equilibrium of absorption-desorption in solution, thereby achieving low energy consumption<2 GJ/ton CO 2 )CO 2 Trapping and purifying. The current process generally employs an organic PCET reactant or recycle H 2 As a carrier for electrochemical redox reactions. Wherein a cycle H is used 2 One of the major difficulties faced lies in H 2 The electrochemical oxidation reaction needs a gas diffusion electrode, and a three-phase reaction interface which is difficult to regulate and control is easy to cause electrode flooding, so that the electrode failure reaction is difficult to stably operate. One of the core challenges with the use of organic PCET reactants is O 2 Influence on the stability of the system. Flue gas CO of coal-fired power plant 2 Usually containing O in a concentration of about 3 to 6% 2 And atmospheric CO 2 Containing O at a concentration of about 21% 2 ，O 2 The presence of (A) can cause rapid decay of electrochemical PCET reactants, making the system difficult to detect in real CO 2 In a trapping environment (containing O) 2 Environment) to operate stably. From the thermodynamic analysis, the oxygen-resistant organic PCET reactant generally has higher electrode potential, and the energy consumption of the system is increased.
Thus, true CO 2 Trapping environment (containing O) 2 Environment) is the current electrochemical CO 2 The trapping technology is urgent to overcome the technical problems.
Disclosure of Invention
The invention aims to provide CO with ultralow energy consumption aiming at the problems in the prior art 2 An electrochemical capture system. The ultra-low energy consumption CO 2 The electrochemical capture system is powered by an external power supply, and changes the pH environment of the solution through electrochemical PCET reaction so as to capture and purify CO 2 The three main processes of reducing and regenerating the organic PCET reactant by the non-electrochemical reaction realize low energy consumption and oxygen-containing CO 2 Ambient CO 2 Stable electrochemical capture and purification process.
In order to realize the aim, the specific technical scheme of the invention is as follows:
ultralow-energy-consumption CO 2 The electrochemical trapping method comprises the following steps of firstly, providing energy for electrochemical reaction by using an external power supply; secondly, the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - The water reaches the anolyte through the anion membrane, the anode generates the oxidation reaction of organic PCET reactant, and H is released + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 (ii) a Finally, hydrogen generated by the cathode is used for reducing the organic PCET reactant of the anode under the action of the catalyst, so that the anolyte is regenerated.
Ultralow-energy-consumption CO 2 The electrochemical trapping system adopts an asymmetric electrochemical reaction structure, namely, the cathode is used for electrochemical hydrogen evolution reaction, and the anode is used for electrochemical oxidation reaction of an organic PCET reactant. And hydrogen generated by the cathode is circulated to the outside of the electrolysis system, and the oxidized organic PCET reactant in the anolyte is spontaneously reduced and regenerated under the action of the Pt catalyst. The system is prepared by electrochemical reaction of organic PCETThe chemical oxidation reaction is decoupled from the non-electrochemical reduction reaction to achieve continuous, stable circulation of the organic PCET reactant. The specific system structure is as follows:
ultralow-energy-consumption CO 2 The electrochemical trapping system comprises an electrolytic cell, an anode area and a cathode area, wherein the anode area and the cathode area are arranged on two sides of the electrolytic cell and are separated by an arranged anion exchange membrane, and alkali liquor is filled in the cathode area; and a water-soluble organic PCET reactant is added into the anode region, and an external power supply is communicated between the anode region and the cathode region.
In a preferred embodiment of the present invention, the system is configured such that electrochemical hydrogen evolution reaction is carried out on the cathode side to capture and absorb CO 2 The method specifically comprises the following steps: the cathode generates electrochemical hydrogen evolution reaction to decompose water to generate H 2 And OH - To increase the alkalinity of the catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - Passes through the anion membrane and reaches the anolyte. The system adopts an anion exchange membrane to separate the anode liquid and the cathode liquid, thereby thoroughly avoiding cathode CO 2 Absorption side O 2 The interference on the anode organic PCET reactant can realize the true oxygen-containing CO 2 Direct capture (of flue gas or atmosphere). Simultaneous catholyte HCO 3 - Can reach the anolyte through an anion membrane to realize the charge balance of the system and desorb CO for the anode 2 Providing a carbon source.
Cathode side reaction equation: 2H 2 O+2e - →2OH - +H 2
Electrochemical oxidation reaction of organic PCET reactant occurs on the anode side, and the anode of the system adopts water-soluble organic PCET reactant to release H through electrochemical oxidation + Releasing H + And with HCO in the anolyte 3 - Reaction to produce high purity CO 2 And water to realize CO 2 Purification and regeneration. Finally, hydrogen generated by the cathode is used for reducing the organic PCET reactant of the anode under the action of the catalyst, so that the anolyte is regenerated. Because only solid-liquid two-phase electrochemical reaction exists in the anode side, the use of a gas diffusion electrode is avoided, the electrochemical gas-liquid-solid three-phase reaction interface is thoroughly eliminated, and the electrochemical gas-liquid-solid three-phase reaction interface is greatly improvedThe stability of the system in long-time operation is improved.
The reaction equation on the anode side is: QH 2 →Q+2H + +2e - (Q/QH 2 The oxidized and reduced states, respectively, of the organic PCET reactant).
As a preferred embodiment herein, the cathode is a hydrogen evolution electrode (e.g., platinum electrode, platinized nickel mesh, etc.), and useful cathodic hydrogen evolution catalysts include, but are not limited to: pt/C, platinum nickel plated mesh, foamed nickel, etc. Anodes include, but are not limited to, graphite felt electrodes, carbon paper, carbon cloth, and the like.
In a preferred embodiment of the present invention, a gas-liquid separator and CO are provided on the cathode side 2 Absorbing in an absorption tower, introducing the alkali-rich cathode liquid into a gas-liquid separator, and separating H 2 And a catholyte; introducing CO into catholyte 2 The absorption tower is used for absorbing CO 2 Production of HCO 3 - . Preferably, the CO is 2 The absorption tower is also respectively connected with a tail gas emptying device and a flue gas source device to realize the treatment of the gas (N) 2 ) And (4) discharging. Preferably, a hydrogen dryer is further arranged at the outlet of the gas-liquid separator, so that the generated hydrogen is dried conveniently.
CO 2 The reaction equation in the absorption tower is as follows: CO 2 2 Absorption: CO 2 2 +OH - →HCO 3 -
In a preferred embodiment of the present invention, CO is provided on the anode side 2 Desorption tower and reduction regeneration tower, electrochemically generating H on anode side + With HCO in the anolyte 3 - In CO 2 Reaction in a desorber to produce high purity CO 2 And produce water to realize CO 2 Purification and desorption; the generated water is balanced by a spontaneous permeation membrane under the action of concentration difference of two sides of the membrane, or the water is quantitatively removed by additionally adding a reverse osmosis device. CO 2 2 The reaction equation in the desorption tower is as follows: h + +HCO 3 - →H 2 O+CO 2 (100％)
As a better embodiment in the application, the water separation device is a reverse osmosis water separator which is connected with the reduction deviceThe regeneration tower is connected. The substance Q rich in the oxidation state of the organic PCET enters a reduction regeneration tower and is separated from H separated by a gas-liquid separator 6 under the action of a platinum catalyst 2 Mixing to carry out organic PCET reduction state QH 2 Non-electrochemical reduction regeneration. Preferably, the reduction regeneration tower is connected with a hydrogen storage tank.
The reaction equation in the reduction regeneration tower is as follows: QH 2 Non-electrochemical reduction regeneration: q + H 2 →QH 2 。
As a preferred embodiment in this application, the outlet of the reduction and regeneration tower is rich in QH 2 The anolyte is circularly led into an anode area of the electrolytic cell, and the stable circulation of the organic PCET reactant is realized.
In a preferred embodiment of the present application, the electrode potential of the organic PCET reactant is higher than the hydrogen evolution reaction potential to ensure H outside the electrochemical system 2 Spontaneously reducing an organic PCET reactant under the action of a catalyst; the organic PCET reactant needs to generate reversible or quasi-reversible electrons (e) under the use environment - ) Proton (H) + ) Transfer reaction to ensure electrochemical acidification of the anolyte; in order to ensure that the anode liquor can be spontaneously reduced by hydrogen under the action of a catalyst and simultaneously avoid high electrolysis energy consumption.
As a preferred embodiment herein, the organic PCET reactant includes, but is not limited to, pyrazines, alloxazines, phenazines, quinones, and the like, and derivatives thereof, such as: FMN, DHPS, DHPC, BHPC, etc.
Wherein R is n ＝-H、-OH、-COOH、-SO 3 H、-NH 2 、-CH 3 、-O-、-S-、-CH 2 -、-F、-Cl、-CH 2 CH 2 COOH, etc.
As a preferred embodiment herein, the reductive regeneration of the organic PCET reactant in the system is carried out externally to the electrolysis system, with the oxidation state of the organic PCET reactant and H being reacted with the catalyst 2 Spontaneous redox reactions take placeAccordingly, a reductive regeneration cycle of the organic PCET reactant is achieved. The reduction regeneration tower is filled with a reduction regeneration catalyst which adopts an alumina platinum catalyst, and the reduction regeneration catalyst can be selected from Pt, pt/C, pd/C, ni and the like.
The working principle of the invention is as follows:
firstly, an external power supply is utilized to provide energy for electrochemical reaction; secondly, the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - The water penetrates through the anion membrane to reach the anolyte, the anode generates the oxidation reaction of organic PCET reactant, and H is released + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 (ii) a Finally, hydrogen generated by the cathode is used for reducing the organic PCET reactant of the anode under the action of the catalyst, so that the anolyte is regenerated. The invention adopts an organic PCET reactant on the anode side, thereby avoiding anode H 2 The use of gas diffusion electrodes; hydrogen evolution reaction occurs on the cathode side and CO is absorbed simultaneously 2 Thoroughly avoid CO 2 O in (1) 2 And the effect of catholyte dissolved oxygen on the anodic organic PCET reactant. While H produced at the cathode 2 Can be used as a reducing agent to realize the reduction and regeneration of an organic PCET reactant, thereby realizing the electrochemical CO 2 Continuous and stable operation of the trapping system.
The organic PCET reactant adopted by the invention can be replaced by an inorganic PCET reactant or a high molecular polymer with PCET reaction performance, such as MnOOH, niOOH, polyaniline and the like.
Compared with the prior art, the positive effects of the invention are as follows:
the system can realize oxygen-containing CO 2 Ambient CO 2 The electrochemical capture and purification process of (1). In practical application, the system can supply power through an external power supply, change the pH environments of the cathode and the anode of the solution by utilizing electrochemical PCET reaction, and promote low-concentration CO in the cathode region 2 High purity CO in absorption and anode region 2 And using the H generated by the cathode 2 The anode liquid is reduced and regenerated outside the system, thereby realizing low energy consumption and continuous productionContinuous stable CO 2 Trapping and purifying.
And (II) the whole system can be designed into a simple integrated device according to the requirement, and can also be designed into a large-scale integrated device through series-parallel connection of the system. Can be suitable for CO in the environments including coal-fired power plant flue gas, factory waste gas, transportation tail gas, even atmosphere and the like 2 And (4) trapping. And the continuous operation is carried out without intermission without the limitation of time and space.
And thirdly, the system has reasonable design and low energy consumption and can stably run for a long time.
Drawings
FIG. 1 shows the ultra-low energy CO of the present invention 2 A schematic diagram of an electrochemical capture system;
FIG. 2 shows the ultra-low energy CO of the present invention 2 A schematic diagram of the structure of the electrochemical capture system;
wherein, 1-external power supply, 2-electrolytic tank, 3-anode region, 4-anion exchange membrane, 5-cathode region, 6-gas-liquid separator, 7-hydrogen drier, 8-CO 2 Absorption tower, 9-evacuation of tail gas, 10-flue gas source, 11-CO 2 Desorption column, 12-CO 2 Dryer, 13-CO 2 A collecting bottle, a 14-reverse osmosis water separator, a 15-reduction regeneration tower and a 16-hydrogen storage tank;
FIG. 3 is a graph of energy consumption of a system employing DHPS in an oxygen-containing environment
FIG. 4 shows the system CO 2 Absorption concentration profile;
FIG. 5 shows the system CO 2 Release concentration profile;
FIG. 6 is a graph of energy consumption in oxygen-containing environment using FMN
FIG. 7 is a graph of energy consumption for a system employing different reduction catalysts in an oxygen-containing environment.
Fig. 8 is a graph comparing stability in an oxygen environment for a symmetric system and an asymmetric system.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail with reference to specific examples, but it should not be construed that the scope of the above-described subject matter of the present invention is limited to the examples. Various substitutions and alterations can be made without departing from the technical idea of the invention as described above, according to the common technical knowledge and conventional means in the field, and the scope of the invention is covered.
Unless otherwise specified, all% described in the following examples represent the volume percentage, i.e., v%.
Example 1:
ultralow-energy-consumption CO 2 The electrochemical trapping system, the system structure of the embodiment is shown in figure 2, the system structure is described in the specific embodiment, and the process is shown in figure 1.
The system comprises an external power supply 1 connected with cathode and anode of an electrolytic reactor 2 for providing electric energy for an electrolytic bath, wherein the electrolytic reactor is the electrolytic bath, and the effective area in the electrolytic bath is 4cm 2 . The electrolytic cell (electrolytic reactor) is divided into two areas, namely an anode area and a cathode area, by an anion exchange membrane (FAA-3-20 \/FAA-3-PK-130)) 4 which only allows anions to permeate but can prevent cations from permeating. 70mL of NaHCO with a concentration of 1mol/L are added in the anode section 3 And 0.02mol/L of substance (1) phenazine derivative 2, 3-dihydroxy-7-sulfonic acid phenazine (DHPS) as anolyte, 70mL of NaHCO with concentration of 1.0mol/L is added in cathode region 3 As catholyte, constant current electrolysis was carried out with a DC current of 40mA, and the system was started to perform electrolysis at a voltage of about 0.1V. The cathode 5 is a hydrogen evolution electrode (platinized nickel net) which generates electrochemical reduction reaction to decompose water to generate H 2 And OH - So that the alkalinity of the catholyte is increased, the reaction equation is as follows:
cathode side: 2H 2 O+2e - →2OH - +H 2
Rich in alkali (OH) - ) The catholyte is passed into a gas-liquid separator 6 to separate H 2 And a catholyte. Wherein the catholyte is introduced with CO 2 The absorption tower 8 is used for low-concentration CO 2 (flue gas or atmospheric CO) 2 ) Absorption of residual gases (e.g. N) 2 ) The reaction in the absorption tower 8 is separated and evacuated at the top, and the reaction equation in the absorption tower is as follows:
CO 2 absorption: CO 2 2 +OH - →HCO 3 -
Outlet of absorption column 8, rich in HCO 3 - The catholyte is circularly led into the cathode side 5 of the electrolytic cell and reaches the anode side 3 through the anion exchange membrane 4 under the action of an electric field, so that HCO in the anolyte 3 - The ion concentration increases. The anode adopts a graphite felt electrode to generate organic PCET reactant QH 2 And release of H + The acidity of the anolyte is increased, and the reaction equation is as follows: (Q/QH) 2 In the oxidized and reduced states, respectively, of an organic PCET reactant
Anode side: QH 2 →Q+2H + +2e -
Electrochemically generated H on the anode side 3 + With HCO in the anolyte 3 - In CO 2 Reaction in the desorber 11 to produce high purity CO 2 And produce water to realize CO 2 Purification and desorption. The generated water is balanced by the spontaneous permeation membrane under the action of concentration difference at two sides of the membrane, and can be quantitatively dewatered by additionally adding a reverse osmosis device 14, and the reaction equation is as follows:
CO 2 desorbing: h + +HCO 3 - →H 2 O+CO 2 (100％)
CO 2 At the outlet of the desorption tower 11, the substance Q rich in the oxidation state of the organic PCET enters a reduction regeneration tower 15, and H separated from the gas-liquid separator 6 in the environment of platinum catalyst 2 Mixing to carry out organic PCET reduction state QH 2 The reaction equation is as follows:
QH 2 non-electrochemical reduction regeneration: q + H 2 →QH 2
Outlet of reduction regeneration tower 15, rich in QH 2 The anolyte is circularly led into the anode chamber 3 of the electrolytic cell to realize the stable circulation of the organic PCET reactant.
The voltage stability of the trapping system in an oxygen-containing environment is shown in figure 3. As shown in FIG. 3, the voltage drops rapidly and slightly, then the electrolytic voltage gradually becomes stable within a plurality of hours, the voltage again becomes about 0.1V after continuous operation for 24 hours, the average electrolytic voltage is extremely low, and the working stability is good. Calculated to capture CO per ton 2 The energy consumption is 0.44GJ, and the technology is proved to have the function of stably trapping CO under the condition of ultralow energy consumption 2 Capability.
In this example, flue gas CO is carried out 2 (15 v%) absorption, CO steady operation on the trap side (cathode) for 48h 2 The concentration first steadily decreases, followed by CO 2 The concentration eventually plateaus with a small rise (fig. 4). CO 2 2 The absorption rate is close to 100%, and the absorption efficiency is high.
The desorption side (anode) stably works for 30h, CO 2 The concentration first rises steadily, followed by CO 2 The concentration tends to be stable, and CO is stably worked for 25 hours 2 The concentration starts to decrease (fig. 5). CO 2 2 The desorption rate is about 98 percent, and the desorption efficiency is high.
Example 2:
ultralow-energy-consumption CO 2 The electrochemical trapping system, the system structure of the embodiment is shown in figure 2, the system structure is described in the specific embodiment, and the process is shown in figure 1. The effective area in the electrolytic cell is 4cm 2 The electrolytic cell of (1). The electrolytic bath (electrolytic reactor) is divided into an anode area and a cathode area by an anion exchange membrane which only allows anions to permeate through and can prevent cations from permeating through, and the operation process of the system is the same as that of the embodiment 1, and only the difference is that:
in this example, 70mL KHCO was added to the anode section at a concentration of 0.5mol/L 3 And 0.02mol/L of substance (1) phenazine derivative 2, 3-dihydroxy-7-sulfophenazine (DHPS) as an anolyte, 70mL of KHCO with a concentration of 0.5mol/L are added in the cathodic compartment 3 As catholyte, constant current electrolysis was carried out with a DC current of 40mA, and the system was started to perform electrolysis at a voltage of about 0.15V. The average electrolytic voltage of the trapping system is extremely low and is only 0.21V under the oxygen-containing environment, and the working stability is good.
In this example, flue gas CO is carried out 2 (15%) absorption, CO stable operation of the trapping side (cathode) within 48h 2 The concentration first steadily decreases, followed by CO 2 The concentration finally tends to stabilize after a small rise. CO 2 2 The absorption rate is close to 100%, and the absorption efficiency is high.
The desorption side (anode) stably works for 30 hours, CO 2 The concentration first rises steadily, followed by CO 2 The concentration tends to be stable, and CO is stably worked for 25 hours 2 The concentration begins to drop. CO 2 2 The desorption rate is about 98 percent, and the desorption efficiency is high.
Example 3:
ultralow-energy-consumption CO 2 The electrochemical trapping system, the system structure of the embodiment is shown in figure 2, the system structure is described in the specific embodiment, and the process is shown in figure 1. The effective area in the electrolytic cell is 4cm 2 The electrolytic cell of (1). The electrolytic bath (electrolytic reactor) is divided into an anode area and a cathode area by an anion exchange membrane which only allows anions to permeate and can prevent cations from permeating; the system operation process is the same as that of example 1, and only differs:
in this example, 70mL NaHCO at a concentration of 1mol/L was added to the anode section 3 And 0.02mol/L of substance (1) phenazine derivative 2, 3-dihydroxy-7-sulfonic acid phenazine (DHPS) as anolyte, 70mL of NaHCO with concentration of 1mol/L is added in the cathode zone 3 As catholyte, constant current electrolysis was carried out with a DC current of 40mA, and the system was started to perform electrolysis at a voltage of about 0.54V. The average electrolytic voltage of the trapping system is extremely low and is only 0.61V under the oxygen-containing environment, and the working stability is good.
In this example, atmospheric CO is carried out 2 Absorption of (400 ppm), stable operation of the capture side (cathode) for 48h, CO 2 The concentration first steadily decreases, followed by CO 2 The concentration finally tends to stabilize with a small rise. CO 2 2 The absorption rate is close to 100%, and the absorption efficiency is high.
The desorption side (anode) stably works for 30h, CO 2 The concentration first steadily increases, followed by CO 2 The concentration tends to be stable, and CO is stably worked for 25 hours 2 The concentration begins to drop. CO 2 2 The desorption rate is about 98 percent, and the desorption efficiency is high. Proves that the technology has the function of absorbing atmospheric CO 2 The potential of (2).
Example 4:
the procedure of this example is essentially the same as that of example 1, except that 70mL of NaHCO at a concentration of 1mol/L are added to the anode section 3 And 0.02mol/L of a substance(2) Isoalloxazine derivative riboflavin (FMN) was used as anolyte, and 70mL NaHCO with 1mol/L concentration was added in the cathode compartment 3 As catholyte, constant current electrolysis was carried out with a direct current of 40mA at a voltage of 0.4V at the start of electrolysis, and the results are shown in FIG. 6, which is a graph of voltage stability of the trapping system in an oxygen-containing environment. As shown in fig. 6, the voltage reached about 0.5V after 24 hours of electrolysis, the average electrolytic voltage was low, and the electrolytic performance stability was good. Different organic PCET substances have proven suitable for use in this technical system.
Example 5:
the procedure of this example is essentially the same as that of example 1, except that 70mL of 1mol/L NaHCO was added to the anode section 3 And 0.02mol/L of substance (3) a phenazine derivative benzo [ a ]]Hydroxyphenazine-7-carboxylic acid BHPC is used as anolyte, and 70mL NaHCO with concentration of 1mol/L is added into the cathode region 3 As a catholyte, constant current electrolysis was carried out with a direct current of 40mA, and the voltage at the start of electrolysis was 0.15V, and after 24 hours of electrolysis, the voltage reached about 0.18V, and the average electrolytic voltage was low and the stability of electrolytic performance was good. Different organic PCET substances have proven suitable for use in this technical system.
Example 6:
the operation procedure of this example is substantially the same as that of example 1 except that the anode reduction catalyst is changed from a nickel platinized mesh to foamed nickel (Pt-based catalyst to Ni-based catalyst), the voltage is 0.16V at the beginning, and the voltage is gradually increased with time, and after 24 hours of continuous operation, the voltage is gradually increased to about 0.25V (fig. 7), and the energy consumption is low and the stability is good.
Comparative example 1:
in this example, the experimental group (asymmetric structure) was prepared by adding 70mL NaHCO at 1mol/L concentration to the anode region 3 And 0.02mol/L of substance (3) reduced 2-sulfonic acid-1, 4-hydroquinone (BQH) 2 ) As an anolyte, 70mL of NaHCO with a concentration of 1.0mol/L were added in the cathode compartment 3 As a catholyte, constant current electrolysis was carried out with a direct current of 120 mA. For comparison, the control (symmetrical structure) was prepared by adding 70mL NaHCO at 1mol/L to the anode area 3 And 0.02mol/L of substance (3) reduced 2-sulfonic acid-1, 4-hydroquinone (BQH) 2 ) As an anolyte in70mL NaHCO with concentration of 1.0mol/L is added into the cathode zone 3 And 0.02mol/L of substance (3) in the oxidation state 2-sulfonic acid-1, 4-Benzoquinone (BQ) as a catholyte, and constant current electrolysis was carried out with a direct current of 120 mA. All experiments were carried out in atmospheric environment (21%) 2 ) The process is carried out. As shown in fig. 8. The experimental group has feasibility of long-term stable operation in an oxygen environment, while the control group is difficult to stably operate due to the fact that the catholyte contacts oxygen in the atmosphere to cause continuous increase of single electrolytic voltage and continuous reduction of system capacity caused by continuous attenuation of reduced substances after multiple cycles. Further proves that the asymmetric structure of cathodic hydrogen evolution adopted by the technology has the capability of long-term stable operation in an oxygen environment.
Comparative example 2:
the procedure of this comparative example is essentially identical to that of example 1, except that 70mL of NaHCO with a concentration of 1mol/L are added in the anode section 3 And 0.02mol/L of substance (4) quinone Derivative (DHBQ) as anolyte, 70mL of NaHCO with concentration of 1.0mol/L is added in the cathode region 3 When the electrolyte is used as catholyte, constant current electrolysis is carried out by direct current of 40mA, the initial voltage of the system is 1.2V, and then the current continuously attenuates to 0A, so that normal electrolysis cannot be carried out. This comparative example illustrates the importance of the anodic organic PCET reactant in adapting to the battery system.
The above examples are only preferred embodiments of the patent, but the scope of protection of the patent is not limited thereto. It should be noted that, for those skilled in the art, without departing from the principle of this patent, several improvements and modifications can be made according to the patent solution and its patent idea, and these improvements and modifications should also be considered as within the protection scope of this patent.
Claims (10)
1. Ultralow-energy-consumption CO 2 The electrochemical trapping method is characterized by comprising the following steps of firstly, providing energy for electrochemical reaction by utilizing an external power supply; secondly, the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - Penetrate through the anionic membrane to reach the anolyte, and the anode generates organic PCET reactionOxidation of the substance to release H + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 (ii) a Finally, hydrogen generated by the cathode is used for reducing an organic PCET reactant of the anode under the action of a catalyst, so that the anolyte is regenerated.
2. The method of claim 1, wherein the CO is used in an ultra-low energy consumption 2 An electrochemical capture system, characterized by: the system comprises an electrolytic cell, an anode area and a cathode area, wherein the anode area and the cathode area are arranged on two sides of the electrolytic cell, and the system specifically comprises the following components: the anode region and the cathode region are separated by an anion exchange membrane, the cathode is a hydrogen evolution electrode, and the anode is a graphite felt electrode; the cathode area is filled with alkali liquor; and a water-soluble organic PCET reactant is added into the anode region, and an external power supply is communicated between the anode region and the cathode region.
3. Ultra low energy CO as claimed in claim 1 2 An electrochemical capture system characterized in that an electrochemical hydrogen evolution reaction occurs on the cathode side in the system, and CO is captured and absorbed 2 (ii) a Specifically, the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of catholyte and is used for absorbing low-concentration CO 2 HCO in catholyte 3 - Penetrate through the anion membrane to reach the anolyte; electrochemical oxidation of the organic PCET reactant occurs on the anode side, releasing H + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 (ii) a Finally, hydrogen generated by the cathode is used for reducing the organic PCET reactant of the anode under the action of the catalyst, so that the anolyte is regenerated.
4. Ultra low energy CO as claimed in claim 1 2 The electrochemical capture system is characterized in that a gas-liquid separator and CO are arranged on the cathode side 2 The absorption tower, the alkali-rich cathode liquid enters a gas-liquid separator to separate H 2 And a catholyte; introducing CO into catholyte 2 The absorption tower is used for absorbing CO 2 Production of HCO 3 - 。
5. As claimed in2, the ultralow energy consumption of CO is calculated 2 An electrochemical capture system, characterized in that on the anode side, CO is provided 2 Desorption tower and reduction regeneration tower, the anode side electrochemically generating H + With HCO in the anolyte 3 - In CO 2 Reaction in a desorber to produce high purity CO 2 And produce water to realize CO 2 Purifying and desorbing; the generated water is balanced by a spontaneous permeation membrane under the action of concentration difference of two sides of an anion membrane, or the water is quantitatively removed by additionally adding a reverse osmosis device.
6. Ultra-low energy CO as claimed in claim 5 2 The electrochemical capture system is characterized in that the reverse osmosis device is a reverse osmosis water separator, and the reverse osmosis water separator is connected with the reduction regeneration tower. The substance Q rich in the oxidation state of the organic PCET enters a reduction regeneration tower and is separated from H of a cathode gas-liquid separator under the action of a platinum catalyst 2 Mixing to obtain reduced QH of organic PCET 2 Non-electrochemical reduction regeneration.
7. Ultra-low energy CO as claimed in claim 5 2 The electrochemical capture system is characterized in that the outlet of the reduction regeneration tower is rich in QH 2 The anolyte is circularly led into an anode area of the electrolytic cell, and the stable circulation of the organic PCET reactant is realized.
8. Ultra-low energy CO according to any of claims 1 to 7 2 The electrochemical capture system is characterized in that the electrode potential of the organic PCET reactant is higher than the hydrogen evolution reaction potential to ensure the spontaneous progress of non-electrochemical reduction reaction; the organic PCET reactant needs to generate reversible or quasi-reversible electrons e under the use environment - Proton H + Transfer reaction to ensure electrochemical acidification of the anolyte.
9. Ultra-low energy CO as claimed in claim 8 2 An electrochemical trapping system characterized by an organic PCET reactant including, but not limited to, pyrazines, alloxazines, phenazines, quinones, and derivatives thereof.
10. Ultra-low energy CO as claimed in claim 5 2 The electrochemical trapping system is characterized in that the reduction regeneration tower is filled with a reduction regeneration catalyst, and the reduction regeneration catalyst is selected from Pt-based, ni-based or Pd-based catalysts.
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