CN115400550B - Ultralow-energy-consumption carbon dioxide electrochemical trapping method and system - Google Patents
Ultralow-energy-consumption carbon dioxide electrochemical trapping method and system Download PDFInfo
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Abstract
The invention belongs to the technical field of electrochemistry, in particular to ultra-low energy consumption CO 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 adding a water-soluble organic proton-coupled electron transfer (PCET) reactant into the anode region, and communicating an external power supply between the anode region and the cathode region. An external power supply provides electric energy for the electrolytic tank. The cathode side is a hydrogen evolution electrode, and the hydrogen evolution electrode generates electrochemical reduction reaction to decompose water to generate H 2 And OH (OH) ‑ The method comprises the steps of carrying out a first treatment on the surface of the Electrochemically generated H on anode side + And HCO in anolyte 3 ‑ In CO 2 High purity CO is produced by reaction in a desorption tower 2 And generate water to realize CO 2 The substances Q rich in the oxidation state of the organic PCET enter a reduction regeneration tower for non-electrochemical reduction regeneration. The system can stably operate under low energy consumption, and can realize the CO of the flue gas 2 Can be used for capturing CO in the environments of factory waste gas, transportation tail gas, atmosphere and the like 2 And (5) capturing.
Description
Technical Field
The invention belongs to the technical field of electrochemistry, and relates to a novel electrochemistry CO based on the pH change of a solution driven by electrochemical redox reaction and a regeneration solvent of coupling non-electrochemical reduction reaction 2 Trapping and purifying system, in particular to ultra-low energy consumption CO 2 An electrochemical capture system.
Background
CO 2 Trapping low concentration CO 2 Absorption separation to high purity for subsequent sequestration or utilization. Order of (A)Front CO 2 Chemical absorption methods employing amine-based absorbents for trapping are most commonly employed, and utilize amines to absorb CO 2 And adopts thermal desorption, and has high desorption energy consumption (-2-4.5 GJ/ton CO) 2 ) Is a technical bottleneck of the system.
Existing electrochemical CO 2 The trapping technology utilizes electrochemical Proton Coupling Electron Transfer (PCET) reaction to change the pH environment of the solution and break CO 2 The absorption-desorption balance in the solution is realized, thereby realizing low energy consumption<2 GJ/ton CO 2 )CO 2 And (3) collecting and purifying. The process at present generally employs an organic PCET reactant or recycle H 2 As a carrier for electrochemical redox reactions. Wherein cycle H is employed 2 One major difficulty faced is H 2 The electrochemical oxidation reaction of the catalyst adopts 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 run. A major core difficulty with the use of organic PCET reactant is O 2 Impact on system stability. Flue gas CO of coal-fired power plant 2 Typically containing O at a concentration of about 3 to 6% 2 While atmospheric CO 2 Containing about 21% O 2 ，O 2 The existence of (2) can cause the rapid decay of the electrochemical PCET reactant, which makes the system difficult to realize in real CO 2 Under the trapping environment (containing O) 2 Environment) stable operation. From the thermodynamic perspective, the oxygen-resistant organic PCET reactant generally has a higher electrode potential, which tends to increase the energy consumption of the system.
Thus, true CO 2 Trapping environment (containing O) 2 Environment) is that the low energy consumption stable operation of the system is the current electrochemical CO 2 The trapping technology has a great need to overcome the technical problems.
Disclosure of Invention
The invention aims to solve the problems existing in the prior art and provides an ultralow-energy-consumption CO 2 An electrochemical capture system. The ultra-low energy consumption CO 2 Electrochemical trapping system, which changes solution pH environment through external power supply energy supply and electrochemical PCET reaction to trap and purify CO 2 Three main processes of non-electrochemical reaction reduction and regeneration of organic PCET reactant realize low energy consumption and oxygen-containing CO 2 CO in the environment 2 Is provided.
In order to achieve the above object, the present invention has the following specific technical scheme:
ultralow-energy-consumption CO 2 The electrochemical trapping method includes the following steps that 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 the catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - Through the anion membrane to the anode liquid, the anode generates oxidation reaction of organic PCET reactant to release H + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 The method comprises the steps of carrying out a first treatment on the surface of the 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 regeneration of anolyte is realized.
Ultralow-energy-consumption CO 2 The electrochemical trapping system adopts an asymmetric electrochemical reaction structure, namely, the cathode is electrochemical hydrogen evolution reaction, and the anode is electrochemical oxidation reaction of organic PCET reactant. 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 decouples the electrochemical oxidation reaction and the non-electrochemical reduction reaction of the organic PCET to realize continuous and 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 tank, and an anode region and a cathode region which are arranged at two sides of the electrolytic tank, wherein the anode region and the cathode region are separated by an anion exchange membrane, and the cathode region is filled with alkali liquor; and adding a water-soluble organic PCET reactant into the anode region, and communicating an external power supply between the anode region and the cathode region.
As a preferred embodiment in the present application, in the system, electrochemical hydrogen evolution reaction occurs at the cathode side, and CO is trapped and absorbed 2 The method specifically comprises the following steps: electrochemical hydrogen evolution reaction occurs at the cathode, and water is decomposed to generate H 2 And OH (OH) - Increasing the alkalinity of the catholyte for absorbing low concentrations of CO 2 HCO in catholyte 3 - Through the anionic membrane and into the anolyte. The system adopts an anion exchange membrane to separate the cathode and anode liquids, thoroughly avoiding cathode CO 2 Absorption side O 2 Interference to the anode organic PCET reactant can realize true oxygen-containing CO 2 Direct capture (of flue gas or atmosphere). At the same time HCO in the catholyte 3 - Can reach the anode liquid through the anion membrane to realize the charge balance of the system and desorb CO for the anode 2 A carbon source is provided.
Cathode side reaction equation: 2H (H) 2 O+2e - →2OH - +H 2
Electrochemical oxidation reaction of organic PCET reactant occurs at anode side, the anode of the system adopts water-soluble organic PCET reactant, H is released by electrochemical oxidation + Release H + And with HCO in the anolyte 3 - High purity CO is generated by reaction 2 And water to realize CO 2 Is purified and regenerated. 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 regeneration of anolyte is realized. The anode side only has solid-liquid two-phase electrochemical reaction, so that the use of a gas diffusion electrode is avoided, an electrochemical gas-liquid-solid three-phase reaction interface is thoroughly eliminated, and the stability of the system in long-time operation is greatly improved.
The reaction equation on the anode side is: QH (quality of service) 2 →Q+2H + +2e - (Q/QH 2 An oxidized state and a reduced state, respectively, of the organic PCET reactant).
As a preferred embodiment in the present application, 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, platinized nickel mesh, nickel foam, etc. Anodes include, but are not limited to, graphite felt electrodes, carbon paper, carbon cloth, and the like.
As a preferred embodiment in the present application, on the cathode side, a gas-liquid separator and CO are provided 2 The absorption tower, the cathode liquid rich in alkali enters a gas-liquid separator to separate H 2 And a catholyte; catholyte CO 2 The absorption tower is used for absorbing CO 2 HCO production 3 - . Preferably, the CO 2 The absorption tower is also respectively connected with an exhaust device and a smoke source device to realize the treatment of the gas (N 2 ) Is arranged in the air. Preferably, a hydrogen dryer is further arranged at the outlet of the gas-liquid separator, so that the generated hydrogen can be dried conveniently.
CO 2 The reaction equation in the absorber is: CO 2 Absorption: CO 2 +OH - →HCO 3 -
As a preferred embodiment in the present application, CO is provided on the anode side 2 Desorber and reduction regeneration tower, H electrochemically generated on anode side + And HCO in anolyte 3 - In CO 2 High purity CO is produced by reaction in a desorption tower 2 And generate water to realize CO 2 Is purified and desorbed; the generated water spontaneously permeates the membrane to balance under the action of the concentration difference at the two sides of the membrane, or the reverse osmosis device is additionally added to quantitatively remove water. CO 2 The reaction equation in the desorber is: h + +HCO 3 - →H 2 O+CO 2 (100％)
As a preferred embodiment in the present application, the water separation device is a reverse osmosis water separator, which is connected to the reduction regeneration column. 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 Hybrid organic PCET reduction QH 2 Is not regenerated by electrochemical reduction. Preferably, the reduction regeneration tower is connected to a hydrogen storage tank.
The reaction equation in the reduction regeneration tower is as follows: QH (quality of service) 2 Non-electrochemical reduction regeneration: Q+H 2 →QH 2 。
As a preferred embodiment in the application, the outlet of the reduction regeneration tower is rich in QH 2 The anolyte is circularly led into the anode region of the electrolytic tank, and the stable circulation of the organic PCET reactant is realized.
As a preferred embodiment in the present application, the electrode potential of the organic PCET reactant must be higher than the hydrogen evolution reaction potential, ensuringOutside the electrochemical system H 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 - ) Proton (H) + ) A transfer reaction ensures the electrochemical acidification of the anolyte; in order to ensure that the anolyte can be spontaneously reduced by hydrogen under the action of a catalyst, and simultaneously high electrolysis energy consumption is avoided.
As a preferred embodiment in the present application, the organic PCET reactants include, but are 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 in the present application, the reduction and regeneration of the organic PCET reactant in the system is carried out outside the electrolysis system, and the oxidation state of the organic PCET reactant and H are carried out under the action of the catalyst 2 Spontaneous redox reactions occur, thereby effecting a reductive regeneration cycle of the organic PCET reactant. The reduction regeneration tower is filled with a reduction regeneration catalyst, the catalyst adopts an alumina-supported 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 the catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - Through the anion membrane to the anode liquid, the anode generates oxidation reaction of organic PCET reactant to release H + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 The method comprises the steps of carrying out a first treatment on the surface of the Finally, the hydrogen generated by the cathode is used for reducing the organic PCE of the anode under the action of the catalystAnd T is a reactant, so that the regeneration of the anolyte is realized. The invention adopts organic PCET reactant on the anode side, avoids 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 (a) 2 And the effect of catholyte dissolved oxygen on the anodic organic PCET reactant. At the same time, H generated by cathode 2 Can be used as a reducing agent to realize the reduction regeneration of an organic PCET reactant, thereby realizing the electrochemical CO 2 The trapping system is continuously and stably operated.
The organic PCET reactant adopted by the invention can be replaced by an inorganic PCET reactant or a high polymer with PCET reactivity, such as MnOOH, niOOH, polyaniline and the like.
Compared with the prior art, the invention has the following positive effects:
(one) the system can realize oxygen-containing CO 2 CO in the environment 2 Is used for electrochemical trapping and purification. In practical application, the system can be powered by an external power supply, and the pH environment of the cathode and anode of the solution is changed by utilizing electrochemical PCET reaction, so that low-concentration CO in the cathode area is promoted 2 Is absorbed by the anode region of the reactor 2 And utilizes H generated by the cathode 2 The anode liquid is reduced and regenerated outside the system, thereby realizing low energy consumption, continuous and stable CO 2 And (3) collecting and purifying.
And secondly, 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 environment including the flue gas of coal-fired power plants, the waste gas of factories, the transportation tail gas, even the atmosphere and the like 2 And (5) capturing. And continuous operation without batch is carried out without limitation of time and space.
And thirdly, the system is reasonable in design, low in energy consumption and capable of stably running for a long time.
Drawings
FIG. 1 shows the ultra-low energy CO according to the invention 2 An electrochemical trapping system schematic diagram;
FIG. 2 shows the ultra-low energy CO according to the invention 2 Schematic structural diagram of electrochemical trapping system；
Wherein, the device comprises a 1-external power supply, a 2-electrolytic tank, a 3-anode region, a 4-anion exchange membrane, a 5-cathode region, a 6-gas-liquid separator, a 7-hydrogen dryer and an 8-CO 2 Absorption tower, 9-exhaust tail gas, 10-smoke source and 11-CO 2 Desorber, 12-CO 2 Dryer, 13-CO 2 The device comprises 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 is a system CO 2 An absorption concentration profile;
FIG. 5 is a system CO 2 A release concentration profile;
FIG. 6 is a graph of energy consumption of a system employing FMN in an oxygen-containing environment
FIG. 7 is a graph of energy consumption of a system employing different reduction catalysts in an oxygen-containing environment.
FIG. 8 is a graph comparing stability in an oxygen environment for a symmetrical system and an asymmetrical system.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments in order to make the objects, technical solutions and advantages of the present invention more apparent, but it should not be construed that the scope of the above subject matter of the present invention is limited to only the following embodiments. Various substitutions and alterations are made by those skilled in the art without departing from the spirit and scope of the invention.
The percentages expressed in the following examples, unless otherwise indicated, refer to the volume percentages, i.e., v%.
Example 1:
ultralow-energy-consumption CO 2 The electrochemical capturing system is shown in fig. 2, the system structure of the embodiment is shown in the specific embodiment, and the process is shown in fig. 1.
The system comprises an external power supply 1 which is connected with the cathode and anode of an electrolytic reactor 2 for supplying electric energy to an electrolytic tank, wherein the electrolytic reactor is an electrolytic tank, and the effective area in the electrolytic tank is 4cm 2 . ElectrolysisThe cell (electrolytic reactor) is divided into an anode region and a cathode region by an anion exchange membrane (fumasep anion exchange membrane (FAA-3-20\FAA-3-PK-130)) 4 which allows only anions to permeate and prevents cations from permeating. 70mL of NaHCO with a concentration of 1mol/L is added to the anode region 3 And 0.02mol/L of substance (1) phenazine derivative 2, 3-dihydroxy-7-sulfophenazine (DHPS) as an anolyte, 70mL of NaHCO having a concentration of 1.0mol/L was added to the anode region 3 As a catholyte, constant current electrolysis was performed with a DC current of 40mA, and electrolysis was started by the system at a voltage of about 0.1V. The cathode 5 is a hydrogen evolution electrode (platinized nickel screen) and generates electrochemical reduction reaction to decompose water to generate H 2 And OH (OH) - The basicity of the catholyte was increased and the reaction equation was as follows:
cathode side: 2H (H) 2 O+2e - →2OH - +H 2
Rich alkali (OH) - ) Is led into a gas-liquid separator 6 to separate H 2 And a catholyte. Wherein, the catholyte is introduced with CO 2 Absorption tower 8 for low concentration CO 2 (flue gas or atmospheric CO) 2 ) Is absorbed by the remaining gas (e.g. N 2 ) The top of the absorption tower 8 is separated and emptied, and the reaction equation in the absorption tower is as follows:
CO 2 absorption: CO 2 +OH - →HCO 3 -
The outlet of the absorption tower 8 is rich in HCO 3 - Is circulated into the cathode side 5 of the electrolyzer and passes through the anion exchange membrane 4 to the anode side 3 under the action of an electric field, so that HCO in the anolyte is obtained 3 - The ion concentration increases. The anode adopts a graphite felt electrode to generate an organic PCET reactant QH 2 Electrochemical oxidation reaction and release of H + The acidity of the anolyte was increased and the reaction equation was as follows: (Q/QH) 2 An oxidation state and a reduction state, respectively, of an organic PCET reactant
Anode side: QH (quality of service) 2 →Q+2H + +2e -
Electrochemically generated H on anode side 3 + And HCO in anolyte 3 - In CO 2 Reaction in desorber 11 to produce high purity CO 2 And generateWater, realize CO 2 Is purified and desorbed. The generated water spontaneously permeates the membrane to balance under the action of the concentration difference at the two sides of the membrane, and can be quantitatively dehydrated by additionally adding a reverse osmosis device 14, wherein the reaction equation is as follows:
CO 2 and (3) desorption: h + +HCO 3 - →H 2 O+CO 2 (100％)
CO 2 The substance Q rich in the oxidation state of the organic PCET enters a reduction regeneration tower 15 at the outlet of the desorption tower 11 and is separated from H separated from the gas-liquid separator 6 under the environment of a platinum catalyst 2 Hybrid organic PCET reduction QH 2 The reaction equation is as follows:
QH 2 non-electrochemical reduction regeneration: Q+H 2 →QH 2
The outlet of the reduction regeneration tower 15 is rich in QH 2 The anolyte is circularly led into the anode chamber 3 of the electrolytic tank, thus realizing the stable circulation of the organic PCET reactant.
The voltage stability diagram of the trapping system in the oxygen-containing environment is shown in fig. 3. As shown in FIG. 3, the voltage is reduced rapidly and slightly, then the electrolytic voltage gradually becomes stable within a few hours, the voltage again becomes about 0.1V after 24 hours of continuous operation, the average electrolytic voltage is extremely low, and the working stability is good. Calculated to capture each ton of CO 2 The energy consumption is 0.44GJ, and the technology has the advantage of stably capturing CO under the ultra-low energy consumption 2 Capability.
In this example, flue gas CO is performed 2 Absorption of (15 v%) and stable operation of the capturing side (cathode) for 48h, CO 2 The concentration first steadily decreases, followed by CO 2 The small increase in concentration eventually stabilizes (fig. 4). CO 2 The absorption rate is close to 100%, and the absorption efficiency is high.
The desorption side (anode) stably works for 30 hours, and CO 2 The concentration first steadily increases, followed by CO 2 The concentration tends to be stable, and CO is generated after stable operation for 25 hours 2 The concentration began to drop (fig. 5). CO 2 The desorption rate is about 98%, and the desorption efficiency is high.
Example 2:
ultralow-energy-consumption CO 2 Electrochemical captureThe system structure of the embodiment is shown in fig. 2, the system structure is shown in the detailed description, and the process is shown in fig. 1. The effective area in the electrolytic tank is 4cm 2 Is provided. The electrolytic cell (electrolytic reactor) is divided into an anode region and a cathode region by an anion exchange membrane which only allows anions to permeate and can prevent cations from permeating, and the system operation process is the same as that of the embodiment 1, and the difference is that:
in this example, 70mL of KHCO was added to the anode region 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, and 70mL of KHCO having a concentration of 0.5mol/L was added to the anode region 3 As a catholyte, constant current electrolysis was performed with a DC current of 40mA, and electrolysis was started by the system at a voltage of about 0.15V. The average electrolysis voltage of the trapping system in the oxygen-containing environment is extremely low and is only 0.21V, and the working stability is good.
In this example, flue gas CO is performed 2 (15%) absorption, stable operation of the capturing side (cathode) for 48h, CO 2 The concentration first steadily decreases, followed by CO 2 The concentration rises slightly and finally stabilizes. CO 2 The absorption rate is close to 100%, and the absorption efficiency is high.
The desorption side (anode) stably works for 30 hours, and CO 2 The concentration first steadily increases, followed by CO 2 The concentration tends to be stable, and CO is generated after stable operation for 25 hours 2 The concentration begins to drop. CO 2 The desorption rate is about 98%, and the desorption efficiency is high.
Example 3:
ultralow-energy-consumption CO 2 The electrochemical capturing system is shown in fig. 2, the system structure of the embodiment is shown in the specific embodiment, and the process is shown in fig. 1. The effective area in the electrolytic tank is 4cm 2 Is provided. The electrolytic tank (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 is identical to that of example 1, except that:
in this example, 70mL of 1mol/L was added to the anode regionNaHCO 3 And 0.02mol/L of substance (1) phenazine derivative 2, 3-dihydroxy-7-sulfophenazine (DHPS) as an anolyte, 70mL of NaHCO having a concentration of 1mol/L was added to the anode region 3 As a catholyte, constant current electrolysis was performed with a DC current of 40mA, and electrolysis was started by the system at a voltage of about 0.54V. The average electrolysis voltage of the trapping system in the oxygen-containing environment is extremely low and is only 0.61V, and the working stability is good.
In this example, atmospheric CO is performed 2 Absorption at 400ppm, stable operation of the capturing side (cathode) for 48h, CO 2 The concentration first steadily decreases, followed by CO 2 The concentration rises slightly and finally stabilizes. CO 2 The absorption rate is close to 100%, and the absorption efficiency is high.
The desorption side (anode) stably works for 30 hours, and CO 2 The concentration first steadily increases, followed by CO 2 The concentration tends to be stable, and CO is generated after stable operation for 25 hours 2 The concentration begins to drop. CO 2 The desorption rate is about 98%, and the desorption efficiency is high. Proved by the technology, the atmospheric CO is absorbed 2 Is not limited by the potential of (a).
Example 4:
the procedure of this example is essentially identical to that of example 1, except that 70mL of NaHCO at a concentration of 1mol/L is added to the anode region 3 And 0.02mol/L of substance (2) isoxazine derivative riboflavin (FMN) as an anolyte, 70mL of NaHCO with a concentration of 1mol/L was added to the anode region 3 As a catholyte, constant current electrolysis was performed with a direct current of 40mA, the voltage at the start of electrolysis was 0.4V, and the specific results are shown in fig. 6, which shows the voltage stability of the trapping system in an oxygen-containing environment. As shown in FIG. 6, the voltage reached about 0.5V after electrolysis for 24 hours, the average electrolysis voltage was low, and the stability of the electrolysis performance was good. It has been demonstrated that different organic PCET substances are applicable in this technical system.
Example 5:
the procedure of this example is essentially identical to that of example 1, except that 70mL of NaHCO at a concentration of 1mol/L is added to the anode region 3 And 0.02mol/L of substance (3) phenazine derivative benzo [ a ]]Hydroxy phenazine-7-carboxylic acid BHPC is used as anode liquid, 70mL NaHCO with concentration of 1mol/L is added in the cathode area 3 Acting as yinThe electrolyte is subjected to constant current electrolysis by using 40mA direct current, the voltage at the beginning of electrolysis is 0.15V, the voltage reaches about 0.18V after 24 hours of electrolysis, the average electrolysis voltage is low, and the stability of the electrolysis performance is good. It has been demonstrated that different organic PCET substances are applicable in this technical system.
Example 6:
the operation of this example was substantially identical to that of example 1, except that the anode reduction catalyst was changed from nickel platinized mesh to foam nickel (Pt-based catalyst was changed to Ni-based catalyst), the voltage was initially 0.16V, and the voltage was gradually increased over time, and the voltage was gradually increased to about 0.25V after continuous operation for 24 hours (fig. 7), with low energy consumption and good stability.
Comparative example 1:
in this example, the experimental group (asymmetric structure) had 70mL of NaHCO with a concentration of 1mol/L added 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 NaHCO with a concentration of 1.0mol/L was added to the cathode zone 3 As a catholyte, constant current electrolysis was performed with a direct current of 120 mA. In contrast, the control group (symmetrical structure) had 70mL NaHCO at 1mol/L in the anode region 3 And 0.02mol/L of substance (3) reduced 2-sulfonic acid-1, 4-hydroquinone (BQH) 2 ) As an anolyte, 70mL NaHCO with a concentration of 1.0mol/L was added to the cathode zone 3 And 0.02mol/L of substance (3) oxidation state 2-sulfonic acid-1, 4-Benzoquinone (BQ) as catholyte, and carrying out constant current electrolysis by using 120mA direct current. All experiments were carried out under atmospheric conditions (21% O) 2 ) Is carried out. As shown in fig. 8. The experimental group has the feasibility of long-term stable operation in an oxygen environment, the control group has the advantages that the single electrolysis voltage is continuously increased due to the fact that the catholyte contacts with oxygen in the atmosphere, the system capacity is continuously reduced due to continuous attenuation of reduced substances after multiple cycles, and the stable operation is difficult. Further proves that the asymmetric structure of the technology adopting the cathode hydrogen evolution has the capability of long-term stable operation in an oxygen environment.
Comparative example 2:
the procedure of this comparative example was substantially identical to that of example 1, except that 70mL of a solution having a concentration of 1mol/L was added to the anode regionNaHCO 3 And 0.02mol/L of a quinone Derivative (DHBQ) of substance (4) as an anolyte, 70mL of NaHCO having a concentration of 1.0mol/L was added to the anode region 3 As a catholyte, constant current electrolysis was performed with a direct current of 40mA, the system initiation voltage was 1.2V, and then the current was continuously decayed to 0A, failing to perform normal electrolysis. This comparative example illustrates the importance of the anode organic PCET reactant to the adaptation of the battery system.
The above examples are only preferred embodiments of the present patent, but the scope of protection of the present patent is not limited thereto. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications according to the technical solution of the present patent and the patent conception thereof without departing from the principle of the present patent, and these improvements and modifications are also considered to be within the protection scope of the present patent.
Claims (5)
1. Ultralow-energy-consumption CO 2 An electrochemical capture system characterized by: the system comprises an electrolytic cell, and an anode area and a cathode area on two sides of the electrolytic cell, and specifically comprises: 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; adding a water-soluble organic PCET reactant into the anode region, and communicating an external power supply between the anode region and the cathode region;
in this system, electrochemical hydrogen evolution reactions take place on the cathode side, capturing and absorbing CO 2 The method comprises the steps of carrying out a first treatment on the surface of the In particular, the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of the catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - The electrolyte passes through the anionic membrane and reaches the anode liquid; 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 The method comprises the steps of carrying out a first treatment on the surface of the 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 regeneration of anolyte is realized;
on the cathode side, a gas-liquid separator and CO are arranged 2 The absorption tower, the cathode liquid rich in alkali enters a gas-liquid separator to separate H 2 And a catholyte;catholyte CO 2 The absorption tower is used for absorbing CO 2 HCO production 3 - ；
On the anode side, CO is provided with 2 Desorber and reduction regeneration tower, H electrochemically generated on anode side + And HCO in anolyte 3 - In CO 2 High purity CO is produced by reaction in a desorption tower 2 And generate water to realize CO 2 Is purified and desorbed; the generated water spontaneously permeates the membrane to balance under the action of the concentration difference at the two sides of the anion membrane, or quantitatively removes water by additionally adding a reverse osmosis device;
the outlet of the reduction regeneration tower is rich in QH 2 The anolyte is circularly introduced into the anode region of the electrolytic tank, so as to realize the stable circulation of the organic PCET reactant;
the organic PCET reactant comprises any one of pyrazine, alloxazine, phenazine, quinone and derivatives thereof.
2. Ultra low energy CO according to claim 1 2 The electrochemical trapping 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 by a cathode gas-liquid separator under the action of a platinum catalyst 2 Hybrid organic PCET reduction QH 2 Is not regenerated by electrochemical reduction.
3. Ultra low energy CO according to claim 1 or 2 2 The electrochemical trapping system is characterized in that the electrode potential of the organic PCET reactant is higher than the hydrogen evolution reaction potential, so that the spontaneous progress of non-electrochemical reduction reaction is ensured; the organic PCET reactant needs to generate reversible or quasi-reversible electron e under the use environment - Proton H + And (3) a transfer reaction, so as to ensure the electrochemical acidification of the anolyte.
4. An ultra low energy CO as claimed in claim 3 2 The electrochemical trapping system is characterized in that the reduction regeneration tower is filled with a reduction regeneration catalyst, and the reduction regeneration catalystSelected from Pt-based, ni-based or Pd-based catalysts.
5. Use of the ultra low energy CO of claim 1 2 Ultra low energy consumption CO for electrochemical capture systems 2 The electrochemical trapping method is characterized by comprising 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 the catholyte for absorbing low-concentration CO 2 HCO in catholyte 3 - Through the anion membrane to the anode liquid, the anode generates oxidation reaction of organic PCET reactant to release H + And with HCO in the anolyte 3 - Reaction releases high purity CO 2 The method comprises the steps of carrying out a first treatment on the surface of the 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 regeneration of anolyte is realized; the organic PCET reactant is adopted at the anode side, so that the anode H is avoided 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 (a) 2 And the effect of catholyte dissolved oxygen on the anodic organic PCET reactant; at the same time, H generated by cathode 2 Can be used as a reducing agent to realize the reduction regeneration of the organic PCET reactant, thereby realizing the CO 2 The electrochemical trapping system is continuously and stably operated.
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| CN104261449A (en) * | 2014-09-22 | 2015-01-07 | 四川大学 | Method for preparing high-purity carbonate by using calcium and magnesium-rich solution to mineralize CO2 |
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