CN117403277A - Method for separating acidic carbon dioxide reduction products and recovering cations - Google Patents
Method for separating acidic carbon dioxide reduction products and recovering cations Download PDFInfo
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- CN117403277A CN117403277A CN202311340847.XA CN202311340847A CN117403277A CN 117403277 A CN117403277 A CN 117403277A CN 202311340847 A CN202311340847 A CN 202311340847A CN 117403277 A CN117403277 A CN 117403277A
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 96
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 48
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000002378 acidificating effect Effects 0.000 title claims abstract description 26
- 150000001768 cations Chemical class 0.000 title claims abstract description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 47
- -1 alkali metal cations Chemical class 0.000 claims abstract description 44
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 40
- 238000000926 separation method Methods 0.000 claims abstract description 34
- 238000002242 deionisation method Methods 0.000 claims abstract description 30
- 239000012528 membrane Substances 0.000 claims abstract description 19
- 239000003011 anion exchange membrane Substances 0.000 claims abstract description 16
- 238000005341 cation exchange Methods 0.000 claims abstract description 16
- 150000007524 organic acids Chemical class 0.000 claims abstract description 14
- 239000002253 acid Substances 0.000 claims abstract description 11
- 239000006229 carbon black Substances 0.000 claims abstract description 11
- 239000011734 sodium Substances 0.000 claims abstract description 7
- 230000005684 electric field Effects 0.000 claims abstract description 6
- 150000001449 anionic compounds Chemical class 0.000 claims abstract description 5
- 238000010494 dissociation reaction Methods 0.000 claims abstract description 5
- 230000005593 dissociations Effects 0.000 claims abstract description 5
- 229910001412 inorganic anion Inorganic materials 0.000 claims abstract description 5
- 239000003115 supporting electrolyte Substances 0.000 claims abstract description 5
- 239000002002 slurry Substances 0.000 claims abstract description 4
- 229910002804 graphite Inorganic materials 0.000 claims description 23
- 239000010439 graphite Substances 0.000 claims description 23
- 238000011084 recovery Methods 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 239000000741 silica gel Substances 0.000 claims description 8
- 229910002027 silica gel Inorganic materials 0.000 claims description 8
- 239000003929 acidic solution Substances 0.000 claims description 7
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 6
- 235000005985 organic acids Nutrition 0.000 claims description 5
- 229910052700 potassium Inorganic materials 0.000 claims description 3
- 229910052792 caesium Inorganic materials 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 28
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 18
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 14
- 235000019253 formic acid Nutrition 0.000 description 14
- 230000000694 effects Effects 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- AIYUHDOJVYHVIT-UHFFFAOYSA-M caesium chloride Chemical compound [Cl-].[Cs+] AIYUHDOJVYHVIT-UHFFFAOYSA-M 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000002572 peristaltic effect Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241000270295 Serpentes Species 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005686 electrostatic field Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 238000011197 physicochemical method Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B15/00—Operating or servicing cells
- C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
- C25B15/083—Separating products
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B15/00—Operating or servicing cells
- C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
- C25B3/01—Products
- C25B3/07—Oxygen containing compounds
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
- C25B3/20—Processes
- C25B3/25—Reduction
- C25B3/26—Reduction of carbon dioxide
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to a method for separating an acidic carbon dioxide reduction product and recovering cations. Specifically, powdered activated carbon, carbon black and Na 2 SO 4 Preparing slurry (as a supporting electrolyte) as a flowing electrode; simultaneously introducing the flowing electrode into an anode chamber and a cathode chamber; applying a voltage to the flowing electrode capacitive deionization device; under the action of an electric field, positively charged alkali metal cations pass through the cation exchange membrane to enter the cathode chamber, negatively charged inorganic anions pass through the anion exchange membrane to enter the anode chamber, and electrochemical product micromolecular organic acid is in an uncharged molecular state under a strong acid condition because of no dissociation and remains in the separation chamber. In short, the invention canA method for separating products of carbon dioxide electroreduction under acidic conditions and recovering alkali metal cations is provided, and the product separation cost and the alkali metal cation use cost are reduced.
Description
Technical Field
The invention belongs to the field of electrochemical membrane separation and electrochemical carbon dioxide utilization, and relates to a method for separating an acidic carbon dioxide reduction product and recovering cations.
Background
CO produced by conventional fossil fuel combustion and industrialization processes 2 The serious environmental and social problems are caused, the carbon dioxide electroreduction can be driven by renewable energy sources, and CO is utilized at normal temperature and normal pressure 2 Producing organic matters. Among them, the electro-reduction of carbon dioxide to small molecular organic acids (e.g., formic acid, acetic acid) is of interest because these small molecular organic acids are promising as raw materials for various chemical processes. The traditional carbon dioxide electroreduction is carried out under the condition of strong alkali so as to inhibit the hydrogen evolution side reaction when the hydrogen ion concentration is too high. However, upon carbon dioxide electroreduction under alkaline conditions, CO 2 Reacts with alkaline solution to form carbonate/bicarbonate, which can cause plugging of cells in the gas diffusion electrode and also CO 2 The conversion of (c) decreases.
The carbon dioxide electroreduction under alkaline condition can inhibit carbonate/bicarbonate formation, avoid the blockage of pore channels in a gas diffusion electrode and improve CO 2 Is a conversion rate of (a). However, when carbon dioxide is electroreduced under alkaline conditions, high concentrations of hydrogen ions are present, promoting hydrogen evolution side reactions, resulting in reduced faradaic efficiency of carbon dioxide electroreduction. Studies have shown that alkali metal cations (e.g., K, cs) can inhibit hydrogen evolution side reactions by altering the electric field distribution in the electric double layer. But also results in both the acidic condition carbon dioxide electroreduction product (small molecule organic acid) and the alkali metal cation being dissolved in the strong acid solution. Currently, the methods for separating small molecule organic acids for the electroreduction of carbon dioxide are mainly conventional physicochemical methods, such as distillation. When distillation techniques are employed, separation is difficult due to the close boiling points of water and small molecule organic acid products, resulting in the formation of azeotropes, while the techniques require high thermal energy input. The study of alkali metal cation recovery for the electroreduction of carbon dioxide under acidic conditions has not been reported. Thus, there is a need for a product separation and alkali metal cation for acidic carbon dioxide electroreductionAn effective method of recovery.
In recent years, the capacitive deionization technology drives ions to move to an electrode with opposite charges by applying an electrostatic field, and the ions are stored in an electric double layer of the electrode, so that the capacitive deionization technology has the advantages of low energy consumption, simplicity in operation, low price, wide application range, environmental friendliness and the like, and is an emerging membrane electrochemical technology. The flow electrode capacitive deionization technology utilizes the flow electrode to replace a solid electrode, can realize stronger adsorption effect, avoid salt concentration and realize continuous operation, and has the potential of large scale. Much research has focused on desalination using a flow electrode capacitive deionization device. Aiming at the characteristic that both a product of carbon dioxide electroreduction under acidic conditions (small molecular organic acid) and alkali metal cations are dissolved in a strong acid solution, the charging properties of the small molecular organic acid product and the alkali metal cations are different. Therefore, the product separation and alkali metal cation recovery of the acidic carbon dioxide electroreduction can be expected to be realized by designing and operating the flowing electrode capacitance deionization device.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for separating an acidic carbon dioxide reduction product and recovering cations, in particular to a method for separating and recovering cations by using powdered activated carbon, carbon black and Na 2 SO 4 Preparing slurry (as a supporting electrolyte) as a flowing electrode; simultaneously introducing the flowing electrode into an anode chamber and a cathode chamber; applying a voltage to the flowing electrode capacitive deionization device; under the action of an electric field, positively charged alkali metal cations pass through the cation exchange membrane to enter the cathode chamber, negatively charged inorganic anions pass through the anion exchange membrane to enter the anode chamber, and electrochemical product micromolecular organic acid is in an uncharged molecular state under a strong acid condition because of no dissociation and remains in the separation chamber.
In order to achieve the above purpose, the technical scheme of the invention is as follows: a method for separating and recovering cations from acidic carbon dioxide reduction products aims at the characteristics that small molecular organic acid and alkali metal cations which are products of acidic carbon dioxide reduction are dissolved in a strong acid solution, and the charging properties of the small molecular organic acid and the alkali metal cations are different, and a flowing electrode capacitance deionization device is used for separating and recovering the acidic carbon dioxide reduction products; the flowing electrode capacitance deionization device comprises an acrylic plate, a cathode graphite plate, a cation exchange membrane, a hollow silica gel pad, an anion exchange membrane, an anode graphite plate and an acrylic plate which are sequentially arranged; serpentine flow channels are engraved on the cathode graphite plate and the anode graphite plate; the cation exchange membrane, the hollow silica gel pad and the anion exchange membrane form a separation chamber, the cathode graphite plate and the cation exchange membrane form a cathode chamber, the anion exchange membrane and the anode graphite plate form an anode chamber, and the flowing electrodes can be introduced into the cathode chamber and the anode chamber.
In one embodiment of the invention, the method comprises the following steps:
(1) Activated carbon, carbon black and Na in powder form 2 SO 4 Preparing a slurry as a flow electrode, wherein Na 2 SO 4 As a supporting electrolyte;
(2) The flowing electrode prepared in the step (1) is utilized, the flowing electrode capacitive deionization device can realize product separation and alkali metal cation recovery aiming at acidic carbon dioxide reduction, and the specific process comprises the following steps:
introducing an acidic solution containing alkali metal cations and a product of carbon dioxide reduction into a separation chamber, and introducing a flowing electrode into an anode chamber and a cathode chamber simultaneously; applying a voltage to the flowing electrode capacitive deionization device; under the action of an electric field, positively charged alkali metal cations pass through the cation exchange membrane to enter the cathode chamber, negatively charged inorganic anions pass through the anion exchange membrane to enter the anode chamber, and the acidic carbon dioxide reduction product, namely small molecular organic acid, is in an uncharged molecular state under the strong acid condition because of no dissociation, and remains in the separation chamber.
In one embodiment of the present invention, in the step (1), the flowing electrode is formed by mixing powdered activated carbon and carbon black in a predetermined proportion, wherein the content of the powdered activated carbon is not more than 10 wt%, and the content of the carbon black is not more than 1.5 wt%. Preferably, the particle size of the powdered activated carbon in the flowing electrode is 10 μm and the particle size of the carbon black is 30 nm. The content of powdered activated carbon in the flowing electrode is 4.5-wt%, and the content of carbon black is 0.5-wt%.
In one embodiment of the present invention, in the step (1), the circulation flow rate of the flowing electrode is 2-20 mL/min. Preferably, the circulation flow rate of the flow electrode is 8 mL/min.
In one embodiment of the present invention, in the step (2), the flow rate of the product containing alkali metal cations and reduced carbon dioxide in the separation chamber is controlled to be 0.5-5 mL/min. Preferably, the acidic solution containing alkali metal cations and products of the electro-reduction of carbon dioxide is passed through the separation chamber at a flow rate of 2 mL/min.
In one embodiment of the present invention, in the step (2), a volume ratio of the flowing electrode to the strong acid solution containing the alkali metal cation and the product of carbon dioxide reduction is 1:6; alkali metal cations refer to K and Cs, and the alkali metal cation concentration is 0.1. 0.1M-3.0M. Preferably, the acidic solution containing alkali metal cations and the product of the electro-reduction with carbon dioxide has a pH of 1 and an alkali metal cation concentration of 0.1M.
In one embodiment of the present invention, in step (2), the voltage applied to the flow electrode capacitive deionization device is 0.9-4.8V, and the running time is 300 min. Preferably, the voltage is 3.6V and the run time is 300 min.
In one embodiment of the present invention, in step (1), the running mode of the flowing electrode is: short circuit closed cycle.
In one embodiment of the present invention, in step (2), the operation mode of the flowing electrode capacitive deionization device is as follows: batch mode.
Compared with the prior art, the invention has the following beneficial effects: according to the invention, by applying voltage to the flowing electrode capacitive deionization device, the flowing electrode in the cathode chamber is negatively charged due to contact with the cathode graphite plate, and the flowing electrode in the anode chamber is positively charged due to contact with the anode graphite plate; under the action of an electric field, positively charged alkali metal cations pass through the cation exchange membrane to enter the cathode chamber and are adsorbed on the negatively charged electrode; the negatively charged inorganic anions pass through the anion exchange membrane to enter the anode chamber and are adsorbed on the positively charged electrode, and the electrochemical product micromolecular organic acid is in an uncharged molecular state under the strong acid condition because of no dissociation and remains in the separation chamber. Therefore, aiming at the fact that the carbon dioxide electroreduction under the acidic condition is carried out, the charged properties of the micromolecular organic acid product and alkali metal cations are different, and the membrane electrochemical technology of a flowing electrode capacitance deionization device is used for realizing product separation and alkali metal cation recovery, so that the purpose of the invention is achieved.
Drawings
FIG. 1 is a schematic diagram of a flow electrode capacitive deionization device according to one embodiment of the present invention;
FIG. 2 illustrates the use of a flow electrode capacitive deionization device to effect formic acid separation and K in one embodiment of the present invention + The recycling effect;
FIG. 3 illustrates the use of a flow electrode capacitive deionization device to effect formic acid separation and Cs in one embodiment of the present invention + The recycling effect;
FIG. 4 illustrates the use of a flow electrode capacitive deionization device to effect acetic acid separation and Cs in one embodiment of the present invention + The recycling effect;
reference numerals illustrate: 1-acrylic plate; 2-cathode graphite plates; 3-cation exchange membrane; 4-cathode chamber; 5-hollow silica gel pad; 6-anion exchange membrane; 7-a separation chamber; 8-anode graphite plates; 9-an anode chamber; 10-acrylic plate.
Detailed Description
The invention will now be further described by way of the following examples, which are intended to be illustrative only and should not be construed as limiting the spirit and scope of the invention in any way, but rather as providing more detailed descriptions of certain details, parameters, and experimental procedures of the invention.
Example 1
In this example, a configuration of a flow electrode capacitive deionization apparatus according to one embodiment of the present invention will be described with reference to fig. 1, which includes:
the device comprises an acrylic plate (1), a cathode graphite plate (2), a cation exchange membrane (3), a hollow silica gel pad (5), an anion exchange membrane (6), an anode graphite plate (8) and an acrylic plate (10) which are sequentially arranged; the cathode graphite plate (2) and the anode graphite plate (8) have the dimensions of 90 mm multiplied by 90 mm multiplied by 4 mm, and each graphite plate is carved with a snake of 44 mm multiplied by 2 mm multiplied by 2 mmThe shaped flow channel serves as a current collector for transporting electrons of an external circuit. The cation exchange membrane (3), the hollow silica gel pad (5) and the anion exchange membrane (6) form a separation chamber (7) for circulating an acidic solution containing alkali metal cations and products of carbon dioxide electroreduction; the cathode graphite plate (2) and the cation exchange membrane (3) form a cathode chamber (4), and the effective contact area of the cation exchange membrane (3) is 11.92 cm 2 The method comprises the steps of carrying out a first treatment on the surface of the The anion exchange membrane (6) and the anode graphite plate (8) form an anode chamber (9), and the effective contact area of the anion exchange membrane (6) is 11.92 cm 2 . The cathode chamber (4) and the anode chamber (9) both contain flowing electrodes and are circulated into the respective chambers. In addition, a silica gel pad of a certain specification is added between each structure to prevent water leakage. Finally, all the components are fixed by bolting.
Example 2
In this example, in combination with FIG. 2, formic acid separation and K are achieved in one embodiment using a flow electrode capacitive deionization device + The effect of recovery will be described.
The artificial simulated acidic solution containing alkali metal cations and products of carbon dioxide electroreduction comprises the following components: 0.05 M HCl, 0.1M KCl and various concentrations (10, 20, 40, mM) of formic acid, by volume 240 mL. The flow electrode consisted of 4.5 wt% powdered activated carbon, 0.5 wt% carbon black and 95 wt% 1 g/L Na 2 SO 4 The solution (as supporting electrolyte). The flow electrode requires stirring with a magnetic stirrer for at least 24 h to ensure adequate wetting of the carbon surface and to adjust the pH to around 7 prior to use. The flowing electrode is pumped into the cathode chamber (4) and the anode chamber (9) respectively at the flow rate of 8 mL/min and circulated by a peristaltic pump, and the flowing electrode needs to be continuously stirred in the experimental process to prevent carbon particles from settling and agglomerating. The acidic solution containing alkali metal cations and the product of the electro-reduction of carbon dioxide was pumped into the separation chamber (7) at a flow rate of 2 mL/min and circulated by a peristaltic pump. The system was run for 300 min using an electrochemical workstation to provide a constant voltage of 3.6V. The concentration of formic acid before and after the reaction is kept in the separation chamber, and more than 94% of formic acid is kept in the separation chamber after operation. Different formic acid concentrations can influence K + Is effective in recovering the components. With the concentration of formic acidThe degree increased from 10 mM to 40 mM, K + Is increased from 71% to 98%.
Example 3
In this example, and in conjunction with FIG. 3, formic acid separation and Cs are achieved in one embodiment using a flow electrode capacitive deionization device + The effect of recovery will be described. Compared with example 1, the difference is that during the operation of the flow electrode capacitive deionization device, the composition of the product solution of carbon dioxide electroreduction of alkali metal cations is: 0.05 M HCl, 0.1M CsCl and different concentrations (10, 20, 40, mM) of formic acid, the other conditions were unchanged. The concentration of formic acid before and after the reaction is kept in the separation chamber, and more than 87% of formic acid is kept in the separation chamber after the operation. Different formic acid concentrations can affect Cs + Is increased from 10 mM to 40 mM, cs + The recovery of (2) was increased from 30% to 45%.
Example 4
In this example, in conjunction with FIG. 4, acetic acid separation and Cs are achieved in one embodiment using a flow electrode capacitive deionization device + The effect of recovery will be described. Compared with example 1, the difference is that during the operation of the flow electrode capacitive deionization device, the composition of the product solution of carbon dioxide electroreduction of alkali metal cations is: 0.05 M HCl, 0.1M CsCl and different concentrations (10, 20, 40, mM) of acetic acid, the other conditions were unchanged. The concentration of acetic acid before and after the reaction is kept in the separation chamber, and more than 92% of acetic acid is kept in the separation chamber after the operation. Different formic acid concentrations can affect Cs + Is increased from 10 to mM to 40 mM, cs + The recovery rate of (2) was increased from 46% to 95%.
While the invention has been described in detail, it will be apparent to those skilled in the art that the foregoing description is by way of example only and is not intended to limit the invention.
The above is a preferred embodiment of the present invention, and all changes made according to the technical solution of the present invention belong to the protection scope of the present invention when the generated functional effects do not exceed the scope of the technical solution of the present invention.
Claims (9)
1. The method for separating and recovering cations from the acidic carbon dioxide reduction products is characterized in that a flowing electrode capacitance deionizing device is used for separating and recovering the acidic carbon dioxide reduction products according to the characteristic that the acidic carbon dioxide reduction products, namely small molecular organic acids and alkali metal cations, are dissolved in a strong acid solution and the charging properties of the small molecular organic acids and the alkali metal cations are different; the flowing electrode capacitance deionization device comprises an acrylic plate, a cathode graphite plate, a cation exchange membrane, a hollow silica gel pad, an anion exchange membrane, an anode graphite plate and an acrylic plate which are sequentially arranged; serpentine flow channels are engraved on the cathode graphite plate and the anode graphite plate; the cation exchange membrane, the hollow silica gel pad and the anion exchange membrane form a separation chamber, the cathode graphite plate and the cation exchange membrane form a cathode chamber, the anion exchange membrane and the anode graphite plate form an anode chamber, and the flowing electrodes can be introduced into the cathode chamber and the anode chamber.
2. The method for separating and recovering cations from an acidic carbon dioxide reduction product according to claim 1, comprising:
(1) Activated carbon, carbon black and Na in powder form 2 SO 4 Preparing a slurry as a flow electrode, wherein Na 2 SO 4 As a supporting electrolyte;
(2) The flowing electrode prepared in the step (1) is utilized, the flowing electrode capacitive deionization device can realize product separation and alkali metal cation recovery aiming at acidic carbon dioxide reduction, and the specific process comprises the following steps:
introducing an acidic solution containing alkali metal cations and a product of carbon dioxide reduction into a separation chamber, and introducing a flowing electrode into an anode chamber and a cathode chamber simultaneously; applying a voltage to the flowing electrode capacitive deionization device; under the action of an electric field, positively charged alkali metal cations pass through the cation exchange membrane to enter the cathode chamber, negatively charged inorganic anions pass through the anion exchange membrane to enter the anode chamber, and the acidic carbon dioxide reduction product, namely small molecular organic acid, is in an uncharged molecular state under the strong acid condition because of no dissociation, and remains in the separation chamber.
3. The method according to claim 2, wherein in the step (1), the flowing electrode is formed by mixing a predetermined ratio of powdered activated carbon with carbon black, the powdered activated carbon content is not more than 10 wt%, and the carbon black content is not more than 1.5 wt%.
4. The method for separating and recovering cations from an acidic carbon dioxide reduction product according to claim 2, wherein in step (1), the circulating flow rate of the flowing electrode is 2-20 mL/min.
5. The method according to claim 2, wherein in the step (2), the flow rate of the product containing alkali metal cations and reduced carbon dioxide is controlled to be 0.5-5 mL/min.
6. The method of claim 2, wherein in step (2), the volume ratio of the mobile electrode to the strong acid solution containing alkali metal cations and carbon dioxide reduced products is 1:6; alkali metal cations refer to K and Cs, and the alkali metal cation concentration is 0.1. 0.1M-3.0M.
7. The method according to claim 2, wherein in step (2), the voltage applied to the flow electrode capacitive deionization unit is 0.9-4.8. 4.8V, and the operation time is 300 min.
8. The method for separating and recovering cations from an acidic carbon dioxide reduction product according to claim 2, wherein in step (1), the flow electrode is operated in the following manner: short circuit closed cycle.
9. The method for separating and recovering cations from an acidic carbon dioxide reduction product according to claim 2, wherein in step (2), the operation mode of the flow electrode capacitive deionization device is as follows: batch mode.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311340847.XA CN117403277A (en) | 2023-10-17 | 2023-10-17 | Method for separating acidic carbon dioxide reduction products and recovering cations |
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| CN202311340847.XA CN117403277A (en) | 2023-10-17 | 2023-10-17 | Method for separating acidic carbon dioxide reduction products and recovering cations |
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