CN114349029A - Decoupling type carbon dioxide mineralization film electrolysis system for producing high-purity carbonate - Google Patents
Decoupling type carbon dioxide mineralization film electrolysis system for producing high-purity carbonate Download PDFInfo
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Abstract
The invention belongs to the technical field of electrochemistry, and particularly relates to a decoupled CO for producing high-purity carbonate2Mineralized membrane electrolysis system. The system changes the pH environment of a solution through external power supply energy supply, electrochemical Proton Coupling Electron Transfer (PCET) reaction, realizes extraction and purification of high-concentration acid by using a high-efficiency extraction separating agent, thereby treating natural minerals or alkali liquor solid waste, and realizes low-cost and high-resource transfer through four main processes of reducing and regenerating organic PCET reactants through non-electrochemical reactionChemical rate of CO2The mineralized membrane electrolysis system is in a stable operation process. The invention adopts organic PCET reactant at the anode, thereby avoiding H2The use of gas diffusion electrodes; hydrogen evolution reaction and CO absorption at the cathode side2Thoroughly avoid CO2Middle O2And the effect of dissolved oxygen on the anodic organic PCET reactant. At the same time, H produced at the cathode2Can be used as a reducing agent to realize the reduction and regeneration of an organic PCET reactant, thereby realizing CO2Continuous and stable operation of the mineralized membrane electrolysis system.
Description
Technical Field
The invention belongs to the technical field of electrochemistry, and particularly relates to a decoupled CO for producing high-purity carbonate2Mineralized membrane electrolysis system.
Background
CO2Mineralization means the conversion of CO2The process of conversion to inorganic carbonates is CO2One of the key technologies for emission reduction utilization (CCU). At present, many processes for CO production by using large amount of calcium and magnesium-containing ores (serpentine, olivine and wollastonite) or solid wastes (carbide slag, steel slag and red mud) have been developed at home and abroad2Study of mineralization.
However, currently CO2The mineralization utilization technology generally faces the technical problems of high energy consumption, high cost and low economic value of products in mineralization reaction activation, and limits CO2Feasibility of large-scale application of mineralization techniques. And the proton cycle driving technical route is utilized to lead the front edge to the electrochemical CO2The combination of the emission reduction technology and natural mineral or solid waste treatment can effectively reduce the energy consumption of mineralization and simultaneously improve the resource recovery and utilization rate, and is expected to realize large-scale, economical and low-energy-consumption CO2Integrated CO of emission reduction, solid waste treatment, resource recovery and chemical production2And (4) mineralization utilization process. Current CO2Mineralized membrane electrolysis techniques typically employ an organic proton-coupled electron transfer (PCET) reactant or recycle H2As a carrier for electrochemical redox reactions. Wherein a cycle H is used2One of the difficulties lies inH2The 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 O2Influence on the stability of the system. Especially for absorbing CO2A small amount of O on the cathode side of2The existence of (gaseous oxygen or dissolved oxygen) can cause the rapid attenuation of the electrochemical proton coupling electron transfer reactant, so that the system is difficult to operate stably. In addition, CO2The mineralized membrane electrolysis system needs to directly treat natural minerals or alkaline solid wastes by using acidic anolyte, and if a PCET reactant is used as an electrochemical oxidation reduction carrier, irreversible loss of the organic PCET reactant is caused, so that the treatment cost is increased.
Thus, CO2The low-cost continuous and stable operation of the mineralized membrane electrolysis system is a technical problem to be overcome urgently.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provide a decoupled CO for producing high-purity carbonate2Mineralized membrane electrolysis system. The system can realize CO2The mineralized membrane electrolysis system has low cost and high resource conversion rate and can continuously and stably run. 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 CO in the cathode region2The absorption and the generation of the anode region acid, the separation and the purification of the anode region acid are realized through the high-efficiency separating agent, and the natural minerals or the alkaline solid wastes are recycled at high resource conversion rate by utilizing the high-concentration acid. H produced at the cathode2The anode liquid is reduced and regenerated outside the system, thereby realizing CO with low cost and high resource conversion rate2The continuous and stable running process of the mineralization film electrolysis.
In order to achieve the above purpose, the specific technical scheme of the invention is as follows:
decoupled CO for producing high-purity carbonate2The mineralized membrane electrolysis method comprises four main processes of external power supply, electrochemical PCET reaction, extraction and purification of high-concentration acid and reduction and regeneration of non-electrochemical reaction; wherein, the external powerThe source provides energy for the electrochemical reaction, and the anode undergoes an oxidation reaction of the organic PCET reactant to release H+The acidity of the anolyte is improved, and the acid solution in the acid-rich anolyte is extracted and purified by an extractant, so that natural minerals or alkaline solid waste can be treated; the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of catholyte, and the catholyte is used for absorbing CO generated by natural mineral or alkaline solid waste treatment in an anode region2Formation of HCO3 -Ions, cations of the anodic region (e.g. Na)+、K+Etc.) to the cathode side through the cation exchange membrane, with HCO at the cathode side3 -High-purity bicarbonate is generated, and finally, hydrogen generated by the cathode is used for reducing an organic PCET reactant of the anode under the action of a catalyst to realize the regeneration of the anolyte.
As a preferred embodiment of the present application, the organic PCET reactant releases H upon electrochemical oxidation+Increasing the acidity of the anode solution, and leading cations in the electrolyte to pass through the membrane to reach the cathode side which is cathode CO2Mineralization provides a source of cations; electrochemical PCET reactants include, but are not limited to, tungstic acid, alloxazines, phenazines, quinones and their derivatives (silicotungstic acid, phosphotungstic acid, FMN, DHPS, DHPC, BHPC, etc.), having the structure:
wherein R isn＝-H、-OH、-COOH、-SO3H、-NH2、-CH3、-O-、-S-、-CH2-, -F or-Cl. Or can be replaced by inorganic PCET reactant or high molecular polymer with PCET reaction performance, such as MnOOH, NiOOH, polyaniline, etc.
As a better embodiment in the application, the separation and purification of acid in the anode liquor of the system are carried out outside the electrolysis system, and the extractant is butyl acetate, ethyl acetate, chloroform, toluene, organic phosphoric acid, organic sulfonic acid or carboxylic acid; under the action of an efficient extracting agent, acid solution and an organic PCET reactant are extracted and separated in an oxidation state, and high-concentration acid is used for efficiently recycling resources of natural minerals or alkaline solid wastes to be treated.
As a preferred embodiment in this application, the decoupled CO used in the above process for producing high purity carbonate2The mineralized membrane electrolysis system comprises an external power supply and an electrolysis reactor, wherein the electrolysis reactor is in an electrolytic tank structure and comprises a cathode and an anode and a cation exchange membrane separating the cathode and the anode, and the anode is filled with an electrolyte electric coupling agent (organic PCET reactant) and an electrolyte (sodium salt, potassium salt and the like, such as 0.5M Na2SO4Solution), the anode is charged with lye (e.g. 1M NaHCO)3A solution). The cathode is a hydrogen evolution electrode (such as a platinum electrode, a platinum nickel plating net and the like).
In a preferred embodiment of the present invention, a gas-liquid separator and CO are provided on the cathode side2An absorption tower and a carbonate crystallization tower; under the action of current, the cathode generates electrochemical reduction reaction to decompose water to generate H2And OH-And increasing the alkalinity of the catholyte, wherein the reaction equation generated on the cathode side is as follows: 2H2O+2e-→2OH-+H2。
Introducing the alkali-rich catholyte into a gas-liquid separator to separate H2And catholyte, wherein CO is introduced into the catholyte2Absorption tower for mineralizing CO2Generation of NaHCO3Enriched NaHCO3Introducing the solution into a carbonate crystallization tower to produce a high-purity carbonate product, and circulating the mother solution to the cathode side of the cell; CO 22CO in the absorption tower2The reaction equation for mineralization is:
CO2+NaOH→NaHCO3。
as a preferred embodiment of the present application, the anode is a graphite felt electrode, and the organic PCET reactant QH is generated2(e.g. tungstic acid derivatives) electrochemical oxidation with liberation of H+The acidity of the anolyte is increased.
The reaction equation on the anode side is: QH2→Q+2H++2e-(Q/QH2The oxidized and reduced states, respectively, of the organic PCET reactant).
In a preferred embodiment of the present invention, an extraction column and an acid-soluble reaction are provided on the anode sideReactor and precipitation reactor, electrochemically produced H on anode side+Forming an acid-rich solution in the anode region, introducing the acid-rich solution and the oxidized reactant (Q) of organic PCET into an extraction tower, separating the acid solution from the oxidized reactant of organic PCET under the action of a high-efficiency extractant, introducing the acid solution into an acid-soluble reactor, and mixing with natural minerals or alkaline solid wastes (such as CaCO)3) Reaction to CO2With calcium salt solution; CO 22CO circulating to the cathode side2Absorbing tower, introducing calcium salt solution into precipitation reactor and Natrii sulfas (Na)2SO4) Reaction to produce CaSO4And (4) the precipitate and sodium salt electrolyte enter the anode side of the electrolytic cell for recycling.
As a better embodiment in the application, a back extraction tower and a reduction regeneration tower are further arranged on the anode side, the mixed solution of the organic PCET reactant Q and the extractant is introduced into the back extraction tower, the re-separation of the extractant and the Q is realized through the back extraction agent, and the high-efficiency extractant is circulated back to the extraction tower; the solution rich in the oxidation state reactant Q of the organic PCET enters a reduction regeneration tower and is separated from a gas-liquid separator at the cathode side in the environment of a platinum catalyst2Non-electrochemical reduction to QH2。
As a preferred embodiment herein, the separation of the organic PCET reactant Q from the extractant in the system is carried out outside the electrolysis system by stripping with a stripping agent, which is a dilute acid solution (e.g., dilute nitric acid, dilute sulfuric acid), water or a carbonate solution (e.g., sodium carbonate, potassium carbonate).
QH2The non-electrochemical reduction regeneration reaction equation is as follows: q + H2→QH2。
As a preferred embodiment in this application, the QH-rich material is obtained at the outlet of the reduction and regeneration tower2The anolyte is circularly led into the anode chamber of the electrolytic cell, and the stable circulation of the organic PCET reactant is realized.
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 catalyst2By spontaneous redox reactions to effect the organic PCET reactantAnd (5) reduction regeneration circulation. Useful reductively regenerated catalysts include: pt, Pt/C, Pd/C, Ni, and the like.
The system adopts an asymmetric electrochemical reaction structure, namely the cathode is an electrochemical hydrogen evolution reaction, and the anode is an 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 decouples the electrochemical oxidation reaction and the non-electrochemical reduction reaction of the organic PCET so as to realize continuous and stable circulation of the organic PCET reactant.
The whole system can be designed into a simple integrated device according to requirements, 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 like2And (4) trapping. The mineralizing raw materials used include, but are not limited to, natural minerals such as wollastonite, serpentine, olivine, potash feldspar, etc.; or industrial alkaline solid wastes such as carbide slag, biomass ash, fly ash, steel slag, red mud and the like. The system can be operated continuously without intermission and without limitation of time and space.
Compared with the prior art, the positive effects of the invention are as follows:
firstly, the invention adopts organic PCET reactant at the anode, thereby avoiding H2The use of gas diffusion electrodes; hydrogen evolution reaction and CO absorption at the cathode side2Thoroughly avoid CO2Middle O2And the effect of dissolved oxygen on the cathode organic PCET reactant. At the same time, H produced at the cathode2Can be used as a reducing agent to realize the reduction and regeneration of an organic PCET reactant, thereby realizing CO2Continuous and stable operation of the mineralized membrane electrolysis system.
(II) the system can realize CO2The mineralized membrane electrolysis system has low cost and high resource conversion rate and can continuously and stably run. 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 CO in the cathode region2The absorption and the anode region acid generation are realized by a high-efficiency separating agentAnd separating and purifying the anode area acid, and recycling natural minerals or alkaline solid wastes at a high resource conversion rate by using the high-concentration acid. H produced at the cathode2The anode liquid is reduced and regenerated outside the system, thereby realizing CO with low cost and high resource conversion rate2The continuous and stable running process of the mineralization film electrolysis.
Thirdly, the positive and negative pole liquids are separated by adopting a cation exchange membrane in the system, thereby thoroughly avoiding the CO of the cathode2Absorption side O2The interference to the anode organic PCET reactant can realize CO in a real environment2(oxygen-containing CO)2) Direct mineralization of (1). Meanwhile, cations in the anode region reach the cathode through the cation exchange membrane to realize charge balance of the system and mineralized CO with the anode2A bicarbonate solution is formed which can be used to produce high purity, high value-added bicarbonate products by achieving saturated crystallization.
And (IV) the anode region realizes the separation and purification of acid through a high-efficiency separating agent, and the high-concentration acid is utilized to carry out high-resource conversion rate recycling on natural minerals or alkaline solid wastes. Because only solid-liquid two-phase electrochemical reaction exists on the anode side, 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.
(V) according to thermodynamic analysis, the oxidation-reduction potential of the organic PCET reactant in an acidic environment is higher than the hydrogen potential in the environment, so that H can be ensured outside the electrochemical system2The organic PCET reactant is spontaneously reduced under the action of the catalyst. Meanwhile, the potential difference between the organic PCET reactant and the hydrogen evolution reaction reacts with the theoretical minimum input energy. In order to ensure that the anolyte can be spontaneously reduced by hydrogen under the action of a catalyst and avoid high electrolysis energy consumption, the system adopts tungstic acid derivatives (such as silicotungstic acid, phosphotungstic acid and the like), alloxazine/isoalloxazine derivatives (such as FMN and the like) or phenazine derivatives (such as DHPS, DHPC, BHPC and the like) with proper potential as organic PCET reactants, and can realize the spontaneous reduction of the anolyte and CO with low energy consumption2And (3) a mineralized membrane electrolysis process.
(VI) catalyst in the anode liquor reduction regeneration tower of the system is adoptedAcid-resistant platinum-carrying catalysts, which are widely used in industrial H2Reduction reaction, simple preparation and low cost. Meanwhile, the efficient extractant adopts butyl acetate, ethyl acetate, chloroform, toluene, organic phosphoric acid, organic sulfonic acid or carboxylic acid, and the back extractant adopts dilute acid solution (dilute nitric acid and dilute sulfuric acid), water or carbonate solution (sodium carbonate and potassium carbonate), so that the raw materials are easy to obtain and the cost is low.
Drawings
FIG. 1 shows the decoupled CO production of high purity carbonate according to the invention2A schematic diagram of a mineralized membrane electrolytic system;
FIG. 2 shows the decoupled CO for producing high purity carbonate according to the invention2A schematic structure diagram of a mineralized membrane electrolysis system;
wherein, 1-external power supply, 2-electrolytic tank, 3-anode region, 4-cation exchange membrane, 5-cathode region, 6-gas-liquid separator, 7-hydrogen drier, 8-CO2The method comprises the following steps of (1) an absorption tower, a 9-carbonate crystallization tower, a 10-extraction tower, an 11-acid dissolution reactor, a 12-precipitation reactor, a 13-stripping tower, a 14-stripping agent storage tank, a 15-reduction regeneration tower and a 16-hydrogen storage tank;
FIG. 3 is a graph of voltage versus time for a system employing silicotungstic acid mineralized apatite;
FIG. 4 is a diagram showing the electrolysis efficiency of a system using silicotungstic acid mineralized apatite;
FIG. 5 is a XRD representation of the product;
FIG. 6 is a XRD representation of the product;
FIG. 7 is a TGA profile of the product;
FIG. 8 is a voltage-time graph of a system employing DHPS to mineralize red mud;
FIG. 9 is a voltage-time graph of a system employing FMN to mineralize red mud;
FIG. 10 is a voltage-time graph of a BQ mineralized red mud adopted by the system;
FIG. 11 is a graph of red mud electrolysis voltage versus time with a hydrogen circulation membrane;
FIG. 12 is a voltage-time graph of system leak oxygen mineralization apatite;
FIG. 13 is a graph of red mud electrolysis voltage versus time for a hydrogen circulating membrane in the presence of water surges.
Detailed Description
Decoupled CO for producing high-purity carbonate2The mineralized membrane electrolysis system comprises an external power supply 1 and an electrolysis reactor 2.
The electrolytic reactor is of an electrolytic bath structure and comprises a cathode area 5, an anode area 3 and a cation exchange membrane 4 for separating the cathode area and the anode area. The cathode is a hydrogen evolution electrode and generates electrochemical reduction reaction, and the anode is a graphite felt electrode and generates electrochemical oxidation reaction of organic PCET reactant.
A gas-liquid separator 6 and CO are provided on the cathode side2An absorption tower 8 and a carbonate crystallization tower 9, wherein the cathode region is connected with a gas-liquid separator 6, and the gas-liquid separator 6 is connected with CO2Absorption column 8 connected, CO2The absorption tower 8 is respectively connected with the carbonate crystallization tower 9 and the cathode chamber 5. Preferably, a hydrogen dryer 7 is provided at the outlet of the gas-liquid separator.
An extraction tower 10, an acid dissolution reactor 11, a precipitation reactor 12, a stripping tower 13 and a reduction regeneration tower 15 are arranged on the anode side; the anode chamber 3 is connected with an extraction tower 10, the extraction tower 10 is respectively connected with an acid dissolution reactor 11 and a back extraction tower 13, a precipitation reactor 12 is arranged at the outlet of the acid dissolution reactor 11, and the outlet of the precipitation reactor 12 is connected with the anode chamber 3; the stripping tower 13 is respectively connected with a stripping agent storage tank 14 and a reduction regeneration tower 15, the reduction regeneration tower 15 is connected with the anode chamber 3, and the reduction regeneration tower 15 is also connected with a hydrogen dryer 7 on the cathode side through a hydrogen storage tank 16. The acid-soluble reactor 11 on the anode side is also connected to CO on the cathode side2The absorption towers 8 are connected. The stripping tower 13 is circularly connected with the extraction tower 10.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to specific embodiments, but it should not be construed that the scope of the above-described subject matter of the present invention is limited to the following 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.
The raw materials and sources used in the following examples are as follows:
analytically pure sodium sulfateSodium bicarbonate, alloxazine derivatives, phenazine derivatives, silicotungstic acid were used directly as experimental starting materials. Limestone and red mud are from Shandong Wei bridge electrolytic aluminum plants, and biomass ash is from Guangdong biomass power plants. H with a purity of 99.99%2And Ar and CO2All purchased from eastern wind (Sichuan) gas. Carrying 1mg/cm2The hydrogen diffusion electrode for the Pt/C catalyst was purchased from heson (shanghai) corporation, the cation exchange membrane used was Nafion115 membrane (dupont corporation), and a nickel-plated platinum mesh (self-made in a laboratory) was used as the cathode electrode.
In the present application, PCET is called Proton cyclic electron transfer throughout english, and chinese means Proton coupled electron transfer, and chinese is commonly called Proton coupled electron transfer and Proton coupling.
Example 1:
the system structure of this embodiment is shown in fig. 2, the connection relationship between the devices in the system is schematically shown in the detailed description, and the process is shown in fig. 1.
Decoupled CO for producing high purity carbonates using the structure of the embodiments2The mineralized membrane electrolysis method comprises the following specific operations:
the cation exchange membrane Nafion115 membrane is placed in an electrolytic tank, the electrolytic tank is divided into a cathode area and an anode area, and 60ml of anolyte (0.01M substance (namely tungstic acid derivative silicotungstic acid (SiW) +0.5M Na)2SO4) And 60ml catholyte (1M NaHCO)3) Placing in 200mL sealed storage tank, circulating at 20mL/min between the electrolytic cell device and the storage tank, and between the extraction tower and the back extraction tower via pump, and introducing into the reduction tower H2The flow rate is 20ml/min, and the extractant chloroform and the back extractant dilute nitric acid (1M) circulate at 20 ml/min. After the electrolysis is finished, CO is discharged2The cathode zone was bubbled at a rate of 20 ml/min. The anode reduction catalyst is a nickel-platinized net, a direct current power supply is applied between the anode electrode and the cathode electrode, the electrolysis reaction is powered by an external direct current power supply (IT6932A, Itech), and the temperature of the electrolytic bath and the storage tank is set to be 50 ℃.
On the cathode side, a gas-liquid separator and CO are provided2An absorption tower and a carbonate crystallization tower; under the action of electric current, cathodic generationElectrochemical reduction of water to produce H2And OH-And increasing the alkalinity of the catholyte, wherein the reaction equation generated on the cathode side is as follows: 2H2O+2e-→2OH-+H2。
Introducing the alkali-rich catholyte into a gas-liquid separator to separate H2And catholyte, wherein CO is introduced into the catholyte2Absorption tower for mineralizing CO2Generation of NaHCO3Enriched NaHCO3Introducing the solution into a carbonate crystallization tower to produce a high-purity carbonate product, and circulating the mother solution to the cathode side of the cell; CO 22CO in the absorption tower2The reaction equation for mineralization is:
CO2+NaOH→NaHCO3。
the anode adopts a graphite felt electrode to generate organic PCET reactant QH2And release of H+The acidity of the anolyte is increased.
The reaction equation on the anode side is: QH2→Q+2H++2e-(Q/QH2The oxidized and reduced states, respectively, of the organic PCET reactant).
On the anode side, an extraction column, an acid dissolution reactor and a precipitation reactor are arranged, and H electrochemically generated on the anode side+Forming an acid-rich solution in the anode region, introducing the acid-rich solution and the oxidized reactant (Q) of organic PCET into an extraction tower, separating the acid solution from the oxidized reactant of organic PCET under the action of a high-efficiency extractant, introducing the acid solution into an acid-soluble reactor, and mixing with natural minerals or alkaline solid wastes (such as CaCO)3) Reaction to CO2With calcium salt solution; CO 22CO circulating to the cathode side2Absorbing tower, introducing calcium salt solution into precipitation reactor and Natrii sulfas (Na)2SO4) Reaction to produce CaSO4And (4) the precipitate and sodium salt electrolyte enter the anode side of the electrolytic cell for recycling.
A back extraction tower and a reduction regeneration tower are also arranged at the anode side, the mixed solution of the organic PCET reactant Q and the extracting agent is introduced into the back extraction tower, the re-separation of the extracting agent and Q is realized, and the high-efficiency extracting agent is circulated back to the extraction tower; the solution rich in the oxidation state reactant Q of the organic PCET enters a reduction regeneration tower in the environment of a platinum catalystH separated from the cathode-side gas-liquid separator2Non-electrochemical reduction to QH2。
QH2The non-electrochemical reduction regeneration reaction equation is as follows: q + H2→QH2。
At the outlet of the reduction regeneration tower, the catalyst is rich in QH2The anolyte is circularly led into the anode chamber of the electrolytic cell, and the stable circulation of the organic PCET reactant is realized.
During the specific operation, the current density was set to 10mA/cm2Initial voltage of 0.275V, average voltage of 0.405V in four hours (FIG. 3), electrolytic efficiency of 90% or more (FIG. 4), and mineralization per ton of CO2The energy consumption is 246.05 kW.h.
Pumping the anode liquor of the electrolytic cell into an extraction tower, introducing a chloroform extractant to separate acid liquor from silicotungstic acid Solution (SiW), returning the silicotungstic acid Solution (SiW) to a water phase again through a back extractant dilute nitric acid, circulating the chloroform extractant to the extraction tower, pumping the silicotungstic acid Solution (SiW) into a reduction tower to be reduced into SiWH by hydrogen2Then pumping the solution back to the electrolytic bath for circular electrolytic reaction. 10g CaCO was added to the acid solution separated in the 100ml extraction column3The reaction was stirred at 300rpm for 2 h. Then 14.6g of Na was added thereto2SO4The solid was reacted at 400rpm for 3h and the suspension was vacuum filtered. After the filter residue is dried in vacuum at 60 ℃, the components of the filter residue are tested by XRD, the XRD test result is shown in figure 5, and the result shows that CaSO4The purity was 99.4% and the conversion 98%.
After the electrolysis is finished, CO is introduced into the cathode rich alkali solution at the gas speed of 50ml/min2After two hours a large amount of solid had precipitated and the suspension was vacuum filtered. After the residue was vacuum dried at 50 deg.C, its composition was measured by XRD and TGA and its purity was checked (see FIGS. 6-7), which was confirmed to be NaHCO of 99.4% purity3。
The detection result is in line with expectation, and the decoupling CO is verified2The mineralization membrane electrolysis system is used for producing carbonate with high added value with low energy consumption.
Example 2:
the operation of this example is substantially the same as that of example 1, except that,60ml of anolyte (alkaline leaching solution of red mud obtained by leaching method +0.01M substance of phenazine derivatives 2, 3-dihydroxy-7-sulfophenazine (DHPS) +0.25M Na2SO4) And 60ml catholyte (0.5M NaHCO)3) Placing in 200mL sealed storage tank, circulating at flow rate of 20mL/min between the electrolytic cell device and the storage tank and between the electrolytic cell device and the reduction tower by pump, and introducing into the reduction tower H2The flow rate is 20ml/min, and CO is added after the electrolysis is finished2The cathode zone was bubbled at a rate of 20 ml/min. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath and the storage tank is set to be 50 ℃.
The current density was set to 10mA/cm2Initial voltage of 0.181V, average voltage of 0.361V in four hours (figure 8), electrolytic efficiency of more than 90%, mineralization of CO per ton2The energy consumption is 219.32 kW.h.
After 4 hours of electrolysis, the alkaline solid waste leaching solution becomes neutral, and the current efficiency is over 95 percent. After the electrolysis is finished, CO is introduced into the cathode alkali-rich solution2After two hours, a large amount of solid was separated out, and the components were tested by XRD and TGA and checked for purity, which was confirmed to be 98.5% pure NaHCO3。
Example 3
The operation process of this example is substantially the same as that of example 1, except that 60ml of anolyte (alkaline red mud leaching solution obtained by leaching +0.01M substance ③ alloxazine derivative riboflavin (FMN) +0.5M Na2SO4) And 60ml catholyte (1M NaHCO)3) Placing in 200mL sealed storage tank, circulating at flow rate of 20mL/min between the electrolytic cell device and the storage tank and between the electrolytic cell device and the reduction tower by pump, and introducing into the reduction tower H2The flow rate is 20ml/min, and CO is added after the electrolysis is finished2The cathode zone was bubbled at a rate of 20 ml/min. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath and the storage tank is set to be 50 ℃.
The current density was set to 10mA/cm2Initial voltage of 0.15V, average voltage of 0.256V for four hours (FIG. 9), mineralization per ton of CO2The energy consumption is 155.52 kW.h.
After 4 hours of electrolysis, the alkaline solid waste leaching solution becomes neutral, and the current efficiency is over 90 percent. After the electrolysis is finished, CO is introduced into the cathode alkali-rich solution2After two hours, a large amount of solid was separated out, and the components were tested by XRD and TGA and checked for purity, which was confirmed to be 98.9% pure NaHCO3。
Example 4
The procedure of this example is essentially the same as that of example 1, except that 60ml of anolyte (alkaline red mud leaching solution obtained by leaching +0.01M substance, quinone derivative Benzoquinone (BQ) +0.5M Na2SO4) And 60ml catholyte (1M NaHCO)3) Placing in 200mL sealed storage tank, circulating at flow rate of 20mL/min between the electrolytic cell device and the storage tank and between the electrolytic cell device and the reduction tower by pump, and introducing into the reduction tower H2The flow rate is 20ml/min, and CO is added after the electrolysis is finished2The cathode zone was bubbled at a rate of 20 ml/min. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath and the storage tank is set to be 50 ℃.
The current density was set to 10mA/cm2Initial voltage of 0.21V, average voltage of 0.303V in four hours (FIG. 10), electrolytic efficiency of more than 90%, mineralization of CO per ton2The energy consumption is 184.08 kW.h.
After 4 hours of electrolysis, the alkaline solid waste leaching solution becomes neutral, and the current efficiency is over 95 percent. After the electrolysis is finished, CO is introduced into the cathode alkali-rich solution2After two hours, a large amount of solid was separated out, and the components were tested by XRD and TGA and the purity was checked, which was confirmed to be 98.1% pure NaHCO3。
Example 5
The procedure of this example was substantially the same as that of example 1 except that the anode reduction catalyst was changed from a nickel platinized mesh to nickel foam and the current density was set to 10mA/cm2Initial voltage of 0.25V, average voltage of 0.356V in four hours, mineralization per ton of CO2The energy consumption is 216.27 kW.h. The method is applicable to different anode reduction catalyst conditions.
Example 6
The procedure of this example is essentially the same as that of example 1, except that the extractant is replaced by ethyl acetate and the stripping agent by dilute sulfuric acid. The current density was set to 10mA/cm2Initial voltage of 0.28V, average voltage of 0.386V in four hours, mineralization per ton of CO2The energy consumption is 234.5 kW.h. The method can be applied to different extraction agents and stripping agents.
Comparative example 1:
the cation exchange membrane Nafion115 membrane is arranged in the electrolytic cell to divide the electrolytic cell into a cathode area and an anode area, and the gas diffusion electrode is arranged in the anode area to separate hydrogen from anolyte. Anolyte (solid waste alkaline leaching solution +0.5M Na2SO4) And catholyte (1M NaHCO)3) Placing in 200mL sealed storage tank, circulating between the electrolytic cell device and the storage tank at 20mL/min flow rate by pump, and introducing H at 20mL/min flow rate into the anode region2. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath is 50 ℃. The current density was set to 10mA/cm2And continuously monitoring and recording the voltage change rule of the electrolytic cell.
FIG. 11 is a graph showing an exemplary current density of 10mA/cm in the comparative example2The cell voltage varies with the reaction time during the electrolysis. As can be seen from the graph, when the current density was 10mA/cm2The initial voltage was 0.51V. The average voltage is 0.686V according to the recorded voltage-time data graph, so that the calculation according to the formula (7) shows that: with the scheme of the comparative group example, the theoretical energy consumption is 416.77 kW.h, and the technical energy consumption is far higher than that applied to the patent.
Comparative example 2:
the operation of this comparative example was substantially the same as that of example 1 except that air (oxygen concentration: 21%) and 60ml of an anolyte (0.01M substance (i) tungstic acid derivative silicotungstic acid (SiW) +0.5M Na) were mixed into the anode side of the electrolytic cell2SO4) And 60ml catholyte (1M NaHCO)3) Circulating and circulating the solution among the electrolytic cell device, the storage tank and the reduction tower at a flow rate of 20ml/min by a pump, and introducing the solutionReduction column H2The flow rate is 20ml/min, and CO is added after the electrolysis is finished2The cathode zone was bubbled at a rate of 20 ml/min. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath and the storage tank is set to be 50 ℃.
The current density was set to 10mA/cm2The initial voltage is 0.21V, the voltage of the comparative example 2 rises steeply at 2750s, probably because oxygen influences the stability of silicotungstic acid substances on the anode side, so that the chemical structure of the silicotungstic acid substances is irreversibly changed, and the comparative example proves that a membrane electrolysis system cannot stably operate in an oxygen environment without adopting the technology used in the patent.
Comparative example 3:
the cation exchange membrane Nafion115 membrane is arranged in an electrolytic cell to divide the electrolytic cell into a cathode area and an anode area, and a self-made gas diffusion electrode (damaged) is arranged in an anode chamber to separate hydrogen from anolyte. Anolyte (solid waste alkaline leaching solution +0.5M Na2SO4) And catholyte (1M NaHCO)3) Placing in 200mL sealed storage tank, circulating between the electrolytic cell device and the storage tank at 20mL/min flow rate by pump, and introducing H at 20mL/min flow rate into the anode region2. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath is 50 ℃. The current density was set to 10mA/cm2And continuously monitoring and recording the voltage change rule of the electrolytic cell.
The current density was set to 10mA/cm2The initial voltage was 0.75V, the average voltage was 0.912V, the comparative example 3 consumed much more energy than the example 1, and the gas diffusion electrode was flooded at 1700s to cause a steep rise in voltage. This comparative example illustrates the necessity of carrying out the process of the patent technology.
Comparative example 4:
the operation of this comparative example is essentially the same as that of example 1, except that 60ml of anolyte (0.01M substance p-quinone Derivative (DHBQ) +0.5M Na)2SO4) And 60ml catholyte (1M NaHCO)3) Between the cell unit and the storage tank and the reduction tower by means of a pumpCirculating at 20ml/min, and introducing into a reduction tower H2The flow rate is 20ml/min, and CO is added after the electrolysis is finished2The cathode zone was bubbled at a rate of 20 ml/min. A direct current power supply is applied between the anode electrode and the cathode electrode, an external direct current power supply (IT6932A, Itech) is adopted for supplying power for the electrolysis reaction, and the temperature of the electrolysis bath and the storage tank is set to be 50 ℃.
The current density was set to 10mA/cm2The initial voltage was 1.2V, and then the current continued to decay to 0A, failing to electrolyze normally. 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. Decoupled CO for producing high-purity carbonate2The mineralized membrane electrolysis method is characterized by comprising four main processes of external power supply, electrochemical PCET reaction, extraction and purification of high-concentration acid and non-electrochemical reaction reduction regeneration; wherein, the external power supply provides energy for electrochemical reaction, the anode generates oxidation reaction of organic PCET reactant to release H+The acidity of the anolyte is improved, and the acid solution in the acid-rich anolyte is extracted and purified by an extractant and is used for treating natural minerals or alkaline solid wastes; the cathode generates electrochemical hydrogen evolution reaction to increase the alkalinity of catholyte, and the catholyte is used for absorbing CO generated by natural mineral or alkaline solid waste treatment in an anode region2Formation of HCO3 -Ions, cations in the anode region pass through the cation exchange membrane to the cathode side, and HCO in the cathode side3 -High-purity bicarbonate is generated, and finally, hydrogen generated by the cathode is used for reducing an organic PCET reactant of the anode under the action of a catalyst to realize the regeneration of the anolyte.
2. Decoupled CO for the production of high purity carbonate according to claim 12The mineralized membrane electrolysis method 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 the non-electrochemical reduction reaction is ensured; 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; organic PCET reactants include, but are not limited to, tungstic acid, alloxazines, phenazines, quinones and derivatives thereof, having the structure:
wherein R isn＝-H、-OH、-COOH、-SO3H、-NH2、-CH3、-O-、-S-、-CH2-, -F or-Cl, etc.
3. Decoupled CO for the production of high purity carbonate according to claim 12Mineralized membrane electrolysis system, characterized in that, the extractant includes but not limited to butyl acetate, ethyl acetate, chloroform, toluene, organic phosphoric acid, organic sulfonic acid or carboxylic acid.
4. Decoupled CO for the production of high purity carbonate according to claim 12The mineralized membrane electrolysis system is characterized in that the catalyst is Pt, Pt/C, Pd/C or Ni.
5. Decoupled CO for the production of high purity carbonate, to be used in the process according to any of claims 1 to 42The mineralized membrane electrolysis system is characterized by comprising an external power supply and an electrolysis reactor, wherein the electrolysis reactor is of an electrolysis bath structure and comprises an anode and a cathode and a cation exchange membrane separating the anode and the cathode, and the anode is adoptedFilling an organic PCET reactant and an electrolyte into the anode by using a graphite felt electrode; the cathode is a hydrogen evolution electrode and is filled with alkali liquor.
6. Decoupled CO for the production of high purity carbonate according to claim 52The mineralized membrane electrolysis system is characterized in that a gas-liquid separator and CO are arranged on the cathode side2An absorption tower and a carbonate crystallization tower; under the action of current, the cathode generates electrochemical reduction reaction to decompose water to generate H2And OH-Increasing the alkalinity of the catholyte, introducing the alkali-rich catholyte into a gas-liquid separator, and separating H2And catholyte, wherein CO is introduced into the catholyte2Absorption tower for mineralizing CO2Generation of NaHCO3Enriched NaHCO3The solution is introduced into a carbonate crystallization tower to produce a high-purity carbonate product, and the mother liquor is circulated to the cathode side of the battery.
7. Decoupled CO for the production of high purity carbonate according to claim 52The mineralized membrane electrolysis system is characterized in that an extraction tower, an acid dissolution reactor and a precipitation reactor are arranged on the anode side, and H electrochemically generated on the anode side+Forming an acid-rich solution in the anode region, introducing the acid-rich solution and the oxidation-state reactant of the organic PCET into an extraction tower together, separating the acid solution from the oxidation-state reactant of the organic PCET under the action of an extracting agent, introducing the acid solution into an acid-soluble reactor, and reacting with natural minerals or alkaline solid wastes to generate CO2With calcium salt solution; CO 22CO circulating to the cathode side2Absorbing tower, introducing the calcium salt solution into a precipitation reactor to react with mirabilite to generate CaSO4And (4) the precipitate and sodium salt electrolyte enter the anode side of the electrolytic cell for recycling.
8. Decoupled CO for the production of high purity carbonate according to claim 52The mineralized membrane electrolysis system is characterized in that a back extraction tower reduction regeneration tower is further arranged on the anode side, the mixed solution of the organic PCET reactant Q and the extracting agent is introduced into the back extraction tower, re-separation of the extracting agent and the organic PCET reactant Q is realized through the back extraction agent, and the high-efficiency extracting agent is circulated back to the extraction tower; rich in organic PCET oxygenThe material Q enters a reduction regeneration tower, and H separated from a gas-liquid separator at the cathode side in the environment of a platinum catalyst2Non-electrochemical reduction to QH2。
9. Decoupled CO for the production of high purity carbonate according to claim 62The mineralized membrane electrolysis system is characterized in that QH is enriched at the outlet of the reduction and regeneration tower2The anolyte is circularly led into the anode chamber of the electrolytic cell, and the stable circulation of the organic PCET reactant is realized.
10. Decoupled CO for the production of high purity carbonate according to claim 62The mineralized membrane electrolysis system is characterized in that the stripping agent comprises but is not limited to dilute acid solution, water and carbonate solution.
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| CN110311146A (en) * | 2019-06-19 | 2019-10-08 | 四川大学 | A kind of carbon dioxide mineralising power generation new method for making catalyst using organic matter |
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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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