A universal CO2 / CO electrocatalytic device

Abstract

The present invention relates to a universal CO2 / CO electrocatalytic device, comprising an anode module, a reduction stack module and a cathode module connected in sequence, wherein the cathode module comprises a check valve, a first back pressure valve and a first gas-liquid separation unit connected in sequence at the stack outlet, the liquid phase outlet end of the first gas-liquid separation unit is connected in sequence to an acidification treatment unit and a liquid phase product separation unit, and the gas outlet end of the first gas-liquid separation unit is connected in sequence to a first drying system and a gas phase product separation unit. The beneficial effect of the present invention is that the present invention can meet the separation of multiple products under different catalyst systems, so that multiple cathode catalyst systems can use the electrocatalytic device of the present invention.

Description

Technical Field

[0001] The present invention relates to the field of energy conversion and CO2 utilization, and more specifically, to a universal CO2 / CO electrocatalytic device. Background Art

[0002] At present, a variety of clean energy (wind energy, solar energy, hydropower, biomass energy and geothermal energy, etc.) has attracted widespread attention. However, due to their respective characteristics, these energy sources have great limitations in their utilization methods, and their practical applications are also greatly restricted. For example, the volatility of wind energy and solar energy changes with weather and surrounding environment. Therefore, in addition to changing the energy structure, energy storage and conversion are equally important. Among them, electrochemical energy conversion is playing an increasingly important role. CO2 electrocatalysis is a type of energy conversion reaction. Choosing a suitable catalytic system can not only effectively reduce CO2 to high-value-added chemical products, but also accelerate the realization of carbon neutrality goals.

[0003] The post-processing steps of the existing CO2 electrocatalytic system only involve the simple separation of CO2 for reuse, and the remaining products are collected and processed in a centralized manner. No online separation means are used, which consumes high time and economic costs. The types of products in the existing CO2 electrocatalytic system are relatively complex, and can be roughly divided into three categories according to the types of main products: 1) CO, the selected catalysts are metals such as Ag, Au, Zn, etc.; 2) HCOOH, the selected catalysts are metals such as Sn, In, etc.; 3) CH4, C2H4, CO, C2H5OH, CH3COOH and HCOOH, etc., the selected catalysts are mainly Cu-based metals. In addition to the above main products, the electrochemical reduction potential of CO2 will be accompanied by the reaction of H2O electrolysis of hydrogen. Therefore, in addition to the above products, H2 will also be produced in the above three systems. In the actual production process, due to the large differences in the products of different CO2 electrocatalytic systems, the post-processing technologies of different catalyst systems are different. Once the catalyst technology route is changed, the device needs to be significantly modified. Therefore, it is necessary to design an electrocatalytic device with high versatility, low cost, and easy operation and maintenance for a variety of product systems. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art. Specifically, the first problem to be overcome is that the existing CO2 fuel cell uses offline separation methods, which consumes high time and economic costs; the second problem is that the products obtained by the existing CO2 fuel cell for different catalyst systems are complex, and the equipment is difficult to be universal.

[0005] In order to solve the above problems, a universal CO2 / CO electrocatalytic device is provided.

[0006] In a first aspect, a universal CO2 / CO electrocatalytic device is provided, comprising: an anode module, a reduction stack module and a cathode module connected in sequence;

[0007] Wherein, the cathode module is provided with a check valve, a first back pressure valve and a first gas-liquid separation unit which are connected in sequence at the outlet of the fuel cell stack.

[0008] The check valve and back pressure valve following the CO2 stack can separate the products after they have accumulated to a certain extent and prevent the backflow of the products during the process of product accumulation. If the first back pressure valve is not set, the first gas-liquid separation unit will start to work when the stack starts to work and there are products. In the early stage of the stack, the content of the product is not high, the separation effect of the gas-liquid separation unit is not good and the energy consumption is large; if the check valve is not set, when the back pressure valve has not reached the opening pressure, the accumulation of products will make the pressure at the outlet of the stack higher than that at the inlet of the stack, causing the product to flow back and cause danger.

[0009] Furthermore, the liquid phase outlet of the first gas-liquid separation unit is sequentially connected to the acidification treatment unit and the liquid phase product separation unit, and the gas outlet of the first gas-liquid separation unit is sequentially connected to the first drying system and the gas phase product separation unit.

[0010] Preferably, the gas source is CO2 or CO. When the gas source is CO2, a CO2 absorption tank is further provided between the gas outlet end of the first gas-liquid separation unit and the first drying system. The CO2 absorption tank is then connected to the gas source via a CO2 regeneration unit and a second back pressure valve.

[0011] Furthermore, the liquid phase product separation unit comprises at least two separation units. Preferably, the liquid phase separation unit comprises 2, 3 or 4 separation units.

[0012] Furthermore, the gas-phase product separation unit comprises at least two separation units. Preferably, the gas-phase product separation unit comprises 2, 3 or 4 separation units.

[0013] By setting up multiple liquid product separation units and gas product separation units, one system can be used to separate the post-treatment products of various catalyst systems online to obtain a universal CO2 device. When using this CO2 device, when the cathode catalyst is Ag, Au and Zn, the exhaust gas at the outlet of the stack includes CO and unreacted CO2. At this time, since there is no liquid product, the liquid phase separation unit after the acidification treatment is closed by a valve, and one gas phase separation unit is retained through a valve to separate the product CO; when the silver-based catalyst is Sn and In, the exhaust gas at the outlet of the stack includes HCOOH, H2 and unreacted CO2, that is, it contains one liquid product and two gas products. One liquid phase separation unit is retained through a valve. After gas-liquid separation and acidification treatment, It is then used to separate HCOOH, and a gas phase separation unit after the first drying system is retained through a valve for separating H2; when the cathode catalyst is Cu, the reaction products in S3 include CH4, C2H4, CO, C2H5OH, CH3COOH, n-C3H7OH, HCOOH, CO2 and H2, that is, it contains 4 liquid products and 5 gases. Four liquid phase separation units are retained through valve control for separating C2H5OH, CH3COOH, n-C3H7OH and HCOOH, and four gas phase product separation units are retained through valve control for separating CH4, C2H4, CO and H2. The separation cost can also be taken into account, the separation units can be reduced, and only the products with higher concentrations can be separated.

[0014] Furthermore, the CO2 absorption tank is sequentially connected to the CO2 regeneration unit, the second back pressure valve, and connected in parallel with the additional CO2 gas source to a gas flow meter, and the gas flow meter is connected to the cathode inlet of the CO2 stack.

[0015] In order to ensure the stable operation of the CO2 stack, the amount of gas at the inlet should remain stable. The inlet gas is obtained by connecting the CO2 regeneration unit and the CO2 gas source in parallel, and the regeneration speed in the CO2 regeneration unit is difficult to control. In order to ensure the stability of the inlet gas pressure, the proportion of the two gas circuits needs to be adjusted in real time. By setting the second back pressure valve, the CO2 in the CO2 regeneration unit is mixed with the CO2 gas source when it reaches a specific gas pressure. That is, the setting of the second back pressure valve can control the CO2 gas pressure ejected from the CO2 regeneration unit at a time to be constant, so that the proportion of mixing with the CO2 gas source each time and the valve opening can be controlled to be stable, further reducing the cost of each adjustment.

[0016] Furthermore, the anode module includes a second gas-liquid separation unit, a first pump system, an anode liquid storage tank, a second pump system, a second drying system and a product storage tank; the liquid outlet end of the second gas-liquid separation unit is connected to the first pump system, the anode liquid storage tank and the second pump system in sequence; the gas outlet end of the second gas-liquid separation unit is connected to the second drying system and the product storage tank in sequence; the reduction stack module includes a DC power supply and a stack; the stack includes an anode module stack inlet, an anode module stack outlet, a cathode module stack inlet and a cathode module stack outlet; the anode module stack inlet is connected to the second pump system, and the anode module stack outlet is connected to the inlet of the second gas-liquid separation unit.

[0017] Preferably, the anode liquid storage tank stores an aqueous electrolyte solution.

[0018] Preferably, the product at the gas outlet of the first gas-liquid separation unit is oxygen.

[0019] Preferably, the fuel cell stack comprises an anode chamber and a cathode chamber.

[0020] In a second aspect, a universal CO2 / CO electrocatalytic method is provided, which is performed by any universal CO2 / CO electrocatalytic device described in the first aspect, comprising:

[0021] S1, the anode module introduces anode liquid into the anode chamber of the electric propulsion module, and the cathode module introduces a gas source into the module of the stack module; a first catalyst is added into the anode chamber, and a second catalyst is added into the cathode chamber; and a voltage is applied to both ends of the cathode and cathode of the stack module;

[0022] S2, a water electrolysis oxygen reaction occurs in the anode chamber, and oxygen and anode liquid flow into the inlet of the second gas-liquid separation unit through the outlet of the anode module stack; the anode liquid flows out from the liquid outlet of the second gas-liquid separation unit, and circulates back to the anode liquid storage tank through the first pump system; oxygen flows out from the gas outlet of the second gas-liquid separation unit, and enters the product storage tank after being dried by the second drying system;

[0023] S3. A cathode reduction reaction occurs in the cathode chamber, and the reaction products pass through the cathode module stack outlet, the check valve, and the first back pressure valve in sequence to enter the inlet of the first gas-liquid separation unit, and are separated into gas and liquid to obtain liquid products and gas products; the liquid products are processed in turn by the acidification treatment unit and the liquid product separation unit; the gas products are processed in turn by the first drying system and the gas product separation unit.

[0024] Preferably, in S1, under the action of the second pump system, the anode liquid is transported into the anode chamber of the fuel cell stack; and the gas source enters the cathode chamber of the fuel cell stack under the control of the gas flow meter.

[0025] Preferably, in S1, the first catalyst comprises IrO2 nanoparticles; and the second catalyst comprises one or more of Ag, Au, Zn, Sn, In or Cu.

[0026] Preferably, when the gas source is CO2 and the second catalyst is Ag, Au and Zn, the reaction products in S3 include CO and unreacted CO2; when the gas source is CO2 and the second catalyst is Sn and In, the reaction products in S3 include HCOOH, H2 and unreacted CO2; when the gas source is CO2 and the second catalyst is Cu, the reaction products in S3 include CH4, C2H4, CO, C2H5OH, CH3COOH, n-C3H7OH, HCOOH, CO2 and H2.

[0027] Preferably, when the gas source is CO2, in S3, the gaseous product is first passed into a CO2 absorption tank to absorb unreacted CO2 before being passed into the second drying system. After the CO2 is regenerated and reaches the pressure threshold of the second back pressure valve, it is re-injected into the gas source.

[0028] The beneficial effects of the present invention are:

[0029] (1) The present invention connects a gas-liquid separation unit, a CO2 absorption tank, a drying system and a CO2 recovery unit after the fuel cell, and connects the CO2 recovery unit to the CO2 gas source module, so as to perform product circulation and derivative product separation of the CO2 electric reduction fuel cell online.

[0030] (2) The present invention uses a check valve and a back pressure valve immediately following the CO2 stack to separate the products after they have accumulated to a certain extent and prevent the backflow of the products during the process of aggregating the products.

[0031] (3) The input gas source of the CO2 fuel cell stack in the present invention needs to be constant. By setting the back pressure valve after the CO2 regeneration unit, the pressure of the CO2 gas ejected from the CO2 regeneration unit can be controlled to be constant, so that the proportion of mixing with the CO2 gas source each time and the valve opening can be controlled to be stable, further reducing the cost of each adjustment.

[0032] (4) The present invention connects a liquid product separation unit and a gas product separation unit after the cathode CO2 stack outlet, and there are multiple specific separation modules in the liquid product separation unit and the gas product separation unit, which can meet the separation of multiple products under different catalyst systems, so that a variety of cathode catalyst systems can use the CO2 stack of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of a universal CO2 / CO electrocatalytic device. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0035] Embodiment 1:

[0036] The present invention provides a highly versatile CO2 / CO electrocatalytic device that can be applied to different product systems. In addition, CO, as an intermediate species for the deep reduction of CO2 to low-valent hydrocarbon products, can also be used as a reaction source for electrocatalytic reduction to obtain different chemicals. Therefore, the electrocatalytic device of the invention is also suitable for CO electrocatalytic reduction.

[0037] like Figure 1 As shown, a universal CO2 / CO electrocatalytic device comprises: an anode module, a reduction stack module and a cathode module connected in sequence;

[0038] Among them, the anode module includes a second gas-liquid separation unit, a first pump system, an anode liquid storage tank, a second pump system, a second drying system and a product storage tank; the liquid outlet end of the second gas-liquid separation unit is connected to the first pump system, the anode liquid storage tank and the second pump system in sequence; the gas outlet end of the second gas-liquid separation unit is connected to the second drying system and the product storage tank in sequence; when the anode liquid storage tank stores an aqueous electrolyte solution, the product of the gas outlet end of the second gas-liquid separation unit is oxygen; the reduction stack module includes a DC power supply and a stack; the stack includes an anode module stack inlet, an anode module stack outlet, a cathode module stack inlet, a cathode module stack outlet, an anode chamber and a cathode chamber; the anode module stack The stack inlet is connected to the second pump system, and the anode module stack outlet is connected to the inlet of the second gas-liquid separation unit; the cathode module includes a gas flow meter, a gas source, a check valve, a first back pressure valve, a first gas-liquid separation unit, an acidification treatment unit, a liquid product separation unit, a first drying system and a gas product separation unit; the gas source is connected to the cathode module stack inlet through a gas flow meter; the cathode module stack outlet is connected to the check valve, the first back pressure valve and the first gas-liquid separation unit in sequence; the liquid outlet end of the first gas-liquid separation unit is connected to the acidification treatment unit and the liquid product separation unit in sequence, and the gas outlet end of the first gas-liquid separation unit is connected to the second drying system and the gas product separation unit in sequence.

[0039] The gas source is CO2 or CO. When the gas source is CO2, a CO2 absorption tank is also provided between the gas outlet of the first gas-liquid separation unit and the first drying system, and the CO2 absorption tank is also connected to the gas source through the CO2 regeneration unit and the second back pressure valve in sequence. The CO2 absorption tank adopts a CO2 capture process, and the captured CO2 can be re-input into the CO2 gas source after regeneration.

[0040] The main purpose of adding an acidification treatment unit below the first gas-liquid separation unit is to adjust the pH value of the liquid product so that it is in an acidic environment. This is because the liquid product is usually in a CO2-saturated state, under which the solution is weakly alkaline. Products such as formic acid and acetic acid mainly exist in the form of formate and acetate under weakly alkaline conditions, which is not conducive to subsequent product separation. Therefore, acidification treatment is required to lower the pH value of the solution and convert formate and acetate into formic acid and acetic acid. The acidification treatment unit can lower the pH value by adding hydrochloric acid.

[0041] A check valve and a first back pressure valve are added between the cathode module stack outlet and the first gas-liquid separation unit, so that the stack products accumulate to a certain extent, and the first back pressure valve is opened by increasing the gas pressure to enter between the first gas-liquid separation unit. The check valve is used to prevent the product from flowing back. This is because in the early stage of the stack operation, due to the small accumulation of products, the products may adhere to the cavity wall and are not enough to reach the separation device for separation. In addition, due to the small accumulation in the early stage, starting separation at this time may increase the operating cost of the device; during the stable operation of the stack, the amount of products remains basically constant. Through the first back pressure valve, the products can also be separated and circulated when they accumulate to a certain stage, further reducing the cost of online post-processing.

[0042] Furthermore, a second back pressure valve is provided between the CO2 regeneration unit and the CO2 gas source. After a certain amount of CO2 is accumulated in the CO2 regeneration unit, it can be merged into the CO2 gas source at a constant pressure. If there is no second back pressure valve, due to the influence of the power stability of the CO2 stack and the gas-liquid separation efficiency, the confluence ratio of the CO2 regeneration unit and the CO2 gas source needs to be adjusted at any time. The specific back pressure valve can make the CO2 gas source merge into the CO2 gas source at a fixed ratio, and there is no need to adjust the valve opening for each influencing.

[0043] For all CO2 electrocatalytic reduction systems, DC power supply, CO2 reduction stack, anode liquid storage tank, second gas-liquid separation unit of anode module, CO2 gas source, gas flow meter, CO2 absorption tank, CO2 regeneration unit and pump system are all necessary units. The first gas-liquid separation unit and the first drying system of the cathode module can meet the product separation requirements of the three existing CO2 electrocatalytic systems. According to different catalyst systems, the matching gas-liquid separation unit and / or the specific separation unit in the first drying system can be selected through simple valve operation to achieve corresponding post-processing.

[0044] Embodiment 2:

[0045] A universal CO2 / CO electrocatalytic method, performed by any universal CO2 / CO electrocatalytic device of the first aspect, comprising:

[0046] S1, the anode module introduces anode liquid into the anode chamber of the electric propulsion module, and the cathode module introduces a gas source into the module of the stack module; the first catalyst is added into the anode chamber, and the second catalyst is added into the cathode chamber; and voltage is applied to the cathode and cathode ends of the stack module;

[0047] S2, a water electrolysis oxygen reaction occurs in the anode chamber, and oxygen and anode liquid flow into the inlet of the second gas-liquid separation unit through the outlet of the anode module stack; the anode liquid flows out from the liquid outlet of the second gas-liquid separation unit, and circulates back to the anode liquid storage tank through the first pump system; oxygen flows out from the gas outlet of the second gas-liquid separation unit, and enters the product storage tank after being dried by the second drying system;

[0048] S3. A cathode reduction reaction occurs in the cathode chamber, and the reaction products pass through the cathode module stack outlet, the check valve, and the first back pressure valve in sequence to enter the inlet of the first gas-liquid separation unit, and undergo gas-liquid separation to obtain liquid products and gas products; the liquid products are processed in turn by the acidification treatment unit and the liquid product separation unit; the gas products are processed in turn by the first drying system and the gas product separation unit.

[0049] In S1, under the action of the second pump system, the anode liquid is transported into the anode chamber of the fuel cell stack; the gas source enters the cathode chamber of the fuel cell stack under the control of the gas flow meter.

[0050] In S1, the first catalyst includes IrO2 nanoparticles; the second catalyst includes Ag, Au, Zn, Sn, In and Cu.

[0051] When the gas source is CO2 and the second catalyst is Ag, Au and Zn, the reaction products in S3 include CO and unreacted CO2; when the gas source is CO2 and the second catalyst is Sn and In, the reaction products in S3 include HCOOH, H2 and unreacted CO2; when the gas source is CO2 and the second catalyst is Cu, the reaction products in S3 include CH4, C2H4, CO, C2H5OH, CH3COOH, n-C3H7OH, HCOOH, CO2 and H2.

[0052] When the gas source is CO2, in S3, the gas phase product is first introduced into the CO2 absorption tank to absorb unreacted CO2 before being introduced into the first drying system. After the CO2 is regenerated and reaches the pressure threshold of the second back pressure valve, it is re-injected into the gas source.

[0053] In the working state, water electrocatalytic oxidation is used to produce oxygen as the anode reaction. The anode storage tank usually stores an electrolyte aqueous solution. Under the action of the second pump system, the aqueous solution is transported to the anode of the stack. The substances at the reaction outlet include product oxygen and aqueous solution. After the mixture passes through the second gas-liquid separation unit, the liquid aqueous solution can be returned to the anode storage tank for recycling under the action of the first pump system. The gas product oxygen first passes through the second drying system to dry the water vapor and is stored in the product storage tank. When the CO2 electrocatalytic reduction reaction is used as the cathode reaction, the gas flow meter controls the CO2 flow value entering the stack. After CO2 enters the reactor at a certain flow rate, the corresponding electrocatalytic reaction occurs. The corresponding product and the unreacted CO2 enter the first gas-liquid separation unit together through the outlet, the liquid phase mixture enters the liquid phase separation unit, the gas phase mixture enters the CO2 absorption tank to absorb the unreacted CO2, and the remaining gas phase mixture enters the gas phase separation unit.

[0054] For the reduction product system whose main product is CO, the representative catalysts are Ag, Au, Zn, etc. Since CO2 can be reduced to CO easily to achieve high selectivity (Faraday efficiency>90%), the substances at the outlet are mainly composed of CO and unreacted CO2, as well as a small amount of H2 and H2O. A very small amount of other substances can be treated as waste liquid, that is, in this system, the main value-added product is CO gas. Therefore, the liquid product separation unit can be closed, and only one gas product separation unit can be retained to purify the CO in the mixed gas and obtain high-concentration CO. At this time, the main units passed by the cathode module in this system include the first gas-liquid separation unit, the CO2 absorption tank, the CO2 regeneration unit, the first drying system and the gas product separation unit 3.

[0055] For the reduction product system whose main product is HCOOH, the representative catalysts are metals such as Sn and In, which can also achieve high reaction selectivity (Faraday efficiency>90%). The substances at the outlet are mainly composed of HCOOH, H2 and unreacted CO2, as well as a small amount of other substances. That is, under this system, the main value-added product is liquid HCOOH, so one liquid product separation unit is retained. At this time, the main units passed by the cathode module under this system include the first gas-liquid separation unit, the CO2 absorption tank, the CO2 regeneration unit, the first drying system, and the liquid phase separation unit 1. In the liquid phase separation unit 1 downstream of the first gas-liquid separation unit, HCOOH is separated and purified and stored in the product storage tank, and the gas phase product H2 downstream of the first drying system is stored in the hydrogen storage tank as a gas product.

[0056] For a system with a complex product composition of CH4, C2H4, CO, C2H5OH, CH3COOH, n-C3H7OH and HCOOH, the representative catalyst is Cu, and the material composition at the outlet includes the above products, CO2, H2 and a very small amount of other substances, that is, under this system, the main product composition is 4 liquid products C2H5OH, CH3COOH, n-C3H7OH, HCOOH and 4 gas products C2H4, H2, CO, CH4, therefore, 3 liquid product separation units and 3 gas product separation units are retained. It is also possible to comprehensively consider the separation cost and choose to only separate liquid products and gas products with high content, thereby reducing the number of liquid separation units used.

[0057] For liquid mixtures, temperature-controlled distillation / fractionation is usually used to separate and purify products according to the different characteristics of the boiling points of each substance. For gas mixtures, low-temperature distillation, membrane separation, pressure swing adsorption and desorption separation, and a combination of different separation methods can be used according to product requirements. As a highly versatile electrocatalytic system, in the liquid separation unit, the separation method in this patent adopts a distillation method. The separation unit 1 intends to select a distillation temperature that is the same as the boiling point of HCOOH. For a system in which the main product is HCOOH, a product composition 1 with high purity of the HCOOH product can be obtained by this method. For a system with more products, a product composition 1 with a boiling point lower than the boiling point of HCOOH (such as C2H5OH, n-C3H7OH and HCOOH, etc.) can be obtained first. Whether the product composition 1 needs to be further purified can be determined according to the specific composition and product quality requirements. If further separation is required, a separation unit needs to be added after the product composition 1 to achieve product separation. The separation unit 2 is to separate products with a boiling point higher than HCOOH (such as CH3COOH), which can be separated by increasing the distillation temperature to obtain a product composition 2 with higher product purity. For the separation of gaseous products, this patent proposes to adopt low-temperature distillation method. In the separation unit 3, a temperature consistent with the boiling point of H2 is selected to distill out a product composition 3 with a lower boiling point, which is mainly composed of H2. Then the distillation temperature is adjusted to separate each gaseous product in turn, and the gaseous products with lower composition are discharged from the system in the form of waste.

[0058] For the reaction system with CO as the gas source, since there is no relatively mature and economical CO absorption method, the CO2 absorption tank, CO2 regeneration unit and the second back pressure valve behind it can be removed during operation. The unreacted CO and the gas phase products enter the gas phase separation unit together. The need to recover the unreacted CO can be determined based on the cost of CO separation.

[0059] In summary, the present invention connects a first gas-liquid separation unit, a CO2 absorption tank, a first drying system and a CO2 recovery unit after the fuel cell, and connects the CO2 recovery unit to the CO2 gas source module to perform product circulation and derivative product separation of the CO2 electric reduction fuel cell online.

[0060] The check valve and the first back-pressure valve immediately following the CO2 stack can separate the products after they have accumulated to a certain extent and prevent the backflow of the products during the accumulation process. In addition, the input gas source of the CO2 stack needs to be constant. The second back-pressure valve after the CO2 regeneration unit can be used to control the pressure of the CO2 gas ejected from the CO2 regeneration unit at a single time, thereby controlling the mixing ratio with the CO2 gas source each time and stabilizing the valve opening, further reducing the cost of each adjustment.

[0061] Embodiment 3:

[0062] Ag nanoparticles are used as catalysts for the cathode reaction, IrO2 nanoparticles are used as catalysts for the anode reaction, and an anion exchange membrane is used as the ion channel for the middle membrane. The CO2 reduction stack consists of 10 single cells, and the voltage applied to the cathode and anode is 30V. In the anode module, the second pump system sets the flow rate of the anode liquid to 100mL / min. The solution flows through the anode chamber in the stack to produce a water-electrolysis oxygen reaction, and then the oxygen and the anode liquid flow out of the stack together. After passing through the second gas-liquid separation unit, the anode liquid flows out from the bottom and circulates back to the anode liquid storage tank through the first pump system. The oxygen is dried from the top through the second drying system and enters the oxygen storage tank for storage. In the cathode module, the gas flow meter sets the flow rate of CO2 to 100 sccm. CO2 enters the cathode chamber to undergo a cathode reduction reaction. At the cathode outlet, when the gas pressure reaches the pressure value of 15 bar set by the first back pressure valve, the reaction products CO and H2 enter the first gas-liquid separation unit (the temperature can be set to 0°C to facilitate gas-liquid separation) along with the unreacted CO2. The liquid mixture is mainly H2O and does not require further separation and can be treated as waste liquid. The gas mixture enters the CO2 absorption tank to absorb the unreacted CO2. After CO2 is regenerated and reaches the pressure value of 5 bar of the second back pressure valve, the CO2 gas source is re-injected. The remaining CO and H2 enter the first drying system to absorb a small amount of water vapor carried. The product enters the gas phase product separation unit. The gas phase separation unit 3 selects the low-temperature distillation method. The separation unit 3 selects the distillation temperature consistent with the boiling point of H2. After H2 is separated, the remaining gas products are mainly CO, which basically meets the product quality requirements and does not need to be separated again.

[0063] Embodiment 4:

[0064] Cu-based materials are used as catalysts for cathode reactions, IrO2 nanoparticles are used as catalysts for anode reactions, anion exchange membranes are used as the middle membranes, and the CO2 reduction stack is composed of 10 single cells, with a voltage of 40 V applied to both ends of the cathode and cathode. In the anode module, the anode liquid is 0.1M KHCO3, and the flow rate of the second pump system is 100mL / min. The solution flows through the anode chamber in the stack to produce oxygen through water electrolysis, and then the oxygen and the anode liquid flow out of the reactor stack together. After passing through the second gas-liquid separation unit, the anode liquid flows out from the bottom and returns to the anode liquid storage tank through the first pump system. The oxygen is dried from the top through the second drying system and enters the oxygen storage tank for storage. In the cathode module, the gas flowmeter sets the CO2 flow rate to 200 sccm. CO2 enters the cathode chamber for a reduction reaction. The products consist of CO, HCOOH, C2H4, CH4, H2, C2H5OH, n-C3H7OH, C2H5CHO, CH3COOH and CH3CHO. Among them, C2H4, C2H5OH and CO have higher selectivity, with Faraday efficiencies of 42%, 13% and 30% respectively. The selectivity of other products is poor, and the Faraday efficiencies are all lower than 5%. After the pressure reaches the set pressure value of 15 bar by the back pressure valve after accumulation, the reaction product enters the first gas-liquid separation unit from the outlet along with the unreacted CO2, and the liquid mixture HCOOH, C2H5OH, n-C3H7OH, C2H5CHO, CH3COOH and CH3CHO enter the liquid product separation unit from below. The separation unit 1 selects a temperature consistent with the boiling point of HCOOH to separate the product composition 1 of HCOOH, C2H5OH, n-C3H7OH, C2H5CHO and CH3CHO. The product composition 1 is further separated, and the distillation temperature of the separation unit 2 is set to 50°C to separate the two substances C2H5CHO and CH3CHO. Subsequently, the distillation temperature is increased to 80°C in the next separation unit to separate the C2H5OH with higher purity. The remaining liquid mixture has a low yield and it is not economical to continue to separate it, so it can be treated as waste liquid. The gas mixture passes through the CO2 absorption tank, and the CO2 is absorbed and then enters the regeneration unit. After the regenerated CO2 reaches the pressure value of 5 bar of the second back pressure valve, it enters the CO2 gas source, and the remaining gas mixture enters the second drying system to absorb moisture in the gas and is transmitted to the gas phase product separation unit. At this time, the gas composition is mainly CO and C2H4. The separation unit 3 selects a distillation temperature consistent with the boiling point of H2 to separate H2. Then the temperature in the separation unit 4 is increased to the same as the boiling point of CO to separate CO. The remaining gas mixture is mainly C2H4. Whether C2H4 needs to be further purified is determined based on the separation economy and product quality requirements.

Claims

1. A CO2 electrocatalytic device, characterized in that: include: An anode module, a reduction stack module and a cathode module connected in sequence; The cathode module includes a check valve, a first back pressure valve and a first gas-liquid separation unit which are connected in sequence at the outlet of the battery stack, the liquid phase outlet end of the first gas-liquid separation unit is connected to the acidification treatment unit and the liquid phase product separation unit in sequence, and the gas outlet end of the first gas-liquid separation unit is connected to the first drying system and the gas phase product separation unit in sequence; the cathode module also includes a gas flow meter and a gas source, and the gas source is connected to the cathode module battery stack inlet through the gas flow meter; when the battery stack gas source is CO2, a CO2 absorption tank is also provided between the gas outlet end of the first gas-liquid separation unit and the first drying system, and the CO2 absorption tank passes through the CO2 regeneration unit and the second back pressure valve in sequence and is connected to the gas source; the number of the liquid phase product separation units is at least two, and the number of the gas phase product separation units is at least two; the number of the liquid phase separation units is 2, 3 or 4, and the number of the gas phase separation units is 2, 3 or 4; Wherein, the anode module includes a second gas-liquid separation unit, a first pump system, an anode liquid storage tank, a second pump system, a second drying system and a product storage tank; the liquid outlet end of the second gas-liquid separation unit is connected to the first pump system, the anode liquid storage tank and the second pump system in sequence; the gas outlet end of the second gas-liquid separation unit is connected to the second drying system and the product storage tank in sequence; the reduction stack module includes a DC power supply and a stack; the stack includes an anode module stack inlet, an anode module stack outlet, a cathode module stack inlet and a cathode module stack outlet; The anode module stack inlet is connected to the second pump system, and the anode module stack outlet is connected to the inlet of the second gas-liquid separation unit.

2. A universal CO2 electrocatalytic method, characterized in that: The CO2 electrocatalytic device according to claim 1 comprises: S1, the anode module introduces anode liquid into the anode chamber of the electric propulsion module, and the cathode module introduces a gas source into the module of the stack module; a first catalyst is added into the anode chamber, and a second catalyst is added into the cathode chamber; and a voltage is applied to both ends of the cathode and cathode of the stack module; S2, a water electrolysis oxygen reaction occurs in the anode chamber, and oxygen and anode liquid flow into the inlet of the second gas-liquid separation unit through the outlet of the anode module stack; the anode liquid flows out from the liquid outlet of the second gas-liquid separation unit, and circulates back to the anode liquid storage tank through the first pump system; oxygen flows out from the gas outlet of the second gas-liquid separation unit, and enters the product storage tank after being dried by the second drying system; S3. A cathode reduction reaction occurs in the cathode chamber, and the reaction products pass through the cathode module stack outlet, the check valve, and the first back pressure valve in sequence to enter the inlet of the first gas-liquid separation unit, and are separated into gas and liquid to obtain liquid products and gas products; the liquid products are processed in turn by the acidification treatment unit and the liquid product separation unit; the gas products are processed in turn by the first drying system and the gas product separation unit.

3. The universal CO2 electrocatalytic method according to claim 2, characterized in that: In S1, the first catalyst includes IrO2 nanoparticles; the second catalyst includes one or more of Ag, Au, Zn, Sn, In or Cu.

4. The universal CO2 electrocatalytic method according to claim 3, characterized in that: When the gas source is CO2 and the second catalyst is Ag, Au and Zn, the reaction products in S3 include CO and unreacted CO2, the liquid phase separation unit after acidification is closed by a valve, and a gas phase separation unit is retained through a valve to separate the product CO; or when the gas source is CO2 and the second catalyst is Sn and In, the reaction products in S3 include HCOOH, H2 and unreacted CO2, a liquid phase separation unit is retained through a valve to separate HCOOH after gas-liquid separation and acidification, and a first drying system is retained through a valve. The gas phase separation unit after the system is used to separate H2; or when the gas source is CO2 and the second catalyst is Cu, the reaction products in S3 include CH4, C2H4, CO, C2H5OH, CH3COOH, n-C3H7OH, HCOOH, CO2 and H2, and 4 liquid phase separation units are retained by valve control to separate C2H5OH, CH3COOH, n-C3H7OH and HCOOH, and 4 gas phase product separation units are retained by valve control to separate CH4, C2H4, CO and H2.

5. The universal CO2 electrocatalytic method according to claim 2, characterized in that: When the gas source is CO2 and the second catalyst is Cu, the reaction products in S3 include CH4, C2H4, CO, C2H5OH, CH3COOH, n-C3H7OH, HCOOH, CO2 and H2. The separation steps in two liquid phase separation units are retained through valve control to separate C2H5OH and HCOOH. The remaining products CH3COOH and n-C3H7OH are not separated further due to their low content and high separation cost. The separation steps in two gas phase product separation units are retained through valve control to separate CH4 and C2H4. The remaining gas by-products CO and H2 are not separated further due to their low content and high separation cost.

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