Process method for efficient conversion and utilization of carbon dioxide through electrocatalytic reduction

Abstract

The invention discloses a process method for efficiently converting and utilizing carbon dioxide through electrocatalytic reduction, which comprises a cathode and anode circulating tank, a cathode and anode liquid inlet pump, a cathode circulating pump, a gas diaphragm pump, a tail gas circulating storage tank and an electric pile. The method comprises the following steps: S1, pre-checking the air tightness of the whole device before driving, respectively injecting electrolyte into a cathode and anode circulating tank through a pump body, and heating until the heating is finished; s2, opening a cathode and anode liquid inlet pump, introducing carbon dioxide, circulating for 5-10min, and wetting the electrode; according to the process method for efficient conversion and utilization of carbon dioxide through electrocatalytic reduction, non-noble metal is adopted as a catalyst metal source in a process catalyst, the catalysis cost is low, the process is simple and repeatable, and the amplification capacity is high; according to the process, efficient carbon dioxide conversion can be achieved, the carbon dioxide conversion rate is 80% or above, meanwhile, the ratio of hydrogen to carbon monoxide is controllable, and the produced synthesis gas can be directly used for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide utilization, and specifically to a process for the efficient conversion and utilization of carbon dioxide through electrocatalytic reduction. Background Art

[0002] With China's rapid economic development and the acceleration of industrialization and urbanization, energy demand continues to grow. Building a stable, economical, clean, and secure energy supply system faces significant challenges. The conflict between increasing energy demand and the environment is particularly prominent. There is an urgent need for an efficient solution to achieve resource recycling while protecting the environment. Electrocatalytic carbon dioxide reduction is a new energy technology that uses green electricity to convert carbon dioxide into chemical feedstocks such as synthesis gas, formic acid, methanol, and ethylene. While addressing carbon emissions, it also enables the storage and transportation of clean energy sources such as wind, solar, tidal, and nuclear power.

[0003] This technical solution realizes the conversion of carbon dioxide into synthesis gas through an electrocatalytic system. The use of non-precious metal catalysts and alkaline catalytic systems greatly reduces the catalytic cost. The development of the circulation system solves the problem of low efficiency of carbon dioxide conversion and utilization. The produced synthesis gas can be directly used in chemical production, which is better than existing industrial production case manufacturers.

[0004] Carbon Energy Technology's CO2 electrocatalytic reduction technology for producing synthesis gas completed the pilot project in November 2020 and successfully passed the on-site assessment. According to its patent (electrocatalytic reduction CO2 device and method, authorization number: CN110344071B), the carbon dioxide after a single conversion needs to be dried in the tail gas and the carbon dioxide in the synthesis gas needs to be separated for recycling. In the process of increasing the conversion and utilization efficiency of carbon resources, this process performs the separation operation of synthesis gas and carbon dioxide, which makes the process more complicated and increases the equipment and separation costs.

[0005] Futan Technology - CO2 electrocatalytic production of formic acid. Futan Technology's "hundred-ton carbon dioxide electrolysis to produce formic acid solution" technology has passed the scientific and technological achievement evaluation of the Petrochemical Federation. According to its patent (a gas preparation and recycling device for carbon dioxide electrolysis to produce formic acid, publication number: CN113897630A), the carbon dioxide electrocatalytic production of formic acid will produce a large amount of hydrogen and carbon monoxide by-products, which will be directly burned to generate carbon dioxide for recycling, greatly reducing the efficiency of electricity conversion.

[0006] In the existing technology, the utilization efficiency of carbon dioxide is low. Industrial production often uses a continuous flow reactor. In order to improve energy utilization efficiency, the flow rate of carbon dioxide is increased, resulting in a low single-pass conversion rate of carbon dioxide of about 5-20%. More than 80% of carbon dioxide is still unconverted. The separation and recycling of carbon dioxide using separation equipment is more complicated and increases equipment and separation costs.

[0007] The competitive reaction at the cathode causes excessive hydrogen production, which reduces the Faraday efficiency of carbon monoxide. After the exhaust gas is recycled, the hydrogen production is uncontrollable, and the synthesis gas needs to be further separated before reuse.

[0008] Catalysts usually use precious metals such as Au, Ag, Pt, Ir, Pd, etc., which have high catalytic costs and high recovery costs. Summary of the Invention

[0009] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0010] 1. Technical problems to be solved:

[0011] The present invention is proposed to solve the above-mentioned problems of high carbon dioxide utilization rate, high hydrogen evolution and high catalytic cost in carbon dioxide electrocatalysis.

[0012] Therefore, the purpose of the present invention is to provide a process for the efficient conversion and utilization of carbon dioxide by electrocatalytic reduction, and the synthesis gas produced can directly meet the raw material demand of aviation fuel production. The process consists of an electrocatalytic reduction system and a gas circulation system. The electrocatalytic system consists of anodes and cathodes. The anode uses MOH (M is an alkali metal) as the electrolyte, and the oxidation reaction OH occurs. - Losing electrons produces oxygen, and the cathode uses water as the electrolyte. Water and carbon dioxide undergo a reduction reaction at the cathode to produce a certain proportion of hydrogen and carbon monoxide, and at the same time produce MHCO3 as a by-product. The gas CO / CO2 / H2 mixture at the cathode outlet is separated by gas-liquid, and the compressed gas enters the storage tank and re-enters the fuel cell stack. At the same time, fresh carbon dioxide is supplemented in a certain proportion, which can achieve continuous production of qualified synthesis gas (hydrogen / carbon monoxide = 2:1-3:1, CO2% ≤ 20%). This process method not only realizes the negative carbon conversion of carbon dioxide into synthesis gas directly for aviation fuel production, but also solves the disadvantage of low carbon dioxide conversion efficiency.

[0013] 2. Technical solution:

[0014] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0015] A process for the efficient conversion and utilization of carbon dioxide by electrocatalytic reduction, comprising anode and cathode circulation tanks, cathode and cathode liquid feed pumps, cathode circulation pumps, gas diaphragm pumps, tail gas circulation storage tanks, and a stack, specifically comprising the following steps:

[0016] S1: Before starting, it is necessary to pre-check the air tightness of the entire device, and inject the electrolyte into the cathode and anode circulation tanks respectively through the pump body, and heat them until the heating is completed;

[0017] S2: Turn on the anode and cathode liquid pumps and introduce carbon dioxide, circulate for 5 to 10 minutes to wet the electrodes, and then energize the stack to start the carbon dioxide to synthesis gas reaction;

[0018] S3: The tail gas after the cathode gas-liquid separation is pressurized and stored, and then enters the fuel cell stack again through the gas diaphragm pump. At the same time, fresh carbon dioxide is added, and the continuous output of qualified synthesis gas is achieved by adjusting the process.

[0019] As a preferred embodiment of the process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the air tightness test method is to introduce an inert gas into the gas path and close the system outlet valve to test the air tightness of the device. The inert gas is nitrogen, and a gas detector is selected to test the air tightness of the device.

[0020] As a preferred embodiment of the process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the electrolyte comprises a cathode electrolyte and an anode electrolyte, the cathode electrolyte is a metal salt, and the anode electrolyte is a metal salt.

[0021] As a preferred embodiment of the process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the power supply for the stack is a DC power supply, and the stack is powered by a constant voltage.

[0022] As a preferred embodiment of the process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the electrode is a catalytic electrode, and the catalytic electrode uses a non-precious metal as an active metal source of the catalyst.

[0023] As a preferred embodiment of the process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the heating temperature of the anode and cathode circulation tanks is 30-60°C, and the range of the cathode pH meter is 7-14.

[0024] As a preferred embodiment of the process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the cathode circulation pump input liquid flow rate is 0.1 to 10 L / min, the cathode circulation pump input liquid flow rate is 0.1 to 10 L / min, and the cathode gas flow rate is 1 to 20 L / min.

[0025] As a preferred embodiment of the process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the pressure of the tail gas circulation storage tank is 0-1 MPa, and the ratio of the circulating gas to the supplementary fresh carbon dioxide is controlled to be 0-10:1.

[0026] As a preferred embodiment of the process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention, the ratio of hydrogen to carbon monoxide in the qualified synthesis gas is controlled at 2:1 to 3:1, and the proportion of carbon dioxide is controlled below 20%.

[0027] 3.Beneficial effects:

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This process method for the efficient conversion and utilization of carbon dioxide through electrocatalytic reduction uses a unique fuel cell system, efficient non-metallic catalytic electrodes and an efficient catalytic cycle process to achieve continuous production of qualified synthesis gas. This process method not only achieves the negative carbon conversion of carbon dioxide into synthesis gas for direct use in aviation fuel production, but also solves the shortcoming of low carbon dioxide conversion efficiency.

[0030] This process method for the efficient conversion and utilization of carbon dioxide by electrocatalytic reduction is invented by developing non-precious metals with high catalytic performance, which reduces the catalyst cost. At the same time, an efficient catalytic stack system is independently developed. The process can achieve a controllable ratio of hydrogen to carbon monoxide and recycling of tail gas, which can achieve a carbon dioxide conversion rate of more than 80% in the synthesis gas product with a controllable ratio of hydrogen to carbon monoxide without affecting the catalytic efficiency, and ultimately achieve continuous production of qualified synthesis gas for direct use in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort. Among them:

[0032] Figure 1This is a data graph showing the time for preparing synthesis gas by electrocatalytic reduction of carbon dioxide with a circulation ratio of 6:1 and the change in composition of the product in a process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention;

[0033] Figure 2 This is a data graph showing the time for preparing synthesis gas by electrocatalytic reduction of carbon dioxide with a circulation ratio of 12:1 and the change in composition of the product in a process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction of the present invention;

[0034] Figure 3 The present invention provides a process flow chart for preparing synthesis gas by electrocatalytic reduction of carbon dioxide in a process method for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] The present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views illustrating device structures may be partially enlarged and not to scale when describing embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0037] The orientation or positional relationship indicated in the terms is based on the orientation or positional relationship shown in the drawings and is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0038] The term "connection" should be understood broadly. For example, "connection" can mean fixed, detachable, or integral; mechanical or electrical; direct or indirect through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0039] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0040] The present invention provides a schematic diagram of the overall structure of an embodiment of a process method for the electrocatalytic reduction and efficient conversion and utilization of carbon dioxide, comprising:

[0041] See also Figure 1-Figure 3, a process method for efficient conversion and utilization of carbon dioxide electrocatalytic reduction in this embodiment includes anode and cathode circulation tanks, cathode and cathode liquid feed pumps, cathode circulation pumps, gas diaphragm pumps, tail gas circulation storage tanks and a stack, specifically the following steps;

[0042] S1: Before starting, the air tightness of the entire device needs to be pre-checked. After the air tightness is good, the electrolyte is injected into the anode and cathode circulation tanks respectively through the pump body and heated until the heating is completed;

[0043] S2: Turn on the anode and cathode liquid pumps and introduce carbon dioxide, circulate for 5 minutes to wet the electrodes, and then energize the stack to start the carbon dioxide to synthesis gas reaction;

[0044] S3: The tail gas after the cathode gas-liquid separation is pressurized and stored, and then enters the fuel cell stack again through the gas diaphragm pump. At the same time, fresh carbon dioxide is added, and the continuous output of qualified synthesis gas is achieved by adjusting the process.

[0045] It is worth mentioning that in order to ensure the effectiveness of the air tightness test method, specifically, the air tightness test method is to introduce inert gas into the gas circuit, close the system outlet valve to test the air tightness of the device, the inert gas can be selected from nitrogen, argon, etc., and the air tightness of the device can be tested by using gas detectors, soapy water, and pressure changes of the device to determine whether the device is airtight.

[0046] Next, in order to increase the selection range of electrolytes, specifically, the electrolyte includes a cathode electrolyte and an anode electrolyte. The cathode electrolyte can use water, metal carbonates, metal bicarbonates, metal hydroxides, halogen metal salts, etc. as the electrolyte, and the anode electrolyte can use water, metal carbonates, metal bicarbonates, metal hydroxides, etc. as the electrolyte.

[0047] At the same time, in order to increase the connection methods of the battery stack, specifically, the battery stack is a single battery stack, a multi-layer series battery stack, a multi-layer parallel battery stack, multiple battery stacks in series and multiple battery stacks in parallel, the power supply for the battery stack is a DC power supply, and the power supply method can be constant voltage or constant current electrolysis.

[0048] Furthermore, in order to increase the selection range of the catalytic electrode, specifically, the electrode is a catalytic electrode, and the catalytic electrode uses non-precious metals such as zinc, nickel, and copper as the active metal source of the catalyst.

[0049] It is worth noting that in order to ensure the selection of the optimal temperature and range, specifically, the heating temperature of the anode and cathode circulation tanks can be 30-60°C, and the range of the cathode pH meter can be 7-14.

[0050] Subsequently, in order to ensure the flow rate and gas flow rate, specifically, the cathode circulation pump input liquid flow rate can be 0.1~10L / min, the cathode circulation pump input liquid flow rate can be 0.1~10L / min, and the cathode gas flow rate can be 1~20L / min.

[0051] Next, in order to ensure the pressure and ratio, specifically, the pressure of the tail gas recycling tank is 0-1MPa, and the ratio of the circulating gas to the supplementary fresh carbon dioxide can be controlled to be 0-10:1.

[0052] It is worth noting that, in order to facilitate better selection of ratio control, specifically, the ratio of hydrogen to carbon monoxide in the qualified synthesis gas is controlled at 2:1 to 3:1, and the ratio of carbon dioxide is controlled below 20%.

[0053] Example 1:

[0054] A process for the efficient conversion and utilization of carbon dioxide by electrocatalytic reduction, comprising anode and cathode circulation tanks, cathode and cathode liquid feed pumps, cathode circulation pumps, gas diaphragm pumps, tail gas circulation storage tanks, and a stack, specifically comprising the following steps:

[0055] S1: Before starting, the air tightness of the entire device needs to be pre-checked. After the air tightness is good, the electrolyte is injected into the anode and cathode circulation tanks respectively through the pump body and heated until the heating is completed;

[0056] S2: Turn on the anode and cathode liquid pumps and introduce carbon dioxide, circulate for 5 minutes to wet the electrodes, and then energize the stack to start the carbon dioxide to synthesis gas reaction;

[0057] S3: The tail gas after the cathode gas-liquid separation is pressurized and stored, and then enters the fuel cell stack again through the gas diaphragm pump. At the same time, fresh carbon dioxide is added, and the continuous output of qualified synthesis gas is achieved by adjusting the process.

[0058] It is worth mentioning that in order to ensure the effectiveness of the air tightness test method, specifically, the air tightness test method is to introduce inert gas into the gas circuit, close the system outlet valve to test the air tightness of the device, the inert gas can be selected from nitrogen, argon, etc., and the air tightness of the device can be tested by using gas detectors, soapy water, and pressure changes of the device to determine whether the device is airtight.

[0059] Next, in order to increase the selection range of electrolytes, specifically, the electrolyte includes a cathode electrolyte and an anode electrolyte. The cathode electrolyte can use water, metal carbonates, metal bicarbonates, metal hydroxides, halogen metal salts, etc. as the electrolyte, and the anode electrolyte can use water, metal carbonates, metal bicarbonates, metal hydroxides, etc. as the electrolyte.

[0060] At the same time, in order to increase the connection methods of the battery stack, specifically, the battery stack is a single battery stack, a multi-layer series battery stack, a multi-layer parallel battery stack, multiple battery stacks in series and multiple battery stacks in parallel, the power supply for the battery stack is a DC power supply, and the power supply method can be constant voltage or constant current electrolysis.

[0061] Furthermore, in order to increase the selection range of the catalytic electrode, specifically, the electrode is a catalytic electrode, and the catalytic electrode uses non-precious metals such as zinc, nickel, and copper as the active metal source of the catalyst.

[0062] It is worth noting that in order to ensure the selection of the optimal temperature and range, specifically, the heating temperature of the anode and cathode circulation tanks can be 50°C, and the range of the cathode pH meter can be 10.

[0063] Subsequently, in order to ensure the flow rate and gas flow rate, specifically, the cathode circulation pump input liquid flow rate can be 6 L / min, the cathode circulation pump input liquid flow rate can be 6 L / min, and the cathode gas flow rate can be 12 L / min.

[0064] Next, in order to ensure the pressure and ratio, specifically, the pressure of the tail gas recycling tank is 0.5MPa, and the ratio of the circulating gas to the supplementary fresh carbon dioxide can be controlled to be 0 to 10:1.

[0065] It is worth noting that, in order to facilitate better selection of ratio control, specifically, the ratio of hydrogen to carbon monoxide in the qualified synthesis gas is controlled at 2:1 to 3:1, and the ratio of carbon dioxide is controlled at 18%.

[0066] Example 2:

[0067] The air tightness test method is to introduce inert gas into the gas line and close the system outlet valve to test the air tightness of the device: the preferred inert gas can be nitrogen, argon, etc. The preferred test method for the air tightness of the device can be to use a gas detector, soapy water, and the pressure change of the device to confirm that the device is airtight.

[0068] Anode electrolyte: The preferred cathode electrolyte is water, metal carbonate, metal bicarbonate, metal hydroxide, halogen metal salt, etc., and the preferred anode electrolyte is water, metal carbonate, metal bicarbonate, metal hydroxide, etc.

[0069] There are multiple connection methods and power-on methods for the fuel cell stack: the preferred fuel cell stack is a single fuel cell stack, a multi-layer series fuel cell stack, a multi-layer parallel fuel cell stack, multiple fuel cell stacks in series, and multiple fuel cell stacks in parallel. The preferred power supply for the fuel cell stack is a DC power supply, and the preferred power-on method can be constant voltage or constant current electrolysis.

[0070] Non-metallic catalysts: Non-precious metals such as zinc, nickel, and copper are preferably used as active metal sources of the catalyst.

[0071] The heating temperature of the anode and cathode circulation tanks can be 30-60°C, and the range of the cathode pH meter can be 7-14.

[0072] The liquid flow rate of the cathode circulation pump is preferably 0.1 to 10 L / min.

[0073] The cathode gas flow rate is preferably 1 to 20 L / min.

[0074] The pressure of the tail gas circulation storage tank is preferably 0 to 1 MPa.

[0075] The ratio of circulating gas to fresh carbon dioxide is controlled, preferably 0 to 10:1.

[0076] The composition of qualified synthesis gas preferably has a ratio of hydrogen to carbon monoxide of 2:1 to 3:1, and the ratio of carbon dioxide is preferably controlled below 20%.

[0077] Example 3:

[0078] 500cm 2 The first step in testing a single-layer fuel cell stack (without circulation) is to inspect the airtightness of the device. Nitrogen is introduced into the entire device through a gas mass flow meter for airtightness testing. The pressure sensor is used to ensure that the device is airtight before proceeding to the next step.

[0079] In the second step, the device introduces electrolyte, inputs water into the cathode electrolyte circulation tank through the cathode pump body, and transports sodium hydroxide from the anode replenishment tank to the anode electrolyte circulation tank through the anode pump body, and passes through the heating device of the anode and cathode circulation tanks to make the electrolyte reach 30°C.

[0080] The third step is to start the electrolysis of the battery stack, open the solenoid valve, adjust the gas mass flow meter to 4-7L / min, and at the same time turn on the anode and cathode liquid circulation pumps, adjust the flow rates to 0.1-0.5L / min and 0.1-0.5L / min respectively, and wetting for more than 5 minutes. Start the DC power supply to power the battery stack, and use constant current electrolysis. The current is controlled at about 50A, the voltage is controlled at about 3V, and the gas circulation is not turned on.

[0081] The fourth step is to replenish the cathode and anode fluids. The pH value of the electrolyte in the cathode circulation tank is detected by a pH meter (controlled at 7-12), and the cathode pump is used to replenish the fluid to maintain a stable pH value. The anode fluid is replenished by the anode pump according to the current or voltage to maintain a stable current or voltage, thereby achieving stable operation of the system. The test results show that in the non-circulation test, the composition of the exhaust gas is about 5% hydrogen, about 6% carbon monoxide, and about 89% carbon dioxide.

[0082] Example 4:

[0083] 500cm 2 The first step in testing the single-layer fuel cell stack (adding cycle) is to check the airtightness of the device. Nitrogen is introduced into the entire device through a gas mass flow meter for airtightness testing. The pressure sensor is used to ensure that the airtightness of the device is good before proceeding to the next step.

[0084] In the second step, the device introduces electrolyte, inputs water into the cathode electrolyte circulation tank through the cathode pump body, and transports sodium hydroxide from the anode replenishment tank to the anode electrolyte circulation tank through the anode pump body, and passes through the heating device of the anode and cathode circulation tanks to make the electrolyte reach 30°C.

[0085] The third step is to start the electrolysis of the battery stack, open the solenoid valve, adjust the gas mass flow meter to 4-7L / min, and at the same time turn on the anode and cathode liquid circulation pumps, adjust the flow rates to 0.1-0.5L / min and 0.1-0.5L / min respectively, and wetting for more than 5 minutes. Start the DC power supply to power the battery stack, and use constant current electrolysis. The current is controlled at about 50A and the voltage is controlled at about 3V.

[0086] The fourth step is gas circulation. After the tail gas of electrolysis is separated by the gas-liquid separation tank, the gas is compressed into the gas compression tank through the gas compression pump, and the pressure of the compression tank is controlled at 0-1MPa. Then it is circulated into the fuel cell stack through the gas diaphragm pump P-6 through the solenoid valve and the gas mass flow meter, and the ratio of the circulating gas to the fresh carbon dioxide is controlled, preferably 6:1, until the synthesis gas is stably produced at the tail end of the mass flow meter.

[0087] The fifth step is to replenish the anode and cathode fluids. The pH meter is used to detect the pH value of the electrolyte in the cathode circulation tank (controlled at 7-12). The cathode pump is used to replenish the fluid to maintain a stable pH value. The anode fluid is replenished according to the current or voltage. The anode pump is used to replenish the fluid to maintain a stable current or voltage, thereby achieving stable operation of the system. The test results show that in the circulation test, the exhaust gas composition is about 57.8% hydrogen, about 28.6% carbon monoxide (H2:CO=2.0:1), and about 13.6% carbon dioxide. Figure 1 As shown, the trend of synthesis gas production over time.

[0088] Embodiment 5:

[0089] 500cm 2 The first step in testing the single-layer fuel cell stack (adding cycle) is to check the airtightness of the device. Nitrogen is introduced into the entire device through a gas mass flow meter for airtightness testing. The pressure sensor is used to ensure that the airtightness of the device is good before proceeding to the next step.

[0090] In the second step, the device introduces electrolyte, inputs water into the cathode electrolyte circulation tank through the cathode pump body, and transports sodium hydroxide from the anode replenishment tank to the anode electrolyte circulation tank through the anode pump body, and passes through the heating device of the anode and cathode circulation tanks to make the electrolyte reach 30°C.

[0091] The third step is to start the electrolysis of the battery stack, open the solenoid valve, adjust the gas mass flowmeter MF-1 to 4-7L / min, and at the same time turn on the anode and cathode liquid circulation pumps, adjust the flow rates to 0.1-0.5L / min and 0.1-0.5L / min respectively, and wetting for more than 5 minutes. Start the DC power supply to power the battery stack, and use constant current electrolysis. The current is controlled at about 50A and the voltage is controlled at about 3V.

[0092] The fourth step is gas circulation. After the tail gas of electrolysis is separated by the gas-liquid separation tank, the gas is compressed into the gas compression tank through the gas compression pump, and the pressure of the compression tank is controlled at 0-1MPa. Then it is circulated into the fuel cell stack through the gas diaphragm pump P-6 through the solenoid valve and the gas mass flow meter, and the ratio of the circulating gas to the fresh carbon dioxide is controlled, preferably at 12:1, until the synthesis gas is stably produced at the tail end of the mass flow meter.

[0093] The fifth step is to replenish the cathode and anode fluids. The pH value of the electrolyte in the cathode circulation tank is detected by a pH meter (controlled at 7-12), and the cathode pump body is used to replenish the fluid to maintain a stable pH value. The anode fluid is replenished according to the current or voltage, and the anode pump body is used to replenish the fluid to maintain a stable current or voltage, thereby achieving stable operation of the system. The test results show that in the circulation test, the composition of the exhaust gas is about 59.4% hydrogen, about 23.3% carbon monoxide (H2:CO=2.6:1), and about 17.3% carbon dioxide. Figure 2 As shown, the trend of synthesis gas production over time.

[0094] in, Figure 3PP-1 is the cathode outlet pressure sensor of the stack; PP-2 is the cathode liquid inlet pressure sensor of the stack; PP-3 is the cathode inlet gas pressure sensor of the stack; PP-4 is the anode outlet pressure sensor of the stack; PP-5 is the anode liquid inlet pressure sensor of the stack; P-1 is the cathode stack water supply pump; P-2 is the cathode liquid stack inlet pump; P-3 is the anode liquid stack inlet pump; P-4 is the anode stack alkali supply pump; P-5 is the gas compression pump; P-6 is the gas diaphragm pump; V-1, V-2, V-3 , V-4, V-5, and V-6 are solenoid valves; T-1 is the cathode circulation tank; T-2 is the cathode gas-liquid separation tank; T-3 is the anode circulation tank; T-4 is the anode liquid replenishment tank; T-5 is the gas compression tank; MF-1, MF-2, and MF-3 are gas mass flow meters; SV-1 and SV-2 are gas solenoid valves; UV gas one-way valve; CG is a gas cylinder; CS is a catalytic cell stack; E is a DC power supply; H-1 and H-2 are heating sensors; pH is a pH sensor; Pipe-1 is the anode gas outlet pipe.

[0095] In addition, the circuits, electronic components and modules involved in the present invention are all existing technologies and can be fully implemented by those skilled in the art. Needless to say, the content protected by the present invention does not involve improvements to internal structures and methods.

[0096] Combine Figure 1-Figure 3 The present embodiment provides a process for the efficient conversion and utilization of carbon dioxide by electrocatalytic reduction, and the specific use process is as follows:

[0097] 1. Check the air tightness of the device. Use the gas mass flow meter MF-1 or MF-2 to pass nitrogen or argon into the entire device for air tightness testing. Use the pressure sensor PP-1 (or PP-2, PP-3, PP-4, PP-5) (or gas detector and soapy water) to ensure that the device is airtight before proceeding to the next step.

[0098] 2. Subsequently, the device is fed with electrolyte, and water (or electrolytes such as metal carbonate, metal bicarbonate, metal hydroxide, or halogen metal salt) is input into the cathode electrolyte circulation tank T-1 through the cathode pump body P-1, and water (or electrolytes such as metal carbonate, metal bicarbonate, or metal hydroxide) is input from the anode replenishment tank T-4 into the anode electrolyte circulation tank T-3 through the anode pump body P-4. The electrolyte is heated to 30-60°C by the heating devices H-1 and H-2 of the anode and cathode circulation tanks;

[0099] 3. Secondly, start the stack electrolysis, open the solenoid valve SV-1, adjust the gas mass flowmeter MF-1 to 1-20 L / min, and at the same time, turn on the anode and cathode liquid circulation pumps P-2 and P-3, adjust the flow rates to 0.1-10 L / min and 0.1-10 L / min respectively. Wetting for more than 5 minutes, start the DC power supply E to power the stack CS. The power supply mode can be constant voltage or constant current electrolysis, with the current controlled at 1-300 A and the voltage controlled at 1-40 V.

[0100] 4. Subsequently, the gas circulates. The tail gas of electrolysis is separated by the gas-liquid separation tank T-2, and then compressed into the T-5 gas compression tank by the gas compression pump P-5. The pressure of the compression tank is controlled at 0-1 MPa. Then, the gas is circulated into the fuel cell stack through the gas diaphragm pump P-6 through the solenoid valve SV-2 and the gas mass flowmeter MF-2. The ratio of the circulating gas to the fresh carbon dioxide is controlled, preferably 0-10:1, until the tail end of the mass flowmeter MF-3 stably produces synthesis gas, in which the ratio of hydrogen to carbon monoxide is 2:1-3:1, and the proportion of carbon dioxide is controlled below 20%.

[0101] 5. Finally, the anode and cathode are replenished. The pH value of the electrolyte in the cathode circulation tank is detected by the pH meter (controlled at 7-14), and the cathode pump P-1 is used to replenish the electrolyte to maintain a stable pH. The anode is replenished according to the current or voltage through the anode pump P-4 to maintain a stable current or voltage, thereby achieving stable operation of the system.

[0102] Although the present invention has been described above with reference to embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, as long as there are no structural conflicts, the various features of the embodiments disclosed herein may be combined with each other in any manner, and the omission of an exhaustive description of such combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A process for the efficient conversion and utilization of carbon dioxide by electrocatalytic reduction, characterized in that: It includes anode and cathode circulation tanks, cathode and cathode liquid inlet pumps, cathode circulation pumps, gas diaphragm pumps, tail gas circulation storage tanks and a stack, specifically the following steps: S1: Before starting, it is necessary to pre-check the air tightness of the entire device, and inject the electrolyte into the cathode and anode circulation tanks respectively through the pump body, and heat them until the heating is completed; S2: Turn on the anode and cathode liquid pumps and introduce carbon dioxide, circulate for 5 to 10 minutes to wet the electrodes, and then energize the stack to start the carbon dioxide to synthesis gas reaction; S3: The tail gas after the cathode gas-liquid separation is pressurized and stored, and then enters the fuel cell stack again through the gas diaphragm pump. At the same time, fresh carbon dioxide is added, and the continuous output of qualified synthesis gas is achieved by adjusting the process.

2. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 1, characterized in that: The air tightness test method is to introduce inert gas into the gas line, close the system outlet valve to test the air tightness of the device, the inert gas is nitrogen, and a gas detector is selected to test the air tightness of the device.

3. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 2, characterized in that: The electrolyte includes a cathode electrolyte and an anode electrolyte. The cathode electrolyte is selected from metal salts, and the anode electrolyte is selected from metal salts.

4. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 3, characterized in that: The power supply for the battery stack is a direct current power supply, and the power supply mode of the battery stack is a constant voltage.

5. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 4, characterized in that: The electrode is a catalytic electrode, and the catalytic electrode uses a non-noble metal as an active metal source of the catalyst.

6. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 5, characterized in that: The heating temperature of the anode and cathode circulation tanks is 30-60° C., and the measuring range of the cathode pH meter is 7-14.

7. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 6, characterized in that: The cathode circulation pump input liquid flow rate is 0.1 to 10 L / min, the cathode circulation pump input liquid flow rate is 0.1 to 10 L / min, and the cathode gas flow rate is 1 to 20 L / min.

8. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 7, characterized in that: The pressure of the tail gas circulation storage tank is 0-1 MPa, and the ratio of the circulating gas to the supplemented fresh carbon dioxide is controlled to be 0-10:

1.

9. The process for efficient conversion and utilization of carbon dioxide by electrocatalytic reduction according to claim 8, characterized in that: The ratio of hydrogen to carbon monoxide in the qualified synthesis gas is controlled at 2:1 to 3:1, and the ratio of carbon dioxide is controlled below 20%.

Images