Device and method for producing hydrogen by bipolar electrolysis of acid-base imbalance-coupled furfural oxidation

Abstract

The present invention relates to the technical field of hydrogen production, and aims to provide a device and method for producing hydrogen by bipolar electrolysis of furfural oxidation coupled with acid-base imbalance. The device comprises an electrolytic cell, an anode alkaline electrolyte circulation system, a cathode acidic electrolyte circulation system, a hydrogen washing and drying system, and a monitoring and control system; the electrolytic cell has a closed cavity, and the anode and the cathode are respectively arranged in two reaction chambers; the anode electrolyte is an alkaline mixed solution prepared with furfural and alkali solution; the cathode electrolyte is an acidic solution. The present invention can realize the simultaneous hydrogen evolution at the cathode and the anode during the electrolysis process accompanied by the generation of furfural acid, thereby reducing the energy consumption of hydrogen production and achieving high value of the product. The equipment avoids the use of high-energy-consuming auxiliary devices and reduces the overall energy consumption of the equipment. By replacing the oxygen evolution reaction with the furfural oxidation reaction, the electrolysis starting potential is greatly reduced, thereby achieving a huge optimization of energy consumption compared with the traditional water electrolysis hydrogen production technology; increasing the efficiency of electric energy utilization and improving the safety of the reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production, and in particular relates to a device and a method for producing hydrogen by bipolar electrolysis through acid-base imbalance coupling furfural oxidation. Background Art

[0002] Hydrogen (H 2 ) has the characteristics of high calorific value (143kJ / g) and zero carbon emission of combustion products, and is regarded as an ideal green and clean energy. Compared with the carbon emission problem in the process of hydrogen production by reforming fossil fuels, water electrolysis technology can achieve the preparation of zero-emission "green hydrogen", so it has greater advantages in the fields of sustainability and environmental protection and has received widespread attention in recent years.

[0003] The water electrolysis process includes two half reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Among them, the cathode HER is a relatively simple two-electron transfer process that can occur at a lower potential. However, the anode OER process requires a four-electron transfer process, and its kinetic reaction is slow; this greatly reduces the energy efficiency of hydrogen production, and the added value of the anode product oxygen is not high.

[0004] In order to solve the energy efficiency problem caused by the oxygen evolution reaction, the current commercial hydrogen production electrolysis equipment chooses to react at a higher temperature by setting a heat exchanger, but this greatly increases the overall energy consumption of the equipment. In addition, the high energy consumption of water electrolysis to produce hydrogen has further restricted the development of technology. Although the theoretical electrolysis voltage is only 1.23V, the operating voltage of commercial electrolyzers is greater than 1.8V, which makes the actual power consumption reach 4.5~5kWh / Nm 3 , and electricity costs account for about 50-80% of the entire water electrolysis hydrogen production cost. In addition, traditional hydrogen production equipment has the risk of product contamination and requires additional high-energy consumption purification equipment.

[0005] Therefore, how to further optimize the process of hydrogen production by electrolysis and reduce the overall energy consumption of hydrogen production equipment is an urgent problem to be solved. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a device and method for producing hydrogen by bipolar electrolysis of acid-base unbalanced coupled furfural oxidation.

[0007] To solve the technical problem, the solution of the present invention is:

[0008] Provided is a device for producing hydrogen by bipolar electrolysis of furfural oxidation by coupling acid-base imbalance, the device comprising: an electrolytic cell, an anode alkaline electrolyte circulation system, a cathode acidic electrolyte circulation system, a hydrogen washing and drying system, and a monitoring and control system; wherein:

[0009] The electrolytic cell has a closed cavity and is divided into an anode reaction chamber and a cathode reaction chamber by a bipolar membrane, and the anode and the cathode are respectively arranged in the two reaction chambers; the anode alkaline electrolyte circulation system comprises an anode electrolyte storage tank, an alkaline solution circulation pump, an anode reaction chamber of the electrolytic cell, and an anode gas-liquid separator, which are sequentially connected by pipelines to form a circulation loop, and the electrolyte is an alkaline mixed solution prepared by furfural and alkaline solution; the cathode acidic electrolyte circulation system comprises a cathode electrolyte storage tank, an acid solution circulation pump, a cathode reaction chamber of the electrolytic cell, and a cathode gas-liquid separator, which are sequentially connected by pipelines to form a circulation loop, and the electrolyte is an acidic solution;

[0010] In the hydrogen scrubbing and drying system, the outlets of the anode reaction chamber and the cathode reaction chamber of the electrolyzer are connected to the anode gas-liquid separator and the cathode gas-liquid separator respectively through pipelines; the bottoms of the two gas-liquid separators are connected to the anode electrolyte storage tank and the cathode electrolyte storage tank respectively through pipelines, and the tops of the two gas-liquid separators are connected to the inside of the anode hydrogen scrubber and the cathode hydrogen scrubber respectively through pipelines and extend below the liquid level of the absorbent; the top outlets of the two hydrogen scrubbers are connected to the hydrogen dryer through pipelines, and the latter is connected to the hydrogen gas cylinder through pipelines;

[0011] The monitoring and control system includes a control terminal, a power cabinet, and multiple control valves and multiple online monitoring devices arranged on the pipelines between the devices; the control terminal is connected to the power cabinet through a signal line, and the power cabinet is connected to each control valve, online monitoring device and circulation pump through a signal line or cable.

[0012] As a preferred solution of the present invention, the online monitoring equipment includes a flow meter, a pressure sensor, a temperature sensor and a liquid level sensor.

[0013] As a preferred embodiment of the present invention, an alkali liquid cooler is provided on the pipeline between the alkali liquid circulation pump and the anode reaction chamber of the electrolytic cell, and an acid liquid cooler is provided on the pipeline between the acid liquid circulation pump and the cathode reaction chamber of the electrolytic cell; the two coolers have a heat exchanger structure, and a circulation loop is formed on the heat exchange medium side through the pipeline with the cooling water storage tank and the cooling water circulation pump, and the heat exchange medium is cooling water.

[0014] As a preferred embodiment of the present invention, the device also includes a nitrogen purge system, including a plurality of valves and a flow meter connected to a nitrogen cylinder and a pipeline; the nitrogen purge system is respectively connected to the anode gas-liquid separator and the cathode gas-liquid separator through pipelines, and the nitrogen used for purge flows through two gas-liquid separators and two hydrogen scrubbers respectively, and is discharged from the outlet of the hydrogen dryer.

[0015] As a preferred embodiment of the present invention, the electrolytic cell is a series-connected monopolar plate structure, which is composed of a plurality of electrodes or plates arranged in series and tightly fitted to form mutually isolated anode reaction chambers and cathode reaction chambers; its structure specifically includes: a circular plate-shaped anode electrode, a circular ring-shaped seal, a circular sieve-shaped anode plate, a circular ring-shaped seal, a circular plate-shaped anode electrode, a circular sieve-shaped anode guide plate, a circular plate-shaped bipolar membrane, a circular sieve-shaped cathode guide plate, a circular plate-shaped cathode electrode, a circular ring-shaped seal, a circular sieve-shaped cathode plate, a circular ring-shaped seal, and a circular plate-shaped cathode electrode; fastening and mounting components are provided at the outermost ends and circumferential periphery of the anode reaction chamber and the cathode reaction chamber;

[0016] In the vertical direction of the anode plate and the cathode plate, radial electrolyte inlet and outlet are respectively arranged on the opposite sides thereof, and axial through holes connected thereto are respectively arranged on the adjacent side surfaces, which are used as electrolyte channels when the plates are stacked on each other; the electrolyte is introduced into the reaction chamber from the inlet at the lower end, and its flow direction is opposite to the direction of gravity, and finally is led out from the outlet at the upper end.

[0017] As a preferred embodiment of the present invention, the fastening and mounting components include circular end plates arranged on both sides, and the two end plates are connected by at least two axial frames; the series-connected monopolar plate structure is seated on a bracket with an arc-shaped opening, and is limited by the end plates and the frames; a plurality of circumferentially arranged bosses are provided on the inner side of one of the end plates, and a plurality of circumferentially arranged hydraulic devices are provided on the inner side of the other end plate, for realizing fixed installation and pressure adjustment of the series-connected monopolar plate structure.

[0018] As a preferred embodiment of the present invention, a check valve, a control valve, a temperature sensor, a flow meter and a pressure sensor are provided on the outlet pipelines of the alkali solution circulation pump and the acid solution circulation pump; a pressure gauge is provided on the pipeline between the gas-liquid separator and the hydrogen scrubber; and a check valve, a pressure gauge and a back pressure valve are provided on the pipeline between the hydrogen dryer and the hydrogen cylinder.

[0019] As a preferred solution of the present invention, liquid level sensors are provided in the anode electrolyte storage tank and the cathode electrolyte storage tank.

[0020] The present invention further provides a method for realizing acid-base imbalance coupled furfural oxidation bipolar electrolysis hydrogen production using the above-mentioned device, comprising the following steps:

[0021] (1) adding an acidic solution to a cathode electrolyte storage tank; adding an alkaline mixed solution of furfural and alkali solution to an anode electrolyte storage tank; adding boric acid / borate buffer or phosphoric acid / phosphate buffer to a cathode hydrogen scrubber and an anode hydrogen scrubber, respectively, to absorb the acid or alkali solution carried by hydrogen; adding cooling water to a cooling water storage tank;

[0022] (2) purging the cathode gas and anode gas product pipelines with nitrogen;

[0023] (3) The power cabinet supplies power to each device, and the circulation pump and corresponding valves are started through the control terminal; when the electrolysis reaction is in progress, the electrolyte flow, cooling water flow and electrolytic cell current are regulated according to the pressure sensor and temperature sensor on the circulation pipeline; the temperature of the cathode electrolyte and the anode electrolyte entering the electrolytic cell is controlled at 20-40°C, and the pressure is controlled at 0.1-0.3Mpa;

[0024] (4) Use a check valve, a pressure gauge and a back pressure valve to adjust the output pressure of hydrogen, and store the dried hydrogen in a hydrogen cylinder;

[0025] (5) During the hydrogen production process, the electrolyte is appropriately replenished according to the drop in the electrolyte level in the storage tank;

[0026] (6) When stopping hydrogen production, first stop the power supply to the electrolyzer to maintain the circulation of the electrolyte; after the hydrogen output pressure drops to zero, close the circulation pump and related valves; finally, purge the gas product pipeline with nitrogen.

[0027] As a preferred embodiment of the present invention, the acidic solution is sulfuric acid or hydrochloric acid solution, H + The molar concentration range is 1 to 2M; the alkali solution is KOH or NaOH solution, OH - The molar concentration of furfural is 1-2M; in the alkaline mixed solution, the molar concentration of furfural is 0.1-0.6M; the pH value of the absorption liquid in the anode hydrogen scrubber is 5-6, and the pH value of the absorption liquid in the cathode hydrogen scrubber is 8-9.

[0028] Description of the invention principle:

[0029] 1. The present invention innovatively proposes to use the acid-base imbalance coupled furfural oxidation bipolar hydrogen production technology (BPM, English full name Bipoler membrane) to build an electrolytic hydrogen production device.

[0030] In the prior art, alkaline solution is usually used as the electrolyte at both the anode and cathode of the water electrolysis equipment. The present invention innovatively adopts an acid-base asymmetric system design on both sides of the electrolytic cell, specifically referring to: using a membrane to separate the anode and cathode, and using acidic and alkaline electrolytes respectively. For this reason, the acid-base asymmetry described in the present invention refers to the asymmetry of the properties of the electrolyte used, rather than the structure of the electrolytic cell. In the present invention, the cathode electrolyte circulation system and the anode electrolyte circulation system are independent of each other, and the pipelines of the two circulation systems are not interconnected. Among them, the cathode electrolyte can be selected as a sulfuric acid or hydrochloric acid solution, and the anode electrolyte is a mixed solution of furfural and alkaline solution (KOH or NaOH).

[0031] In the electrolyzer, the conventional hydrogen evolution reaction (HER) is carried out at the cathode electrode, while the oxygen evolution reaction is replaced by furfural oxidation reaction at the anode electrode. The specific reaction process is shown in the following formula:

[0032] (1) According to Gibbs free energy:

[0033] ΔG cell =-nF(E θ +0.0591*ΔpH)

[0034] When ΔpH=14, a voltage of 0.83V can be generated, which is the electrochemical neutralization energy, reducing the pressure of the electrolytic hydrogen production cell.

[0035] (2) Principle of Furfural Oxidation and Hydrogen Evolution:

[0036] 2R-CHO+OH - =R-COO - +2H 2 O+2e - +H 2

[0037] In addition, adding furfural, which has thermodynamic advantages, to the anode to replace the traditional OER reaction can further reduce the pressure of the electrolytic hydrogen production cell. In the lower oxidation potential range, the two H on CHO will couple to generate one H after undergoing the Tafel process. 2 .

[0038] 2. In the present invention, in the furfural oxidation reaction, the theoretical starting potential is 0.05V, which is significantly lower than the 1.23V of the OER process; and the acid-base asymmetric electrolysis reaction design is adopted to convert the acid-base neutralization energy into electrochemical energy for utilization, further reducing the voltage of the overall reaction; therefore, the starting potential of the electrolyzer is usually only 0.35V, and the same current density as the traditional water electrolysis process is achieved at a lower voltage input during the reaction. In order to achieve higher hydrogen production efficiency, traditional water electrolysis equipment needs to be operated at a higher temperature, so the electrolyte temperature needs to be heated to above 90°C, which further increases the overall energy consumption of the equipment; but the furfural oxidation reaction has excellent thermodynamic performance and can be easily carried out at room temperature; therefore, the temperature control of the electrolyzer usually only needs to avoid overheating, without the need for additional heating equipment, and can be achieved by configuring a cooler in the cathode electrolyte circulation system and the anode electrolyte circulation system for heat exchange with cooling water. Therefore, compared with the traditional water electrolysis hydrogen production technology, the present invention has a huge energy consumption advantage.

[0039] 3. The present invention further proposes a new electrolytic cell structure design, which is composed of a plurality of electrodes or plates arranged in series and tightly fitted to form mutually isolated anode reaction zones and cathode reaction zones. A plurality of monopolar plates are stacked to form a plurality of monomer electrolysis chambers adjacent to each other in sequence. In the vertical direction of the anode plate and the cathode plate, radial electrolyte inlet and outlet ports are respectively arranged at their relative side edges, and axial through holes connected to the inlet and outlet ports are respectively arranged at adjacent positions. When the plates are stacked on each other, an electrolyte channel is formed. The electrolyte flows in the opposite direction of gravity, that is, the inlet at the lower end serves as the inlet of the electrolyte, and after the cathode and anode electrolytes are introduced, they flow into the corresponding reaction chambers respectively. The outlet at the upper end serves as the outlet of the electrolyte, and the electrolyte in the corresponding chamber is discharged after being collected.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The acid-base imbalance coupled furfural oxidation bipolar hydrogen production (BPM) device provided by the present invention can realize the simultaneous hydrogen evolution at the cathode and anode during the electrolysis process accompanied by the generation of furoic acid, thereby reducing the energy consumption of hydrogen production and achieving high value of the product. The equipment avoids the use of high-energy-consuming auxiliary devices (electrolyte heater, deoxidation equipment), reducing the overall energy consumption of the equipment.

[0042] 2. By replacing the oxygen evolution reaction (>1.23V) with the furfural oxidation reaction (>0.05V), the electrolysis starting potential is greatly reduced, thereby achieving a huge optimization of energy consumption compared to the traditional water electrolysis hydrogen production technology. The process design of anode hydrogen evolution further increases the efficiency of electrical energy utilization, avoids the mixing of hydrogen and oxygen products, and improves the safety of the reaction.

[0043] 3. The conversion reaction of furfural to furoic acid at the anode realizes the added value of biomass derivatives, which further optimizes the cost of hydrogen production process. The process requires low reaction conditions and avoids the use of high temperature and high pressure as well as organic solvents, which makes the oxidation process easy to implement and environmentally friendly.

[0044] 4. Conventional water electrolysis hydrogen production equipment needs to be at a temperature of about 90°C to achieve a considerable hydrogen production efficiency, and a cooler is also required to reduce the hydrogen temperature to below 40°C, which requires a lot of energy input and waste. The reaction temperature in the device of the present invention is between 20 and 40°C, and no additional heating device is required, thereby reducing the overall energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the process of the BPM hydrogen production device in the present invention.

[0046] Figure 2 This is a structural diagram of a chamber of the electrolytic cell of the present invention.

[0047] Figure 3 It is a schematic diagram of the external structure of the electrolytic cell in the present invention.

[0048] Reference numerals in the figure: cathode electrolyte storage tank 1, cooling water storage tank 2, cathode gas-liquid separator 3, pressure gauge 4, cathode hydrogen scrubber 5, check valve 6, check valve 7, anode hydrogen scrubber 8, pressure gauge 9, anode gas-liquid separator 10, nitrogen gas cylinder 11, anode electrolyte storage tank 12, control terminal 13, acid circulation pump 14, cooling water circulation pump 15, check valve 16, valve 17, control valve 18, control valve 19, flow meter 20, valve 21, hydrogen dryer 22, valve 23, discharge port 24, check valve 25, pressure gauge 26, back pressure valve 27, hydrogen gas cylinder 28, flow meter 29, valve 3 0, check valve 31, control valve 32, valve 33, discharge port 34, alkali liquid circulation pump 35, power cabinet 36, acid liquid cooler 37, temperature sensor 38, flow meter 39, pressure sensor 40, electrolytic cell 41, pressure sensor 42, flow meter 43, temperature sensor 44, alkali liquid cooler 45, control valve 46, check valve 47, end plate 48, boss 49, plate 50, seal 51, bracket 52, frame 53, hydraulic equipment 54, end plate 55, anode plate 56, anode guide plate 57, bipolar membrane 58, cathode guide plate 59, cathode plate 60, anode electrode 61, cathode electrode 62. DETAILED DESCRIPTION

[0049] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0050] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0051] like Figure 1 As shown, the acid-base imbalance coupled furfural oxidation bipolar electrolysis hydrogen production device of the present invention comprises: an electrolytic cell 41, an anode alkaline electrolyte circulation system, a cathode acidic electrolyte circulation system, a hydrogen washing and drying system, and a monitoring and control system. Each functional unit is described in detail as follows:

[0052] The electrolytic cell 41 has a closed cavity and is divided into an anode reaction chamber and a cathode reaction chamber by a bipolar membrane, and the anode and the cathode are respectively arranged in the two reaction chambers. The device is the place for electrolytic reaction, the product of hydrogen evolution reaction in the cathode reaction chamber is hydrogen, and the product of furfural oxidation reaction in the anode reaction chamber is hydrogen and furoic acid. Since isolated dual chambers are used to produce hydrogen simultaneously in the electrolytic cell 41, there is no risk of oxygen and hydrogen cross-talk.

[0053] In order to achieve a lower starting potential, the electrolytic cell 41 is designed as an acid-base asymmetric system; the cathode and anode are separated by a membrane and set as acid and alkali respectively, the cathode is an acidic electrolyte, and the anode is an alkaline electrolyte, so the structure involved in the cathode reaction chamber should be acid-resistant. The cathode and anode are separated by a bipolar membrane 58 to avoid contact between acid and alkali electrolytes while ensuring circuit connectivity. The electrolytic cell is designed as a monopolar plate structure and consists of a plurality of electrolytic chambers connected in series. Exemplarily, the cathode part of the electrolytic cell 41 can be selected from pure titanium, nickel-plated titanium or stainless steel-plated titanium; the cathode electrolyte can be a sulfuric acid solution, and the anode electrolyte is a mixed solution of furfural and alkali (KOH, NaOH) solution. To ensure the stability of the bipolar membrane 58, the operating temperature of the electrolytic cell 41 is controlled at 20-40°C, and the working pressure of the electrolytic cell is 0.1-0.3Mpa.

[0054] like Figure 2 As shown, the electrolytic cell 41 is a series-connected monopolar plate structure, which is composed of a plurality of electrodes or plates arranged in series and closely fitted, thereby forming mutually isolated anode reaction areas and cathode reaction areas. A plurality of monopolar plates are stacked in a stacked form, and are adjacent to each other in sequence to form a plurality of monomer electrolysis chambers, and the structure specifically includes: a circular plate-shaped anode electrode 61, a circular ring-shaped seal 51, a circular sieve plate-shaped anode plate 56, a circular ring-shaped seal 51, a circular plate-shaped anode electrode 61, a circular sieve mesh anode guide plate 57, a circular plate-shaped bipolar membrane 58, a circular sieve mesh cathode guide plate 59, a circular plate-shaped cathode electrode 62, a circular ring-shaped seal 51, a circular sieve plate-shaped cathode plate 60, a circular ring-shaped seal 51, and a circular plate-shaped cathode electrode 62. Fastening and mounting components are provided at the outermost ends and circumferential periphery of the anode reaction chamber and the cathode reaction chamber. In the vertical direction of the anode plate 56 and the cathode plate 60, radial electrolyte inlet and outlet ports are respectively provided at the opposite side edges thereof, and axial through holes (i.e., Figure 2 The two circular openings and two square openings in the plate form an electrolyte channel when the plates are stacked on each other. The inlet at the lower end serves as the electrolyte inlet, and after the cathode and anode electrolytes are introduced, they flow into the corresponding reaction chambers respectively. The outlet at the upper end serves as the electrolyte outlet, and the electrolyte in the corresponding chamber is discharged after being collected.

[0055] The working mode of each layer of plates or electrodes is as follows: an electrolytic reaction zone is formed between two adjacent plates, and each anode (or cathode) plate passes direct current positive and negative current respectively. Different plates are separated by bipolar membranes, and sealing gaskets are respectively arranged on both sides of the bipolar membrane. Electrodes and guide plates are arranged in sequence between the plates and the bipolar membrane; the electrode is the place for electrochemical reaction, which is a self-supporting catalyst or has a catalyst loaded on the surface; the plate plays the role of conducting electricity and supporting internal components, and its surface has a papillary structure, which cooperates with the guide plate (complex mesh structure) on both sides of the electrode to optimize the electrolyte flow channel. The bipolar membrane separates the positive and negative electrodes to avoid acid-base neutralization reaction, while allowing ions to pass selectively to ensure the connectivity of the circuit. The electrolyte flows in the opposite direction of gravity, flows into the reaction chamber from the lower opening, and flows out from the upper opening; in order to reduce the resistance in the tank, the various components need to be close to each other.

[0056] When in use, a single current is applied to each plate, and both sides of the plate are the same anode (or cathode). Exemplarily, the cathode guide plate 59 and the cathode plate 60 are made of pure titanium, nickel-plated titanium or stainless steel-plated titanium; the cathode electrode 62 is made of titanium felt, titanium mesh, titanium foam or nickel mesh-plated titanium, and a hydrogen evolution catalyst is sprayed on the surface. The anode guide plate 56 and the anode plate 61 are made of nickel or high-performance stainless steel; the anode electrode 61 is made of copper mesh, copper plate and copper foam, and its surface is electrochemically treated to give it better furfural catalysis ability. The material of the bipolar membrane is (the bipolar membrane is selected as a common product on the market, and the specific material is not required).

[0057] The outer structure of the electrolytic cell 41 is as follows: Figure 3 As shown. The fastening and mounting components include circular end plates 48 and end plates 55 arranged on both sides, and the two end plates are connected by at least two axial frames 53; the series-connected monopolar plate structure is seated on a bracket 52 with an arc-shaped opening, and is limited by the end plates 48, the end plates 55 and the frames 53. A plurality of circumferentially arranged bosses 49 are provided on the inner side of the end plate 48, and a plurality of circumferentially arranged hydraulic devices 54 are provided on the inner side of the end plate 55, which are used to realize the fixed installation and pressure adjustment of the series-connected monopolar plate structure. The electrolytic cell structure can realize convenient installation and disassembly, and is convenient for the replacement of electrode materials and subsequent maintenance.

[0058] The cathode acid electrolyte circulation system includes a cathode electrolyte storage tank 1, an acid circulation pump 14, a cathode reaction chamber of an electrolytic cell 41, and a cathode gas-liquid separator 3, and the pipelines are connected in sequence to form a circulation loop. A check valve 16, a control valve 18, a flow meter 39, and a pressure sensor 40 are arranged in sequence on the pipeline at the pump outlet; wherein, the cathode electrolyte inlet of the electrolytic cell 41 is connected to the flow meter 39, the cathode electrolyte outlet of the electrolytic cell 41 is connected to the liquid phase inlet of the cathode gas-liquid separator 3, and the liquid phase outlet of the gas-liquid separator 3 is connected to the cathode electrolyte storage tank 1, so as to realize the flow of the cathode acid electrolyte in the circulation loop. The pipelines and flow-through equipment in the cathode acid electrolyte circulation system must be acid-resistant. Exemplarily, the material of the cathode electrolyte storage tank 1 and the cathode gas-liquid separator 3 can be selected from one of polyetheretherketone (PEEK), acrylic, and polytetrafluoroethylene (or polytetrafluoroethylene inner coating); the acid circulation pump 14 selects an acid-resistant pump or a peristaltic pump.

[0059] The anode alkaline electrolyte circulation system includes an anode electrolyte storage tank 12, an alkaline solution circulation pump 35, an anode reaction chamber of an electrolytic cell 41, and an anode gas-liquid separator 10, which are connected in sequence by pipelines to form a circulation loop. A check valve 47, a control valve 46, a flow meter 43, and a pressure sensor 42 are sequentially arranged on the pipeline at the pump outlet; wherein the anode electrolyte inlet of the electrolytic cell 41 is connected to the flow meter 43, the cathode electrolyte outlet of the electrolytic cell 41 is connected to the liquid phase inlet of the anode gas-liquid separator 10, and the liquid phase outlet of the gas-liquid separator 10 is connected to the anode electrolyte storage tank 12, so that the anode alkaline electrolyte flows in the above-mentioned circulation loop.

[0060] In the present invention, the cathode electrolyte circulation system and the anode electrolyte circulation system are independent of each other, and the circulation pipelines are not intercommunication. The flowmeter 39 and the flowmeter 43 provided on the circulation pipeline are used to measure the flow of the two electrolytes in real time, respectively, and after being transmitted to the control terminal 13 through the power cabinet 36, the latter is adjusted as needed through the control valve 18 and the control valve 46.

[0061] The device further includes an electrolyte temperature control system, including: a cooling water storage tank 2, a cooling water circulation pump 15, a valve 17, a control valve 19, an acid cooler 37, a temperature sensor 38, a control valve 32, an alkali cooler 45, and a temperature sensor 44. Among them, the valve 17 is connected to the control valve 19 and the control valve 32 at the same time, and the cooling water outlets of the acid cooler 37 and the alkali cooler 45 are connected to the cooling water storage tank 2, so that a single pump drives two coolers to achieve the purpose of reducing energy consumption. The temperature sensor 38 and the temperature sensor 44 collect the electrolyte temperature flowing into the electrolytic cell, and after being transmitted to the control terminal 13 through the power cabinet 36, the cooling water flow rate is accurately controlled by controlling the control valve 19 and the control valve 32.

[0062] The hydrogen scrubbing and drying system mainly performs gas-liquid separation, acid / base removal, hydrogen drying and hydrogen collection. The system includes a cathode gas-liquid separator 3, an anode gas-liquid separator 10, a pressure gauge 4, a pressure gauge 9, a cathode hydrogen scrubber 5, an anode hydrogen scrubber 8, a check valve 6, a check valve 7, a hydrogen dryer 22, a check valve 25, a pressure gauge 26, a back pressure valve 27 and a hydrogen cylinder 28. The hydrogen from the cathode and the anode are collected after flowing through the check valve 6 and the check valve 7 respectively, and flow to the hydrogen dryer 22 together to achieve the common drying of bipolar hydrogen production.

[0063] Thanks to the innovative process principle, there is no need to consider the removal of oxygen during the hydrogen washing and drying process, only the electrolyte needs to be removed. The acid / alkali solution carried in the gas can be further purified by neutralizing the corresponding weak base / weak acid absorbent in the scrubber to enhance safety. The hydrogen after drying is stored in the hydrogen cylinder 28 after the pressure of the output hydrogen is adjusted by the check valve 25, the pressure gauge 26 and the back pressure valve 27. Exemplarily, the absorption liquid placed in the cathode hydrogen scrubber 5 in the implementation can be selected from one of borax / sodium hydroxide buffer and phosphate / sodium hydroxide, and the absorption liquid placed in the anode hydrogen scrubber 8 can be selected from one of boric acid / borate buffer or phosphoric acid / phosphate buffer.

[0064] The nitrogen purge system includes a nitrogen cylinder 11, a check valve 31, a valve 21, a flow meter 20, a valve 30, a flow meter 29, a valve 23, and a discharge port 24; wherein the valve 21 and the valve 30 are simultaneously connected to the check valve 31 to realize nitrogen purge of the cathode and anode gas product pipelines. Nitrogen is released from the nitrogen cylinder 11 and is divided into two directions after passing through the check valve 31, which are respectively: line (1) valve 21, flow meter 20, cathode gas-liquid separator 3, cathode hydrogen scrubber 5, check valve 6; and line (2) valve 30, flow meter 29, anode gas-liquid separator 10, anode hydrogen scrubber 8, check valve 7; the two streams of nitrogen are combined before the inlet of the hydrogen dryer 22, and are discharged into the atmosphere at the discharge port 24 after flowing through the valve 23. Nitrogen purge operation must be performed before and after the equipment is started up, which helps to improve the purity of hydrogen production and ensure the safe operation of the equipment.

[0065] The power cabinet 36 is used to realize the conversion of the AC power of the grid to the DC power of the electrolyzer, and can monitor the power supply voltage, current and energy consumption of the electrolyzer. At the same time, the power cabinet 36 can also serve as a signal line transfer point for each online monitoring device, and connect with the signal line from the control terminal 13.

[0066] The control terminal 13 may be a host computer with a built-in software platform having data acquisition and control functions, and can collect monitoring data of the following devices (or send control signals according to action feedback): pressure gauge 4, pressure gauge 9, flow meter 20, pressure gauge 26, flow meter 29, power supply 36, temperature sensor 38, flow meter 39, pressure sensor 40, pressure sensor 42, flow meter 43, temperature sensor 44; the system control function is realized by adjusting the following devices: acid circulation pump 14, cooling water circulation pump 15, valve 17, control valve 18, control valve 19, valve 21, valve 23, back pressure valve 27, valve 30, control valve 32, valve 33, alkali circulation pump 35, power supply 36, control valve 46. The function realization mode of the control terminal can adopt the well-known technology in the art, and the present invention does not make special requirements, so it will not be repeated.

[0067] Example use of the device of the present invention:

[0068] (1) adding sulfuric acid or hydrochloric acid solution to the cathode electrolyte storage tank;

[0069] Add an acidic solution to the cathode electrolyte storage tank; add an alkaline mixed solution of furfural and alkali solution to the anode electrolyte storage tank; add a borax / sodium hydroxide buffer or a phosphate / sodium hydroxide buffer as an absorption liquid for the acid solution carried by hydrogen to the cathode hydrogen scrubber; add a boric acid / borate buffer or a phosphoric acid / phosphate buffer as an absorption liquid for the alkali solution carried by hydrogen to the anode hydrogen scrubber; and add cooling water to the cooling water storage tank.

[0070] The acid solution may be sulfuric acid or hydrochloric acid solution. + The molar concentration range is 1 to 2M; the alkali solution is KOH or NaOH solution, OH - The molar concentration of furfural is 1-2M; in the alkaline mixed solution, the molar concentration of furfural is 0.1-0.6M; the pH value of the absorption liquid in the anode hydrogen scrubber is 5-6, and the pH value of the absorption liquid in the cathode hydrogen scrubber is 8-9.

[0071] (2) purging the cathode gas product pipeline and the anode gas product pipeline with nitrogen;

[0072] (3) The power cabinet supplies power to each device, and the circulation pump and corresponding valves are started through the control terminal; when the electrolysis reaction is in progress, the electrolyte flow, cooling water flow and electrolytic cell current are regulated according to the pressure sensor and temperature sensor on the circulation pipeline; the temperature of the cathode electrolyte and the anode electrolyte entering the electrolytic cell is controlled at 20-40°C, and the pressure is controlled at 0.1-0.3Mpa;

[0073] (4) Use a check valve, a pressure gauge and a back pressure valve to adjust the output pressure of hydrogen, and store the dried hydrogen in a hydrogen cylinder;

[0074] (5) During the hydrogen production process, the electrolyte is appropriately replenished according to the drop in the electrolyte level in the storage tank;

[0075] (6) When stopping hydrogen production, first stop the power supply to the electrolyzer to maintain the circulation of the electrolyte; after the hydrogen output pressure drops to zero, close the circulation pump and related valves; finally, purge the gas product pipeline with nitrogen.

[0076] The above is a preferred schematic block diagram of this example, but the technical form involved in the present invention can be implemented in other similar solutions and is not limited to the description given in the specific implementation mode of the present invention. More precisely, the implementation process given in the present invention is a better way to more thoroughly and comprehensively understand the technical route of the present invention in the technical field involved in the invention. Any changes, improvements and modifications in structure, mode or method made according to the relevant content of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for producing hydrogen by bipolar electrolysis of furfural oxidation coupled with acid-base imbalance, It is characterized in that The method is realized based on the following acid-base imbalance coupled furfural oxidation bipolar electrolysis hydrogen production device: The device includes: an electrolytic cell, an anode alkaline electrolyte circulation system, a cathode acidic electrolyte circulation system, a hydrogen washing and drying system, and a monitoring and control system; wherein, The electrolytic cell has a closed cavity and is divided into an anode reaction chamber and a cathode reaction chamber by a bipolar membrane, and the anode and the cathode are respectively arranged in the two reaction chambers; the anode alkaline electrolyte circulation system comprises an anode electrolyte storage tank, an alkaline solution circulation pump, an anode reaction chamber of the electrolytic cell, and an anode gas-liquid separator, which are sequentially connected by pipelines to form a circulation loop, and the electrolyte is an alkaline mixed solution prepared by furfural and alkaline solution; the cathode acidic electrolyte circulation system comprises a cathode electrolyte storage tank, an acid solution circulation pump, a cathode reaction chamber of the electrolytic cell, and a cathode gas-liquid separator, which are sequentially connected by pipelines to form a circulation loop, and the electrolyte is an acidic solution; In the hydrogen scrubbing and drying system, the outlets of the anode reaction chamber and the cathode reaction chamber of the electrolyzer are connected to the anode gas-liquid separator and the cathode gas-liquid separator respectively through pipelines; the bottoms of the two gas-liquid separators are connected to the anode electrolyte storage tank and the cathode electrolyte storage tank respectively through pipelines, and the tops of the two gas-liquid separators are connected to the inside of the anode hydrogen scrubber and the cathode hydrogen scrubber respectively through pipelines and extend below the liquid level of the absorbent; the top outlets of the two hydrogen scrubbers are connected to the hydrogen dryer through pipelines, and the latter is connected to the hydrogen gas cylinder through pipelines; The monitoring and control system includes a control terminal, a power cabinet, and a plurality of control valves and a plurality of online monitoring devices arranged on the pipeline between the devices; the control terminal is connected to the power cabinet via a signal line, and the power cabinet is connected to each control valve, online monitoring device and circulation pump via a signal line or cable; The electrolytic cell is a series-connected monopolar plate structure, which is composed of a plurality of electrodes or plates arranged in series and tightly fitted to form an anode reaction chamber and a cathode reaction chamber isolated from each other; its structure specifically comprises: a circular plate-shaped anode electrode, a circular ring-shaped seal, a circular sieve-shaped anode plate, a circular ring-shaped seal, a circular plate-shaped anode electrode, a circular sieve-shaped anode guide plate, a circular plate-shaped bipolar membrane, a circular sieve-shaped cathode guide plate, a circular plate-shaped cathode electrode, a circular ring-shaped seal, a circular sieve-shaped cathode plate ... anode plate, a circular sieve-shaped cathode plate, a circular sieve-shaped cathode plate, a circular sieve-shaped anode plate, a circular sieve-shaped anode plate, a circular sieve-shaped cathode plate, a circular sieve-shaped cathode plate, a circular sieve-shaped anode plate, a circular sieve-shaped anode plate, a circular sieve-shaped cathode plate, a circular Anode plates, annular seals, and a circular cathode electrode; fastening and mounting components are provided at the outermost ends and circumferential peripheries of the anode reaction chamber and the cathode reaction chamber; radial electrolyte inlet and outlet ports are respectively provided on opposite sides of the anode plate and the cathode plate in the vertical direction, and axial through holes communicating therewith are respectively provided on adjacent side surfaces, which are used as electrolyte channels when the plates are stacked on each other; the electrolyte is introduced into the reaction chamber from the inlet port at the lower end, and its flow direction is opposite to the gravity, and finally led out from the outlet port at the upper end; The fastening and mounting component includes circular end plates arranged on both sides, and the two end plates are connected by at least two axial frames; the series-connected monopolar plate structure is seated on a bracket with an arc-shaped opening, and is limited by the end plates and the frames; a plurality of circumferentially arranged bosses are provided on the inner side of one of the end plates, and a plurality of circumferentially arranged hydraulic devices are provided on the inner side of the other end plate, for realizing fixed installation and pressure adjustment of the series-connected monopolar plate structure; The method for producing hydrogen by bipolar electrolysis through acid-base imbalance coupling furfural oxidation comprises the following steps: (1) Add an acidic solution to the cathode electrolyte storage tank; add an alkaline mixed solution of furfural and alkali solution to the anode electrolyte storage tank; add boric acid / borate buffer or phosphoric acid / phosphate buffer to the cathode hydrogen scrubber and the anode hydrogen scrubber, respectively, to absorb the acid or alkali solution carried by the hydrogen; add cooling water to the cooling water storage tank; The acidic solution is sulfuric acid or hydrochloric acid solution, H + The molar concentration range is 1 to 2 M; the alkali solution is KOH or NaOH solution, OH - The molar concentration of furfural is 1-2 M; in the alkaline mixed solution, the molar concentration of furfural is 0.1-0.6 M; the pH value of the absorption liquid in the cathode hydrogen scrubber is 8-9, and the pH value of the absorption liquid in the anode hydrogen scrubber is 5-6; (2) Purging the cathode gas and anode gas product pipelines with nitrogen; (3) The power cabinet supplies power to each device, and the circulation pump and corresponding valves are started through the control terminal; when the electrolysis reaction is in progress, the electrolyte flow, cooling water flow and electrolytic cell current are regulated according to the pressure sensor and temperature sensor on the circulation pipeline; the temperature of the cathode electrolyte and the anode electrolyte entering the electrolytic cell is controlled at 20-40°C, and the pressure is controlled at 0.1-0.3Mpa; (4) Use a check valve, pressure gauge and back pressure valve to adjust the output pressure of hydrogen, and store the dried hydrogen in a hydrogen cylinder; (5) During the hydrogen production process, the electrolyte is appropriately replenished according to the drop in the electrolyte level in the storage tank; (6) When stopping hydrogen production, first stop the power supply to the electrolyzer to maintain the circulation of the electrolyte; after the hydrogen output pressure drops to zero, close the circulation pump and related valves; finally, purge the gas product pipeline with nitrogen.

2. The method according to claim 1, It is characterized in that The online monitoring equipment includes a flow meter, a pressure sensor, a temperature sensor and a liquid level sensor.

3. The method according to claim 1, It is characterized in that An alkali liquid cooler is provided on the pipeline between the alkali liquid circulation pump and the anode reaction chamber of the electrolytic cell, and an acid liquid cooler is provided on the pipeline between the acid liquid circulation pump and the cathode reaction chamber of the electrolytic cell; the two coolers have a heat exchanger structure, and a circulation loop is formed on the heat exchange medium side through the pipeline with the cooling water storage tank and the cooling water circulation pump, and the heat exchange medium is cooling water.

4. The method according to claim 1, It is characterized in that The device also includes a nitrogen purge system, including a plurality of valves and flow meters connected to a nitrogen cylinder and pipelines; the nitrogen purge system is connected to the anode gas-liquid separator and the cathode gas-liquid separator through pipelines, and the nitrogen used for purge flows through two gas-liquid separators and two hydrogen scrubbers respectively, and is discharged from the outlet of the hydrogen dryer.

5. The method according to claim 1, It is characterized in that Check valves, control valves, temperature sensors, flow meters and pressure sensors are installed on the outlet pipelines of the alkali liquid circulation pump and the acid liquid circulation pump; pressure gauges are installed on the pipeline between the gas-liquid separator and the hydrogen scrubber; check valves, pressure gauges and back pressure valves are installed on the pipeline between the hydrogen dryer and the hydrogen cylinder.

6. The method according to claim 1, It is characterized in that Liquid level sensors are provided in the anolyte storage tank and the catholyte storage tank.

Images