CN113151853B - SO (SO) device 2 Depolarized electrolytic cell and method of operating same - Google Patents

SO (SO) device 2 Depolarized electrolytic cell and method of operating same Download PDF

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CN113151853B
CN113151853B CN202110250759.5A CN202110250759A CN113151853B CN 113151853 B CN113151853 B CN 113151853B CN 202110250759 A CN202110250759 A CN 202110250759A CN 113151853 B CN113151853 B CN 113151853B
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cathode
electrolytic cell
cathode side
anode
washing liquid
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CN113151853A (en
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陈崧哲
张平
王来军
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Tsinghua University
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    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00Operating or servicing cells
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/36Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

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Abstract

SO (SO) device 2 A depolarized electrolytic cell and an operation method thereof belong to the technical fields of electrochemistry and chemical industry. The electrolytic cell comprises one or more single cells which are sequentially arranged, wherein a membrane electrode assembly of the electrolytic cell consists of an anode catalytic layer and a proton selective permeable membrane, the membrane electrode does not comprise a cathode catalytic layer, and a cathode side support body made of graphite felt and other materials is loaded with a catalyst. The operation method is to wash the cathode side by active washing or passive decompression, so that potential elemental sulfur accumulation is reduced, and the performance of the electrolytic cell can be effectively maintained. The invention can avoid the SO in the anode region 2 The membrane electrode assembly is damaged after the reduction reaction occurs across the PEM membrane, and has the advantages of long service life and strong maintainability.

Description

SO (SO) device 2 Depolarized electrolytic cell and method of operating same
Technical Field
The invention relates to an SO 2 A depolarized electrolytic cell and an operation method thereof belong to the technical field of mixed sulfur circulation hydrogen production.
Background
SO 2 Depolarized Electrolysis (SDE) is one of the key steps in mixed sulfur cycle hydrogen production (HyS-cycle). The mixed sulfur cycle is the simplest one in the thermochemical water splitting process and only comprises two reactions, wherein one is thermochemical reaction-sulfuric acid splitting reaction; while the other reaction is an electrochemical reaction-i.e. an SDE process. The reaction formulas of the two reactions are as follows:
H 2 SO 4 →SO 2 +H 2 O+1/2O 2
2H 2 O+SO 2 →H 2 SO 4 +H 2
the two reactions are combined, and the net reaction is water splitting to generate hydrogen and oxygen.
It can be seen that SDE is the hydrogen-generating step of the mixed sulfur cycle, which corresponds to half-cell reactions of:
anode: 2H (H) 2 O(l)+SO 2 (aq.)→H 2 SO 4 (aq.)+2H + +2e -
And (3) cathode: 2H (H) + +2e - →H 2 (g)
The standard potential for the reaction of electrolyzed water at 25℃is 1.229V, while SO 2 The standard potential of depolarization electrolysis reaction is only 0.158V, so that SDE electrolysis is introduced, and the electrolysis efficiency is expected to be greatly improved.Under the condition that sulfuric acid decomposition reaction (which is carried out at 850 ℃) of the mixed sulfur circulation is coupled with a high-temperature gas cooled reactor, the mixed sulfur circulation is expected to realize high-efficiency and large-scale clean hydrogen production. In addition, in the presence of SO 2 Under the supply condition, the SDE electrolysis process can also be independently applied, namely, the SDE electrolysis process is carried out by SO 2 Sulfuric acid is prepared, and water is electrolyzed to prepare hydrogen.
SDE electrolysis has been more studied since the advent of mixed sulfur recycle by western house corporation in the united states. In terms of cell construction, the transition from the original parallel plate construction of western house corporation to the current PEM (proton exchange membrane) cell construction has been made. In the SDE cell of this construction, a "sandwich" type Membrane Electrode Assembly (MEA) consisting of an anode catalyst layer, PEM and cathode catalyst layer is an important component thereof. Us plug Wen Na river national laboratory (SRNL) design and use of PEM-based liquid phase feed (i.e., anolyte is SO-dissolved 2 Sulfuric acid) is provided. Based thereon, university of South Carolina (USC) proposes PEM-based gas phase feed (i.e., anode gaseous SO 2 The cathode is pure water).
The above technology, while having numerous advantages, has faced a bottleneck problem from the beginning of the advent of PEM (proton exchange membrane) SDE, SO in the anode region 2 The reduction reaction occurs across the PEM into the cathode side to form elemental sulfur, which not only results in loss of elemental sulfur from the mixed sulfur cycle (this portion of elemental sulfur leaves the mixed sulfur cycle feed system) but also results in catalyst deactivation and Membrane Electrode Assembly (MEA) damage. In particular SO in the anode material 2 After crossing the PEM membrane, a reduction reaction occurs with the catalyst layer on the cathode side to generate elemental sulfur, which accumulates between the PEM membrane and the cathode catalyst layer of the mea, and as elemental sulfur increases in this location, the mea "swells" and increases in resistance, and proton passage capacity decreases, ultimately leading to rapid failure of the mea. It should be noted that elemental sulfur is deposited between the PEM membrane and the cathode catalyst layer, and the resulting failure of the membrane electrode assembly is irreversible, and recovery and reuse of such membrane electrode assemblies and their catalysts is also difficult.
For the upper partThe SO 2 Membrane diffusion, MEA failure problems, some researchers have attempted to solve under moderate compromise principles, representative methods are as described in document [ US patent 8,709,229B2.April 29,2014]And [ Development and testing of a PEM SO ] 2 -depolarized electrolyzer and an operating method that prevents sulfur accumulation.J.L.Steimke,International Journal of Hydrogen Energy,2015,Volume 40,Issue 39,Page13281-13294]By controlling the electrolysis voltage, and adopting specific start-up and stop procedures to enable SO in the anode material to be close to the anode catalyst layer of the MEA 2 Consume as much as possible SO that 2 There is little chance of penetrating the PEM into the cathode side and little SO into the cathode side 2 Also to generate H 2 S gas is mainly used, so that solid elemental sulfur can be generated as little as possible in the running process.
The method is expedient, and the effect achieved is limited after all, SO 2 Not completely isolated, but still penetrates between the PEM and the cathode catalyst layer of the MEA, elemental sulfur is still generated inside the MEA with prolonged operation, causing irreversible damage and performance degradation to the MEA, which is clearly unacceptable as an important and high value component in the SDE electrolyte.
Disclosure of Invention
The invention aims to provide an SO 2 Depolarized electrolytic cell and operation method thereof, aiming at solving the existing SO 2 Depolarized cells and the following problems in their operation: SO in the anode region 2 Across the PEM into the cathode side, a reduction reaction occurs to produce elemental sulfur which accumulates between the PEM membrane and the cathode catalyst layer of the membrane electrode assembly, and as elemental sulfur increases in this location, the membrane electrode assembly "swells up" causing an increase in resistance and a decrease in proton throughput, ultimately leading to failure of the membrane electrode assembly and thus the entire SDE cell. Moreover, membrane electrode assembly failure due to deposition of elemental sulfur between the PEM membrane and the cathode catalyst layer is irreversible, and recovery reuse of such membrane electrode assemblies and their catalysts is also difficult.
The technical scheme of the invention is as follows:
SO (SO) device 2 The depolarization electrolytic cell comprises one or more single cells which are sequentially arranged, each single cell comprises a membrane electrode assembly, a cathode side support body, an anode side support body, an upper polar plate and a lower polar plate, a cathode sealing ring is wrapped on the outer periphery of the cathode side support body, and an anode sealing ring is wrapped on the outer periphery of the anode side support body; the anode side of the electrolytic cell is provided with an anode material feeding hole and an anode material discharging hole, and the cathode side is provided with a product hydrogen discharging hole; the method is characterized in that: the membrane electrode assembly consists of an anode catalytic layer and a proton selective permeable membrane, and a cathode side support body is loaded with a catalyst.
Further, the cathode side support adopts a graphite felt loaded with a catalyst, the void ratio is more than or equal to 70%, and the carbon content of the graphite felt before loading the catalyst is more than or equal to 98%.
Further, a groove is provided in a surface of the cathode side support body to which the membrane electrode assembly is attached.
The invention provides the SO 2 A method of operating a depolarized electrolytic cell, the method comprising the steps of:
1) A cathode washing liquid inlet, a washing liquid outlet, a cathode washing liquid storage tank, a cathode washing pump, a cathode washing liquid recovery storage tank, an accessory pipeline and a valve are arranged on the cathode side of the electrolytic cell; a hydrogen product outlet is arranged at the upper part of the cathode washing liquid recovery storage tank;
2)SO 2 in the operation process of the depolarized electrolytic cell, anode materials enter from an anode material inlet and are discharged from an anode material outlet; hydrogen generated on the cathode side enters a cathode washing liquid recovery storage tank through a pipeline from a cathode washing liquid outlet and is finally discharged from a hydrogen product discharge port;
3) The cathode washing pump is started every 5min to 24h, washing liquid in the cathode washing liquid storage tank is injected into the cathode side through the cathode washing liquid inlet and is discharged to the cathode washing liquid recovery storage tank through the cathode washing liquid outlet.
The invention provides the SO 2 A second method of operating a depolarized cell, characterized in thatThe method comprises the following steps:
1) A hydrogen product outlet, a pressure relief opening, a pressure relief valve and a pressure relief drainage recovery tank are arranged on the cathode side (10) of the electrolytic cell; the hydrogen product outlet is arranged at the upper part of the cathode side; the pressure relief opening is arranged at the lower part of the cathode side and is connected with the inlet of the pressure relief drainage recovery tank through a pipeline and a pressure relief valve;
2) The SO 2 In the operation process of the depolarized electrolytic cell, anode materials enter from an anode material inlet and are discharged from an anode material outlet; the cathode side of the cell is operated at a pressure above 1 atmosphere, preferably the cathode side of the cell is operated at a pressure in the range of 1.05 atmospheres to 7MPa; the generated hydrogen is discharged from a hydrogen product outlet through a hydrogen product pipeline; the initial set pressure of the pressure relief drainage recovery tank is lower than the cathode side pressure of the electrolytic cell, preferably the initial set pressure is lower than the pressure of the cathode side of the electrolytic cell by 0.1 to 0.7MPa;
3) The pressure release valve is opened once every 5min to 24h, and part of liquid materials in the cathode side of the electrolytic cell are carried by gas and enter the pressure release drainage recovery tank; and after the pressure relief valve is closed, the liquid in the pressure relief drainage recovery tank is emptied, and the pressure in the tank is controlled to an initial set value.
Compared with the prior art, the invention has the following advantages and outstanding technical effects:
(1) SO of the invention 2 In a depolarized cell, the cathode catalyst layer of the MEA is eliminated, and in turn, the cathode catalyst is supported on a cathode side support such that the anode region SO 2 After the reduction reaction across the PEM membrane, no elemental sulfur build-up, MEA "swelling" and deactivation occurs between the PEM layer and cathode catalyst layer like a typical MEA (a tightly bonded three-layer structure, and PEM membrane layer, and anode and cathode catalyst layers made by spraying or transfer on both sides of the PEM layer). (2) The original elemental sulfur particles are not firmly combined with the surface of the PEM membrane or the surface of the cathode side support body, and the particles are fine and are easy to wash and remove. Therefore, according to the operation scheme provided by the invention, the cathode support is washed in time, so that the aggregation of elemental sulfur in the cathode region can be effectively prevented, and SDE electrolysis caused by the aggregation of elemental sulfur is preventedPool performance decreases. (3) The SDE pool following the structure and the operation method provided by the invention has the characteristics of long service life and strong maintainability because the MEA is ensured not to be damaged and fail. In addition, according to the proposal of the invention, the graphite felt loaded with the catalyst is adopted as the cathode side support, and the surface of the cathode side support, which is attached to the MEA, is provided with grooves, so that the excellent performance of the proposal can be enhanced. (4) During operation of the SDE, water in the anode feed will constantly permeate into the cathode zone. By adopting the scheme of the invention, under the condition of cathode pressurization operation, the pressure in the cathode region is released periodically and controllably, so that the water accumulated in the cathode is discharged along with the pressure release operation, and the sulfur simple substance possibly accumulated in the cathode is effectively carried out. When the method is adopted, a washing liquid and a driving device for the washing liquid are not required to be additionally arranged for the cathode region of the SDE electrolytic cell, so that the flow can be effectively simplified, and the cost can be saved.
Drawings
FIG. 1 shows an SO 2 Schematic of the cell structure of a depolarized cell.
FIG. 2 shows an SO 2 Schematic of equipment involved in the method of operating a depolarized cell.
FIG. 3 shows an SO 2 Schematic of equipment involved in the method of operating a depolarized cell.
In the figure: 1-an upper polar plate; 2-a cathode side support; 3-cathode sealing ring; 4-membrane electrode assembly; 5-an anode side support; 6-an anode sealing ring; 7-a lower polar plate; 8-proton permselective membrane; 9-an anode catalytic layer; 10-cathode side of the cell; 11-anode side of the cell; 12-anode material inlet; 13-an anode material outlet; 14-cathode cleaning solution inlet; 15-cathode scrubbing liquid outlet (also hydrogen product outlet of the cell); 16-cathode cleaning solution storage tank; 17-cathode wash pump; 18-cathode cleaning solution recovery storage tank; 19-hydrogen product take-off line; 20 hydrogen product outlet; 21-a pressure relief port; 22-a pressure relief valve; 23-a decompression drainage recovery tank.
Detailed Description
The principles, structure and implementation of the present invention are further described below with reference to the drawings and examples.
FIG. 1 shows an SO 2 The structure principle of the depolarized electrolytic cell is schematically shown, the electrolytic cell comprises at least one single cell which is sequentially arranged, and each single cell comprises a membrane electrode assembly 4, a cathode side support body 2, an upper polar plate 1, an anode side support body 5 and a lower polar plate 7. The cathode sealing ring 3 is wrapped on the outer periphery of the cathode side support body, and the anode sealing ring 6 is wrapped on the outer periphery of the anode side support body 5. The anode side 11 of the electrolytic cell is provided with an anode feed inlet 12 and an anode feed outlet 13; the cathode side is provided with a product hydrogen discharge port. The membrane electrode assembly 4 is composed of an anode catalytic layer 9 and a proton permselective membrane 8, and the cathode side support 2 is supported with a catalyst.
The cathode-side support 2 preferably employs a catalyst-supporting graphite felt having a porosity of 70% or more and a carbon content of 98% or more before supporting the catalyst. The cathode-side support 2 has grooves on the surface thereof that is bonded to the MEA.
SO provided by the invention 2 An operation method of the depolarized electrolytic cell is an active washing method, and the operation is as follows: the anode side 11 of the cell is provided with an anode inlet 12 and an anode outlet 13; the cathode side 10 of the electrolytic cell is provided with a cathode washing liquid inlet 14, a cathode washing liquid outlet 15, a cathode washing liquid storage tank 16, a cathode washing pump 17, a cathode washing liquid recovery storage tank 18, and auxiliary pipelines and valves, and a hydrogen product discharge pipeline 19 (the cathode washing liquid outlet 15 is also a product hydrogen outlet of the electrolytic cell) is arranged at the upper part of the cathode washing liquid recovery storage tank; the SO 2 During operation of the depolarized electrolytic cell, anode materials enter through an anode material inlet 12 and are discharged through an anode material outlet 13; the hydrogen gas generated on the cathode side 10 of the cell is piped from the cathode scrubbing liquid outlet 15 to the cathode scrubbing liquid recovery tank 18 and finally to the hydrogen product discharge line 19. The cathode wash pump 17 is started every 5min to 24h, and the wash liquid in the cathode wash liquid reservoir 16 is injected into the cathode side 10 of the electrolytic cell and discharged to the cathode wash liquid recovery reservoir 18.
The other operation method provided by the invention is a passive pressure relief method, and the specific operation is as follows: on the anode side of the cell11 is provided with an anode inlet 12 and an anode outlet 13; the cathode side 10 of the electrolytic cell is provided with a hydrogen product outlet 20, a pressure relief port 21, a pressure relief valve 22, a pressure relief drain recovery tank 23 and an accessory pipeline; a pressure relief port 21 is provided in the lower part of the cathode side, and is connected to the inlet of the pressure relief drain recovery tank 23 via a line and a pressure relief valve 22. SO (SO) 2 During operation of the depolarized electrolytic cell, anode materials enter through an anode material inlet 12 and are discharged through an anode material outlet 13; the cell cathode side 10 is operated at a pressure above 1 atmosphere, i.e. the cell cathode side may be operated at a pressure in the range of 1.05 atmospheres to 7MPa; the generated hydrogen is discharged from a hydrogen product outlet through a hydrogen product pipeline; the initial set pressure of the pressure relief drainage recovery tank is lower than the cathode side pressure of the electrolytic cell, and the pressure of the initial set pressure is generally lower than the pressure of the cathode side of the electrolytic cell by 0.1 to 0.7MPa; the hydrogen produced is discharged from the hydrogen product outlet 20 through the hydrogen product discharge line 19, and the initial set pressure of the pressure relief drain recovery tank 23 is lower than the pressure on the cathode side 10 of the cell. The pressure release valve 22 is opened once every 5min to 24h, and part of liquid materials in the cathode side (10) of the electrolytic cell are carried by gas into the pressure release drainage recovery tank 23. After the pressure release valve 22 is closed, the liquid in the pressure release drain recovery tank 23 is emptied, and the pressure in the tank is controlled to an initial set value.
The applicant cancels the cathode catalyst layer of the MEA in the research process, and loads the cathode catalyst on the cathode side support, and the experimental result shows that the anode region SO 2 After the reduction reaction occurs across the PEM membrane, the initial elemental sulfur particles produced by the reduction reaction are not firmly bound to the surface of the PEM membrane or the surface of the cathode side support, and the particles are fine and are easier to wash and remove. Therefore, the cathode support body is washed in time, so that the aggregation of elemental sulfur in the cathode area can be effectively prevented, and the decrease of the efficiency of the SDE electrolytic cell caused by the aggregation of the elemental sulfur is prevented. The SDE pool following the structure and the operation method has the characteristics of long service life and strong maintainability because the MEA is ensured not to be damaged and fail. After long-time use, the MEA, the cathode side support body and the like in the SDE pool can be disassembled and taken out if necessary, and the original state can be restored through simple treatment. In addition, the experimental results show that 1) the negative is caused to be formedThe excellent performance of the above-described scheme can be enhanced by providing a groove in the surface of the electrode side support that is bonded to the MEA, facilitating the flushing of the cathode side, and 2) using a catalyst-supporting graphite felt as the cathode side support.
During operation of the SDE, water in the anode feed will constantly permeate into the cathode zone. The applicant has observed that in the case of a washing operation, in the case of a cathodic pressurized operation, the pressure in the cathode zone is released periodically and controllably, so that the water accumulated in the cathode is discharged with a pressure relief operation, which effectively carries out the elemental sulphur that may accumulate in the cathode. With this method of operation, there is no need to provide additional washing liquid and driving means for the washing liquid for the cathode region of the SDE cell.
The following examples are given to provide a further understanding of the present invention.
Example 1:
by adopting the scheme of the invention, SO formed by 6 single cells which are sequentially stacked and arranged is manufactured 2 Depolarized electrolytic cells. The membrane electrode assembly of the electrolytic cell consists of an anode catalytic layer and a proton selective permeable membrane. The cathode sealing ring is wrapped on the outer periphery of the cathode side support body, and the anode sealing ring is wrapped on the outer periphery of the anode side support body. The anode side of the electrolytic cell is provided with an anode material feeding hole and an anode material outlet; the cathode side was provided with 1 product hydrogen discharge port. The membrane electrode assembly consists of an anode catalytic layer and a proton selective permeable membrane, and a cathode side support body is loaded with a catalyst.
The effective membrane area of each single cell was 50cm 2 Wherein the proton selective permeation membrane is Nafion 117 proton exchange membrane of DuPont, and the anode side is coated with Pt/C catalyst layer, and the Pt dosage is 0.4mg/cm 2 The cathode side of the proton selective permeable membrane was not sprayed with catalyst. The cathode side support was a carbon paper of 0.3mm thickness, the surface facing the proton selective permeable membrane was coated with a Pt/C catalyst layer, and the amount of Pt used was 0.4mg/cm 2 . The anode side support was a graphite felt of 1.5 mm.
The cathode side support body and the anode side support body are wrapped with a cathode sealing ring and an anode sealing ring, and the cathode side support body and the anode side support body are made of Viton A fluororubber. The upper polar plate and the lower polar plate are graphite plates with the thickness of 1.5 mm.
After the 6 single battery units are stacked and arranged, aluminum alloy end plates are arranged on the two outermost sides, pull rods penetrating through the end plates are arranged, and after the battery units and the end plates are pressed by a press machine, the whole electrolytic cell is fastened by screwing pull rod nuts.
For the SO 2 The depolarized cell was configured as shown in fig. 2, and the cathode side thereof was provided with a cathode washing liquid inlet and a cathode washing liquid outlet, a cathode washing liquid storage tank (storing 30wt.% sulfuric acid as a washing liquid, volume 10L), a cathode washing pump (peristaltic pump), a cathode washing liquid recovery storage tank (volume 15L), and auxiliary lines and valves. The cathode washing liquid outlet and the hydrogen product outlet are a shared outlet. The hydrogen generated on the cathode side enters a cathode washing liquid recovery storage tank through a pipeline from a cathode washing liquid outlet, and is finally discharged through a hydrogen product pipeline.
At 60 ℃ with SO as described above 2 The depolarized electrolytic cell performs electrolytic operation, and anode material is saturated SO-containing material 2 The external direct current keeps the current constant at 25A, the total tank voltage is 5.6V, and the hydrogen production rate of the cathode region is measured to be 60L/h.
In the running process, the cathode washing pump is started every 10min, 200mL of washing liquid is pumped from the cathode washing liquid storage tank and injected into the cathode side for washing, and after the washing pump is closed, the residual washing liquid in the electrolytic cell is discharged to the cathode washing liquid recovery storage tank along with part of product hydrogen. After 1000 hours of operation of the device, the total tank voltage was still 5.6V.
Example 2
SO in example 1 2 The depolarized electrolytic cell was configured as shown in fig. 3 by removing a cathode washing liquid tank, a cathode washing pump, a cathode washing liquid recovery tank, and auxiliary lines and valves provided on the cathode side, and a pressure release port 21, a pressure release valve 22, a pressure release drain recovery tank 23, and auxiliary lines were provided on the cathode side.
At 60 ℃ with SO as described above 2 The depolarized electrolytic cell performs electrolytic operation, and anode material is saturated SO-containing material 2 30wt.% sulfuric acid, external direct current keeps current constantThe total cell voltage was set to 25A and 5.6V, and the hydrogen production rate in the cathode region was measured to be 60L/h.
The cathode side of the cell was operated at 1.5 atmospheres with an initial set pressure of 1 atmosphere for the pressure relief drain recovery tank. The pressure release valve is opened once every 10min, the opening time is 3 seconds each time, and part of liquid materials in the cathode side of the electrolytic cell are carried by product hydrogen to enter the pressure release drainage recovery tank. And after the pressure relief valve is closed, the liquid in the pressure relief drainage recovery tank is emptied, and the pressure in the tank is controlled to return to 1 atmosphere. After the device is operated for 1000 hours, the total cell voltage is 5.67V, and the reduction of the electrolysis performance is very small.
Example 3:
by adopting the scheme of the invention, SO composed of 20 single cells which are sequentially stacked and arranged is manufactured 2 Depolarized electrolytic cells. The membrane electrode assembly of the electrolytic cell consists of an anode catalytic layer and a proton selective permeable membrane. The anode side of the electrolytic cell is provided with an anode material inlet and an anode material outlet; the cathode side was provided with 2 product hydrogen vents. The membrane electrode assembly consists of an anode catalytic layer and a proton selective permeable membrane, and a cathode side support body is loaded with a catalyst.
The effective membrane area of each single cell is 100cm 2 Wherein the proton selective permeation membrane is Nafion 115 proton exchange membrane of DuPont company, the anode side is provided with Pt/C catalyst layer, and the dosage of Pt is 0.3mg/cm 2 The cathode side of the proton selective permeable membrane is free of a catalyst layer. The cathode side support was a graphite felt (porosity 92%, carbon content 99.9%) 2.5mm thick, and was impregnated with a Pt/C catalyst at a Pt usage level of 0.6mg/cm 2 . The anode side support was a graphite felt of 2.5 mm.
The cathode side support body and the surface of the MEA are provided with grid-shaped grooves which are vertically staggered, the width of each groove is 2mm, the depth is 0.5mm, the transverse line spacing of the grid is 25mm, and the longitudinal line spacing of the grid is 25mm.
The cathode side support body and the anode side support body are wrapped with a cathode sealing ring and an anode sealing ring, and the cathode side support body and the anode side support body are made of Viton A fluororubber. Both the upper and lower plates were 1.5mm thick graphite plates (available from POCO Inc. of America).
After the 20 single battery units are stacked and arranged, aluminum alloy end plates are arranged on the two outermost sides, pull rods penetrating through the end plates are arranged, and after the battery units and the end plates are pressed by a press machine, the whole electrolytic cell is fastened by screwing pull rod nuts.
For the SO 2 The depolarized cell was configured as shown in fig. 2, and the cathode side thereof was provided with a cathode washing liquid inlet and outlet, a cathode washing liquid storage tank (storing 45wt.% sulfuric acid as a washing liquid, volume of 30L), a cathode washing pump (peristaltic pump), a cathode washing liquid recovery storage tank (volume of 15L), and auxiliary lines and valves. The cathode washing liquid outlet and the hydrogen product outlet are a shared outlet. The hydrogen generated on the cathode side enters a cathode washing liquid recovery storage tank through a pipeline from a cathode washing liquid outlet, and is finally discharged through a hydrogen product pipeline.
At 70 ℃, adopt the SO 2 The depolarized electrolytic cell performs electrolytic operation, and anode material is saturated SO-containing material 2 The cathode region was not charged with material, the external direct current kept constant at 53A, the total cell voltage was 18.0V, and the hydrogen production rate at the cathode region was measured to be 400L/h.
In the running process, the cathode washing pump is started every 3 hours, 500mL of washing liquid is pumped from the cathode washing liquid storage tank and injected into the cathode side for washing, and after the washing pump is closed, the residual washing liquid in the electrolytic cell is discharged to the cathode washing liquid recovery storage tank along with part of product hydrogen. After the device is operated for 2000 hours, the rising amplitude of the total tank voltage is very small and is 18.1V.
Example 4
SO in example 3 2 The depolarized electrolytic cell has cathode washing liquid storage tank, cathode washing pump, cathode washing liquid recovering storage tank, accessory pipeline and valve. The configuration is as shown in fig. 3, and a pressure relief port, a pressure relief valve, a pressure relief drain recovery tank, and auxiliary lines are provided on the cathode side.
At 70 ℃, adopt the SO 2 The depolarized electrolytic cell performs electrolytic operation, and anode material is saturated SO-containing material 2 43wt.% sulfuric acid, the cathode area is not charged with material, and the external direct current keeps the current constant at 53A, the total cell voltage is 18.0V, and the hydrogen production rate of the cathode region is 400L/h.
The cathode side of the electrolytic cell was operated at 5MPa, and the initial set pressure of the pressure-relief drain recovery tank was 4.5MPa. The pressure release valve is opened once every 5h, the opening time is 5 seconds each time, and part of liquid materials in the cathode side of the electrolytic cell are carried by product hydrogen to enter the pressure release drainage recovery tank. And after the pressure relief valve is closed, the liquid in the pressure relief drainage recovery tank is emptied, and the pressure in the tank is controlled to return to 4.5MPa. After the device is operated for 3000 hours, the rising amplitude of the total tank voltage is very small and is 18.3V.
Example 5
By adopting the scheme of the invention, SO composed of 20 single cells which are sequentially stacked and arranged is manufactured 2 The membrane electrode assembly of the depolarized electrolytic cell consists of an anode catalytic layer and a proton selective permeable membrane. The anode side of the electrolytic cell is provided with an anode material inlet and an anode material outlet; the cathode side was provided with 1 product hydrogen discharge port. The membrane electrode assembly consists of an anode catalytic layer and a proton selective permeable membrane, and a cathode side support body is loaded with a catalyst.
The effective membrane area of each single cell is 1000cm 2 Wherein the proton selective permeation membrane is Nafion 115 proton exchange membrane of DuPont company, the anode side is provided with Pt/C catalyst layer, and the dosage of Pt is 0.5mg/cm 2 The cathode side of the proton selective permeable membrane is free of a catalyst layer. The cathode side support was a graphite felt (porosity 95%, carbon content 99.9%) 2.5mm thick, and Pt/C catalyst was supported by impregnation, with Pt usage at 0.5mg/cm 2 . The anode side support was a graphite felt of 2.5 mm.
The cathode side support body and the surface of the MEA are provided with grid-shaped grooves which are vertically staggered, the width of each groove is 2mm, the depth is 0.8mm, the transverse line spacing of the grid is 30mm, and the longitudinal line spacing of the grid is 30mm.
The cathode side support body and the anode side support body are wrapped with a cathode sealing ring and an anode sealing ring, and the cathode side support body and the anode side support body are made of Viton A fluororubber. Both the upper and lower plates were 1.5mm thick graphite plates (available from POCO Inc. of America).
After the 20 single battery units are stacked and arranged, aluminum alloy end plates are arranged on the two outermost sides, pull rods penetrating through the end plates are arranged, and after the battery units and the end plates are pressed by a press machine, the whole electrolytic cell is fastened by screwing pull rod nuts.
For the SO 2 The depolarized cell was configured as shown in fig. 2, and the cathode side thereof was provided with a cathode washing liquid inlet and outlet, a cathode washing liquid storage tank (storing 46wt.% sulfuric acid as a washing liquid, volume 100L), a cathode washing pump (peristaltic pump), a cathode washing liquid recovery storage tank (volume 80L), and auxiliary lines and valves. The cathode washing liquid outlet and the hydrogen product outlet are a shared outlet. The hydrogen generated on the cathode side enters a cathode washing liquid recovery storage tank through a pipeline from a cathode washing liquid outlet, and is finally discharged through a hydrogen product pipeline.
At 80℃using the SO described above 2 The depolarized electrolytic cell performs electrolytic operation, and anode material is saturated SO-containing material 2 45wt.% sulfuric acid, the cathode area is not fed with materials, the external direct current keeps the current constant 500A, the total tank voltage is 17.1V, and the hydrogen production rate of the cathode area is measured to be-3.81 m 3 /h。
In the running process, the cathode washing pump is started every 20 hours, 2000mL of washing liquid is pumped from the cathode washing liquid storage tank and injected into the cathode side for washing, and after the washing pump is closed, the residual washing liquid in the electrolytic cell is discharged to the cathode washing liquid recovery storage tank along with part of product hydrogen. After the device runs for 2000 hours, the rising amplitude of the total tank voltage is very small and is 17.5V.
Example 6:
SO in example 3 2 The depolarized electrolytic cell and its operation scheme, during operation, the volume of the washing liquid in the cathode washing liquid storage tank is kept not lower than 20L, and the cathode washing liquid recovery storage tank is emptied in time. After continuous operation for 100h, the cathode washing pump was started every 3h, instead of every 12h, to artificially cause a certain amount of elemental sulfur accumulation inside the electrolytic cell, and when the total running time was 5000h (current was always constant at 53A), the total cell voltage was 18.7V. Stopping, washing the cathode region and the anode region of the electrolytic cell by deionized water, and restarting the electrolytic cell under the condition of keeping various parameters such as original temperature, current and the like unchanged before stoppingThe total tank voltage was 18.4V during operation. And stopping the machine again, dismantling the electrolytic cell, washing the MEA and the cathode support body by deionized water, reassembling the electrolytic cell, and running again under the same condition, wherein the total cell voltage is reduced back to 18.0V again. The above description shows that the SO provided by the invention 2 The depolarized electrolytic cell and the operation scheme thereof can ensure that the performance of the MEA is only slightly reduced after long-time operation and can be completely recovered.

Claims (5)

1. SO (SO) device 2 The operation method of the depolarized electrolytic cell comprises one or more single cells which are sequentially arranged, wherein each single cell comprises a membrane electrode assembly (4), a cathode side support body (2), an anode side support body (5), an upper polar plate (1) and a lower polar plate (7), a cathode sealing ring (3) is wrapped on the periphery of the cathode side support body (2), and an anode sealing ring (6) is wrapped on the periphery of the anode side support body (5); the anode side (11) of the electrolytic cell is provided with an anode material inlet (12) and an anode material outlet (13), and the cathode side is provided with a product hydrogen discharge port; the method is characterized in that: the membrane electrode assembly (4) consists of an anode catalytic layer (9) and a proton selective permeable membrane (8), and the cathode side support body (2) is loaded with a catalyst;
the operation method of the electrolytic cell comprises the following steps:
1) A cathode washing liquid inlet (14), a washing liquid outlet (15), a cathode washing liquid storage tank (16), a cathode washing pump (17), a cathode washing liquid recovery storage tank (18) and accessory pipelines and valves are arranged on the cathode side (10) of the electrolytic cell; a hydrogen product discharge pipeline (19) is arranged at the upper part of the cathode washing liquid recovery storage tank;
2)SO 2 in the operation process of the depolarized electrolytic cell, anode materials enter from an anode material inlet (12) and are discharged from an anode material outlet (13); hydrogen generated on the cathode side (10) of the electrolytic cell enters a cathode washing liquid recovery storage tank (18) through a cathode washing liquid outlet (15) and is finally discharged through a hydrogen product discharge pipeline (19);
3) The cathode washing pump (17) is started every 5min to 24h, washing liquid in the cathode washing liquid storage tank (16) is injected into the cathode side (10) of the electrolytic cell through the cathode washing liquid inlet (14), and is discharged to the cathode washing liquid recovery storage tank (18) through the cathode washing liquid outlet (15).
2. SO (SO) device 2 The operation method of the depolarized electrolytic cell comprises one or more single cells which are sequentially arranged, wherein each single cell comprises a membrane electrode assembly (4), a cathode side support body (2), an anode side support body (5), an upper polar plate (1) and a lower polar plate (7), a cathode sealing ring (3) is wrapped on the periphery of the cathode side support body (2), and an anode sealing ring (6) is wrapped on the periphery of the anode side support body (5); the anode side (11) of the electrolytic cell is provided with an anode material inlet (12) and an anode material outlet (13), and the cathode side is provided with a product hydrogen discharge port; the method is characterized in that: the membrane electrode assembly (4) consists of an anode catalytic layer (9) and a proton selective permeable membrane (8), and the cathode side support body (2) is loaded with a catalyst;
the operation method of the electrolytic cell comprises the following steps:
1, a hydrogen product outlet (20), a pressure relief opening (21), a pressure relief valve (22) and a pressure relief drainage recovery tank (23) are arranged on the cathode side (10) of the electrolytic cell; the hydrogen product outlet (20) is arranged at the upper part of the cathode side; the pressure relief opening (21) is arranged at the lower part of the cathode side and is connected with the inlet of the pressure relief drainage recovery tank (23) through a pipeline and a pressure relief valve (22);
2) The SO 2 In the operation process of the depolarized electrolytic cell, anode materials enter from an anode material inlet and are discharged from an anode material outlet; the cathode side of the electrolytic cell operates under the condition of higher than 1 atmosphere, and the generated hydrogen is discharged from a hydrogen product outlet through a hydrogen product pipeline; the initial set pressure of the decompression drainage recovery tank is lower than the cathode side pressure of the electrolytic cell;
3) The pressure release valve (22) is opened once every 5min to 24h, and part of liquid materials in the cathode side (10) of the electrolytic cell are carried by gas to enter the pressure release drainage recovery tank (23); after the pressure release valve (22) is closed, the liquid in the pressure release drainage recovery tank (23) is emptied, and the pressure in the tank is controlled to an initial set value.
3. A SO as claimed in claim 1 or claim 2 2 Method for operating a depolarized cell, characterized in that the cathode sideThe support body (2) adopts a graphite felt loaded with a catalyst, the void ratio is more than or equal to 70 percent, and the carbon content of the graphite felt before loading the catalyst is more than or equal to 98 percent.
4. A SO as claimed in claim 1 or claim 2 2 The operation method of the depolarized electrolytic cell is characterized in that a groove is arranged on one surface of the cathode side support body (2) which is attached to the membrane electrode assembly.
5. An SO as claimed in claim 2 2 A method of operating a depolarized cell, characterized in that in step 2) the cathode side of the cell is operated at a pressure higher than 1 atmosphere, meaning that the cathode side of the cell is operated at a pressure in the range of 1.05 atmospheres to 7MPa; the initial setting pressure of the pressure relief drainage recovery tank being lower than the cathode side pressure of the electrolytic cell means that the initial setting pressure is lower than the pressure of the cathode side of the electrolytic cell by 0.1 atmosphere to 0.7MPa.
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CN109778217A (en) * 2017-11-15 2019-05-21 株式会社东芝 Electrolytic cell and device for producing hydrogen
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CN109778217A (en) * 2017-11-15 2019-05-21 株式会社东芝 Electrolytic cell and device for producing hydrogen
CN111424286A (en) * 2020-02-28 2020-07-17 清华大学 SO (SO)2Depolarized electrolytic cell

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