CN113235119A

CN113235119A - Plate-frame type flowing electrolytic tank and application thereof

Info

Publication number: CN113235119A
Application number: CN202110144112.4A
Authority: CN
Inventors: 林海波; 张成耀; 丛林川
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-02-02
Filing date: 2021-02-02
Publication date: 2021-08-10

Abstract

The invention discloses a plate-and-frame type flowing electrolytic cell and application thereof, belonging to the field of electrochemical industry. The electrolytic cell comprises baffles, sealing gaskets, cell plates, sealing gaskets and baffles which are sequentially arranged, the baffles, the sealing gaskets, the cell plates, the sealing gaskets and the baffles are integrated together through fasteners, the electrolytic cell groups can be connected in series or in parallel as required to carry out large-scale industrial production, and meanwhile, separable parts are easy to maintain and replace. The trough plate with the baffle plate and the spoiler can increase the mixed flow degree of the electrolyte in the trough chamber, prolong the retention time and improve the electrolysis efficiency. The invention is mainly applied to electrolyze N, N '-diacetyl-L-cystine to prepare N-acetyl-L-cysteine, the solution of N, N' -diacetyl-L-cystine hydrochloric acid or sulfuric acid flows in a cathode chamber, and a lead or carbon electrode is used as a cathode; hydrochloric acid or sulfuric acid solution flows in the anode chamber, and the noble metal oxide coating titanium electrode is used as an anode.

Description

Plate-frame type flowing electrolytic tank and application thereof

Technical Field

A plate-frame flow electrolytic cell and its application belong to the electrochemical industry field, mainly used for electrolyzing N, N' -diacetyl-L-cystine to prepare N-acetyl-L-cysteine.

Background

N-acetyl-L-cysteine NAC is an acetylation product of L-cysteine, and is widely applied to the pharmaceutical industry as a pharmaceutical adjuvant, a bulk drug and a pharmaceutical intermediate. Sulfydryl contained in the NAC molecule can break a disulfide bond of a protein peptide bond, can decompose mucin in mucus sputum, and is used as an expectorant to reduce the viscosity of the sputum and promote the excretion; 3% NAC in water can also be used as eye drops for treating keratitis; NAC is also a potent collagenase inhibitor and antioxidant, and can inhibit tissue and cell necrosis of the body due to canceration. Meanwhile, NAC can reduce melanin under the epidermis, so that NAC is widely applied to whitening skin care cosmetics and is popular with people.

Due to the wide application of N-acetyl-L-cysteine in the pharmaceutical and cosmetic industries, the market demand is gradually increased at home and abroad in recent years, and the preparation technology of the N-acetyl-L-cysteine is increasingly concerned by people. There are two main processes for the preparation of N-acetyl-L-cysteine, one is acetylation of L-cysteine, which needs to be reduced from L-cystine. Another technical route is to acetylate L-cystine directly and then reduce. However, either method requires the disulfide bond to be opened. Traditionally, a reducing agent is added for chemical reduction, but the product obtained by the method contains heavy metal impurities which are difficult to treat, and has low yield and high pollution. With the development of the electrochemical industry, the electrochemical reduction technology is gradually favored. The electrochemical reduction method has the advantages of good product quality, low cost, easy separation, small pollution and the like, and has a great development prospect. The electrolytic reaction of N, N' -diacetyl-L-cystine is as follows:

the electrolytic cell is a main device for electrochemical reduction, and the common electrolytic cell has large resistance and high cell pressure in the electrolytic process, is accompanied with serious heat release and hydrogen and oxygen evolution, and is not beneficial to industrial design and installation. The plate-and-frame type flowing electrolytic cell has the advantages of compact structure, large volume current density, high space-time yield, low cell pressure, easy heat dissipation and the like, and is widely applied to the electrochemical industry.

Disclosure of Invention

The invention aims to solve the problems of large resistance, high cell pressure, severe heat release, hydrogen evolution, oxygen evolution and the like of a common electrolytic cell in the process of electrolyzing N, N' -diacetyl-L-cystine and provides a plate-frame type electrolytic cell and an application method thereof.

Therefore, the technical scheme adopted by the invention is as follows:

the utility model provides a plate and frame flow electrolysis trough, the electrolysis trough comprises baffle I1, sealed pad I2, anode electrode 3, frid I4, sealed pad II 5, cation exchange membrane 6, sealed pad III 7, frid II 8, cathode electrode 9, sealed pad IV 10, baffle II 11 that arrange in proper order, assembles together through the fastener. The baffle I1 and the groove plate I4 form an anode chamber through a sealing gasket II 5, and an anode 3 is arranged in the anode chamber; the groove plate II 8 and the baffle plate II 11 form a cathode chamber through a sealing gasket IV 10, and a cathode 9 is arranged in the cathode chamber; a cation exchange membrane 6 is arranged between the groove plate I4 and the groove plate II 8 and is respectively sealed by two sealing gaskets II 5 and III 7;

the electrolytic cell is of a cuboid structure, wherein the baffle I1 and the baffle II 11 are cuboid plates; frid I4 and frid II 8 are hollow square frame board, and the cavity recess becomes two-stage ladder space, and first order recess 12 shape size matches with used positive pole or cathode electrode size, and second level recess 13 is anode chamber or cathode chamber, and there are hole and cell intercommunication in the upper left corner and the lower right corner, and the outside has the pipeline of stretching out to supply external.

The second-stage grooves 13 of the groove plates I4 and II 8 are added with baffle plates 14 and flow blocking plates 15, the baffle plates are arranged in a Z shape to increase the flow, and the flow blocking plates are vertical to the baffle plates to intensify the turbulence degree. The height of the baffle plate is the same as that of the spoiler, and a gap is reserved between the baffle plate and the electrode, so that the effective electrolysis area of the electrode is not reduced.

Baffle I1, baffle II 11, frid I4 and frid II 8 all adopt polypropylene or the acidproof plastics material of polytetrafluoroethylene to make.

The sealing gasket I2 and the sealing gasket IV 10 are both in a cuboid plate shape, and the size of the sealing gasket is matched with that of the corresponding surface of the baffle I1 and the baffle II 11; the sealing gasket II 5 and the sealing gasket III 7 are both hollow frame-shaped, and the sizes of the sealing gaskets are matched with the sizes of corresponding surfaces of the groove plate I4 and the groove plate II 8.

The sealing gasket I2, the sealing gasket II 5, the sealing gasket III 7 and the sealing gasket IV 10 are all made of rubber or silica gel acid-resistant materials.

The cation exchange membrane 6 is a sulfonic acid type ion exchange membrane.

Preferably, the anode electrode 3 is a noble metal oxide coated titanium electrode; the cathode electrode 9 is a lead electrode, a silver electrode, other metal and alloy electrodes thereof, a carbon electrode, a graphite electrode and other non-metal electrodes.

The baffle, the sealing gasket, the trough plate and the cation exchange membrane are all provided with 8 holes which are symmetrically distributed, so that all the parts of the electrolytic cell are assembled together through screw fasteners.

The invention also provides the application of the plate-frame type flowing electrolytic cell, wherein 0.1-2 mol L of anode chamber flows^-1Hydrochloric acid, sulfuric acid or nitric acid solution of (a); the cathode chamber flows 0.1-2 mol L^-1The concentration of the supporting solvent is 0.1-2 mol L^-1Hydrochloric acid or sulfuric acid; electrolyte flows in all chambers are from the lower port to the upper port, and the circulating pump is driven by the matched corrosion-resistant magnetic force to circulate.

The electrolysis process is constant current electrolysis, and the current density is 20-500 mA cm^-2。

Several electrolytic cells can be connected in series or in parallel to form an electrolytic cell group. When in series connection, the outlet of the anode chamber or cathode chamber of the previous electrolytic cell unit is connected with the inlet of the corresponding anode chamber or cathode chamber of the next electrolytic cell unit; when in parallel connection, one pipeline is divided into a plurality of branches, and the electrolyte enters a plurality of unit electrolytic cells simultaneously. Or series and parallel connection according to requirements.

The anodes and the cathodes of the unit electrolytic cells are connected together in parallel regardless of the serial connection or the parallel connection.

The invention has the advantages that

The electrolytic cell disclosed by the invention is simple in structure, and the separable parts are easy to transport, install, maintain and replace, so that the problems of large resistance, high cell pressure, heat release, hydrogen evolution, oxygen evolution and the like of a common electrolytic cell used in the conventional process of electrolyzing the N, N' -diacetyl-L-cystine are solved, and industrial large-scale production can be realized.

The cell plate of the electrolytic cell is added with the baffle plate and the flow baffle plate to increase the flow and turbulence degree of electrolyte in the electrode chamber, and the height of the baffle plate is the same as that of the flow baffle plate and a gap is reserved between the baffle plate and the electrode, so that the effective electrolysis area of the electrode is not reduced, and the electrolysis efficiency is improved.

The electrolytic cell can be used for the industrial amplification of preparing N-acetyl-L-cysteine by electrolyzing N, N' -diacetyl-L-cystine, and can also be used for the production of other chemical products related to electrochemical reaction.

Drawings

FIG. 1: a plate and frame flow cell decomposition scheme;

FIG. 2: a left view of the assembled cell;

FIG. 3: FIG. 2 is a sectional view taken along line A-A;

FIG. 4: a structural schematic diagram of the groove plate;

FIG. 5: a schematic diagram of the electrode shape;

FIG. 6: a process flow chart for applying plate-frame type flowing electrolytic cell;

in the figure: 1-baffle I, 2-sealing gasket I, 3-anode, 4-groove plate I, 5-sealing gasket II, 6-cation exchange membrane, 7-sealing gasket III, 8-groove plate II, 9-cathode, 10-sealing gasket IV, 11-baffle II, 12-first-stage groove, 13-second-stage groove, 14-baffle plate and 15-spoiler plate.

Detailed Description

The invention will now be further illustrated by reference to the following figures and examples:

example 1:

1) assembling the electrolytic cell: according to the decomposition schematic diagram of a plate and frame type flow electrolytic cell shown in figure 1, a baffle plate I1, a sealing gasket I2, an anode electrode 3, a channel plate I4, a sealing gasket II 5, a cation exchange membrane 6, a sealing gasket III 7, a channel plate II 8, a cathode electrode 9, a sealing gasket IV 10 and a baffle plate II 11 are assembled in sequence and are assembled together through eight fastening screws, figure 2 is a left side view after the assembly is completed, and figure 3 is a cross-sectional view of the inside of the cell body of the cross section of figure 2A-A. The groove plates I4 and II 8 adopt plate frames as shown in figure 4. The baffle I1, the baffle II 11, the groove plate I4 and the groove plate II 8 are all made of polypropylene materials, and the sealing gasket I2, the sealing gasket II 5, the sealing gasket III 7 and the sealing gasket IV 10 are made of rubber materials and are all stable in acid electrolyte; the cation exchange membrane 6 adopts a perfluorinated sulfonic acid cation exchange membrane; the anode electrode 3 adopts an iridium oxide titanium electrode of 5 multiplied by 5 cm; the cathode electrode 9 was a lead electrode 5X 5cm in shape as shown in FIG. 5.

2) An electrolysis process: the electrolytic process flow is shown in figure 6. 16.22g of N, N' -diacetyl-L-cystine are dissolved in 500mL of 0.1mol L^-10.1mol L of hydrochloric acid solution^-1The N, N' -diacetyl-L-cystine hydrochloride solution of (a) as a catholyte; 500mL0.1mol L of the anolyte was used^-1Sulfuric acid solution of (2); constant current electrolysis with current density of 20mA cm^-2(ii) a The electrolysis time is 8 h. Distilling electrolyzed catholyte under reduced pressure at 70 ℃, cooling for crystallization, performing suction filtration to obtain a crude product of N-acetyl-L-cysteine, dissolving the crude product in water, adding activated carbon for decoloring at 60 ℃ for 1h, performing vacuum distillation at 70 ℃, recrystallizing, performing suction filtration, and drying to obtain a refined product of N-acetyl-L-cysteine 15.33g, wherein the yield is 93.9 percent and C is₅H₉NO₃The S content is 98.9%.

Example 2:

1) assembling the electrolytic cell: according to the decomposition schematic diagram of a plate-and-frame type flow electrolytic cell shown in figure 1, a baffle plate I1, a sealing gasket I2, an anode electrode 3, a groove plate I4, a sealing gasket II 5, a cation exchange membrane 6, a sealing gasket III 7, a groove plate II 8, a cathode electrode 9, a sealing gasket IV 10 and a baffle plate II 11 are assembled in sequence and are assembled together through eight fastening screws. The baffle I1 and the baffle II 11, the groove plate I4 and the groove plate II 8 are all made of polytetrafluoroethylene materials, and the sealing gasket I2, the sealing gasket II 5, the sealing gasket III 7 and the sealing gasket IV 10 are made of silica gel materials and are all stable in acid electrolyte; the cation exchange membrane 6 adopts a CMI-7000 cation exchange membrane; the anode electrode 3 adopts a Ru-Ti-Sn ternary oxide coating titanium electrode of 5 multiplied by 5 cm; the cathode electrode 9 is a silver electrode of 5X 5 cm.

2) An electrolysis process: the electrolytic process flow is shown in figure 6. 48.66g of N, N' -diacetyl-L-cystine were dissolved in 500mL of 0.3mol L^-10.3mol L of sulfuric acid solution^-1The N, N' -diacetyl-L-cystine sulfuric acid solution is used as a cathode electrolyte; 500mL of 1mol L anolyte was used^-1Nitric acid solution of (4); constant current electrolysis with current density of 60mA cm^-2(ii) a The electrolysis time is 8 h. Distilling electrolyzed catholyte under reduced pressure at 70 ℃, cooling for crystallization, performing suction filtration to obtain a crude product of N-acetyl-L-cysteine, dissolving the crude product in water, adding activated carbon for decoloring at 60 ℃ for 1h, performing vacuum distillation at 70 ℃, recrystallizing, performing suction filtration, and drying to obtain 46.27g of refined product of N-acetyl-L-cysteine with yield of 94.5 percent and C content₅H₉NO₃The S content is 99.3%.

Example 3:

1) assembling the electrolytic cell: according to the decomposition schematic diagram of a plate-and-frame type flow electrolytic cell shown in figure 1, a baffle plate I1, a sealing gasket I2, an anode electrode 3, a groove plate I4, a sealing gasket II 5, a cation exchange membrane 6, a sealing gasket III 7, a groove plate II 8, a cathode electrode 9, a sealing gasket IV 10 and a baffle plate II 11 are assembled in sequence and are assembled together through eight fastening screws. The baffle I1 and the baffle II 11, the groove plate I4 and the groove plate II 8 are all made of polytetrafluoroethylene materials, and the sealing gasket I2, the sealing gasket II 5, the sealing gasket III 7 and the sealing gasket IV 10 are made of silica gel materials and are all stable in acid electrolyte; the cation exchange membrane 6 adopts a perfluorinated sulfonic acid cation exchange membrane; the anode electrode 3 adopts a Ru-Ti-Sn ternary oxide coating titanium electrode of 5 multiplied by 5 cm; the cathode electrode 9 was a carbon electrode of 5X 5 cm.

2) An electrolysis process: the electrolytic process flow is shown in figure 6. 81.09g of N, N' -diacetyl-L-cystine were dissolved in 500mL of 0.5mol L^-10.5mol L of hydrochloric acid solution^-1N, N' -diacetyl-L-cystine hydrochloride of (1)A liquid as a catholyte; 500mL0.5mol L of the anolyte was used^-1Sulfuric acid solution of (2); constant current electrolysis with current density of 80mA cm^-2(ii) a The electrolysis time is 10 h. Distilling electrolyzed catholyte under reduced pressure at 70 ℃, cooling for crystallization, performing suction filtration to obtain a crude product of N-acetyl-L-cysteine, dissolving the crude product in water, adding activated carbon for decoloring at 60 ℃ for 1h, performing vacuum distillation at 70 ℃, recrystallizing, performing suction filtration, and drying to obtain 77.27g of refined product of N-acetyl-L-cysteine with yield of 94.7 percent and C content₅H₉NO₃The S content is 99.8%.

Example 4:

1, assembling the electrolytic cell: according to the decomposition schematic diagram of a plate-and-frame type flow electrolytic cell shown in figure 1, a baffle plate I1, a sealing gasket I2, an anode electrode 3, a groove plate I4, a sealing gasket II 5, a cation exchange membrane 6, a sealing gasket III 7, a groove plate II 8, a cathode electrode 9, a sealing gasket IV 10 and a baffle plate II 11 are assembled in sequence and are assembled together through eight fastening screws. The baffle plates I1 and 11 and the groove plates I4 and 8 are made of polytetrafluoroethylene materials, and the sealing gaskets I2, 5, 7 and 10 are made of silica gel materials and are stable in acid electrolyte; the cation exchange membrane 6 adopts a CMI-7000 cation exchange membrane; the anode electrode 3 adopts a Ru-Ti-Sn ternary oxide coating titanium electrode of 10 multiplied by 10 cm; the cathode electrode 9 is a carbon electrode of 10X 10 cm.

2, electrolysis process: the electrolytic process flow is shown in figure 6. 162.19g of N, N '-diacetyl-L-cystine is dissolved in 500mL of 1mol of L-1 hydrochloric acid solution to prepare 1.0mol of L-1N, N' -diacetyl-L-cystine hydrochloric acid solution which is used as a cathode electrolyte; 500mL of 1.0mol L-1 sulfuric acid solution is used as the anolyte; electrolyzing at constant current with current density of 40mA cm-2; the electrolysis time is 10 h. Distilling electrolyzed catholyte under reduced pressure at 70 ℃, cooling for crystallization, performing suction filtration to obtain a crude product of N-acetyl-L-cysteine, dissolving the crude product in water, adding activated carbon for decoloring at 60 ℃ for 1h, performing vacuum distillation at 70 ℃, recrystallizing, performing suction filtration, and drying to obtain 153.75g of refined product of N-acetyl-L-cysteine with yield of 94.1 percent and C content₅H₉NO₃The S content is 100.1%.

Example 5:

2, electrolysis process: the electrolytic process flow is shown in figure 6. Dissolving 324g of N, N '-diacetyl-L-cystine in 500mL of 2.0mol of L-1 hydrochloric acid solution to prepare 2.0mol of L-1N, N' -diacetyl-L-cystine hydrochloric acid solution as a cathode electrolyte; 500mL of 2mol L-1 sulfuric acid solution is used as the anolyte; electrolyzing at constant current with current density of 100mA cm-2; the electrolysis time was 9 h. Distilling electrolyzed catholyte under reduced pressure at 70 ℃, cooling for crystallization, performing suction filtration to obtain a crude product of N-acetyl-L-cysteine, dissolving the crude product in water, adding activated carbon for decoloring at 60 ℃ for 1h, performing vacuum distillation at 70 ℃, recrystallizing, performing suction filtration, and drying to obtain 305.16g of a refined product of N-acetyl-L-cysteine, wherein the yield is 93.5 percent and C is₅H₉NO₃The S content is 99.6%.

Claims

1. A plate and frame type flow electrolytic cell is characterized in that: the electrolytic cell consists of a baffle I (1), a sealing gasket I (2), an anode electrode (3), a cell plate I (4), a sealing gasket II (5), a cation exchange membrane (6), a sealing gasket III (7), a cell plate II (8), a cathode electrode (9), a sealing gasket IV (10) and a baffle II (11) which are sequentially arranged and assembled together through a fastener; the baffle I (1) and the groove plate I (4) are sealed through a sealing gasket II (5), an anode chamber is arranged between the baffle I (1) and the groove plate I (4), and an anode (3) is arranged in the anode chamber; the trough plate II (8) and the baffle plate II (11) are sealed through a sealing gasket IV (10), a cathode chamber is arranged between the trough plate II and the baffle plate II, and a cathode (9) is arranged in the cathode chamber; a cation exchange membrane (6) is arranged between the groove plate I (4) and the groove plate II (8) and is respectively sealed by a sealing gasket II (5) and a sealing gasket III (7);

the electrolytic bath is of a cuboid structure, wherein the baffle I (1) and the baffle II (11) are cuboid plates; frid I (4) and frid II (8) are hollow square frame board, and the cavity recess becomes two-stage ladder space, and first order recess (12) shape and size matches with used positive pole or cathode electrode size, and second level recess (13) are anode chamber or cathode chamber, and there are hole and cell intercommunication in the upper left corner and the lower right corner, and the outside has the pipeline of stretching out in order to supply external.

2. A plate and frame flow cell according to claim 1, wherein: a baffle plate (14) and a flow baffle plate (15) are added to a second-stage groove (13) of the groove plate I (4) and the groove plate II (8), the baffle plates are arranged in a Z shape to increase the flow, and the flow baffle plate is vertical to the baffle plates to intensify the turbulence degree. The height of the baffle plate is the same as that of the spoiler, and a gap is reserved between the baffle plate and the electrode, so that the effective electrolysis area of the electrode is not reduced.

3. A plate and frame flow cell according to claim 1, wherein: baffle I (1), baffle II (11), frid I (4), frid II (8) all adopt polypropylene or polytetrafluoroethylene acidproof plastics material to make.

4. A plate and frame flow cell according to claim 1, wherein: the sealing gasket I (2) and the sealing gasket IV (10) are both in a cuboid plate shape, and the size of the sealing gasket I (2) and the size of the sealing gasket IV (10) are matched with the size of corresponding surfaces of the baffle I (1) and the baffle II (11); the sealing gasket II (5) and the sealing gasket III (7) are both hollow frame-shaped, and the sizes of the sealing gaskets are matched with the sizes of the corresponding surfaces of the groove plate I (4) and the groove plate II (8).

5. A plate and frame flow cell according to claim 4, wherein: the sealing gasket I (2), the sealing gasket II (5), the sealing gasket III (7) and the sealing gasket IV (10) are all made of rubber or silica gel acid-resistant materials.

6. A plate and frame flow cell according to claim 1, wherein: the cation exchange membrane (6) is a sulfonic acid type ion exchange membrane.

7. A plate and frame flow cell according to claim 1, wherein: the anode electrode (3) is a noble metal oxide coating titanium electrode; the cathode electrode (9) is a lead electrode, a silver electrode and a carbon electrode or a graphite electrode.

8. A plate and frame flow cell according to claim 1, wherein: baffle I (1) and baffle II (11), sealed I (2) of filling up, sealed II (5) of filling up, sealed III (7) of filling up and sealed IV (10), frid I (4), frid II (8) and cation exchange membrane all have all around 8 holes that are the symmetric distribution to supply to assemble all parts of electrolysis trough together through screw fastener.

9. Use of a plate and frame flow cell according to claim 1, wherein: 0.1-2 mol L of anode chamber flows^-1Hydrochloric acid, sulfuric acid or nitric acid solution of (a); the cathode chamber flows 0.1-2 mol L^-1The concentration of the supporting solvent is 0.1-2 mol L^-1Hydrochloric acid or sulfuric acid; electrolyte flows in all chambers are from the lower port to the upper port, and the circulating pump is driven by the matched corrosion-resistant magnetic force to circulate.

10. Use of a plate and frame flow cell according to claim 9, wherein: the electrolysis process is constant current electrolysis, and the current density is 20-500 mA cm^-2。