PBS plastic co-production of succinic acid by electro-oxidation of anode and electro-reduction of cathode

Abstract

The application discloses a PBS plastic electro-oxidation and maleic acid electro-reduction cathode and anode co-production succinic acid process and belongs to the field of electrochemical synthesis and plastic recycling. After pretreatment, PBS plastic is depolymerized into butanediol and succinic acid salt monomers by using an alkaline solution, without separation and purification, maleic acid / maleic anhydride is directly added into the depolymerization solution, and the solution is directly used as an electrolyte after uniform stirring, so that the succinic acid is co-produced at the cathode and anode. The solution obtained after electrolysis is purified by adopting a CO2 assisted sequential precipitation succinic acid and NaHCO3 strategy. The cathode and anode co-production strategy has higher Faraday efficiency and production rate compared with a traditional half-cell reaction, ion exchange membranes are not used, the process operation is simple, and the cost is lower. The CO2 assisted sequential precipitation strategy can greatly reduce the acid consumption, improve the succinic acid yield and purity, and produce NaHCO3 as a by-product, and has higher economic value compared with a direct acidification purification method.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrochemical synthesis and plastic recycling, and relates to a method for electrochemically synthesizing succinic acid, in particular to a method for co-producing succinic acid by using PBS-based plastic and maleic acid as raw materials, and purifying succinic acid by using CO2 acidification and by-produced NaHCO3. BACKGROUND

[0002] Succinic acid, also known as succinic acid, is a dibasic acid containing four carbons, which is colorless crystal, sour taste, soluble in water, ethanol and diethyl ether, and insoluble in chloroform and dichloromethane. Succinic acid is an important precursor for the preparation of five-membered heterocyclic compounds, and can be used as a precursor raw material for BDO, PBS, tetrahydrofuran, Y-butyrolactone, NMP, 2-pyrrolidone and other important compounds, and is widely used in the fields of biological medicine, food, agriculture and the like. The most important application is to synthesize biodegradable plastic (PBS).

[0003] There are many industrial preparation methods for succinic acid, mainly including oxidation method, hydrogenation method, propylene acid carbonyl synthesis method, electrolytic oxidation method, acetylene method and fermentation method. In the oxidation method, paraffin is deeply oxidized to form a mixture of various carboxylic acids, which can be obtained by succinic acid after separation steps such as steam distillation and crystallization. In the hydrogenation method, maleic anhydride or fumaric acid is hydrogenated under the action of a catalyst to form succinic acid, which is then separated to obtain the finished product. The catalyst is nickel or noble metal, and the reaction temperature is about 130-140℃. In the propylene acid carbonyl synthesis method, propylene acid and carbon monoxide are reacted under the action of a catalyst to form succinic acid. It has not been industrialized. In the electrolytic oxidation method, phthalic anhydride is electrolyzed with sulfuric acid and water in a ceramic electrolytic cell at a ratio of 1:0.5:4 to obtain succinic acid. The raw material for electrolytic synthesis is maleic acid or phthalic anhydride, the cathode and anode liquid are separated by a cation membrane, the cathode and anode are generally made of lead plate, and a plate and frame electrolytic cell is usually used for synthesis. In the acetylene method, acetylene, carbon monoxide and water are reacted in the presence of a catalyst in an acidic medium to obtain succinic acid. Compared with traditional chemical methods, the microbial fermentation method for producing succinic acid has many advantages: the production cost is competitive; renewable agricultural resources including carbon dioxide are used as raw materials, avoiding the dependence on petrochemical raw materials; and the environmental pollution caused by chemical synthesis process is reduced. At present, the main synthesis methods are electrolytic synthesis and fermentation method.

[0004] The latest resolution adopted by the United Nations Environment Assembly emphasizes the full life cycle management of plastics, taking the reuse and recycling of plastic products into consideration during the design phase, and focusing on diversified management of plastic pollution. As people's environmental awareness increases, traditional plastics that are difficult to recycle and degrade (such as PE and PP) will gradually fade away, and the proportion of biodegradable plastics will become increasingly higher. PBS, as a raw material that can be derived from bio-based and biodegradable plastics with excellent performance, will be increasingly widely used. As its use becomes more and more widespread, the recycling problem needs to be solved urgently. Due to its unique chemical structure, the product after hydrolysis contains only butanediol and succinic acid. Adding maleic acid to it to achieve the co-production of succinic acid by anode and cathode is a very promising technology that maximizes the utilization of electrons and greatly increases the yield of succinic acid. It not only improves economic benefits but also protects the environment. Summary of the Invention

[0005] The present invention aims to provide a method for producing succinic acid from both anodes and cathodes, improving electron utilization in electrolysis and enabling chemical recovery of PBS-based plastics. This method, which utilizes carbon dioxide to assist in the purification of succinic acid, not only reduces the amount of acid used in the acidification process but also produces baking soda (NaHCO3) as a byproduct, further reducing production costs. Based on these advantages, this method is expected to provide a new and feasible approach to alleviating the plastic crisis.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A process for producing succinic acid by electro-oxidation of PBS plastic and electro-reduction of maleic acid at both cathode and anode, specifically comprising the following steps:

[0008] (1) The recycled waste PBS-based plastic is pretreated to remove impurities that may affect subsequent reactions. After being fully crushed, it is added to a sodium hydroxide or potassium hydroxide solution with a solution concentration range of 0.1 mol / L to 10 mol / L. The higher the alkali concentration, the shorter the hydrolysis time and the more complete the hydrolysis, but it is not conducive to subsequent separation and purification. It is necessary to select an appropriate concentration according to the actual situation, and the heating temperature is controlled at 60°C to 160°C, and the heating time is 12h to 48h;

[0009] (2) directly adding an equivalent amount of maleic acid / maleic anhydride to the hydrolyzate obtained in step (1), and mixing thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid / maleic anhydride;

[0010] (3) the mixed solution obtained in step (2) is directly used as an electrolyte, a non-precious metal catalyst (Ni-based or Co-based metal oxide, sulfide, phosphide, selenide or bimetallic layered hydroxide, metal organic framework, etc.) is used at the anode to electro-oxidize 1,4-butanediol to succinic acid, and a Pd-based / Cu-based catalyst (metallic Pd, Pd alloy, Pd-loaded composite catalyst, metal Cu, Cu alloy, Cu-loaded composite catalyst, foamed Cu, OD-Cu, etc.) is used at the cathode to electro-reduce maleic acid / maleic anhydride to succinic acid;

[0011] (4) introducing an excess of CO2 gas derived from industrial waste gas such as flue gas into the reaction solution obtained in step (3) to pre-acidify the reaction solution, first separating out baking soda with lower solubility, then adding a small amount of acid for acidification, and obtaining succinic acid by filtering, washing, and drying.

[0012] It can be seen from the above technical solution that compared with the prior art, the process of producing succinic acid by electro-oxidation of PBS plastic and electro-reduction of maleic acid by both cathode and anode provided by the present invention has the following excellent effects:

[0013] Compared with traditional landfill and incineration processes, the method of the present invention is more environmentally friendly. The produced succinic acid can be used as a PBS-based plastic monomer to re-enter the plastic economy, reducing carbon dioxide emissions and causing no additional damage to the environment. From an application perspective, the electrochemical device has a small investment, is modular, and can be flexibly configured to meet the needs of the scale. By co-producing succinic acid with the anode and cathode, the electron utilization rate and succinic acid yield can be significantly improved. By assisted purification of succinic acid with carbon dioxide, the amount of acid used in the acidification process can be reduced, and NaHCO3 can be produced as a by-product, further reducing the production cost of succinic acid. In general, the disclosed PBS plastic electro-oxidation and maleic acid electro-reduction process for co-producing succinic acid with the cathode and cathode can not only alleviate the plastic crisis, but also fully utilize electrons, save electricity, and create higher economic value through the co-production of the anode and cathode. The carbon dioxide-assisted purification method can significantly reduce separation costs and complete carbon dioxide capture, meeting the requirements of the "dual carbon" strategic goal. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0015] Figure 1 This is a schematic diagram of the co-production of succinic acid by the anode and cathode in Example 1. DETAILED DESCRIPTION

[0016] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0017] The embodiment of the present invention discloses a process for producing succinic acid by electro-oxidation of PBS plastic and electro-reduction of maleic acid by cathode and anode.

[0018] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0019] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0020] Example 1

[0021] A method for producing succinic acid by anode and cathode, comprising the following steps:

[0022] (1) Here, a small-scale laboratory test was conducted. 17.93 g of the recovered PBS-based plastic was added to 1000 ml of 3 M NaOH solution and hydrothermaled at 90 °C for 12 h.

[0023] (2) filtering the PBS hydrolyzate obtained in step (1) to remove impurities that cannot be dissolved in NaOH to obtain a filtrate, and detecting the concentration of butanediol in the filtrate to be 0.098 mol / L and the concentration of succinic acid to be 0.100 mol / L;

[0024] (3) adding maleic acid at a concentration of 0.392 mol / L to the filtrate obtained in step (2), and stirring thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid;

[0025] (4) 100 ml of the mixed solution of butanediol, succinic acid and maleic acid obtained in step (3) was used as the electrolyte. The anode catalyst used was the non-precious metal catalyst Ni(OH)2 / NF, and the cathode catalyst used was PdCu / NF. The electrode areas were 3*3 cm 2 , assemble the electrolysis system;

[0026] (5) applying a current of 0.6 A to the electrolysis system assembled in step (4) and stopping the electrolysis after the theoretical charge (7564C, 3h30min) is reached;

[0027] (6) introducing CO2 gas into the electrolyte obtained in step (5) to adjust the pH of the solution to 7.8;

[0028] (7) filtering the solution obtained in step (6) to obtain a solid byproduct of NaHCO3 and a filtrate containing succinic acid and a small amount of NaHCO3;

[0029] (8) The filtrate obtained in step (7) was evaporated until a white solid appeared, and the NaHCO3 solid was filtered out again to obtain a filtrate;

[0030] (9) Concentrated hydrochloric acid (11 ml) was added to the filtrate obtained in step (8) to adjust the pH to 1-2. A white solid appeared, which was cooled, filtered, washed and dried to obtain a succinic acid solid with a purity of >96%.

[0031] Example 2

[0032] A method for producing succinic acid by anode and cathode, comprising the following steps:

[0033] (1) 17.93 g of the recovered PBS-based plastic was added to 1000 ml of 3 M NaOH solution and hydroheated at 90 °C for 12 h;

[0034] (2) filtering the PBS hydrolyzate obtained in step (1) to remove impurities that cannot be dissolved in NaOH to obtain a filtrate, and detecting the concentration of butanediol in the filtrate to be 0.098 mol / L and the concentration of succinic acid to be 0.100 mol / L;

[0035] (3) adding maleic acid at a concentration of 0.392 mol / L to the filtrate obtained in step (2), and stirring thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid;

[0036] (4) 100 ml of the mixed solution of butanediol, succinic acid and maleic acid obtained in step (3) was used as the electrolyte. A non-precious metal catalyst was used as the anode catalyst, and a PdCu / NF catalyst was used as the cathode catalyst. The electrode areas were 3*3 cm 2 , assemble the electrolysis system;

[0037] (5) applying a current of 0.7 A to the electrolysis system assembled in step (4) and stopping the electrolysis after the theoretical charge (7564 C, 3 h) is reached;

[0038] (6) introducing CO2 gas into the electrolyte obtained in step (5) to adjust the pH of the solution to 7.8;

[0039] (7) filtering the solution obtained in step (6) to obtain a solid byproduct of NaHCO3 and a filtrate containing succinic acid and a small amount of NaHCO3;

[0040] (8) The filtrate obtained in step (7) was evaporated until a white solid appeared, and the NaHCO3 solid was filtered out again to obtain a filtrate;

[0041] (9) Concentrated hydrochloric acid (11 ml) was added to the filtrate obtained in step (8) to adjust the pH to 1-2. A white solid appeared, which was cooled, filtered, washed and dried to obtain a succinic acid solid with a purity of >96%.

[0042] Example 3

[0043] A method for producing succinic acid by anode and cathode, comprising the following steps:

[0044] (1) 17.93 g of the recovered PBS-based plastic was added to 1000 ml of 3 M NaOH solution and hydroheated at 90 °C for 12 h;

[0045] (2) filtering the PBS hydrolyzate obtained in step (1) to remove impurities that cannot be dissolved in NaOH to obtain a filtrate, and detecting the concentration of butanediol in the filtrate to be 0.098 mol / L and the concentration of succinic acid to be 0.100 mol / L;

[0046] (3) adding maleic acid at a concentration of 0.392 mol / L to the filtrate obtained in step (2), and stirring thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid;

[0047] (4) 100 ml of the mixed solution of butanediol, succinic acid and maleic acid obtained in step (3) was used as the electrolyte. A non-precious metal catalyst was used as the anode catalyst, and a PdCu / NF catalyst was used as the cathode catalyst. The electrode areas were 3*3 cm 2 , assemble the electrolysis system;

[0048] (5) applying a current of 0.8 A to the electrolysis system assembled in step (4) and stopping the electrolysis after the theoretical charge (7564C, 2h38min) is reached;

[0049] (6) introducing CO2 gas into the electrolyte obtained in step (5) to adjust the pH of the solution to 7.8;

[0050] (7) filtering the solution obtained in step (6) to obtain a solid byproduct of NaHCO3 and a filtrate containing succinic acid and a small amount of NaHCO3;

[0051] (8) The filtrate obtained in step (7) was evaporated until a white solid appeared, and the NaHCO3 solid was filtered out again to obtain a filtrate;

[0052] (9) Concentrated hydrochloric acid (11 ml) was added to the filtrate obtained in step (8) to adjust the pH to 1-2. A white solid appeared, which was cooled, filtered, washed and dried to obtain a succinic acid solid with a purity of >96%.

[0053] Example 4

[0054] A method for producing succinic acid by anode and cathode, comprising the following steps:

[0055] (1) 17.93 g of the recovered PBS-based plastic was added to 1000 ml of 3 M NaOH solution and hydroheated at 90 °C for 12 h;

[0056] (2) filtering the PBS hydrolyzate obtained in step (1) to remove impurities that cannot be dissolved in NaOH to obtain a filtrate, and detecting the concentration of butanediol in the filtrate to be 0.098 mol / L and the concentration of succinic acid to be 0.100 mol / L;

[0057] (3) adding maleic acid at a concentration of 0.392 mol / L to the filtrate obtained in step (2), and stirring thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid;

[0058] (4) 100 ml of the mixed solution of butanediol, succinic acid and maleic acid obtained in step (3) was used as the electrolyte. A non-precious metal catalyst was used as the anode catalyst, and PdCu / NF was used as the cathode catalyst. The electrode areas were 3*3 cm 2 , assemble the electrolysis system;

[0059] (5) applying a current of 0.9 A to the electrolysis system assembled in step (4) and stopping the electrolysis after the theoretical charge (7564C, 2h20min) is reached;

[0060] (6) introducing CO2 gas into the electrolyte obtained in step (5) to adjust the pH of the solution to 7.8;

[0061] (7) filtering the solution obtained in step (6) to obtain a solid byproduct of NaHCO3 and a filtrate containing succinic acid and a small amount of NaHCO3;

[0062] (8) The filtrate obtained in step (7) was evaporated until a white solid appeared, and the NaHCO3 solid was filtered out again to obtain a filtrate;

[0063] (9) Concentrated hydrochloric acid (11 ml) was added to the filtrate obtained in step (8) to adjust the pH to 1-2. A white solid appeared, which was cooled, filtered, washed and dried to obtain a succinic acid solid with a purity of >96%.

[0064] Example 5

[0065] A method for producing succinic acid by anode and cathode, comprising the following steps:

[0066] (1) 17.93 g of the recovered PBS-based plastic was added to 1000 ml of 3 M NaOH solution and hydroheated at 90 °C for 12 h;

[0067] (2) filtering the PBS hydrolyzate obtained in step (1) to remove impurities that cannot be dissolved in NaOH to obtain a filtrate, and detecting the concentration of butanediol in the filtrate to be 0.098 mol / L and the concentration of succinic acid to be 0.100 mol / L;

[0068] (3) adding maleic acid at a concentration of 0.392 mol / L to the filtrate obtained in step (2), and stirring thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid;

[0069] (4) 100 ml of the mixed solution of butanediol, succinic acid and maleic acid obtained in step (3) was used as the electrolyte. A non-precious metal catalyst was used as the anode catalyst, and PdCu / NF was used as the cathode catalyst. The electrode areas were 3*3 cm 2 , assemble the electrolysis system;

[0070] (5) applying a current of 1 A to the electrolysis system assembled in step (4) and stopping the electrolysis after the theoretical charge (7564C, 2h6min) is reached;

[0071] (6) introducing CO2 gas into the electrolyte obtained in step (5) to adjust the pH of the solution to 7.8;

[0072] (7) filtering the solution obtained in step (6) to obtain a solid byproduct of NaHCO3 and a filtrate containing succinic acid and a small amount of NaHCO3;

[0073] (8) The filtrate obtained in step (7) was evaporated until a white solid appeared, and the NaHCO3 solid was filtered out again to obtain a filtrate;

[0074] (9) Concentrated hydrochloric acid (11 ml) was added to the filtrate obtained in step (8) to adjust the pH to 1-2. A white solid appeared, which was cooled, filtered, washed and dried to obtain a succinic acid solid with a purity of >96%.

[0075] Comparative Example 1

[0076] A method for producing succinic acid by anode and cathode, comprising the following steps:

[0077] (1) 17.93 g of the recovered PBS-based plastic was added to 1000 ml of 3 M NaOH solution and hydroheated at 90 °C for 12 h;

[0078] (2) The PBS hydrolysate obtained in step (1) is filtered to remove impurities that cannot be dissolved in NaOH to obtain a filtrate, and the concentration of butanediol in the filtrate is 0.098 mol / L and the concentration of succinic acid is 0.100 mol / L;

[0079] (3) Maleic acid with a concentration of 0.392 mol / L is added to the filtrate obtained in step (2), and the mixture solution of butanediol, succinic acid and maleic acid is obtained by fully stirring;

[0080] (4) 100 ml of the mixture solution of butanediol, succinic acid and maleic acid obtained in step (3) is used as an electrolyte, a non-noble metal catalyst is used as an anode catalyst, and PdCu / NF is used as a cathode catalyst, and the electrode area is 3*3 cm 2 , and an electrolysis system is assembled;

[0081] (5) A current of 1 A is applied to the electrolysis system assembled in step (4), and the electrolysis is stopped after passing through the theoretical charge quantity (7564 C, 2h6min);

[0082] (6) Concentrated hydrochloric acid (50 ml) is added to the electrolyte obtained in step (5) until the pH is acidic, and no solid is precipitated;

[0083] (7) The solution obtained in step (6) is rotary evaporated until white solid appears, and then cooled, filtered, washed and dried to obtain succinic acid solid with a purity of >94%, 1.3028 g.

[0084] Comparative Example 2

[0085] A method for producing succinic acid by oxidizing butanediol, comprising the following steps:

[0086] (1) 100 ml of 0.1 mol / L butanediol solution (2 mol / L KOH) is taken, a non-noble metal catalyst is used as an anode catalyst, and PdCu / NF is used as a cathode catalyst, and the electrode area is 3*3 cm 2 , and an electrolysis system is assembled;

[0087] (2) A current of 1 A is applied to the electrolysis system assembled in step (1), and the electrolysis is stopped after passing through the theoretical charge quantity (7564 C, 2h6min);

[0088] Performance test

[0089] Table 1 Comparison of performance indicators of the present application

[0090] project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 FE (%) 179.5 181.5 171 176.3 172.5 172.5 72 <![CDATA[产生速率(g h -1 )]]> 1.82 2.14 2.41 2.73 3.02 3.02 0.85 Hydrochloric acid dosage (ml) 11 11 11 11 11 50 - purity(%) 96 96 96 96 96 94 -

[0091] As can be seen from the above table data, the FE of Examples 1 to 5 of the present application all exceed 170%, and the maximum production rate is 3 g h- 1As shown in the above, the amount of acid used is small; since no CO2 is introduced to adjust the pH in Comparative Example 1, the amount of hydrochloric acid used is 4 times that of the embodiment, and the purified succinic acid product is less and the purity is lower; Comparative Example 2 only uses the anode electro-oxidation reaction of butanediol, and the FE and yield are much smaller than those of the embodiment.

[0092] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the present invention specification under the concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A process for producing succinic acid by electro-oxidation of PBS-based plastics and electro-reduction of maleic acid, characterized in that: The following steps are involved: (1) Add the recycled PBS-based plastic to an alkaline solution and heat it to fully depolymerize it into butanediol and succinic acid; (2) adding a certain concentration of maleic acid / maleic anhydride to the filtrate obtained in step (1), and stirring thoroughly to obtain a mixed solution of butanediol, succinic acid, and maleic acid / maleic anhydride; (3) The mixed solution of butanediol, succinic acid and maleic acid / maleic anhydride obtained in step (2) is used as an electrolyte, a non-precious metal catalyst is used at the anode to electro-oxidize and upgrade the depolymerized 1,4-butanediol to succinic acid, and a Pd-based / Cu-based catalyst is used at the cathode to electro-reduce the maleic acid / maleic anhydride to succinic acid; the Pd-based / Cu-based catalyst is one of metal Pd, a Pd alloy, a Pd-loaded composite catalyst, metal Cu, a Cu alloy, a Cu-loaded composite catalyst, foamed Cu, and oxide-derived copper; (4) Excess CO2 gas is introduced into the reaction solution obtained in step (3) to assist in purifying succinic acid and produce baking soda as a by-product.

2. The PBS-based plastic electro-oxidation and maleic acid electro-reduction process for producing succinic acid in both positive and negative electrodes according to claim 1, wherein: The PBS-based plastic in step (1) is polybutylene succinate.

3. The PBS-based plastic electro-oxidation and maleic acid electro-reduction process for producing succinic acid in both positive and negative electrodes according to claim 1, wherein: The alkaline solution in step (1) is sodium hydroxide, and the concentration of the alkaline solution is 0.1 mol / L to 10 mol / L.

4. The PBS-based plastic electro-oxidation and maleic acid electro-reduction process for producing succinic acid in both positive and negative electrodes according to claim 1, wherein: The heating temperature in step (1) is 60° C. to 160° C., and the heating time is 12 h to 48 h.

5. The PBS-based plastic electro-oxidation and maleic acid electro-reduction cathode and anode co-production of succinic acid process according to claim 1, characterized in that: The maleic acid / maleic anhydride in step (2) is derived from one of petroleum-based and bio-based.

6. The PBS-based plastic electro-oxidation and maleic acid electro-reduction process for producing succinic acid in both cathode and anode according to claim 1, wherein: The non-noble metal catalyst in step (3) is one of Ni-based or Co-based metal oxides, sulfides, phosphides, selenides or double metal layered hydroxides and metal organic frameworks.

7. The PBS-based plastic electro-oxidation and maleic acid electro-reduction process for producing succinic acid in both cathode and anode according to claim 1, wherein: The carbon dioxide in step (4) comes from one of flue gas, industrial waste gas and pure carbon dioxide gas.

8. The PBS-based plastic electro-oxidation and maleic acid electro-reduction process for producing succinic acid by cathode and anode according to claim 1, wherein: The purification method in step (4) is not limited to the carbon dioxide-assisted purification method, but also includes one of complex extraction, two-phase aqueous extraction, calcium salt method, direct crystallization method, ion exchange method, electrodialysis method or distillation method.

Images