Application of ionic liquid coupled metal organic framework material as succinic acid extraction material and method

Abstract

The invention relates to the technical field of separation of organic acids, and discloses an application of an ionic liquid coupled metal organic framework material as a succinic acid extraction material and a method, and succinic acid in fermentation liquor is extracted by taking an ionic liquid and a metal organic framework (MOF) as extraction agents. The method comprises the following steps: extracting succinic acid through the affinity difference between ionic liquid and organic acid, and adsorbing acetic acid which is difficult to separate through the dynamic size difference to obtain high-purity succinic acid. The ionic liquid obtained after reverse extraction is washed with deionized water and dried for reuse, and the MOF material can be washed with methanol and dried for reuse. And evaporating and crystallizing the strip liquor to obtain succinic acid. The ionic liquid used in the method is high in extraction capacity, and the polymer-grade-purity succinic acid is obtained after part of acetic acid is removed through MOF adsorption. The ionic liquid and the MOF material used in the method can be regenerated, so that the use amount of the organic solvent can be reduced, and the greenization of the extraction process is realized.

Description

Technical Field

[0001] The invention relates to the technical field of separation of organic acids, in particular to the application of ionic liquids and MOF materials in separation technology, and also to a new separation method for obtaining high-purity organic acids. Background Art

[0002] As an important four-carbon dicarboxylic acid, succinic acid is widely used in food, chemical, pharmaceutical and agricultural fields, and has a huge market demand. Succinic acid is mainly used as an ion chelating agent in the chemical industry and is used to prevent metal dissolution and pitting in the electroplating industry; it can be used for sizing to prevent shrinkage, improve dyeability, improve caprolactam viscosity and fire resistance in textile processing; in the pharmaceutical industry, succinic acid can be used to produce sulfonamides, vitamin A, vitamin B, antispasmodics, diuretics, hemostatics and expectorants. In particular, high-purity succinic acid is a monomer of the important biodegradable plastic polybutylene succinate. However, the product concentration in the succinic acid fermentation broth is low and the composition is complex, mainly including bacteria, residual sugars in the fermentation broth, inorganic salts and fermentation by-products. The cost of downstream separation accounts for 50%-70% of the total production cost, and it is urgent to develop an efficient succinic acid purification method.

[0003] At present, the main separation methods of succinic acid from biological fermentation include calcium salt method, ammonia precipitation method, magnesium salt method, electrodialysis method and liquid-liquid extraction. The calcium salt method has low yield, many by-products, and the acid and alkali in the precipitation process cannot be recovered; the ammonia precipitation method and the magnesium salt method have high thermal cracking energy consumption and difficult to recover the alkali solution; the electrodialysis method is expensive. Liquid-liquid extraction uses alkaline amine extractants to produce hydrogen bonds, electrostatic interactions and other interactions with the carboxyl groups of organic acids. It is simple to operate, has mild separation conditions, and exhibits a certain organic acid extraction ability. Single alkaline amine extractants often have a certain solubility and high viscosity in the aqueous phase, so polarity regulators (such as kerosene and tributyl phosphate) and diluents (such as n-octanol) are often required. However, simple amine extractants have low extraction efficiency, and due to the similar separation mechanism, succinic acid and its miscellaneous acids cannot be effectively distinguished. Therefore, based on the characteristics of succinic acid and its miscellaneous acids, from the perspective of molecular recognition and separation, an ionic liquid and metal organic framework coupling system is designed to achieve efficient purification of succinic acid in the fermentation broth by means of affinity differences and molecular size differences.

[0004] Among them, metal organic frameworks (MOFs) are composed of metal ions / clusters coordinated by organic ligands, and have the advantages of chemical and structural tunability, excellent thermal stability, ultra-high porosity, and large specific surface area. Ionic liquids refer to salts that are liquid at room temperature or close to room temperature and are completely composed of anions and cations, also known as low-temperature molten salts. The structures of ionic liquids and metal organic framework materials are highly designable and can be adjusted according to specific separation tasks. The composite system has the potential to separate succinic acid with high selectivity, low cost, and low energy consumption. Summary of the invention

[0005] In view of this, one of the purposes of the present invention is to use ionic liquid coupled metal organic framework materials as materials for extracting succinic acid; a second purpose of the present invention is to provide a method for purifying succinic acid using ionic liquid coupled metal organic framework materials.

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

[0007] 1. Application of ionic liquid coupled metal organic framework materials as materials for extracting succinic acid.

[0008] Preferably, the ionic liquid is composed of guanidine cations and halogen anions, the guanidine cations are hexaalkylguanidine ions with different carbon chains, and the halogen anions are bromide ions and chloride ions.

[0009] Preferably, the metal organic framework material of the present invention is a metal organic framework material having acid stability and water stability with zirconium, zinc or cobalt ions as metal sites and organic carboxylic acids as ligands.

[0010] Preferably, in the present invention, the mass ratio of the ionic liquid to the metal organic framework material in the ionic liquid coupled metal organic framework material is 10-50:5-20.

[0011] 2. A method for purifying succinic acid by coupling an ionic liquid to a metal organic framework material, comprising the following steps:

[0012] (1) mixing an ionic liquid with a metal organic framework material to obtain a coupling system of the ionic liquid and the metal organic framework material, then adding a succinic acid fermentation broth to the mixture, adding n-octanol to perform liquid-liquid extraction, separating the two phases after the extraction, and centrifuging to separate the ionic liquid phase and the MOF and metal organic framework material phase;

[0013] (2) adding a stripping agent to the ionic liquid phase for secondary extraction, and evaporating and crystallizing the stripping agent to obtain succinic acid with a purity higher than 99%; the 1 mol / L NaOH solution, distilled water or n-hexane.

[0014] Preferably, in step (1), the ionic liquid, the metal organic framework material and n-octanol constitute an extraction system, the volume ratio of the ionic liquid in the extraction system is 10% to 50%, the volume ratio of the metal organic framework material in the extraction system is 5% to 20%; the volume ratio of the n-octanol in the extraction system is 50% to 85%, the mass ratio of the extraction system to the fermentation liquid is 1:5 to 5:1, the extraction temperature is 10 to 50°C, the extraction time is 2h, and the pH of the extraction system is 2 to 6.

[0015] Preferably, in step (2), the ratio of stripping agent to ionic liquid phase is 1:1 to 2:1, and the stripping temperature is 25°C to 70°C.

[0016] Preferably, the ionic liquid is [diHTMG]Cl, [diOTMG]Cl, [diDTMG]Cl, [diOTMG]Br, [diHTMG]Br or [diBTMG]Br; the metal organic framework material is MET-Fe, UiO-66, Zr-oxa, Zr-bptc, ​​Zr-fru, ZiF-7 or ZiF-79.

[0017] Preferably, in the present invention, the mass ratio of the ionic liquid to the metal organic framework material is 20:1.

[0018] Preferably, the present invention further includes a recovery step after step (2), specifically, washing the ionic liquid with deionized water, and drying it for later use; washing the metal organic framework material with methanol, and drying it for later use.

[0019] The beneficial effects of the present invention are as follows: the present invention discloses a method for extracting and separating succinic acid with high recognition, which adopts the method of extraction coupled adsorption, firstly selectively enriching succinic acid by affinity difference through ionic liquid, and then further removing acetic acid by MOF material according to kinetic size difference. Ionic liquid and MOF material are highly designable, and can achieve high extraction rate and high recognition separation of succinic acid and acetic acid. The single extraction rate of a single ionic liquid for high-concentration succinic acid fermentation broth (0.83 mol / L) reaches 80.13%. The porous adsorbent can achieve selective adsorption of succinic acid and acetic acid, and the final purity of succinic acid can reach 99.97% after adsorption and stripping. Compared with the traditional recovery method, this method does not require thermal cracking, has mild conditions and lower energy consumption; compared with the traditional organic solvent liquid-liquid extraction, this method is greener, and has higher extraction efficiency and selectivity. The present method has the characteristics of significant energy saving, environmental protection, safety and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0021] Figure 1 is the extraction rate of succinic acid by different ionic liquids and common extractants;

[0022] Figure 2 is the adsorption rate of acetic acid and succinic acid by different adsorbents;

[0023] Figure 3 The effects of different neutralizers, succinic acid concentrations, and acetic acid concentrations on extraction in a real fermentation system;

[0024] Figure 4 The stripping effect of different recovery methods. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0026] Example 1. Preparation of functionalized guanidine ionic liquid

[0027] 0.06 mol 1,1,3,3-tetramethylguanidine, 0.2 mol alkyl halide, 2% tetrabutylammonium bromide and 10 g potassium carbonate were added to a round-bottom flask containing 120 mL acetonitrile, and heated under reflux at 50 °C with mechanical stirring for 12 hours. After the reaction was completed, it was cooled to room temperature, filtered, and 100 mL H 2 O in the filtrate. The mixture was extracted three times with 45 mL of petroleum ether to remove impurities such as unreacted alkyl halide and pentaalkylguanidine. The petroleum ether phase was washed with 30 mL of H 2 O was used for back extraction, and 40 mL of saturated sodium chloride aqueous solution was added to the combined mixed aqueous phase. Finally, the saturated aqueous layer was extracted three times with 50 mL of dichloromethane, and the extracted organic layer was dried over anhydrous magnesium sulfate, filtered, and then subjected to reduced pressure distillation. After drying, guanidine-based ionic liquids with different side chains were obtained, which were [diHTMG]Cl, [diOTMG]Cl, [diDTMG]Cl, [diOTMG]Br, [diHTMG]Br, and [diBTMG]Br. The corresponding alkyl halides of [diHTMG]Cl, [diOTMG]Cl, [diDTMG]Cl, [diOTMG]Br, [diHTMG]Br, and [diBTMG]Br were hexyl chloride, octyl chloride, decyl chloride, octyl bromide, hexyl bromide, and butyl bromide.

[0028] Example 2: Recovery of Succinic Acid by Liquid-Liquid Extraction with Different Ionic Liquids

[0029] Take 1 ml of 10 g / L succinic acid solution, 250 μL of ionic liquid, and 750 μL for liquid-liquid extraction. The extraction temperature is 25°C and the extraction time is 2 h. The ionic liquids are [diHTMG]Cl, [diOTMG]Cl, [diDTMG]Cl, [diOTMG]Br, [diHTMG]Br, and [diBTMG]Br. After the extraction, the two phases are separated. The extraction rate of succinic acid for [diHTMG]Cl is 40.13%, [diOTMG]Cl is 68.91%, [diDTMG]Cl is 51.86%, [diOTMG]Br is 29.29%, [diHTMG]Br is 37.14%, and [diBTMG]Br is 33.05% ( Figure 1 ).

[0030] Example 3: Preparation of Metal MOF Materials

[0031] Preparation of UiO-66, Zr-oxa, and Zr-fru: 1.08 mmol ZrCl 4 and 2mL concentrated hydrochloric acid were dissolved in 10mL N,N-dimethylformamide, added to the lining of the hydrothermal synthesis reactor, and ultrasonically treated for 30min until the solid was completely dissolved. 1.5mmol of the corresponding organic ligand and 20mL N,N-dimethylformamide were added, and ultrasonically treated for 30min until the solid was completely dissolved. The mixture was sealed in a hydrothermal synthesis reactor and reacted at 120℃ for 8h. After 8h, the solid was centrifuged and washed three times with DMF, soaked in DMF for 2h, washed with acetone after centrifugation, soaked in acetone for 12h, washed with acetone again after centrifugation, soaked in acetone for 2h, and centrifuged to obtain a solid. The solid was placed in a vacuum drying oven and dried at 60℃. The corresponding organic ligands of UiO-66, Zr-oxa, and Zr-fru are terephthalic acid, oxalic acid, and fumaric acid, respectively.

[0032] Preparation of Zr-bptc: ZrOCl 2 8H 2 O (322mg, 1.0mmol), biphenyl-3,3',5,5'-tetracarboxylic acid (330mg, 1.0mmol), N,N-dimethylformamide and formic acid were mixed in a 200mL reactor. Placed in an oven preheated to 120°C and reacted for 8h. After cooling to ambient temperature, centrifugation was performed to obtain white Zr-bptc powder, which was then soaked in 80ml DMF and 80ml methanol for 48h and 72h respectively. The washed Zr-bptc was dried in a vacuum oven at 60°C for 8h.

[0033] Preparation of ZIF-7: Mix zinc nitrate hexahydrate (0.891 g) and benzimidazole (0.991 g) in a ratio of 1:2.8, add to a 100 ml reactor containing 60 ml DMF, stir to dissolve, and react at 140 °C for 2 h. Cool to room temperature, filter, wash the product with DMF and methanol, and dry at 60 °C.

[0034] Preparation of ZIF-79: Take 1 mmol (0.2974 g) of zinc nitrate hexahydrate, 1 mmol (0.1130 g) of 2-nitroimidazole and 1 mmol (0.1322 g) of 5-methylbenzimidazole and mix them in 15 ml of DMF. Stir to obtain a yellow clear solution. React in an oven at 80°C for 48 h. After the reaction, filter and wash the crystals 3 times with 10 ml of DMF and methanol respectively, and dry them in a vacuum drying oven at 60°C for at least 24 h.

[0035] Preparation of MET-Fe: Anhydrous ferrous chloride (2.282 g) was placed in a round-bottom flask, and vacuumed and filled with nitrogen three times. 75 ml of DMF was added to the flask and stirred under nitrogen atmosphere to make FeCl 2 Completely dissolved. Prepare ligand solution (3.16 ml 1h-1,2,3-triazole dissolved in 25 ml DMF) and slowly add it to a round-bottom flask, react at 80°C for 48 hours, cool to room temperature, collect pink solid by centrifugation, wash with fresh DMF and methanol three times each, soak in methanol for 3 days, and then vacuum dry at 60°C to obtain an activated sample.

[0036] Example 4: Adsorption of supernatant after ionic liquid extraction by different MOF materials

[0037] Take 300 μL of the ionic liquid extraction phase in Example 2, add 50 mg of MOF material, the MOF materials are MET-Fe, UiO-66, Zr-oxa, Zr-bptc, ​​Zr-fru, ZiF-7 and ZiF-79 (MET-Fe, Zr-oxa, Zr-bptc, ​​Zr-fru, ZiF-7 and ZiF-79), shake at 220 rpm in a 37 ° C shaker for 2 h, centrifuge and take the supernatant for detection, the acetic acid adsorption rate of MET-Fe is 26.82%, the acetic acid adsorption rate of UiO-66 is 22.26%, the acetic acid adsorption rate of Zr-oxa is 25.73%, the acetic acid adsorption rate of Zr-bptc is 29.50%, the acetic acid adsorption rate of Zr-fru is 20.29%, the acetic acid adsorption rate of ZiF-7 is 16.48%, and the acetic acid adsorption rate of ZiF-79 is 26.65% ( Figure 2 ).

[0038] Example 5: Extraction and separation of succinic acid in a real sodium salt fermentation system using coupled ionic liquids and MOFs

[0039] The ionic liquid [diOTMG]Cl and the metal organic framework material (MOF) Zr-bptc were ultrasonically mixed in a ratio of 20:1, with a power of 100W and a time of 5 minutes. Take 225μL of the ionic liquid and MOF coupling system, 250μL of sodium salt fermentation broth (sodium succinate concentration 0.83mol / L, sodium acetate concentration 26.70mmol / L), and 380μL of n-octanol for liquid-liquid extraction. The extraction temperature was 37°C, the extraction time was 2h, and the pH was 4. After the extraction, the two phases were separated, and the MOF and the extraction phase were separated by centrifugation to obtain 640μL of extract. The succinic acid extraction rate was 80.10%, the MOF adsorption rate of acetic acid was 32.62%, and the purity was 99.47% ( Figure 3 ).

[0040] Example 6: Coupled ionic liquid and MOF are used for extraction and separation of succinic acid in a real ammonium salt fermentation system

[0041] The ionic liquid [diOTMG]Cl and the metal organic framework material (MOF) Zr-bptc were ultrasonically mixed in a ratio of 20:1, with a power of 100W and a time of 5min. 225μL of the ionic liquid and MOF coupling system, 250μL of ammonium salt fermentation broth (ammonium succinate concentration 0.68mol / L, ammonium acetate concentration 0.17mol / L), and 380μL of n-octanol were taken for liquid-liquid extraction. The extraction temperature was 37℃, the extraction time was 2h, and the pH was 4. After the extraction, the two phases were separated, and the MOF and the extraction phase were separated by centrifugation to obtain 690μL of extract. The succinic acid extraction rate was 61.36%, the MOF adsorption rate of acetic acid was 26.72%, and the purity was 94.81%.

[0042] Example 7: Stripping of Succinic Acid and Recovery of Separation Medium

[0043] After the extraction, centrifuge to separate MOF and ionic liquid phase, take the ionic liquid phase, add a stripping agent for stripping, wherein the stripping agent is 1 mol / L NaOH solution, distilled water or n-hexane, stripping agent: ionic liquid phase = 1:1 or 2:1, and the stripping temperature is 25°C or 70°C. At 70°C, when distilled water: ionic liquid phase = 1:1, the recovery rate of succinic acid was 40.11% and the purity was 99.08%; at 70°C, when distilled water: ionic liquid phase = 2:1, the recovery rate of succinic acid was 47.71% and the purity was 99.23%; at 70°C, when NaOH solution: ionic liquid phase = 1:1, the recovery rate of succinic acid was 100% and the purity was 99.58%; at 25°C, when NaOH solution: ionic liquid phase = 1:1, the recovery rate of succinic acid was 94.09% and the purity was 99.63%; at 25°C, when NaOH solution: ionic liquid phase = 2:1, the recovery rate of succinic acid was 96.10% and the purity was 99.59%; at 25°C, when n-hexane: ionic liquid phase = 1:1, the recovery rate of succinic acid was 25.23% and the purity was 99.97% ( Figure 4 ). After stripping, the ionic liquid is washed with deionized water and dried, and the MOF material is washed with methanol and dried, and then recycled.

[0044] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. Application of ionic liquid coupled metal organic framework materials as materials for extracting succinic acid.

2. The use according to claim 1, characterized in that: The ionic liquid is composed of guanidine cations and halogen anions, the guanidine cations are hexaalkylguanidine ions with different carbon chains, and the halogen anions are bromide ions and chloride ions.

3. The use according to claim 1, characterized in that: The metal organic framework material is a metal organic framework material with acid stability and water stability, which uses zirconium, zinc or cobalt ions as metal sites and organic carboxylic acids as ligands.

4. The use according to claim 1, characterized in that: The mass ratio of the ionic liquid to the metal organic framework material in the ionic liquid coupled metal organic framework material is 10-50:5-20.

5. A method for purifying succinic acid using ionic liquid coupled metal organic framework materials, characterized in that: The steps include: (1) mixing an ionic liquid with a metal organic framework material to obtain a coupling system of the ionic liquid and the metal organic framework material, then adding a succinic acid fermentation broth to the mixture, adding n-octanol to perform liquid-liquid extraction, separating the two phases after the extraction, and centrifuging to separate the ionic liquid phase and the MOF and metal organic framework material phase; (2) adding a stripping agent to the ionic liquid phase for secondary extraction, and evaporating and crystallizing the stripping agent to obtain succinic acid with a purity higher than 99%; the 1 mol / L NaOH solution, distilled water or n-hexane.

6. The method for purifying succinic acid by using ionic liquid coupled metal organic framework materials according to claim 5, characterized in that: In step (1), the ionic liquid, the metal organic framework material and n-octanol constitute an extraction system, the volume ratio of the ionic liquid in the extraction system is 10% to 50%, the volume ratio of the metal organic framework material in the extraction system is 5% to 20%; the volume ratio of the n-octanol in the extraction system is 50% to 85%, the mass ratio of the extraction system to the fermentation liquid is 1:5 to 5:1, the extraction temperature is 10 to 50°C, the extraction time is 2h, and the pH of the extraction system is 2 to 6.

7. The method for purifying succinic acid by using ionic liquid coupled metal organic framework materials according to claim 5, characterized in that: In step (2), the ratio of stripping agent to ionic liquid phase is 1:1 to 2:1, and the stripping temperature is 25°C to 70°C.

8. The method for purifying succinic acid by using ionic liquid coupled metal organic framework materials according to claim 5, characterized in that: The ionic liquid is [diHTMG]Cl, [diOTMG]Cl, [diDTMG]Cl, [diOTMG]Br, [diHTMG]Br or [diBTMG]Br; the metal organic framework material is MET-Fe, UiO-66, Zr-oxa, Zr-bptc, ​​Zr-fru, ZiF-7 or ZiF-79.

9. The method for purifying succinic acid by using ionic liquid coupled metal organic framework materials according to claim 8, characterized in that: The mass ratio of the ionic liquid to the metal organic framework material is 20:

1.

10. The method for purifying succinic acid by using ionic liquid coupled metal organic framework materials according to any one of claims 5 to 8, characterized in that: After step (2), a recovery step is also included, specifically, the ionic liquid is washed with deionized water, and then dried for later use; the metal organic framework material is washed with methanol, and then dried for later use.

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