Method for recovering 2, 5-hexanedione from p-xylene bio-based reaction liquid

Abstract

The invention relates to a method for recovering 2, 5-hexanedione from p-xylene bio-based reaction liquid, which comprises the following steps: uniformly mixing a skeleton monomer, a cross-linking agent, a functional monomer, a pore-foaming agent, an initiator and a dispersing agent, and then carrying out suspension polymerization reaction; collecting the polymeric microspheres, removing the pore-foaming agent, and drying to obtain the polar macroporous adsorption resin for specific separation. A chromatographic column is filled with adsorption resin for column packing, and an adsorption resin separation system is formed; the method comprises the following steps: introducing a p-xylene bio-based reaction liquid containing 2, 5-hexanedione into an adsorption resin separation system, and further adsorbing and separating 2, 5-hexanedione in the p-xylene bio-based reaction liquid; and regenerating the resin by using an eluent, and collecting the 2, 5-hexanedione. Compared with the prior art, the method provided by the invention successfully realizes efficient recovery of p-2, 5-hexanedione from the p-xylene bio-based reaction liquid.

Description

Technical Field

[0001] This invention relates to the field of separation and purification technology, and in particular to a method for recovering 2,5-hexanedione from p-xylene bio-based reaction solutions. Background Technology

[0002] p-Xylene has always been a very important raw material in the chemical industry. Currently, p-xylene is widely used in the synthesis of polyesters, with polyethylene terephthalate (PET) being the most common application. my country's polyester industry has developed rapidly. The current industrial synthesis method for PET involves oxidizing p-xylene (PX) to produce terephthalic acid, which is then esterified with ethylene glycol (EG) and polymerized. Therefore, the consumption of p-xylene, as a major raw material, is growing rapidly.

[0003] The production and purification processes of paraxylene using petroleum-based feedstocks are already quite mature. However, issues such as production safety and environmental pollution limit the expansion of paraxylene production capacity. Annual carbon dioxide emissions from paraxylene industrial production exceed 100 million tons, accounting for approximately 3% of global carbon dioxide emissions, posing a significant challenge to global environmental protection. The current global shortage of oil resources also puts pressure on paraxylene production.

[0004] The production of paraxylene from biomass has attracted widespread attention. Studies have shown that bio-based paraxylene can be synthesized through rapid pyrolysis of 5-hydroxymethylfurfural with a catalyst, followed by aqueous reforming of bioethanol and isobutanol. Producing paraxylene from biomass can turn waste into treasure, while also reducing environmental pollution from paraxylene production and alleviating the supply-demand imbalance.

[0005] CN118637972A discloses a method for preparing bio-based p-xylene from inexpensive lignocellulose biomass. Specifically, it describes a novel two-step process for preparing p-xylene from cellulose via 2,5-hexanedione. The feasibility of this process route was theoretically analyzed and experimentally verified. Preliminary studies were conducted on the optimization of product yields at each step and the reaction system mechanism. This process uses 2,5-hexanedione as a macroscopic intermediate, converting cellulose into p-xylene through two macroscopic reaction systems, achieving a total molar yield of 54.4%.

[0006] However, due to incomplete reaction, a high concentration of 2,5-hexanedione remains in the reaction solution, leading to waste and low substrate utilization. Therefore, in order to recover and utilize the incompletely reacted 2,5-hexanedione substrate, a new method for recovering 2,5-hexanedione from p-xylene-based reaction solutions is urgently needed. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art and provide a method for recovering 2,5-hexanedione from p-xylene bio-based reaction solution.

[0008] The objective of this invention can be achieved through the following technical solutions: This invention first provides a method for recovering 2,5-hexanedione from a p-xylene-based bio-based reaction solution, comprising the following steps: S1: The backbone monomer, crosslinking agent, functional monomer, porogen, initiator and dispersant are mixed evenly, and then a suspension polymerization reaction is carried out; after collecting the polymerized microspheres, the porogen is removed and dried to obtain a polar macroporous adsorption resin for specific separation. S2: The adsorption resin obtained in S1 is packed into a chromatography column to form an adsorption resin separation system; S3: The p-xylene bio-based reaction solution containing 2,5-hexanedione is passed into the adsorption resin separation system of S2, thereby adsorbing and separating 2,5-hexanedione in the p-xylene bio-based reaction solution. S4: Regenerate the resin using an eluent and collect 2,5-hexanedione.

[0009] Further, in step S1, the molar ratio of the backbone monomer, crosslinking agent, functional monomer, porogen, initiator and dispersant is 1: (1~1.2): (0.05~0.15): (0.4~0.6): (0.05~0.2): (0.1~0.2).

[0010] Furthermore, in step S1, the skeleton monomer is styrene.

[0011] Further, in step S1, the crosslinking agent is divinylbenzene.

[0012] Further, in step S1, the functional monomer is any one or more of acrylonitrile, acrylamide, and N-vinylpyrrolidone.

[0013] Further, in step S1, the pore-forming agent is one or more of toluene, cyclohexanol, cyclohexane, or n-heptane.

[0014] Further, in step S1, the initiator is one or more of benzoyl peroxide, potassium persulfate, or azobisisobutyronitrile.

[0015] Further, in step S1, the dispersant is polyvinyl alcohol.

[0016] Furthermore, in step S1, the temperature of the suspension polymerization reaction is 50-70℃, and the time of the suspension polymerization reaction is 8-15h.

[0017] Furthermore, in step S1, the removal of the pore-forming agent is carried out using an organic solvent, specifically one or more of chloroform, dichloroethane, and carbon tetrachloride.

[0018] Furthermore, in step S1, the volume of the organic solvent is 8-12 times the volume of the polymerized microspheres, preferably 10 times.

[0019] Furthermore, in step S2, the column is packed using a wet method, and the height-to-diameter ratio of the packed column is (10-20):1.

[0020] Further, in step S3, the flow rate of the p-xylene bio-based reaction solution onto the column is 0.2-1.0 BV / h, preferably 0.4 BV / h.

[0021] Furthermore, in step S4, the eluent is an ethanol solution with a concentration of 80-99%.

[0022] Further, in step S4, the flow rate of the eluent is 0.5-1.5 BV / h, preferably 1.2 BV / h.

[0023] Further, in step S4, the volume of the eluent is 1-5 BV, preferably 3 BV.

[0024] Compared with the prior art, the present invention has the following technical advantages: (1) The present invention uses a polar macroporous adsorption resin for specific separation to successfully selectively recover high-purity unreacted substrate 2,5-hexanedione from p-xylene bio-based reaction solution, thereby improving substrate utilization, reducing production costs, and being green and environmentally friendly.

[0025] (2) Based on the fact that 2,5-hexanedione contains two carbonyl oxygen atoms and has moderate polarity, this invention uses polar functional monomers such as acrylonitrile, acrylamide, and N-vinylpyrrolidone to give the resin surface polar groups, which interact specifically with the highly polar 2,5-hexanedione (carbonyl compound) (such as dipole-dipole interactions and hydrogen bonds), thereby selectively adsorbing 2,5-hexanedione in complex reaction solutions and reducing interference from other components. The use of porogens forms macroporous structures, which is beneficial for the diffusion of the reaction solution inside the resin, improves mass transfer efficiency, and is suitable for systems containing complex bio-based components.

[0026] (3) The present invention can regenerate resin by elution with ethanol, without complicated treatment, which is simple to operate and reduces operating costs. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process for recovering 2,5-hexanedione according to the present invention.

[0028] Figure 2 The image shows the gas chromatogram of the isolated 2,5-hexanedione. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] like Figure 1 As shown, in order to recover and utilize the unreacted substrate 2,5-hexanedione from a p-xylene bio-based reaction solution, this invention presents a method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution. The method includes the following steps: S1: The backbone monomer, crosslinking agent, functional monomer, porogen, initiator and dispersant are mixed evenly, and then a suspension polymerization reaction is carried out; after collecting the polymerized microspheres, the porogen is removed and dried to obtain a polar macroporous adsorption resin for specific separation. S2: The adsorption resin obtained in S1 is packed into a chromatography column to form an adsorption resin separation system; S3: The p-xylene bio-based reaction solution containing 2,5-hexanedione is passed into the adsorption resin separation system of S2, thereby adsorbing and separating 2,5-hexanedione in the p-xylene bio-based reaction solution. S4: Regenerate the resin using an eluent.

[0031] In some specific embodiments, in step S1, the molar ratio of the backbone monomer, crosslinking agent, functional monomer, porogen, initiator and dispersant is 1: (1~1.2): (0.05~0.15): (0.4~0.6): (0.05~0.2): (0.1~0.2).

[0032] In some specific embodiments, in step S1, the skeleton monomer is styrene.

[0033] In some specific embodiments, in step S1, the crosslinking agent is divinylbenzene.

[0034] In some specific embodiments, in step S1, the functional monomer is any one or more of acrylonitrile, acrylamide, and N-vinylpyrrolidone.

[0035] In some specific embodiments, in step S1, the pore-forming agent is one or more of toluene, cyclohexanol, cyclohexane, or n-heptane.

[0036] In some specific embodiments, in step S1, the initiator is one or more of benzoyl peroxide, potassium persulfate, or azobisisobutyronitrile.

[0037] In some specific embodiments, in step S1, the dispersant is polyvinyl alcohol.

[0038] In some specific embodiments, in step S1, the temperature of the suspension polymerization reaction is 50-70°C, and the time of the suspension polymerization reaction is 8-15 hours.

[0039] In some specific embodiments, in step S1, the removal of the pore-forming agent is carried out using an organic solvent, specifically one or more of chloroform, dichloroethane, and carbon tetrachloride.

[0040] In some specific embodiments, in step S1, the volume of the organic solvent is 8-12 times the volume of the polymerized microspheres, preferably 10 times.

[0041] In some specific implementations, in step S2, a wet method is used to pack the column, and the height-to-diameter ratio of the packed column is (10-20):1.

[0042] In some specific embodiments, in step S3, the flow rate of the p-xylene bio-based reaction solution onto the column is 1-3 ml / min, preferably 2 ml / min.

[0043] In some specific embodiments, in step S4, the eluent is an ethanol solution with a concentration of 80-99%.

[0044] In some specific embodiments, in step S4, the flow rate of the eluent is 1-3 ml / min, preferably 2 ml / min.

[0045] In some specific embodiments, in step S4, the volume of the eluent is 1-5 BV, preferably 3 BV.

[0046] Each of the above embodiments can be implemented individually, or in any combination of two or more. The following detailed description of specific examples will further illustrate these embodiments.

[0047] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0048] Example 1: This embodiment provides a method for recovering 2,5-hexanedione from a p-xylene-based bio-based reaction solution, specifically including the following steps: S1. Synthesis of polar macroporous adsorption resin for specific separation: The backbone monomer (styrene), crosslinking agent (divinylbenzene), functional monomer (N-vinylpyrrolidone), porogen (toluene), initiator (benzoyl peroxide), and dispersant (polyvinyl alcohol) were mixed uniformly in a ratio of 1:1:0.1:0.5:0.1:0.15 and then subjected to suspension polymerization at 60°C and 500 r / min for 12 hours.

[0049] The polymerized microspheres were collected and the porogen was removed with 10 times the volume of chloroform. After drying, a polar macroporous adsorption resin that specifically separates ketone and aldehyde substances was obtained.

[0050] S2, Column mounting: The macroporous adsorption resin was packed into a glass chromatography column using a wet packing method, with a height-to-diameter ratio of 15:1.

[0051] S3, Column adsorption separation: A bio-based reaction solution containing p-xylene was passed into a macroporous adsorption resin separation system packed with a column for the adsorption and separation of 2,5-hexanedione. The sample loaded onto the column was a p-xylene feed solution synthesized from bio-based raw materials. The bio-based reaction solution was passed into the column at a flow rate of 0.2 BV / h, and the eluent was collected in test tubes, with 15 ml collected in each tube, for a total of 10 tubes.

[0052] S4, Washing: After phase-to-phase adsorption separation was completed at a flow rate of 2 ml / min, 3 BV of anhydrous ethanol was introduced into the column for elution to regenerate the resin and collect 2,5-hexanedione.

[0053] The collected eluent was analyzed by gas chromatography. The gas chromatographic column used was an Agilent HP-innowax, 0.25 μm*250 μm*30 m, with nitrogen as the carrier gas and a flame ionization detector (FID). The injection volume was 0.2 μL, the split ratio was 30:1, the detector temperature was 270℃, and the column temperature was 50-240℃. This yielded a 2,5-hexanedione solution containing ethanol and trace impurities. The purity of 2,5-hexanedione was 98.0%, and the yield was 92.8%.

[0054] like Figure 2 As shown in the gas chromatogram, this embodiment successfully achieved the efficient recovery of 2,5-hexanedione substrate from xylene-based bio-based reaction solution.

[0055] Example 2: This embodiment provides a method for recovering 2,5-hexanedione from a p-xylene-based bio-based reaction solution, specifically including the following steps: S1. Synthesis of polar macroporous adsorption resin for specific separation: The backbone monomer (styrene), crosslinking agent (divinylbenzene), functional monomer (acrylamide), porogen (cyclohexanol), initiator (azobisisobutyronitrile), and dispersant (polyvinyl alcohol) were mixed evenly in a ratio of 1:1:0.1:0.5:0.1:0.15 and then subjected to suspension polymerization at 70°C and 500 r / min for 10 hours.

[0056] The polymerized microspheres were collected and the porogen was removed with 10 times the volume of chloroform. After drying, a polar macroporous adsorption resin that specifically separates ketone and aldehyde substances was obtained.

[0057] S2, Column mounting: The macroporous adsorption resin was packed into a glass chromatography column using a wet packing method, with a height-to-diameter ratio of 10:1.

[0058] S3, Column adsorption separation: A bio-based reaction solution containing p-xylene was passed into a macroporous adsorption resin separation system packed with a column for the adsorption and separation of 2,5-hexanedione. The sample loaded onto the column was a p-xylene feed solution synthesized from bio-based raw materials. The bio-based reaction solution was passed into the column at a flow rate of 0.8 BV / h, and the eluent was collected in test tubes, with 15 ml collected in each tube, for a total of 10 tubes.

[0059] S4, Washing: After phase adsorption separation was completed at a flow rate of 3 ml / min, 5 BV of anhydrous ethanol was introduced into the column for elution and resin regeneration.

[0060] The collected eluent was analyzed by gas chromatography using an Agilent HP-innowax column (0.25 μm x 250 μm x 30 m), nitrogen as the carrier gas, and a flame ionization detector (FID). The injection volume was 0.2 μL, the split ratio was 30:1, the detector temperature was 270 °C, and the column temperature was 50-240 °C. A 2,5-hexanedione solution containing ethanol and trace impurities was obtained, with a purity of 97.6% and a yield of 91.6%. Successful recovery of the 2,5-hexanedione substrate from the xylene-based bio-based reaction solution was achieved.

[0061] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for recovering 2,5-hexanedione from a p-xylene-based bio-based reaction solution, characterized in that, Includes the following steps: S1: The backbone monomer, crosslinking agent, functional monomer, porogen, initiator and dispersant are mixed evenly, and then a suspension polymerization reaction is carried out; after collecting the polymerized microspheres, the porogen is removed and dried to obtain a polar macroporous adsorption resin for specific separation. S2: The adsorption resin obtained in S1 is packed into a chromatography column to form an adsorption resin separation system; S3: The p-xylene bio-based reaction solution containing 2,5-hexanedione is passed into the adsorption resin separation system of S2, thereby adsorbing and separating 2,5-hexanedione in the p-xylene bio-based reaction solution. S4: Regenerate the resin using an eluent and collect 2,5-hexanedione.

2. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S1, the molar ratio of the backbone monomer, crosslinking agent, functional monomer, porogen, initiator and dispersant is 1: (1~1.2): (0.05~0.15): (0.4~0.6): (0.05~0.2): (0.1~0.2).

3. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S1, the skeleton monomer is styrene; The crosslinking agent is divinylbenzene; The functional monomer is any one or more of acrylonitrile, acrylamide, and N-vinylpyrrolidone.

4. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S1, the pore-forming agent is one or more of toluene, cyclohexanol, cyclohexane, or n-heptane; The initiator is one or more of benzoyl peroxide, potassium persulfate, or azobisisobutyronitrile; The dispersant is polyvinyl alcohol.

5. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S1, the temperature of the suspension polymerization reaction is 50-70℃, and the time of the suspension polymerization reaction is 8-15h.

6. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S1, the removal of the pore-forming agent is carried out using an organic solvent, specifically one or more of chloroform, dichloroethane, and carbon tetrachloride. The volume of the organic solvent is 8-12 times the volume of the polymerized microspheres.

7. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S2, the column is packed using a wet method, and the height-to-diameter ratio of the packed column is (10-20):

1.

8. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S3, the flow rate of the p-xylene bio-based reaction solution onto the column is 0.2-1.0 BV / h.

9. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S4, the elution is performed using an ethanol solution with a concentration of 80-99%.

10. The method for recovering 2,5-hexanedione from a p-xylene bio-based reaction solution according to claim 1, characterized in that, In step S4, the flow rate of the eluent is 0.5-1.5 BV / h; The volume of the eluent is 1-5 BV.

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