A method for catalyzing the thermal decomposition of poly-beta-hydroxybutyrate using a metal catalyst
By catalyzing the pyrolysis of polyβ-hydroxybutyrate in polar organic solvents under normal pressure, the pyrolysis problem under harsh conditions in the prior art is solved, and rapid and efficient polyβ-hydroxybutyrate recovery is achieved, with high yield and environmental advantages.
Patent Information
- Application Number
- CN202311381375.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-24
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2043-10-24
AI Technical Summary
The existing polyβ-hydroxybutyrate pyrolysis methods require harsh high temperature and high pressure conditions and use toxic catalysts, and lack a fast and efficient green catalytic system under mild conditions.
The depolymerization of polyβ-hydroxybutyrate at 20-300°C is used to obtain crotonic acid by using a mixture of polar organic solvents such as N,N-dimethylformamide, dimethylsulfoxide, acetonitrile or toluene under normal pressure and inert gas protection to obtain crotonic acid.
It realizes efficient and rapid pyrolysis of polyβ-hydroxybutyrate under mild conditions, avoids high energy consumption, and uses non-toxic metal catalysts, which improves recycling efficiency and environmental protection.
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Figure CN117362168B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of chemical recovery of organic materials, and particularly relates to a method for catalyzing the thermal decomposition of poly-β-hydroxybutyrate with a metal catalyst. Background Art
[0002] Poly (β-hydroxybutyrate) (PHB) is a microbially synthesized plastic with room-temperature properties similar to those of polypropylene and polystyrene. For example, they share similar glass transition temperatures, melting points, crystallinity, and tensile strength. Furthermore, PHB exhibits advantages such as good optical activity, high specific gravity, low oxygen permeability, biodegradability, UV resistance, and biocompatibility. Therefore, as a new functional material, PHB is expected to find widespread application in numerous high-tech fields, including optics, electronics, and biomedicine.
[0003] As the production cost of poly(β-hydroxybutyrate) decreases and its production and sales increase, the amount of waste poly(β-hydroxybutyrate) will also increase. Although waste poly(β-hydroxybutyrate) plastics can be biodegraded into non-toxic and harmless products, they are significantly affected by environmental factors and degrade slowly. Therefore, chemical depolymerization of poly(β-hydroxybutyrate) plastics is a more effective approach. Chemical methods can not only rapidly degrade poly(β-hydroxybutyrate) but also depolymerize it into monomers with high added value. Hydrolysis, alcoholysis, and pyrolysis are the most explored chemical recycling methods for depolymerizing poly(β-hydroxybutyrate).
[0004] There have been several reports on the pyrolysis of poly (β-hydroxybutyrate). However, these methods for recovering poly (β-hydroxybutyrate) require harsh, high-temperature reaction conditions and lack a catalytic system that can rapidly and efficiently decompose poly (β-hydroxybutyrate) under mild conditions. Therefore, it is crucial to develop a novel, environmentally friendly, and highly efficient poly (β-hydroxybutyrate) pyrolysis catalyst for its efficient depolymerization. Summary of the Invention
[0005] The present invention addresses the technical problems that existing methods for pyrolyzing waste poly-β-hydroxybutyrate require harsh conditions (high temperature and high pressure) and the use of toxic catalysts, and lack a green catalytic system and method that can quickly and efficiently pyrolyze poly-β-hydroxybutyrate under mild conditions. The present invention provides a method for catalyzing the pyrolysis of poly-β-hydroxybutyrate using a low-toxic and efficient metal catalyst, which helps to achieve green recycling of waste poly-β-hydroxybutyrate plastics.
[0006] The technical solution of the present invention:
[0007] One of the objectives of the present invention is to provide a method for catalyzing the thermal decomposition of poly (β-hydroxybutyrate) using a metal catalyst. The method comprises the following steps: under normal pressure and inert gas protection, in the presence of a metal catalyst, catalyzing the depolymerization of poly (β-hydroxybutyrate) in an organic solvent to obtain crotonic acid (CA).
[0008] It is further defined that the metal catalyst is wherein R1 is each independently selected from alkyl.
[0009] In a further embodiment, R1 is methyl.
[0010] It is further defined that the organic solvent is a polar organic solvent.
[0011] It is further defined that the polar organic solvent is a mixture of one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (MeCN), and toluene.
[0012] It is further defined that the amount of the metal catalyst is 0.1 to 50 wt % of the poly (β-hydroxybutyrate).
[0013] It is further defined that the concentration of poly (β-hydroxybutyrate) in the organic solvent is 0.01M to 100M.
[0014] It is further defined that the depolymerization temperature is 20 to 300° C. and the depolymerization time is 4 to 7 hours.
[0015] Furthermore, the depolymerization temperature is 150°C.
[0016] It is further defined that the number average molecular weight (M n ) is 10 2 ~10 7 g / mol.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] (1) The present invention uses green and environmentally friendly metal catalysts to catalyze the thermal decomposition of poly (β-hydroxybutyrate). Metal zinc and magnesium are non-toxic and odorless, and have little harm to the environment, thus avoiding the harm to the ecological environment caused by the use of other toxic metal catalysts.
[0019] (2) The catalytic system of the present invention has high catalytic efficiency and can catalyze the rapid and efficient thermal decomposition of poly (β-hydroxybutyrate) under mild conditions, thereby avoiding the increase in energy consumption caused by reaction conditions such as high temperature and high pressure.
[0020] (3) The present invention can use various organic solvents of different polarities. Small organic molecules with high added value can be recovered at a high yield, thereby achieving high-yield recycling of poly (β-hydroxybutyrate) materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is the H NMR spectrum of crotonic acid, a thermal decomposition product of poly-β-hydroxybutyrate in Example 1;
[0022] Figure 2 This is the NMR carbon spectrum of crotonic acid, the thermal decomposition product of poly (β-hydroxybutyrate) in Example 1. DETAILED DESCRIPTION
[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.
[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0025] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.
[0026] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional in the art and can be obtained commercially by those skilled in the art unless otherwise specified.
[0027] Example 1: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine zinc is as follows:
[0028]
[0029] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =69.4 kg / mol), 38.6 mg of Zn[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating unit) was added, followed by 2 mL of DMF, and the reaction was stirred at 150°C in a fume hood. After 5 hours of reaction, a sample was taken for NMR monitoring. The H NMR and C NMR spectra of the product crotonic acid were as follows: Figure 1-2The results showed that the characteristic peak of the polymer disappeared and the conversion rate of the polymer pyrolysis was greater than 99%. After removing the solvent by distillation under reduced pressure and then separating and purifying by column chromatography, 398 mg of white crotonic acid crystals were obtained, with a yield of 93%.
[0030] Example 2: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine zinc is as follows:
[0031]
[0032] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =69.4 kg / mol), 38.6 mg of Zn[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating units) was added, followed by 2 mL of DMSO, and the reaction was stirred at 150°C in a fume hood. After 6 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion rate was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by column chromatography separation and purification, to obtain 380 mg of crotonic acid as white crystals, with a yield of 88%.
[0033] Example 3: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine zinc is as follows:
[0034]
[0035] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =69.4 kg / mol), 38.6 mg of Zn[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating units) was added, followed by 2 mL of MeCN, and the reaction was stirred at 150°C in a fume hood. After 6 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by column chromatography separation and purification, to obtain 367 mg of crotonic acid as white crystals, with a yield of 85%.
[0036] Example 4: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine zinc is as follows:
[0037]
[0038] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =69.4 kg / mol), 38.6 mg of Zn[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating units) was added, followed by 2 mL of Toluene, and the reaction was stirred at 150°C in a fume hood. After 7 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by column chromatography separation and purification, to obtain 350 mg of crotonic acid as white crystals, with a yield of 81%.
[0039] Example 5: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine magnesium is as follows:
[0040]
[0041] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =69.4 kg / mol), 34.5 mg of Mg[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating units) was added, followed by 2 mL of DMF, and the reaction was stirred at 150°C in a fume hood. After 4 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion rate was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by column chromatography separation and purification, to obtain 391 mg of crotonic acid as white crystals, with a yield of 91%.
[0042] Example 6: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine magnesium is as follows:
[0043]
[0044] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n=75.1 kg / mol), 34.5 mg of Mg[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating units) was added, followed by 2 mL of DMSO, and the reaction was stirred at 150°C in a fume hood. After 5 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion rate was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by separation and purification by column chromatography, to obtain 385 mg of crotonic acid as white crystals, with a yield of 89%.
[0045] Example 7: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine magnesium is as follows:
[0046]
[0047] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =75.1 kg / mol), 34.5 mg of Mg[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating units) was added, followed by 2 mL of MeCN, and the reaction was stirred at 150°C in a fume hood. After 5 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by column chromatography separation and purification, to obtain 375 mg of crotonic acid as white crystals, with a yield of 87%.
[0048] Example 8: The reaction process of the thermal decomposition of poly (β-hydroxybutyrate) catalyzed by bis (bistrimethylsilyl) amine magnesium is as follows:
[0049]
[0050] Take a 5 mL Schlenk bottle, bake it out and replace the argon atmosphere, then add 430 mg (5 mmol polymer repeating units) of poly (β-hydroxybutyrate) (M n =75.1 kg / mol), 34.5 mg of Mg[N(SiMe3)2]2 catalyst (0.1 mmol, 2 mol% relative to the polymer repeating unit) was added, followed by 2 mL of Toluene, and the reaction was stirred at 150°C in a fume hood. After 6 hours of reaction, sampling and NMR monitoring revealed the disappearance of the characteristic peaks of the polymer, and the polymer pyrolysis conversion was greater than 99%. The solvent was removed by distillation under reduced pressure, followed by column chromatography separation and purification, to obtain 380 mg of crotonic acid as white crystals, with a yield of 88%.
[0051] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.
Claims
1. A metal catalyst catalyzes polymerization β - Method for the thermal decomposition of hydroxybutyrate, characterized in that Under normal pressure and inert gas protection, the polymerization is catalytically carried out in an organic solvent under the action of a metal catalyst. β -Hydroxybutyrate depolymerization to obtain crotonic acid, the metal catalyst is or , wherein R1 is independently selected from an alkyl group, and the organic solvent is a polar organic solvent.
2. The method according to claim 1, characterized in that R1 is methyl.
3. The method according to claim 1, characterized in that The polar organic solvent is a mixture of one or more of DMF, DMSO, acetonitrile and toluene.
4. The method according to claim 1, wherein The amount of metal catalyst used is β 0.1~50 wt% of hydroxybutyrate.
5. The method according to claim 1, wherein Organic solvent polymerization β The concentration of β-hydroxybutyrate is 0.01M~100M.
6. The method according to claim 1, characterized in that The depolymerization temperature is 20~300℃ and the time is 4~7 h.
7. The method according to claim 6, characterized in that The depolymerization temperature is 150°C.
8. The method according to claim 1, characterized in that Gather β β-Hydroxybutyrate M n is 10 2 ~10 7 g / mol.