Metal-supported zinc glutarate catalyst, method of preparation and use in synthesis of carbon dioxide copolymer

Abstract

The present application relates to the technical field of catalyst, in particular to a metal supported zinc glutarate catalyst, a preparation method and application in synthesis of carbon dioxide copolymer. The metal supported zinc glutarate catalyst is a zinc glutarate catalyst with metal supported on the surface; the metal is selected from one or more of Na, K, Li, Mg and Al. The present application utilizes the stability of metal to carbonate intermediates in the polymerization process through the synergistic coordination mechanism of bimetal, further improves the catalyst activity and selectivity, and improves the polymerization efficiency. Higher ether ester selectivity is achieved, and the catalytic copolymerization of epoxy compounds and carbon dioxide can maintain excellent catalytic activity and high polycarbonate segment selectivity in a wide range; the three-component copolymerization of epoxy compounds, carbon dioxide and cyclic ester can be catalyzed by one-pot method to obtain multi-block copolymer; the chain segment ratio can be adjusted by adjusting monomer feeding ratio, reaction temperature and reaction pressure.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more particularly to a metal-supported zinc glutarate catalyst, its preparation method, and its application in the synthesis of carbon dioxide copolymers. Background Technology

[0002] One of the most pressing environmental challenges globally is replacing widely used petroleum-derived polymers with biodegradable polymers. Carbon dioxide, as a greenhouse gas, is harmful to the climate. At the same time, it is also an abundant and inexpensive carbon source. Therefore, using carbon dioxide as a raw material to prepare biodegradable polymers is an ideal method, consistent with the concept of green chemistry.

[0003] Since Inoue's pioneering work in 1969, the ring-opening copolymerization of epoxides and carbon dioxide (ROCOP) has been extensively studied. Currently, in industry, aliphatic polycarbonates are mainly used as low molecular weight polyols in the manufacture of polyurethanes due to their unique mechanical and thermal properties. However, considering that polyurethanes are not completely biodegradable, they do not fully comply with the aforementioned sustainable strategies. Therefore, the introduction of rigid biodegradable segments to replace the rigid segments in traditional polyurethanes to obtain greener polymers has attracted attention.

[0004] The synthesis of these materials requires specific tandem polymerization strategies and appropriate segment selection. Currently, methods for introducing biodegradable rigid segments mainly include lactide (LA) ring-opening polymerization (ROP) and phthalic anhydride (PA) / propylene oxide (PO) ROCOP. Although many catalysts are available for LA ROP or PO / CO2 ROCOP alone, only a few catalysts are active for both polymerization processes. The development of novel catalyst systems, such as metal-based catalysts, Lewis acid-base pairs, and organic catalysts, has greatly aided in the design and synthesis of these sustainable polymers, facilitating the synthesis of these ideal polymers. However, these types of catalysts are complex and expensive to design, and are sensitive to water and oxygen, failing to meet the needs of industrial applications. The preparation process uses large amounts of organic solvents, which is environmentally unfriendly, and the prepared catalysts require water activation before use, making them inconvenient. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a metal-supported zinc glutarate catalyst, a preparation method thereof, and its application in the synthesis of carbon dioxide copolymers, wherein the catalyst has high selectivity and catalytic activity.

[0006] To achieve the above objectives, the present invention provides a metal-supported zinc glutarate catalyst, wherein a metal is supported on the surface of the zinc glutarate catalyst; the metal is selected from one or more of Na, K, Li, Mg, and Al.

[0007] The aforementioned metals form bonding bonds with the hydroxyl or carboxyl groups on the surface of the zinc glutarate catalyst, thereby being loaded onto the surface of the zinc glutarate catalyst.

[0008] This invention provides a method for preparing the above-mentioned metal-supported zinc glutarate catalyst, comprising the following steps:

[0009] Zinc glutarate catalyst and metal salt were reacted in an aqueous medium to load the metal onto the surface of the zinc glutarate catalyst, thus obtaining a metal-supported zinc glutarate catalyst.

[0010] The metal salt is a chloride, fluoride, or bromide salt of the metals Na, K, Li, Mg, or Al.

[0011] The present invention does not have any particular limitation on the source of the above-mentioned zinc glutarate catalyst, which can be commercially available or prepared according to methods known to those skilled in the art.

[0012] Preferably, the zinc glutarate catalyst is prepared by reacting glutaric acid and zinc oxide in toluene solvent.

[0013] The reaction temperature is preferably 60~80℃, more preferably 70℃; the reaction time is preferably 10~15h, more preferably 12h.

[0014] This invention uses water as a medium to simultaneously achieve the post-modification and activation of zinc glutarate using an aqueous solution of alkali metal salts, so that the metal is uniformly loaded on the surface of the zinc glutarate catalyst, which is more environmentally friendly. At the same time, the catalyst prepared does not require water activation.

[0015] The reaction temperature is 40~80℃, more preferably 60℃; the reaction time is 6~12h, more preferably 12h.

[0016] The preferred molar ratio of the zinc glutarate catalyst to the metal salt is 1:0.01~1.

[0017] Preferably, the reaction further includes: high-temperature heat treatment;

[0018] The preferred temperature for the high-temperature heat treatment is 250~350℃, more preferably 300℃; the preferred duration for the high-temperature heat treatment is 5~7h, more preferably 6h.

[0019] The high-temperature heat treatment can remove excess moisture from the catalyst and activate it.

[0020] Preferably, the high-temperature heat treatment further includes drying.

[0021] The present invention does not specifically limit the drying method, and can be any drying method known to those skilled in the art, with vacuum drying being preferred.

[0022] The drying temperature is preferably 80~100℃, more preferably 125℃; the vacuum drying time is 24~48h, more preferably 24h.

[0023] The above drying process can completely remove moisture from the catalyst, resulting in a dry catalyst.

[0024] This invention provides the application of the above-described metal-supported zinc glutarate catalyst or the metal-supported zinc glutarate catalyst prepared by the above preparation method as a catalyst in the synthesis of carbon dioxide copolymers.

[0025] Specifically, the present invention provides a method for preparing polycarbonate, comprising: using carbon dioxide, an epoxy compound and a cyclic ester as raw materials, and carrying out a polymerization reaction under the catalysis of the above-mentioned metal-supported zinc glutarate catalyst or the metal-supported zinc glutarate catalyst prepared by the above-mentioned preparation method, to obtain a carbon dioxide-epoxide-cyclic ester copolymer.

[0026] The preferred molar ratio of the catalyst, cyclic ester, and epoxide is 1:(5~100):(100~1000), more preferably 1:(10~75):(400~600).

[0027] The present invention does not specifically limit the epoxy compound, including but not limited to propylene oxide, etc.

[0028] The present invention does not specifically limit the type of cyclic ester, including but not limited to one or more of glycolide, lactide, and caprolactone.

[0029] The preferred temperature for the polymerization reaction is 50~120℃, and the preferred reaction time is 6~48h.

[0030] Compared with the prior art, the present invention provides a metal-supported zinc glutarate catalyst, wherein a metal is supported on the surface of the zinc glutarate catalyst; the metal is selected from one or more of Na, K, Li, Mg, and Al.

[0031] The metal-supported zinc glutarate catalyst provided by this invention utilizes a bimetallic synergistic coordination mechanism, leveraging the stabilizing effect of the metal on the carbonate intermediate during polymerization, to further enhance catalyst activity and selectivity, thereby improving polymerization efficiency. Compared to traditional zinc glutarate catalysts, it achieves higher ether-ester selectivity and exhibits unique catalytic performance: it maintains excellent catalytic activity and high polycarbonate segment selectivity over a wide range in the copolymerization of epoxides and carbon dioxide; it can catalyze the ternary copolymerization of epoxides, carbon dioxide, and cyclic esters in a one-pot process to obtain multi-block copolymers; and the segment ratio can be adjusted by regulating the monomer feed ratio, reaction temperature, and reaction pressure.

[0032] Experimental results show that the polyester material obtained by terpolymerization of propylene oxide, carbon dioxide, and lactide using the above-mentioned metal-supported zinc glutarate catalyst can reach a molecular weight of 210 kDa. Furthermore, the supported ZnGA catalyst is recyclable, and its simple, low-cost preparation process is compatible with existing infrastructure and manufacturing and processing methods. Attached Figure Description

[0033] Figure 1 Schematic diagrams of supported zinc glutarate catalysts and blended zinc glutarate catalysts;

[0034] Figure 2 SEM-EDS images of supported zinc glutarate catalyst and blended zinc glutarate catalyst;

[0035] Figure 3 The infrared absorption spectrum (top) and pXRD image (bottom) of the supported zinc glutarate catalyst.

[0036] Figure 4 The DOSY NMR spectrum of the polycarbonate prepared in Example 1;

[0037] Figure 5 The DOSY NMR spectrum of the product prepared in Comparative Example 1. Detailed Implementation

[0038] To further illustrate the present invention, a detailed description is provided below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.

[0039] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0040] Preparation of zinc glutarate:

[0041] 13.2 g of glutaric acid was added to 1000 mL of toluene solvent, stirred for 30 min, and then 8.1 g of zinc oxide was added. The mixture was heated at 70 °C and stirred for 12 h to obtain zinc glutarate catalyst.

[0042] Example 1

[0043] 10g of zinc glutarate catalyst and 0.29g of NaCl were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0044] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 50 molar equivalents of lactide (7.4 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the mixture was heated to 70 °C and reacted for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate the copolymer. The precipitate was filtered, collected, and dried to obtain the product. Samples were taken for further processing. 1 ¹H NMR testing showed that the polyester unit content was 61%, and the polycarbonate unit content was also tested, with a molecular weight of 210 kDa and a PDI of 1.91.

[0045] Figure 1 The left-middle figure is a schematic diagram of the above-mentioned supported zinc glutarate catalyst.

[0046] Figure 2 The lower half of the image shows the SEM-EDS combined image of the supported zinc glutarate catalyst, while the upper half shows the SEM-EDS combined image of the blended zinc glutarate catalyst. Yellow represents zinc, and blue represents sodium. Figure 2 It can be seen that both catalysts exhibit typical plate-like crystal structures. Zinc and sodium are distributed overlapping and uniformly on the surface of the catalyst crystals in the supported catalyst, while the NaCl / ZnGA mixture shows the opposite result.

[0047] Figure 3 The above-mentioned supported zinc glutarate catalyst has an infrared absorption spectrum (top) and a pXRD image (bottom). Figure 3 It can be seen that the introduction of metal ions does not cause any phase transition or structural deformation of the crystal lattice.

[0048] Figure 4 This is the DOSY NMR spectrum of the polycarbonate obtained in this embodiment, from... Figure 4 It can be seen that supported catalysts can yield copolymer products.

[0049] Example 2

[0050] 10g of zinc glutarate catalyst and 0.29g of NaCl were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0051] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 25 molar equivalents of lactide (3.8 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the mixture was heated to 70 °C and reacted for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate, filtered, and the filter cake was collected, dried, and the final material was obtained. Samples were then taken for further processing. 1 1H NMR testing showed that the polyester unit content was 39%, and the polycarbonate unit content was also tested, with a molecular weight of 180kDa and a PDI of 1.85.

[0052] Example 3

[0053] 10g of zinc glutarate catalyst and 0.29g of NaCl were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0054] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 12.5 molar equivalents of lactide (1.9 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the reactor was heated to 70°C and reacted for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate the copolymer. The precipitate was filtered, the filter cake was collected, and dried to obtain the final material. Samples were then taken for further processing. 1 1H NMR testing showed that the polyester unit content was 19%, and the polycarbonate unit content was also tested, with a molecular weight of 150 kDa and a PDI of 1.83.

[0055] Example 4

[0056] 10g of zinc glutarate catalyst and 0.38g of KCl were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0057] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 50 molar equivalents of lactide (7.4 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the reactor was heated to 70 °C and reacted for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate the copolymer. The precipitate was filtered, collected, and dried to obtain the final material. Samples were taken for further processing. 1 ¹H NMR testing showed that the polyester unit content was 23%, and the polycarbonate unit content was also tested, with a molecular weight of 160 kDa and a PDI of 2.36.

[0058] Example 5

[0059] 10g of zinc glutarate catalyst and 0.48g of MgCl2 were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0060] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 50 molar equivalents of lactide (7.4 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the mixture was heated to 70°C and reacted for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate the copolymer. The precipitate was filtered, collected, and dried to obtain the final material. Samples were then taken for further processing. 1 ¹H NMR testing showed no polyester units, a polycarbonate unit content of 99%, and only trace amounts of polyether. Subsequent measurements showed a molecular weight of 150 kDa and a PDI of 1.56.

[0061] Example 6

[0062] 10g of zinc glutarate catalyst and 2.9g of NaCl were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0063] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 50 molar equivalents of lactide (7.4 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the reactor was heated to 70 °C and reacted for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate the copolymer. The precipitate was filtered, collected, and dried to obtain the final material. Samples were taken for further processing. 1¹H NMR testing showed that the polyester unit content was 76%, and the polycarbonate unit content was also tested, with a molecular weight of 85 kDa and a PDI of 1.89.

[0064] Example 7

[0065] 10g of zinc glutarate catalyst and 0.58g of NaCl were added to 500mL of water in a 1L flask and stirred in a water bath at 60℃ for 12h to achieve uniform loading. The mixture was then heated in a muffle furnace at 300℃ for 6h and finally dried in a vacuum oven at 90℃ for 24h to obtain the supported zinc glutarate catalyst.

[0066] The supported catalyst (0.2 g), 500 molar equivalents of propylene oxide (29.7 g), and 50 molar equivalents of lactide (7.4 g) were added to a high-pressure reactor. Carbon dioxide was introduced at 2 MPa, and the temperature was raised to 70°C. The reaction was carried out for 24 h to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0 g) to precipitate, filtered, and the filter cake was collected, dried, and the material was obtained. Samples were taken for further processing. 1 ¹H NMR testing showed that the polyester unit content was 46%, and the polycarbonate unit content was also tested, with a molecular weight of 163 kDa and a PDI of 2.32.

[0067] Comparative Example 1

[0068] 10g of zinc glutarate catalyst and 0.29g of NaCl were added to a mortar and ground for 20 minutes to ensure uniform mixing. The aforementioned blended catalyst (0.2g), 500 molar equivalents of propylene oxide (29.7g), and 50 molar equivalents of lactide (7.4g) were added to a high-pressure reactor, and carbon dioxide was introduced at 2 MPa. The temperature was raised to 70℃, and the reaction was carried out for 24 hours to obtain a carbon dioxide-epoxide-cyclic ester copolymer. The polymer was added to ethanol (200.0g) to precipitate, filtered, and the filter cake was collected, dried, and the material was obtained. Samples were taken for further processing. 1 ¹H NMR analysis showed a polyester unit content of 41%, and the polycarbonate unit content was also tested, with a molecular weight of 135 kDa and a PDI of 3.41, exhibiting a distinct bimodal pattern. Characterization using the DOSY technique confirmed that it was not a copolymer, but rather a mixture of PLA homopolymer, PPC homopolymer, and copolymers of both. Results are as follows... Figure 5 As shown.

[0069] Figure 1 The middle right figure is a schematic diagram of a blended zinc glutarate catalyst.

[0070] Figure 2 The upper middle image shows a combined SEM-EDS image of the blended zinc glutarate catalyst, where yellow represents zinc and blue represents sodium. Figure 5The image shows the DOSY NMR spectrum of the product obtained in Comparative Example 1. Figure 5 It can be seen that the diffusion coefficient of the product obtained by the blended catalyst is different from that of Example 1, and no copolymer product was obtained.

[0071] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A metal-supported zinc glutarate catalyst, wherein a metal is supported on the surface of the zinc glutarate catalyst; said metal is selected from one or more of Na, K, Li, Mg, and Al; The above-mentioned loading is the formation of linkages between the metal and the hydroxyl or carboxyl groups on the surface of the zinc glutarate catalyst.

2. A method for preparing a metal-supported zinc glutarate catalyst, comprising the following steps: Zinc glutarate catalyst and metal salt were reacted in an aqueous medium to load the metal onto the surface of the zinc glutarate catalyst, thus obtaining a metal-supported zinc glutarate catalyst. The metal salt is a chloride, fluoride, or bromide salt of the metals Na, K, Li, Mg, or Al.

3. The preparation method according to claim 2, characterized in that, The reaction temperature is 40~80℃, and the reaction time is 6~12h.

4. The preparation method according to claim 2, characterized in that, The molar ratio of the zinc glutarate catalyst to the metal salt is 1:0.01~1.

5. The preparation method according to claim 2, characterized in that, The reaction is followed by: high-temperature heat treatment; The high-temperature heat treatment is performed at a temperature of 250~350℃ for 5~7 hours.

6. The preparation method according to claim 5, characterized in that, The high-temperature heat treatment also includes drying.

7. The preparation method according to claim 6, characterized in that, The drying process is vacuum drying; The drying temperature is 80~100℃, and the vacuum drying time is 24~48h.

8. The preparation method according to claim 2, characterized in that, The zinc glutarate catalyst was prepared by reacting glutaric acid and zinc oxide in toluene solvent.

9. The application of the metal-supported zinc glutarate catalyst according to claim 1 or the metal-supported zinc glutarate catalyst prepared by any one of claims 2 to 8 as a catalyst in the synthesis of carbon dioxide copolymers.

10. A method for preparing polycarbonate, comprising: Using carbon dioxide, epoxy compounds, and cyclic esters as raw materials, a copolymerization reaction is carried out under the catalysis of the metal-supported zinc glutarate catalyst as described in claim 1 or the metal-supported zinc glutarate catalyst prepared by any one of claims 2 to 8 to obtain a carbon dioxide-epoxide-cyclic ester copolymer.

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