Catalyst, preparation method thereof and application of catalyst in carbon dioxide-based degradable plastic

Abstract

The invention relates to the technical field of catalysts, and provides a catalyst and a preparation method thereof, and an application of the catalyst in carbon dioxide-based degradable plastics, the catalyst is a supported catalyst, and comprises a carrier and an active component; the carrier comprises ternary hydrotalcite, and the active component comprises double metal cyanide and a rare earth yttrium complex; the raw material of the double metal cyanide comprises a cyano coordination compound; the cyano coordination compound comprises potassium hexacyanomanganate and / or potassium hexacyanocobaltate. According to the technical scheme, the problems of low yield and more byproducts when the catalyst is used for catalyzing and preparing the carbon dioxide-based degradable plastic in the related technology are solved.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to catalysts, their preparation methods, and their application in carbon dioxide-based biodegradable plastics. Background Technology

[0002] Carbon dioxide-based biodegradable plastic polypropylene carbonate (PPC) is synthesized from industrial waste gas CO2 and propylene oxide in the presence of a catalyst. Its production has been industrialized, and it possesses 100% biodegradability, making it a novel type of biodegradable plastic. The synthesis process of PPC involves anionic polymerization of carbon dioxide and propylene oxide under catalysis. It not only possesses the mechanical and performance properties of traditional plastics but also completely degrades in the natural environment, making it of significant research importance.

[0003] The catalyst is a key component in the polymerization reaction of carbon dioxide and propylene oxide, and its catalytic performance directly determines the yield and material properties of the final polymer product. An ideal catalytic system should possess high activity, high selectivity, and excellent stability, effectively activating inert carbon dioxide molecules, promoting their alternating insertion with propylene oxide, suppressing side reactions, and thus improving the formation efficiency and molecular weight of the target polymer.

[0004] However, the catalytic systems currently used for this polymerization reaction still have several key technical bottlenecks: First, some catalysts have insufficient activation capacity for carbon dioxide, making it difficult to effectively overcome its thermodynamic stability and kinetic inertness, resulting in low polymerization reaction activity and limited monomer conversion rate; Second, many catalysts perform poorly in terms of selectivity control, failing to effectively suppress the formation of byproducts such as cyclic carbonates, resulting in waste of reaction raw materials, decreased propylene oxide selectivity, and low molecular weight of the obtained polymer.

[0005] Therefore, developing novel and highly efficient catalytic systems to address the shortcomings of existing catalysts in terms of activity, selectivity, and stability has become a key research direction for improving the synthesis efficiency and product performance of carbon dioxide-based biodegradable plastics. Summary of the Invention

[0006] This invention proposes a catalyst, its preparation method, and its application in carbon dioxide-based biodegradable plastics, solving the problems of low yield and excessive by-products in the catalytic preparation of carbon dioxide-based biodegradable plastics in related technologies.

[0007] The technical solution of the present invention is as follows: This invention proposes a catalyst, which is a supported catalyst comprising a support and an active component; The carrier comprises ternary hydrotalcite, and the active component comprises a bimetallic cyanide and a rare earth yttrium complex; The raw materials for the bimetallic cyanide include cyano coordination compounds; The cyano coordination compounds include potassium hexacyanomanganese(III) and / or potassium hexacyanocobalt(III).

[0008] As a further technical solution, the cyano coordination compound comprises potassium hexacyanomanganese(III) and potassium hexacyanocobalt(III) in a mass ratio of 5.6~8.3:41.7~44.4; the mass ratio of potassium hexacyanomanganese(III) to potassium hexacyanocobalt(III) is as follows.

[0009] In the active components of the catalyst of this invention, potassium hexacyanomanganese(III) and potassium hexacyanocobalt(III) are used as bimetallic cyanide raw materials. The synergistic effect of manganese and cobalt elements in reducing the activation energy of the reaction improves the yield of carbon dioxide-based biodegradable plastics. In particular, when the mass ratio of potassium hexacyanomanganese(III) to potassium hexacyanocobalt(III) is 5.6~8.3:41.7~44.4, the catalytic activity and selectivity are better, which promotes the polymerization of carbon dioxide-based biodegradable plastics and reduces the generation of by-products.

[0010] As a further technical solution, the ternary hydrotalcite includes zinc-magnesium-aluminum hydrotalcite.

[0011] This invention also proposes a method for preparing the catalyst, comprising the following steps: The support and zinc chloride solution were mixed, and then cyano coordination compound and polyethylene glycol were added sequentially. After centrifugation, the precipitate was washed, dried, and ground to obtain catalyst A. The trichloroacetic acid solution and yttrium hydroxide dispersion were mixed, and catalyst A was added and mixed again. The mixture was then filtered and dried to obtain the catalyst.

[0012] In the preparation of the catalyst of this invention, polyethylene glycol has good solubility and dispersibility. When polyethylene glycol is added during the preparation of the catalyst, it acts as a dispersant to reduce the surface tension between the components, promote the uniform dispersion of cyano coordination compounds on the surface of the support, and avoid agglomeration.

[0013] As a further technical solution, the mass-to-volume ratio of the carrier to the zinc chloride solution is 1g:2~4mL, for example, it can be 1g:2mL, 1g:2.5mL, 1g:3mL, 1g:3.5mL, or 1g:4mL; The mass ratio of the carrier, cyano coordination compound, and polyethylene glycol is 1:0.5:0.3 to 0.6, for example, it can be 1:0.5:0.3, 1:0.5:0.35, 1:0.5:0.4, 1:0.5:0.45, 1:0.5:0.5, 1:0.5:0.55, or 1:0.5:0.6.

[0014] As a further technical solution, the mass ratio of the carrier, trichloroacetic acid solution and yttrium hydroxide dispersion is 1:10:2.8~3.2, for example, it can be 1:10:2.8, 1:10:2.9, 1:10:3.0, 1:10:3.1, or 1:10:3.2.

[0015] The present invention also proposes the application of the catalyst described herein or the catalyst prepared by the method described herein in the preparation of carbon dioxide-based biodegradable plastics.

[0016] As a further technical solution, the method for preparing the carbon dioxide-based biodegradable plastic includes the following steps: Propylene oxide and acid anhydride are mixed, the catalyst is added, carbon dioxide is introduced to carry out the reaction, and after post-treatment and granulation, carbon dioxide-based biodegradable plastic is obtained.

[0017] As a further technical solution, the mass of the catalyst is 0.03% to 0.065% of the mass of the acid anhydride.

[0018] As a further technical solution, the molar ratio of propylene oxide to acid anhydride is 8~10:1, for example, it can be 8:1, 8.5:1, 9:1, 9.2:1, 9.5:1, 9.8:1, or 10:1.

[0019] As a further technical solution, the carbon dioxide is introduced at a pressure of 0.5~2MPa; The reaction takes 8-10 hours and is carried out at a temperature of 60-70°C.

[0020] The working principle and beneficial effects of this invention are as follows: This invention employs a supported catalyst, using ternary layered double hydroxides (LLDPs) as the carrier, and a bimetallic cyanide and rare earth yttrium complex as the active components. This approach improves the yield of carbon dioxide-based biodegradable plastics and reduces byproducts. Unlike existing technologies where insufficient catalyst catalysis leads to low yields in the preparation of carbon dioxide-based biodegradable plastics, this invention uses ternary LLDPs as the carrier. Its layered structure and high specific surface area provide a more stable catalytic environment for the bimetallic cyanide and rare earth yttrium complex active components, allowing them to fully contact the reactants and accelerating the reaction. The synergistic catalysis of the ternary LLDPs, bimetallic cyanide, and rare earth yttrium complex increases the reaction rate while ensuring high selectivity, resulting in a higher yield of carbon dioxide-based biodegradable plastics and a lower byproduct rate. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] In the following examples and comparative examples, the zinc chloride solution is a 2% (w / w) aqueous solution of zinc chloride; The trichloroacetic acid solution is a 2% (w / w) aqueous solution of trichloroacetic acid, and the yttrium hydroxide dispersion is a 2% (w / w) dispersion of yttrium hydroxide and water. Zinc-magnesium-aluminum hydrotalcite is a ternary hydrotalcite, containing MgO content of 21.9wt%~23.9wt%, Al2O3 content of 18.3wt%~20.3wt%, ZnO content of 14.4wt%~16.4wt%, and a specific surface area ≥10m². 2 / g, average particle size ≤100nm, CAS: 119758-00-8, purchased from Beijing Techleil Technology Co., Ltd.

[0023] Example 1 The catalyst is a supported catalyst, consisting of a zinc-magnesium-aluminum hydrotalcite support and an active component; The preparation method of supported catalysts includes the following steps: 100g of zinc magnesium aluminum hydrotalcite and 200mL of zinc chloride solution were mixed, and 50g of potassium hexacyanocobalt(III) and 30g of polyethylene glycol were added sequentially. The mixture was centrifuged, and the precipitate was washed, dried, and ground into powder to obtain catalyst A. 1000g of trichloroacetic acid solution and 280g of yttrium hydroxide dispersion were mixed, catalyst A was added, and the mixture was stirred at 45°C for 2.5h. After filtration and drying, the supported catalyst was obtained. A method for preparing carbon dioxide-based biodegradable plastics includes the following steps: 116 kg of propylene oxide and 29.62 kg of phthalic anhydride were mixed, and 0.018 kg of catalyst was added. Carbon dioxide was introduced (at a pressure of 0.5 MPa), and the reaction was carried out at 60 °C for 10 h. 5 wt% deionized water was added to inactivate the reaction. The catalyst was then removed by filtration. The above materials were washed with water at 80 °C to remove the byproduct propylene carbonate and unreacted propylene oxide. The mixture was then extruded and granulated in a twin-screw extruder to obtain carbon dioxide-based biodegradable plastic.

[0024] Example 2 The catalyst is a supported catalyst, consisting of a zinc-magnesium-aluminum hydrotalcite support and an active component; The preparation method of supported catalysts includes the following steps: 100g of zinc magnesium aluminum hydrotalcite and 400mL of zinc chloride solution were mixed, and 50g of potassium hexacyanocobalt(III) and 60g of polyethylene glycol were added sequentially. The mixture was centrifuged, and the precipitate was washed, dried, and ground into powder to obtain catalyst A. 1000g of trichloroacetic acid solution and 300g of yttrium hydroxide dispersion were mixed, catalyst A was added, and the mixture was stirred at 45°C for 2.5h. After filtration and drying, the supported catalyst was obtained. A method for preparing carbon dioxide-based biodegradable plastics includes the following steps: 116 kg of propylene oxide and 29.62 kg of phthalic anhydride were mixed, and 0.011 kg of catalyst was added. Carbon dioxide was introduced (at a pressure of 2 MPa), and the reaction was carried out at 70 °C for 8 h. 10 wt% deionized water was added to inactivate the reaction. The catalyst was then removed by filtration. The above materials were washed with water at 100 °C to remove the byproduct propylene carbonate and unreacted propylene oxide. The mixture was then extruded and granulated in a twin-screw extruder to obtain carbon dioxide-based biodegradable plastic.

[0025] Example 3 The catalyst is a supported catalyst, consisting of a zinc-magnesium-aluminum hydrotalcite support and an active component; The preparation method of supported catalysts includes the following steps: 100g of zinc magnesium aluminum hydrotalcite and 300mL of zinc chloride solution were mixed, and 50g of potassium hexacyanocobalt(III) and 40g of polyethylene glycol were added sequentially. The mixture was centrifuged, and the precipitate was washed, dried, and ground into powder to obtain catalyst A. 1000g of trichloroacetic acid solution and 320g of yttrium hydroxide dispersion were mixed, catalyst A was added, and the mixture was stirred at 45°C for 2.5h. After filtration and drying, the supported catalyst was obtained. A method for preparing carbon dioxide-based biodegradable plastics includes the following steps: 92.8 kg of propylene oxide and 29.62 kg of phthalic anhydride were mixed, and 0.013 kg of catalyst was added. Carbon dioxide was introduced (at a pressure of 1 MPa), and the reaction was carried out at 65 °C for 9 h. 8 wt% deionized water was added to inactivate the reaction. The catalyst was then removed by filtration. The above materials were washed with water at 90 °C to remove the byproduct propylene carbonate and unreacted propylene oxide. The mixture was then extruded and granulated in a twin-screw extruder to obtain carbon dioxide-based biodegradable plastic.

[0026] Example 4 The only difference between this embodiment and Embodiment 3 is that potassium hexacyanocobalt(III) is replaced with potassium hexacyanomanganese(III).

[0027] Example 5 The only difference between this embodiment and Embodiment 3 is that 50g of potassium hexacyanocobalt(III) is replaced with 5g of potassium hexacyanomanganese(III) and 45g of potassium hexacyanocobalt(III).

[0028] Example 6 The only difference between this embodiment and Embodiment 3 is that 50g of potassium hexacyanocobalt(III) is replaced with 10g of potassium hexacyanomanganese(III) and 40g of potassium hexacyanocobalt(III).

[0029] Example 7 The only difference between this embodiment and Embodiment 3 is that 50g of potassium hexacyanocobalt(III) is replaced with 8.3g of potassium hexacyanomanganese(III) and 41.7g of potassium hexacyanocobalt(III).

[0030] Example 8 The only difference between this embodiment and Embodiment 3 is that 50g of potassium hexacyanocobalt(III) is replaced with 5.6g of potassium hexacyanomanganese(III) and 44.4g of potassium hexacyanocobalt(III).

[0031] Comparative Example 1 The only difference between this comparative example and Example 3 is that the preparation method of the supported catalyst includes the following steps: 45g of zinc magnesium aluminum hydrotalcite and 300mL of zinc chloride solution were mixed, and then 50g of potassium hexacyanocobalt(III) and 40g of polyethylene glycol were added sequentially. The mixture was centrifuged, and the precipitate was washed, dried, and ground into powder to obtain the supported catalyst.

[0032] Comparative Example 2 The only difference between this comparative example and Example 3 is that zinc magnesium aluminum hydrotalcite is replaced with activated carbon.

[0033] Comparative Example 3 The only difference between this comparative example and Example 3 is that zinc magnesium aluminum hydrotalcite is replaced with magnesium aluminum hydrotalcite (MgO content 34wt%, Al2O3 content 18wt%, purchased from Rongsheng New Material Technology (Nantong, Jiangsu) Co., Ltd.).

[0034] Experimental Example The molecular weights of the carbon dioxide-based biodegradable plastics prepared in Examples 1-8 and Comparative Examples 1-3 were tested, and the mass of the prepared carbon dioxide-based biodegradable plastics and the mass of the byproduct polycarbonate were recorded. The results are shown in Table 1 below.

[0035] Table 1 Yield Calculation Results

[0036] Compared with Comparative Examples 1-3, the carbon dioxide-based biodegradable plastics prepared in Examples 1-8 were of higher quality, and the byproduct polycarbonate was of lower quality. This indicates that the use of a supported catalyst, with zinc magnesium aluminum hydrotalcite as the support and bimetallic cyanide and rare earth complex as the active components improved the yield of carbon dioxide-based biodegradable plastics and reduced the quality of the byproduct polycarbonate.

[0037] Compared with Examples 3-4, the carbon dioxide-based biodegradable plastics prepared in Examples 5-8 have higher quality, lower quality of the byproduct polycarbonate, and higher molecular weight. This indicates that the bimetallic cyanide raw material of the active component of the supported catalyst was replaced with potassium hexacyanocobalt(III) and potassium hexacyanomanganese(III) and potassium hexacyanocobalt(III). Manganese is used to regulate the electron cloud and provide diverse catalytic sites, improving product selectivity. Cobalt stabilizes the reaction intermediate and works synergistically with manganese to lower the reaction activation energy and accelerate the reaction rate, which is beneficial to the preparation of carbon dioxide-based biodegradable plastics. In particular, when the mass ratio of potassium hexacyanomanganese(III) and potassium hexacyanocobalt(III) is 5.6-8.3:41.7-44.4 in Examples 7-8, the catalytic activity and selectivity are better, promoting the polymerization of carbon dioxide-based biodegradable plastics.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A catalyst, characterized in that, The catalyst is a supported catalyst, comprising a support and an active component; The carrier comprises ternary hydrotalcite, and the active component comprises a bimetallic cyanide and a rare earth yttrium complex; The raw materials for the bimetallic cyanide include cyano coordination compounds; The cyano coordination compounds include potassium hexacyanomanganate and / or potassium hexacyanocobaltate.

2. The catalyst according to claim 1, characterized in that, The cyano coordination compound comprises potassium hexacyanomanganate and potassium hexacyanocobaltate in a mass ratio of 5.6~8.3:41.7~44.

4.

3. The catalyst according to claim 1, characterized in that, The ternary hydrotalcite includes zinc-magnesium-aluminum hydrotalcite.

4. A method for preparing a catalyst, used to prepare the catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: The support and zinc chloride solution were mixed, and then cyano coordination compound and polyethylene glycol were added sequentially. After centrifugation, the precipitate was washed, dried, and ground to obtain catalyst A. The trichloroacetic acid solution and yttrium hydroxide dispersion were mixed, and catalyst A was added and mixed again. The mixture was then filtered and dried to obtain the catalyst.

5. The method for preparing the catalyst according to claim 4, characterized in that, The mass-to-volume ratio of the carrier to the zinc chloride solution is 1g:2~4mL; The mass ratio of the carrier, cyano coordination compound, and polyethylene glycol is 1:0.5:0.3~0.

6.

6. The method for preparing the catalyst according to claim 4, characterized in that, The mass ratio of the carrier, trichloroacetic acid solution, and yttrium hydroxide dispersion is 1:10:2.8~3.

2.

7. The application of the catalyst according to any one of claims 1 to 3 or the catalyst prepared by the preparation method according to any one of claims 4 to 6 in the preparation of carbon dioxide-based biodegradable plastics.

8. The application according to claim 7, characterized in that, The method for preparing the carbon dioxide-based biodegradable plastic includes the following steps: Propylene oxide and acid anhydride are mixed, the catalyst is added, carbon dioxide is introduced to carry out the reaction, and after post-treatment and granulation, carbon dioxide-based biodegradable plastic is obtained.

9. The application according to claim 8, characterized in that, The mass of the catalyst is 0.03% to 0.065% of the mass of the acid anhydride.

10. The application according to claim 8, characterized in that, The molar ratio of propylene oxide to acid anhydride is 8~10:1.

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