Catalyst, method for preparing the same, and use thereof in carbon dioxide-based degradable plastics

Abstract

The application relates to the technical field of catalysts, and discloses a catalyst, a preparation method thereof and application of the catalyst in carbon dioxide-based degradable plastics. The catalyst is a supported catalyst, which comprises a carrier and an active component. The carrier comprises a ternary hydrotalcite, and the active component comprises a double-metal cyanide and a rare earth yttrium complex. Raw materials of the double-metal cyanide comprise a cyano ligand compound. The cyano ligand compound comprises potassium hexacyanomanganate and / or potassium hexacyanocobaltate. Through the technical scheme, the problem that the yield of the catalyst in related technologies is low and the amount of by-products is large when the catalyst is used for catalytically preparing carbon dioxide-based degradable plastics is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular, to a catalyst, a preparation method thereof and application of the catalyst in carbon dioxide-based degradable plastics. BACKGROUND

[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, and its product has realized industrialized production. It is a new type of biodegradable plastic with 100% biodegradable properties. The synthesis process of PPC is as follows: under the action of a catalyst, carbon dioxide and propylene oxide are prepared by anionic polymerization reaction. It not only has the mechanical and use properties of traditional plastics, but also can be completely degraded in the natural environment, and has important research significance.

[0003] Among them, 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 polymerization product. An ideal catalytic system should have high activity, high selectivity and excellent stability, which can effectively activate inert carbon dioxide molecules, promote the alternating insertion of carbon dioxide and propylene oxide, and inhibit the occurrence of side reactions, thereby improving the generation efficiency and molecular weight of the target polymer.

[0004] However, the current catalytic system for the polymerization reaction still has several key technical bottlenecks: first, the activation ability of some catalysts for carbon dioxide is insufficient, which makes it difficult to effectively overcome the thermodynamic stability and kinetic inertness of carbon dioxide, resulting in low polymerization activity and limited monomer conversion; second, many catalysts perform poorly in terms of selectivity control, which cannot effectively inhibit the generation of cyclic carbonate and other by-products, resulting in waste of reaction raw materials, decrease in propylene oxide selectivity, and low molecular weight of the obtained polymer.

[0005] Therefore, in view of the deficiencies of existing catalysts in activity, selectivity and stability, developing new efficient catalytic systems has become a key research direction to improve the synthesis efficiency and product performance of carbon dioxide-based degradable plastics. SUMMARY

[0006] The present application proposes a catalyst, a preparation method thereof and application of the catalyst in carbon dioxide-based degradable plastics, which solves the problem of low yield and excessive by-products of the catalyst in the related art when catalytically preparing carbon dioxide-based degradable plastics.

[0007] The technical scheme of the present application is as follows:

[0008] The present application proposes a catalyst, which is a supported catalyst, comprising a carrier and an active component;

[0009] The carrier comprises a ternary hydrotalcite, and the active component comprises a double-metal cyanide and a rare earth yttrium complex;

[0010] The raw material of the double-metal cyanide comprises a cyano coordination compound;

[0011] The cyano coordination compound comprises potassium hexacyanomanganate (III) and / or potassium hexacyanocobaltate (III).

[0012] As a further technical solution, the cyano coordination compound comprises potassium hexacyanomanganate (III) and potassium hexacyanocobaltate (III) in a mass ratio of 5.6-8.3:41.7-44.4.

[0013] In the active component of the catalyst, the raw material of the double-metal cyanide is potassium hexacyanomanganate (III) and potassium hexacyanocobaltate (III), which cooperates with manganese and cobalt elements to reduce the reaction activation energy, thereby improving the yield of carbon dioxide-based degradable plastics, especially when the mass ratio of potassium hexacyanomanganate (III) and potassium hexacyanocobaltate (III) is 5.6-8.3:41.7-44.4, the catalytic activity and selectivity are more optimal, which promotes the polymerization of carbon dioxide-based degradable plastics and reduces the generation of by-products.

[0014] As a further technical solution, the ternary hydrotalcite comprises a zinc-magnesium-aluminum hydrotalcite.

[0015] The application further provides a preparation method of the catalyst.

[0016] The carrier and the zinc chloride solution are mixed, the cyano coordination compound and polyethylene glycol are sequentially added and mixed, centrifugation is performed, the precipitate is washed, dried, ground, and the catalyst A is obtained.

[0017] The trichloroacetic acid solution and the yttrium hydroxide dispersion liquid are mixed, the catalyst A is added and continuously mixed, filtration is performed, and the catalyst is dried.

[0018] During the preparation of the catalyst, the polyethylene glycol has good solubility and dispersibility, and the polyethylene glycol plays a role of a dispersant during the preparation of the catalyst, so as to reduce the surface tension between the components and promote the uniform dispersion of the cyano coordination compound on the surface of the carrier, thereby avoiding the agglomeration phenomenon.

[0019] As a further technical solution, the mass-volume ratio of the carrier and 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.

[0020] The mass ratio of the carrier, the cyano ligating compound and the polyethylene glycol is 1:0.5:0.3~0.6, for example, 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, 1:0.5:0.6.

[0021] As a further technical solution, the mass ratio of the carrier, the trichloroacetic acid solution and the yttrium hydroxide dispersion is 1:10:2.8~3.2, for example, can be 1:10:2.8, 1:10:2.9, 1:10:3.0, 1:10:3.1, 1:10:3.2.

[0022] The application also proposes the application of the catalyst or the catalyst prepared by the preparation method in the preparation of carbon dioxide-based degradable plastics.

[0023] As a further technical solution, the preparation method of the carbon dioxide-based degradable plastics comprises the following steps:

[0024] The propylene oxide and the acid anhydride are mixed, the catalyst is added, carbon dioxide is introduced for reaction, post-treatment, granulation, and the carbon dioxide-based degradable plastics are obtained.

[0025] As a further technical solution, the mass of the catalyst is 0.03%~0.065% of the mass of the acid anhydride.

[0026] As a further technical solution, the molar ratio of the propylene oxide and the acid anhydride is 8~10:1, for example, can be 8:1, 8.5:1, 9:1, 9.2:1, 9.5:1, 9.8:1, 10:1.

[0027] As a further technical solution, the introduction pressure of the carbon dioxide is 0.5~2MPa;

[0028] The reaction time is 8~10h, and the temperature is 60~70℃.

[0029] The working principle and beneficial effects of the application are as follows:

[0030] In the present application, the supported catalyst is used, the ternary hydrotalcite is used as the carrier, and the bimetallic cyanide and the rare earth yttrium complex are used as the active components, so that the yield of the carbon dioxide-based degradable plastic is improved, and the by-products are reduced. Different from the prior art, the ternary hydrotalcite is used as the carrier, the layered structure and the high specific surface area thereof are utilized, a more stable catalytic environment is provided for the bimetallic cyanide and the rare earth yttrium complex active components, the active components can fully contact the reactants, the reaction is accelerated, the ternary hydrotalcite, the bimetallic cyanide and the rare earth yttrium complex are synergistically catalyzed, the reaction rate is improved, the high selectivity of the reaction is ensured, the yield of the generated carbon dioxide-based degradable plastic is improved, and the by-products are reduced. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also fall within the scope of protection of the present application.

[0032] In the following examples and comparative examples, the zinc chloride solution is a 2% mass concentration zinc chloride aqueous solution;

[0033] The trichloroacetic acid solution is a 2% mass concentration trichloroacetic acid aqueous solution, and the yttrium hydroxide dispersion is a 2% mass concentration yttrium hydroxide and water dispersion;

[0034] The zinc-magnesium-aluminum hydrotalcite is a ternary hydrotalcite, wherein the content of MgO is 21.9wt%-23.9wt%, the content of Al2O3 is 18.3wt%-20.3wt%, the content of ZnO is 14.4wt%-16.4wt%, the specific surface area is ≥10m 2 / g, the average particle size is ≤100nm, the CAS is 119758-00-8, and it is purchased from Beijing Tekler Technology Co., Ltd.

[0035] Example 1

[0036] The catalyst is a supported catalyst, which comprises a carrier zinc-magnesium-aluminum hydrotalcite and an active component;

[0037] The preparation method of the supported catalyst comprises the following steps:

[0038] 100g of zinc-magnesium-aluminum hydrotalcite and 200mL of zinc chloride solution are mixed, 50g of potassium hexacyanocobaltate (III) and 30g of polyethylene glycol are sequentially added and mixed, centrifuged, the precipitate is washed, dried, and ground into powder to obtain the catalyst A;

[0039] Mixing 1000g of trichloroacetic acid solution and 280g of yttrium hydroxide dispersion liquid, adding catalyst A, stirring and mixing at 45℃ for 2.5h, filtering, drying, to obtain a supported catalyst;

[0040] The preparation method of the carbon dioxide-based degradable plastic comprises the following steps:

[0041] Mixing 116kg of propylene oxide and 29.62kg of phthalic anhydride, adding 0.018kg of catalyst, introducing carbon dioxide (the introduction pressure is 0.5MPa), and reacting at 60℃ for 10h; adding 5wt% of deionized water to inactivate the reaction, then filtering to remove the catalyst, washing the material with water at 80℃ to remove the byproduct propylene carbonate and unreacted propylene oxide, then extruding and granulating in a double-screw extruder to obtain the carbon dioxide-based degradable plastic.

[0042] Example 2

[0043] The catalyst is a supported catalyst, comprising a carrier zinc magnesium aluminum hydrotalcite and an active component;

[0044] The preparation method of the supported catalyst comprises the following steps:

[0045] Mixing 100g of zinc magnesium aluminum hydrotalcite and 400mL of zinc chloride solution, sequentially adding 50g of potassium hexacyanocobaltate (III) and 60g of polyethylene glycol for mixing, centrifuging to obtain a precipitate, washing, drying, and grinding to powder to obtain catalyst A;

[0046] Mixing 1000g of trichloroacetic acid solution and 300g of yttrium hydroxide dispersion liquid, adding catalyst A, stirring and mixing at 45℃ for 2.5h, filtering, drying, to obtain a supported catalyst;

[0047] The preparation method of the carbon dioxide-based degradable plastic comprises the following steps:

[0048] Mixing 116kg of propylene oxide and 29.62kg of phthalic anhydride, adding 0.011kg of catalyst, introducing carbon dioxide (the introduction pressure is 2MPa), and reacting at 70℃ for 8h; adding 10wt% of deionized water to inactivate the reaction, then filtering to remove the catalyst, washing the material with water at 100℃ to remove the byproduct propylene carbonate and unreacted propylene oxide, then extruding and granulating in a double-screw extruder to obtain the carbon dioxide-based degradable plastic.

[0049] Example 3

[0050] The catalyst is a supported catalyst, comprising a carrier zinc magnesium aluminum hydrotalcite and an active component;

[0051] The method for preparing the supported catalyst comprises the following steps:

[0052] 100 g of zinc-magnesium-aluminum hydrotalcite and 300 mL of zinc chloride solution were mixed, 50 g of potassium hexacyanocobaltate (III) and 40 g of polyethylene glycol were sequentially added and mixed, centrifuged, the precipitate was washed and dried, and was ground into powder to obtain catalyst A;

[0053] 1000 g of trichloroacetic acid solution and 320 g of yttrium hydroxide dispersion liquid were mixed, catalyst A was added, and the mixture was stirred at 45°C for 2.5 h, filtered, and dried to obtain the supported catalyst;

[0054] The method for preparing the carbon dioxide-based degradable plastic comprises the following steps:

[0055] 92.8 kg of propylene oxide and 29.62 kg of phthalic anhydride were mixed, 0.013 kg of catalyst was added, carbon dioxide was introduced (the introduction pressure was 1 MPa), and the reaction was carried out at 65°C for 9 h; 8 wt% of deionized water was added to inactivate the reaction, then the catalyst was removed by filtration, and the material was washed with water at 90°C to remove the byproduct propylene carbonate and unreacted propylene oxide, and then was extruded and granulated in a twin-screw extruder to obtain the carbon dioxide-based degradable plastic.

[0056] Example 4

[0057] The difference between this example and Example 3 is that the potassium hexacyanocobaltate (III) is replaced by potassium hexacyanomanganate (III).

[0058] Example 5

[0059] The difference between this example and Example 3 is that the 50 g of potassium hexacyanocobaltate (III) is replaced by 5 g of potassium hexacyanomanganate (III) and 45 g of potassium hexacyanocobaltate (III).

[0060] Example 6

[0061] The difference between this example and Example 3 is that the 50 g of potassium hexacyanocobaltate (III) is replaced by 10 g of potassium hexacyanomanganate (III) and 40 g of potassium hexacyanocobaltate (III).

[0062] Example 7

[0063] The difference between this example and Example 3 is that the 50 g of potassium hexacyanocobaltate (III) is replaced by 8.3 g of potassium hexacyanomanganate (III) and 41.7 g of potassium hexacyanocobaltate (III).

[0064] Example 8

[0065] The difference between this example and Example 3 is that 50 g of potassium hexacyanocobaltate is replaced by 5.6 g of potassium hexacyanomanganate and 44.4 g of potassium hexacyanocobaltate.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 3 is that the preparation method of the supported catalyst comprises the following steps:

[0068] 45 g of zinc-magnesium-aluminum hydrotalcite and 300 mL of zinc chloride solution are mixed, 50 g of potassium hexacyanocobaltate and 40 g of polyethylene glycol are sequentially added and mixed, centrifuged, the precipitate is washed, dried, and ground to powder to obtain a supported catalyst.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 3 is that the zinc-magnesium-aluminum hydrotalcite is replaced by activated carbon.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 3 is that the zinc-magnesium-aluminum hydrotalcite is replaced by magnesium-aluminum hydrotalcite (MgO content 34 wt%, Al2O3 content 18 wt%, purchased from Rongsheng New Material Technology (Nantong) Co., Ltd.).

[0073] Experimental Example

[0074] The molecular weight of the carbon dioxide-based degradable plastics prepared in Examples 1-8 and Comparative Examples 1-3 is tested, and the mass of the prepared carbon dioxide-based degradable plastics and the mass of the byproduct polycarbonate are recorded, and the results are shown in Table 1 below.

[0075] Table 1 Yield calculation results

[0076]

[0077] Compared with Comparative Examples 1-3, the carbon dioxide-based degradable plastics prepared in Examples 1-8 have higher mass and lower mass of byproduct polycarbonate, indicating that the use of the supported catalyst, the carrier being zinc-magnesium-aluminum hydrotalcite, and the active component being double metal cyanide and rare earth complex improves the yield of carbon dioxide-based degradable plastics and reduces the mass of byproduct polycarbonate.

[0078] Compared with examples 3~4, the carbon dioxide-based degradable plastics prepared in examples 5~8 have higher quality, the by-product polycarbonate has lower quality, and the carbon dioxide-based degradable plastics have higher molecular weight, which indicates that the double metal cyanide raw material of the active component of the supported catalyst replaces potassium hexacyanocobaltate with potassium hexacyanomanganate and potassium hexacyanocobaltate, adjusts the electron cloud by using manganese element, provides various catalytic sites, improves the product selectivity, stabilizes the reaction intermediate state by using cobalt element, cooperates with manganese element to reduce the reaction activation energy, speeds up the reaction rate, is conducive to the preparation of carbon dioxide-based degradable plastics, and especially when the mass ratio of potassium hexacyanomanganate and potassium hexacyanocobaltate in examples 7~8 is 5.6~8.3:41.7~44.4, the catalytic activity and selectivity are more optimal, and the polymerization of the carbon dioxide-based degradable plastics is promoted.

[0079] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

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 compound comprises potassium hexacyanomanganate and potassium hexacyanocobaltate in a mass ratio of 5.6~8.3:41.7~44.4; The ternary hydrotalcite includes zinc-magnesium-aluminum hydrotalcite; The mass ratio of the support to the cyano coordination compound is 1:0.5; The rare earth yttrium complex was prepared by mixing a trichloroacetic acid solution and a yttrium hydroxide dispersion. The mass ratio of the carrier, trichloroacetic acid solution, and yttrium hydroxide dispersion is 1:10:2.8~3.2; The mass concentration of the yttrium hydroxide dispersion is 2%.

2. A method for preparing a catalyst, used to prepare the catalyst according to claim 1, 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.

3. The method for preparing the catalyst according to claim 2, 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.

4. The application of the catalyst according to claim 1 or the catalyst prepared by the preparation method according to any one of claims 2 to 3 in the preparation of carbon dioxide-based biodegradable plastics.

5. The application according to claim 4, 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.

6. The application according to claim 5, characterized in that, The mass of the catalyst is 0.03% to 0.065% of the mass of the acid anhydride.

7. The application according to claim 5, characterized in that, The molar ratio of propylene oxide to acid anhydride is 8~10:1.

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