Preparation method of azoimidazole-modified Mn-Mg nanoclusters catalyzing copolymerization of carbon dioxide and propylene oxide

Abstract

The invention discloses a method for preparing azoimidazole-modified Mn-Mg nanoclusters for catalyzing the copolymerization of carbon dioxide and propylene oxide, which belongs to the technical field of polymer materials; the method uses potassium permanganate and tetrabutylammonium bromide as basic raw materials, and obtains tetrabutylammonium permanganate salt after reaction. Then, pivalic acid, tetrabutylammonium permanganate salt, manganese acetate tetrahydrate and magnesium acetate tetrahydrate are reacted, and the product is reacted with azodiimidazole propane, and finally, azoimidazole-modified Mn-Mg nanoclusters are obtained, which are catalysts used for the copolymerization of carbon dioxide and propylene oxide; the raw materials used in the preparation method are easy to obtain, and the method is applied to the copolymerization of carbon dioxide and propylene oxide, with high catalytic efficiency and mild reaction conditions.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a preparation method of azoimidazole-modified Mn-Mg nanoclusters catalyzing the copolymerization of carbon dioxide and propylene oxide. Background Art

[0002] In the copolymerization reaction of carbon dioxide, various catalysts have been developed, including heterogeneous and homogeneous metal-based complexes; for heterogeneous catalytic systems, Sebastian Joby et al. prepared Co-Zn double metal cyanide (DMCs) catalysts in 2015, which have good catalytic activity for the copolymerization of epoxides and carbon dioxide; Zhang Xinghong et al. prepared the [Zn-Co (III) DMCC] catalytic system in 2016; copolymerization with epoxides is carried out through free radical initiators.

[0003] With the rapid development of nanotechnology, the concepts of nanocatalysis and nanocatalysts have been proposed one after another. Among them, metal nanoclusters, due to their unique structural advantages, show excellent activity and selectivity in catalytic reactions and have quickly become a hot topic in the field of scientific research. Compared with macroscopic block catalyst materials, metal nanoclusters show physical and chemical properties different from block materials and high catalytic activity due to their unique quantum size effect, surface effect and small size effect.

[0004] In the prior art, metal nanoclusters used to catalyze the copolymerization reaction of carbon dioxide and propylene oxide have high costs, violent reactions and low safety during the production process. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of azoimidazole-modified Mn-Mg nanoclusters catalyzing the copolymerization of carbon dioxide and propylene oxide, so as to solve the problems of high production cost and low safety of metal nanoclusters used for catalyzing the copolymerization reaction of carbon dioxide and propylene oxide in the prior art described in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The preparation method of azoimidazole-modified Mn-Mg nanoclusters catalyzing the copolymerization of carbon dioxide and propylene oxide comprises the following steps:

[0008] (1) Pour water into a high-speed mixer, pour potassium permanganate and tetrabutylammonium bromide into the water and stir and mix at 0 to 50° C., react for 4 to 5 hours, filter the material in the mixer, collect the purple precipitate, wash the purple precipitate with distilled water and ether, and finally dry the washed purple precipitate to obtain tetrabutylammonium permanganate salt for later use;

[0009] (2) heating acetonitrile to boiling state, then adding pivalic acid, tetrabutylammonium permanganate, manganese acetate tetrahydrate and magnesium acetate tetrahydrate to the boiling acetonitrile, mixing and reacting for 30 to 60 minutes, then filtering the reacted material to obtain a filtrate, placing the filtrate in an environment of -10 to 0° C. for 1 to 3 days to obtain a brown solid crystalline powder for standby use;

[0010] (3) dissolving the brown solid crystalline powder and azobisimidazole propane in ethyl acetate for 1-3 days, filtering the dissolved material to obtain a solid crystalline powder, and then washing the solid crystalline powder with cyclohexane to obtain azoimidazole-modified Mn-Mg nanoclusters.

[0011] Preferably, the molar ratio of potassium permanganate to tetrabutylammonium bromide in step (1) is 1:1-4.

[0012] Preferably, in step (2), the molar ratio of pivalic acid, tetrabutylammonium permanganate, manganese acetate tetrahydrate and magnesium acetate tetrahydrate is 10:4:1-2:1-2;

[0013] Preferably, the molar ratio of the brown solid crystalline powder to azobisimidazolylpropane in step (3) is 1:0.1-1.

[0014] The beneficial effects of adopting the above technical solution are:

[0015] The invention adopts a chemical synthesis method, adopts potassium permanganate to react with tetrabutylammonium bromide to obtain tetrabutylammonium permanganate; then pivalic acid, tetrabutylammonium permanganate, manganese acetate tetrahydrate and magnesium acetate tetrahydrate are mixed in a certain proportion and reacted; the product is reacted with azodiimidazole propane to finally obtain azoimidazole-modified Mn-Mg nano clusters, which are catalysts used for copolymerization of carbon dioxide and propylene oxide; the nano clusters of the invention are applied to copolymerization of carbon dioxide and propylene oxide, have high catalytic efficiency and mild reaction conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the chemical formula of the Mn-Mg nanoclusters of the present invention.

[0017] Figure 2 It is the chemical formula of the white solid polypropylene carbonate of the present invention. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below:

[0019] Example 1

[0020] The preparation method of azoimidazole-modified Mn-Mg nanoclusters catalyzing the copolymerization of carbon dioxide and propylene oxide comprises the following steps: Figure 1

[0021] (1) Pour 400 mmol of water into a high-speed stirrer, pour 50 mmol of potassium permanganate and 55 mmol of tetrabutylammonium bromide into the water at 20° C., stir and mix, react for 5 hours, filter the material in the stirrer, collect the purple precipitate, wash the purple precipitate with distilled water and ether, and finally dry the washed purple precipitate to obtain tetrabutylammonium permanganate salt for later use;

[0022] (2) 200 mmol of acetonitrile was heated to a boiling state, and then 40 mmol of pivalic acid, 4 mmol of tetrabutylammonium permanganate, 1 mmol of manganese acetate tetrahydrate and 1 mmol of magnesium acetate tetrahydrate were added to the boiling acetonitrile, and the mixture was mixed and reacted for 60 minutes, and then the reacted material was filtered to obtain a filtrate, and the filtrate was placed in an environment of 0° C. for 2 days to obtain a brown solid crystalline powder for standby use;

[0023] (3) 2 mmol of brown solid crystalline powder and 1 mmol of azobisimidazole propane were dissolved in 50 mmol of ethyl acetate for 3 days, and then the dissolved material was filtered to obtain solid crystalline powder, and then the solid crystalline powder was washed with cyclohexane to obtain azoimidazole-modified Mn-Mg nanoclusters.

[0024] Polymerization, see Figure 2 , 1mmol azoimidazole-modified Mn-Mg nanocluster catalyst and 2mol propylene oxide were added in the following order at ambient temperature in an autoclave with a volume of 500ml, and then carbon dioxide gas was introduced into the autoclave and a constant pressure of 1.0MPa was maintained, and then the temperature was controlled at 60°C, and the reaction was carried out under stirring for 24 hours, and then the temperature was cooled to room temperature, and then the unreacted carbon dioxide in the autoclave was slowly discharged, and the unreacted propylene oxide was recovered, and then acetone was added to the autoclave to dissolve the polymer at the bottom, and washed with 5% dilute hydrochloric acid, and then dropped into 8 times ethanol while stirring to obtain polypropylene carbonate white solid. The performance parameters of the polypropylene carbonate are as follows: Table 1

[0025] Table 1 Properties of polyester polyurethane

[0026] project index Tensile strength(MPa) 35 Tear strength (KN / m) 61 Elongation at break (%) 428 Shore A Hardness 86

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing azoimidazole-modified Mn-Mg nanoclusters catalyzing the copolymerization of carbon dioxide and propylene oxide, characterized in that: The following steps are involved: (1) Pour water into a high-speed mixer, pour potassium permanganate and tetrabutylammonium bromide into the water and stir and mix at a temperature of 0 to 50° C., wherein the molar ratio of potassium permanganate to tetrabutylammonium bromide is 1:1-4. After reacting for 4 to 5 hours, filter the material in the mixer and collect the purple precipitate, then wash the purple precipitate with distilled water and ether, and finally dry the washed purple precipitate to obtain tetrabutylammonium permanganate salt for later use; (2) heating acetonitrile to a boiling state, then adding pivalic acid, tetrabutylammonium permanganate, manganese acetate tetrahydrate and magnesium acetate tetrahydrate to the boiling acetonitrile, wherein the molar ratio of pivalic acid, tetrabutylammonium permanganate, manganese acetate tetrahydrate and magnesium acetate tetrahydrate is 10:4:1-2:1-2, mixing and reacting for 30 to 60 minutes, then filtering the reacted material to obtain a filtrate, placing the filtrate in an environment of -10 to 0°C for 1 to 3 days, and obtaining a brown solid crystalline powder for standby use; (3) dissolving the brown solid crystalline powder and azobisimidazole propane in ethyl acetate, wherein the molar ratio of the brown solid crystalline powder to the azobisimidazole propane is 1:0.1-1, and the dissolution time is 1-3 days, and then filtering the dissolved material to obtain a solid crystalline powder, and then washing the solid crystalline powder with cyclohexane to obtain azoimidazole-modified Mn-Mg nanoclusters.

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