Environment-friendly composite catalyst, preparation method and application thereof

Abstract

The present application belongs to the technical field of catalysts used in the synthesis of water-reducing agent macromonomer, and particularly relates to an environment-friendly composite catalyst, a preparation method and application thereof, wherein the mass fraction of sodium in the composite catalyst is 30wt%-80wt%; the preparation method comprises the following steps: contacting a sodium catalyst with polyethylene glycol to generate sodium polyethylene glycol through reaction; and then mixing the sodium polyethylene glycol with the hydroxide of an alkaline earth metal and performing calcination to obtain the environment-friendly catalyst with a composite structure. The composite catalyst prepared by the present application basically does not generate water or hydrogen during the ring-opening reaction, is more safe and environment-friendly, and ensures that the obtained product is better and more stable in quality.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology used in the synthesis of macromonomers for water-reducing agents, and particularly relates to an environmentally friendly composite catalyst, its preparation method and application. Background Technology

[0002] The macromonomer of water-reducing agent is a polymer obtained by polymerizing a small molecule alcohol containing double bonds with ethylene oxide. This polymer can be further reacted with acrylic acid to prepare water-reducing agent. Water-reducing agent can play the role of reducing water and maintaining slump in concrete.

[0003] Alkali metal catalysts are generally used in the polymerization of macromonomers of water-reducing agents. Commonly used alkali metal catalysts in the industry include sodium metal, NaH, NaOH, and KOH. When using sodium metal or NaH as a catalyst, the catalyst needs to be added to the small molecule alcohol for reaction, generating small molecule sodium alkoxide and hydrogen gas (waste gas). The flammability and explosiveness of hydrogen gas also pose safety risks. When using KOH or NaOH as a catalyst, the catalyst reacts with the small molecule alcohol to produce water. Because the boiling points of water and small molecule alcohol are close, water is difficult to remove from the system, and polyethylene glycol (PEG) byproducts are generated during the reaction, thus reducing product purity. To avoid excessive PEG byproducts, the industry often uses a two-step synthesis method when using KOH or NaOH as a catalyst: first, a small amount of catalyst is used to synthesize a low molecular weight intermediate (generally 400-500 g / mol), and then KOH or NaOH catalyst is added to the intermediate for dehydration, aiming to obtain water-reducing agent monomers with low PEG byproduct content. However, this method often results in long production cycles and generates wastewater.

[0004] Therefore, it is necessary to develop a new environmentally friendly catalyst for use in the polymerization process of macromonomers of water-reducing agents, in order to enable the direct polymerization reaction between small molecule alcohols and ethylene oxide without producing hydrogen and water during the reaction, thereby ensuring more stable product quality. Summary of the Invention

[0005] The purpose of this invention is to address the problems with catalysts used in the polymerization process of water-reducing agent macromonomers, and to provide an environmentally friendly composite catalyst, its preparation method, and its application in the synthesis reaction of water-reducing agent macromonomers. This composite catalyst is easy to use, can be directly mixed with the raw material initiator alcohol, and then participates in the ring-opening reaction to prepare water-reducing agent macromonomers. Moreover, it basically does not produce water or hydrogen during the ring-opening reaction, making it safer and more environmentally friendly, and ensuring that the obtained product has better and more stable quality.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, an environmentally friendly composite catalyst for the synthesis reaction of macromonomers of water-reducing agents is provided, wherein the mass fraction of sodium in the environmentally friendly composite catalyst is 30wt%-80wt% (e.g., 35wt%, 42wt%, 45wt%, 50wt%, 55wt%, 65wt%, 70wt%, 75wt%), preferably 40wt%-60wt%; based on a total weight of 100wt% of the catalyst.

[0008] The environmentally friendly composite catalyst was prepared by the following method:

[0009] Sodium catalysts are contacted with polyethylene glycol to produce sodium polyethylene glycol; the sodium polyethylene glycol is then mixed with an alkaline earth metal hydroxide and calcined in a mixed atmosphere of inert gas and oxygen to obtain an environmentally friendly composite catalyst (such as powder).

[0010] In some embodiments of the environmentally friendly composite catalyst provided by the present invention, the sodium catalyst is selected from one or more of metallic sodium, NaOH, sodium methoxide, and sodium tert-butoxide.

[0011] In some embodiments, the alkaline earth metal hydroxide is selected from one or more of beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide.

[0012] In the second aspect, a method for preparing an environmentally friendly composite catalyst for the synthesis reaction of water-reducing agent macromonomers is provided, comprising the following steps:

[0013] a) A sodium catalyst is mixed with polyethylene glycol and reacted to obtain sodium polyethylene glycol;

[0014] b) Mix the alkaline earth metal hydroxide with the obtained sodium polyethylene glycol (in liquid form) to obtain a mixture;

[0015] c) In an atmosphere of inert gas and oxygen, the mixture obtained in step b) is calcined to obtain a powdered composite catalyst.

[0016] According to the preparation method provided by the present invention, in some embodiments, the mass fraction of sodium in the obtained composite catalyst is 30wt%-80wt%.

[0017] According to the preparation method provided by the present invention, in some embodiments, the sodium catalyst is selected from one or more of metallic sodium, NaOH, sodium methoxide and sodium tert-butoxide, preferably sodium methoxide.

[0018] In some embodiments, the polyethylene glycol has a molecular weight of 1000-8000 g / mol (e.g., 1100 g / mol, 1500 g / mol, 1800 g / mol, 2200 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 3800 g / mol), preferably 2000-4000 g / mol.

[0019] In some embodiments, in step a), the molar ratio of sodium catalyst to polyethylene glycol is 0.8:1 to 2.0:1 (e.g., 0.85:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1), preferably 1.1:1 to 1.5:1.

[0020] In some implementations, step a) is carried out under vacuum and heating conditions.

[0021] In some implementations, the process conditions for the reaction in step a) include:

[0022] The vacuum degree is <-0.95MPa, the heating temperature is 70-130℃ (e.g., 75℃, 80℃, 95℃, 100℃, 115℃, 120℃), preferably 90-110℃, and the reaction time under vacuum and heating conditions is 8-20h (e.g., 10h, 11h, 14h, 15h, 17h, 18h), preferably 12-16h.

[0023] In some embodiments, the alkaline earth metal hydroxide is selected from one or more of beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide, preferably from magnesium hydroxide and / or calcium hydroxide.

[0024] In some embodiments, in step b), the molar ratio of the alkaline earth metal hydroxide to sodium polyethylene glycol is 1:3 to 1:0.5 (e.g., 1:2.5, 1:2, 1:1.8, 1:1.4, 1:1.2, 1:1, 1:0.6), preferably 1:0.8 to 1:1.5.

[0025] In some implementations, in step c), the calcination process conditions include: a calcination temperature of 300-800℃ (e.g., 350℃, 400℃, 500℃, 550℃, 650℃, 700℃, 750℃), preferably 450-600℃; and a calcination time of 24-60h (e.g., 28h, 30h, 35h, 40h, 42h, 45h), preferably 36-48h.

[0026] In some embodiments, in step c), the mass fraction of oxygen in the mixed gas is 0.5wt%-5wt% (e.g., 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.8wt%, 2.0wt%, 2.5wt%, 3.2wt%, 3.5wt%, 4.0wt%, 4.5wt%), preferably 1.5wt%-3wt%; this can be based on a total volume of 100wt% of the mixed gas.

[0027] The inert gas in the gas mixture can be a type of gas commonly found in the art. In some embodiments, the gas mixture is a mixture of nitrogen and oxygen.

[0028] In a third aspect, the application of the environmentally friendly composite catalyst as described above or the environmentally friendly composite catalyst prepared by the method described above in ring-opening reactions is provided, preferably in the application in the ring-opening polymerization reaction of ethylene oxide to prepare water-reducing agent macromonomers.

[0029] The environmentally friendly composite catalyst prepared by this invention can be directly used to synthesize water-reducing agent macromonomers, including methyl allyl alcohol polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether, vinyl glycol ether polyoxyethylene ether, vinyl diethylene glycol ether polyoxyethylene ether, vinyl butylene glycol ether polyoxyethylene ether, etc.

[0030] In some embodiments of the application provided by the present invention, the water-reducing agent macromonomer is selected from one or more of methyl allyl alcohol polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether, vinyl glycol ether polyoxyethylene ether, vinyl diethylene glycol ether polyoxyethylene ether, and vinyl butylene glycol ether polyoxyethylene ether.

[0031] The process of synthesizing water-reducing agent macromonomers using the environmentally friendly composite catalyst prepared by this invention can be achieved by conventional means in the art. For example, the process of synthesizing water-reducing agent macromonomers using the catalyst prepared by this invention can be as follows: the composite catalyst (based on the final product) prepared by reacting an initiator alcohol with 300-3000 ppm (e.g., 400 ppm, 500 ppm, 800 ppm, 1000 ppm, 1500 ppm, 1800 ppm, 2000 ppm, 2500 ppm) is added to a reactor under nitrogen atmosphere, stirring is started and the temperature is heated to 80-110°C (e.g., 85°C, 90°C, 100°C), and metered ethylene oxide is introduced to carry out the polymerization reaction. After the reaction is completed, the material is aged (e.g., using conventional aging treatment processes and conditions) and the monomers are removed to obtain the water-reducing agent macromonomers.

[0032] In the environmentally friendly composite catalyst of this invention, if the sodium content is low, the catalytic activity is low; if the sodium content is too high, the catalytic activity is not easily activated. Therefore, it is necessary to control the sodium content within a suitable range.

[0033] The positive effects of this invention are at least as follows:

[0034] 1) The composite catalyst is obtained by reacting sodium catalyst with polyethylene glycol to produce sodium polyethylene glycol, and then calcining it after mixing with a certain proportion of alkaline earth metal hydroxide. The synthesis process of the catalyst is stable and reliable, and the catalyst obtained has excellent catalytic performance in the synthesis of water-reducing agent macromonomers.

[0035] 2) This composite catalyst is easy to use. It can be directly mixed with the raw material initiator alcohol to participate in the ring-opening reaction to prepare water-reducing agent macromonomers. Moreover, it basically does not produce water or hydrogen during the ring-opening reaction, making it safer and more environmentally friendly, and ensuring that the resulting product has better and more stable quality. Detailed Implementation

[0036] To provide a detailed understanding of the technical features and content of this invention, preferred embodiments will be described in more detail below. While preferred embodiments are described in the examples, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply.

[0037] <Source of Raw Materials>

[0038] In the following examples and comparative examples, the sources of some reagents or raw materials used, unless otherwise specified, are all conventional products that can be purchased commercially.

[0039] Preparation of environmentally friendly composite catalysts

[0040] Example 1

[0041] a) Weigh out sodium methoxide and polyethylene glycol (molecular weight 2000 g / mol) and mix them thoroughly. Control the molar ratio of sodium methoxide to polyethylene glycol to be 1.1:1. Heat the system to 90°C, control its vacuum degree to be <-0.95 MPa, and react under these conditions for 12 h to obtain the sodium salt of polyethylene glycol.

[0042] b) Weigh calcium hydroxide and add it to the liquid phase of the obtained sodium polyethylene glycol salt above, controlling the molar ratio of calcium hydroxide to sodium polyethylene glycol to be 1:0.8, and stir quickly until uniform to obtain a mixed solution;

[0043] c) Place the mixture in a crucible and place it in a muffle furnace. Introduce a nitrogen / oxygen mixture with an oxygen mass fraction of 1.5 wt%. Then, calcine it at a high temperature of 450 °C for 36 h to obtain powdered catalyst A.

[0044] The elemental content of catalyst A obtained from the test was as follows: the mass fraction of metallic sodium was approximately 59.5 wt%.

[0045] Example 2

[0046] a) Weigh out sodium metal and polyethylene glycol (molecular weight 1000 g / mol) and mix them thoroughly. Control the molar ratio of sodium metal to polyethylene glycol to be 0.8:1. Heat the system to 70°C, control its vacuum degree to be <-0.95 MPa, and react under these conditions for 8 hours to obtain the sodium salt of polyethylene glycol.

[0047] b) Weigh beryllium hydroxide and add it to the liquid phase of the obtained sodium polyethylene glycol salt. Control the molar ratio of beryllium hydroxide to sodium polyethylene glycol to be 1:3, and stir quickly until homogeneous to obtain a mixed solution.

[0048] c) Place the mixture in a crucible and place it in a muffle furnace. Introduce a nitrogen / oxygen mixture with an oxygen mass fraction of 0.5 wt%. Then, calcine it at a high temperature of 300 °C for 24 h to obtain powdered catalyst B.

[0049] The elemental content of catalyst B obtained from the test was as follows: the mass fraction of metallic sodium was approximately 30.2 wt%.

[0050] Example 3

[0051] a) Weigh NaOH and polyethylene glycol (molecular weight 4000 g / mol) and mix them thoroughly. Control the molar ratio of NaOH to polyethylene glycol to be 1.5:1. Heat the system to 110℃, control its vacuum degree to be <-0.95MPa, and react under these conditions for 16h to obtain the sodium salt of polyethylene glycol.

[0052] b) Weigh magnesium hydroxide and add it to the liquid phase of the obtained sodium polyethylene glycol salt, controlling the molar ratio of magnesium hydroxide to sodium polyethylene glycol to be 1.0:1.5, and stir quickly until uniform to obtain a mixed solution;

[0053] c) Place the mixture in a crucible and place it in a muffle furnace. Introduce a nitrogen / oxygen mixture with an oxygen mass fraction of 3.0 wt%. Then, calcine it at a high temperature of 600 °C for 60 h to obtain powdered catalyst C.

[0054] The elemental content of the catalyst C obtained from the test was as follows: the mass fraction of metallic sodium was approximately 39.5 wt%.

[0055] Example 4

[0056] a) Weigh sodium tert-butoxide and polyethylene glycol (molecular weight 8000 g / mol) and mix them thoroughly. Control the molar ratio of sodium tert-butoxide to polyethylene glycol to be 2:1. Heat to 130°C, control the vacuum degree to be <-0.95 MPa, and react under these conditions for 20 h to obtain the sodium salt of polyethylene glycol.

[0057] b) Weigh barium hydroxide and add it to the liquid phase of the obtained sodium polyethylene glycol salt above, controlling the molar ratio of barium hydroxide to sodium polyethylene glycol to be 2:1, and stir quickly until uniform to obtain a mixed solution;

[0058] c) Place the mixture in a crucible and place it in a muffle furnace. Introduce a nitrogen / oxygen mixture with an oxygen mass fraction of 5 wt%. Then, calcine it at a high temperature of 800 °C for 48 h to obtain powdered catalyst D.

[0059] The elemental content of the catalyst D obtained by testing is as follows: the mass fraction of metallic sodium is approximately 79.8 wt%.

[0060] Comparative Example 1

[0061] The catalyst preparation process is the same as in Example 1, except that step a) to obtain sodium polyethylene glycol is omitted; instead, step b) of mixing sodium methoxide and calcium hydroxide in a molar ratio of 1:0.5 is performed directly. Step c) is the same as in Example 1. Powdered catalyst A' is finally obtained.

[0062] The elemental content of the catalyst A' obtained by testing is as follows: the mass fraction of metallic sodium is approximately 59.3 wt%.

[0063] Comparative Example 2

[0064] The catalyst preparation process is the same as in Example 1, except that step b) is omitted. That is, step c) is performed after step a), and the obtained sodium salt of polyethylene glycol is directly placed in a crucible and calcined in a muffle furnace. Steps a) and c) are the same as in Example 1. Finally, powdered catalyst B' is obtained.

[0065] The elemental content of the catalyst B' obtained by testing is as follows: the mass fraction of metallic sodium is approximately 82.3 wt%.

[0066] Examples and comparative examples of the synthesis of macromonomers for water-reducing agents

[0067] Using catalyst AD prepared in Examples 1-4 and catalysts A' and B' prepared in Comparative Examples 1-2, a macromonomer for synthesizing water-reducing agents was prepared.

[0068] Example 5: Synthesis of macromonomers for water-reducing agents

[0069] 72 parts by weight of methyl allyl alcohol and 1000 ppm of catalyst A (based on the final product) prepared above were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 100°C. 2380 parts by weight of ethylene oxide were introduced to carry out the polymerization reaction, and the reaction pressure was controlled not to exceed 1 MPa. After the reaction was completed, the system pressure was aged until it no longer decreased (pressure controlled at 0.7 MPa). The aging temperature was 110°C and the aging time was 2 hours. After removing the monomer, the water-reducing agent macromonomer A was obtained. No bubbling phenomenon was observed during the reaction, indicating that no hydrogen was generated.

[0070] The double bond retention rate of monomer A in the water-reducing agent was 98.5%, and the content of PEGs byproducts was 0.5 wt%.

[0071] Example 6: Synthesis of macromonomers for water-reducing agents

[0072] 72 parts by weight of methyl allyl alcohol and 500 ppm of catalyst B (based on the final product) prepared above were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 85°C. 2380 parts by weight of ethylene oxide were introduced to carry out the polymerization reaction, and the reaction pressure was controlled not to exceed 1 MPa. After the reaction, the system pressure was aged until it no longer decreased (pressure controlled at 0.7 MPa). The aging temperature was 110°C and the aging time was 2 hours. After removing the monomer, the water-reducing agent macromonomer B was obtained. No bubbling phenomenon was observed during the reaction, indicating that no hydrogen was generated.

[0073] The double bond retention rate of monomer B in the water-reducing agent was 98.2%, and the content of PEGs byproducts was 0.45 wt%.

[0074] Example 7 of the synthesis of macromonomers for water-reducing agents

[0075] 72 parts by weight of methyl allyl alcohol and 1500 ppm of the catalyst C prepared above (based on the final product) were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 90°C. 2380 parts by weight of ethylene oxide were introduced to carry out the polymerization reaction, and the reaction pressure was controlled not to exceed 1 MPa. After the reaction, the system pressure was aged until it no longer decreased (pressure controlled at 0.7 MPa). The aging temperature was 110°C and the aging time was 2 hours. After removing the monomer, the water-reducing agent macromonomer C was obtained. No bubbling phenomenon was observed during the reaction, indicating that no hydrogen was generated.

[0076] The double bond retention rate of monomer C in the water-reducing agent was 98.9%, and the content of PEGs byproducts was 0.48 wt%.

[0077] Example 8: Synthesis of macromonomers for water-reducing agents

[0078] 72 parts by weight of methyl allyl alcohol and 2500 ppm of the catalyst D prepared above (based on the final product) were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 110°C. 2380 parts by weight of ethylene oxide were introduced to carry out the polymerization reaction, and the reaction pressure was controlled not to exceed 1 MPa. After the reaction, the system pressure was aged until it no longer decreased (pressure controlled at 0.7 MPa). The aging temperature was 110°C and the aging time was 2 hours. After removing the monomer, the water-reducing agent macromonomer D was obtained. No bubbling was observed during the reaction, indicating that no hydrogen was generated.

[0079] The double bond retention rate of monomer D in the water-reducing agent was 99.0%, and the content of PEGs byproducts was 0.35 wt%.

[0080] Comparative Example 3: Synthesis of macromonomers for water-reducing agents

[0081] 72 parts by weight of methyl allyl alcohol and 1000 ppm of the catalyst A' (based on the final product) prepared above were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 100°C. After ethylene oxide was introduced, almost no reaction occurred, indicating that the added catalyst was inactive or had extremely low activity.

[0082] Comparative Example 4: Synthesis of Macromonomers for Water-Reducing Agents

[0083] 72 parts by weight of methyl allyl alcohol and 1000 ppm of the catalyst B' (based on the final product) prepared above were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 100°C. After ethylene oxide was introduced, almost no reaction occurred, indicating that the added catalyst was inactive or had extremely low activity.

[0084] Comparative Example 5: Synthesis of Macromonomers for Water-Reducing Agents

[0085] 72 parts by weight of methyl allyl alcohol and 1000 ppm NaOH (based on the final product) were added to a reactor under nitrogen atmosphere. The nitrogen pressure was controlled at 0.3 MPa. Stirring was started and the mixture was heated to 100°C. 2380 parts by weight of ethylene oxide were introduced to carry out the polymerization reaction. The reaction pressure was controlled not to exceed 1 MPa. After the reaction was completed, the system pressure was aged until it no longer decreased (pressure controlled at 0.71 MPa). The aging temperature was 110°C and the aging time was 2 hours. After removing the monomer, the water-reducing agent macromonomer E was obtained.

[0086] The double bond retention rate of monomer E in the water-reducing agent was 96.5%, and the content of PEG byproducts was 2.5 wt%.

[0087] Comparative Example 6: Synthesis of Macromonomers for Water-Reducing Agents

[0088] 72 parts by weight of methyl allyl alcohol and 1000 ppm of metallic sodium (based on the final product) were added to a reactor under nitrogen atmosphere. The sodium was allowed to react completely to produce hydrogen gas. The system was then purged with nitrogen 3-5 times, and the nitrogen pressure was controlled at 0.3 MPa. The mixture was stirred and heated to 100°C. 2380 parts by weight of ethylene oxide were introduced to carry out the polymerization reaction, and the reaction pressure was controlled not to exceed 1 MPa. After the reaction was completed, the system was aged until the pressure no longer decreased (the pressure was controlled at 0.71 MPa). The aging temperature was 110°C and the aging time was 2 hours. After removing the monomer, the water-reducing agent macromonomer F was obtained.

[0089] The double bond retention rate of the macromonomer F in the water-reducing agent was 98.3%, and the content of PEGs byproducts was 1.0 wt%.

[0090] Catalyst AD prepared in Examples 1-4 was used to prepare the synthetic macromonomer of water-reducing agent. When catalysts A' and B' prepared in Comparative Examples 1-2 were used to prepare the synthetic macromonomer of water-reducing agent (Comparative Examples 3-4), almost no reaction occurred because catalysts A' and B' were inactive or had extremely low activity.

[0091] The more water introduced into the synthesis reaction of the water-reducing agent macromonomer, the higher the content of the by-product PEGs; the content of by-product PEGs can indirectly indicate the amount of water generated. A comparison between the water-reducing agent synthesis examples and synthesis comparative example 5 shows that, because the catalyst prepared according to this invention does not generate water during the synthesis of the water-reducing agent macromonomer, the synthesized water-reducing agent monomer contains less PEGs as a by-product. A comparison between the water-reducing agent synthesis examples and synthesis comparative example 6 shows that the catalyst prepared according to this invention avoids the generation of hydrogen during the synthesis of the water-reducing agent macromonomer, resulting in a safer and more environmentally friendly product with more stable and superior quality.

[0092] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the spirit of the invention.

Claims

1. An environmentally friendly composite catalyst for the synthesis reaction of macromonomers of water-reducing agents, characterized in that, In the aforementioned environmentally friendly composite catalyst, the mass fraction of sodium is 30wt%-80wt%. The environmentally friendly composite catalyst was prepared by the following method: A sodium catalyst is reacted with polyethylene glycol to produce sodium polyethylene glycol; the sodium polyethylene glycol is then mixed with an alkaline earth metal hydroxide and calcined in a mixed atmosphere of inert gas and oxygen to obtain an environmentally friendly composite catalyst; wherein the molar ratio of alkaline earth metal hydroxide to sodium polyethylene glycol is 1:3 to 1:0.5; the calcination temperature is 300-800℃ and the calcination time is 24-60h.

2. The environmentally friendly composite catalyst according to claim 1, characterized in that, In the aforementioned environmentally friendly composite catalyst, the mass fraction of sodium is 40wt%-60wt%.

3. The environmentally friendly composite catalyst according to claim 1, characterized in that, The sodium catalyst is selected from one or more of metallic sodium, NaOH, sodium methoxide, and sodium tert-butoxide; The alkaline earth metal hydroxide is selected from one or more of beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide.

4. A method for preparing an environmentally friendly composite catalyst for the synthesis reaction of macromonomers of water-reducing agents, characterized in that, Includes the following steps: a) A sodium catalyst is mixed with polyethylene glycol and reacted to obtain sodium polyethylene glycol; b) Mix the alkaline earth metal hydroxide with the obtained sodium polyethylene glycol to obtain a mixture; wherein the molar ratio of the alkaline earth metal hydroxide to the sodium polyethylene glycol is 1:3 to 1:0.

5. c) In an atmosphere of inert gas and oxygen, the mixture obtained in step b) is calcined at a temperature of 300-800℃ for 24-60h to obtain a powdered composite catalyst; wherein the mass fraction of sodium is 30wt%-80wt%.

5. The preparation method according to claim 4, characterized in that, The sodium catalyst is selected from one or more of metallic sodium, NaOH, sodium methoxide, and sodium tert-butoxide; and / or The molecular weight of the polyethylene glycol is 1000-8000 g / mol.

6. The preparation method according to claim 4, characterized in that, The sodium catalyst is sodium methoxide.

7. The preparation method according to claim 4, characterized in that, The molecular weight of the polyethylene glycol is 2000-4000 g / mol.

8. The preparation method according to any one of claims 4-7, characterized in that, In step a), the molar ratio of sodium catalyst to polyethylene glycol is 0.8:1 to 2.0:

1.

9. The preparation method according to claim 8, characterized in that, In step a), the molar ratio of sodium catalyst to polyethylene glycol is 1.1:1 to 1.5:

1.

10. The preparation method according to any one of claims 4-7 and 9, characterized in that, Step a) React under vacuum and heating conditions.

11. The preparation method according to claim 10, characterized in that, The process conditions for the reaction in step a) include: a vacuum degree of <-0.95MPa, a heating temperature of 70-130℃, and a reaction time of 8-20h under vacuum and heating conditions.

12. The preparation method according to claim 11, characterized in that, The heating temperature in step a) is 90-110℃.

13. The preparation method according to claim 11, characterized in that, The reaction time under vacuum and heating conditions in step a) is 12-16 hours.

14. The preparation method according to any one of claims 4-7, 9, and 11-13, characterized in that, The alkaline earth metal hydroxide is selected from one or more of beryllium hydroxide, magnesium hydroxide, calcium hydroxide, and barium hydroxide.

15. The preparation method according to claim 14, characterized in that, The alkaline earth metal hydroxide is selected from magnesium hydroxide and / or calcium hydroxide.

16. The preparation method according to any one of claims 4-7, 9, 11-13, and 15, characterized in that, In step b), the molar ratio of the alkaline earth metal hydroxide to sodium polyethylene glycol is 1:0.8 to 1:1.

5.

17. The preparation method according to any one of claims 4-7, 9, 11-13, and 15, characterized in that, In step c), the calcination process conditions include: a calcination temperature of 450-600℃; a calcination time of 36-48h; and / or The mass fraction of oxygen in the mixed gas is 0.5wt%-5wt%.

18. The preparation method according to claim 17, characterized in that, In step c), the mass fraction of oxygen in the mixed gas is 1.5wt%-3wt%.

19. The preparation method according to claim 17, characterized in that, Step c) The mixed gas is a mixture of nitrogen and oxygen.

20. The application of the environmentally friendly composite catalyst according to any one of claims 1-3 or the environmentally friendly composite catalyst prepared by any one of claims 4-19 in ring-opening reactions.

21. The application according to claim 20, characterized in that, The application of the environmentally friendly composite catalyst in the ring-opening polymerization reaction of ethylene oxide to prepare water-reducing agent macromonomers.

22. The application according to claim 21, characterized in that, The water-reducing agent macromonomer is selected from one or more of methyl allyl alcohol polyoxyethylene ether, isopentenyl alcohol polyoxyethylene ether, vinyl glycol ether polyoxyethylene ether, vinyl diethylene glycol ether polyoxyethylene ether, and vinyl butylene glycol ether polyoxyethylene ether.