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US-20260124609-A1 - PREPARATION METHOD OF DUAL-ANION CATALYST, AND USE OF DUAL-ANION CATALYST IN CATALYTIC DEGRADATION OF POLYURETHANE MATERIAL

US20260124609A1US 20260124609 A1US20260124609 A1US 20260124609A1US-20260124609-A1

Abstract

A preparation method of a dual-anion catalyst, and a use of the dual-anion catalyst in catalytic degradation of a polyurethane material are provided. The preparation method includes: dissolving a metal salt in deionized water to produce a metal salt solution; adding a nitrogen-containing heterocyclic compound with hydroxyl or amino as a substrate to a reactor, adding the metal salt solution dropwise to the reactor, and conducting condensation reflux at 60° C. to 150° C. for 1 h to 8 h; adding an amine compound dropwise, and conducting a reaction; after the reaction is completed, conducting vacuum filtration to produce a filtrate; and subjecting the filtrate to evaporation, and oven-drying a resulting product to produce the dual-anion catalyst. A recovered polyol obtained through the degradation with the catalyst exhibits basically the same fundamental physical properties such as hydroxyl value, amine value, and viscosity to a virgin polyol.

Inventors

  • Huiwen He
  • Kaiming DU
  • Xu Wang
  • Yulu ZHU
  • Si Chen
  • Meng Ma
  • Yanqin SHI

Assignees

  • ZHEJIANG UNIVERSITY OF TECHNOLOGY

Dates

Publication Date
20260507
Application Date
20251231
Priority Date
20240827

Claims (18)

  1. 1 . A preparation method of a dual-anion catalyst, comprising following steps: 1) dissolving a metal salt in deionized water to produce a metal salt solution; 2) adding a nitrogen-containing heterocyclic compound with hydroxyl or amino as a substrate to a reactor, adding the metal salt solution dropwise to the reactor, and conducting condensation reflux at 60° C. to 150° C. for 1 h to 8 h; 3) after the condensation reflux in the step 2) is completed, adding an amine compound dropwise to the reactor, and conducting a reaction for 2 h to 5 h; and after the reaction is completed, conducting vacuum filtration to produce a filtrate; 4) subjecting the filtrate obtained in the step 3) to evaporation; and 5) oven-drying a product obtained in the step 4) to produce the dual-anion catalyst.
  2. 2 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 1), the metal salt is one or more of zinc acetate, magnesium acetate, zinc nitrate, cadmium nitrate, nickel nitrate, and cobalt nitrate.
  3. 3 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 2), the nitrogen-containing heterocyclic compound with hydroxyl or amino is one or more of 4-(hydroxymethyl)imidazole, 2-hydroxymethyl-1-methylimidazole, 6-(hydroxymethyl)pyridin-3-ol, 3,4-bis(hydroxymethyl)furan, and 6-hydroxymethylquinoline.
  4. 4 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 2), the metal salt solution is slowly added dropwise to the reactor for 20 min to 40 min.
  5. 5 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 2), the condensation reflux is conducted at 100° C. to 150° C. for 1 h to 4 h.
  6. 6 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 3), the amine compound is one or more of phenylethylamine, triphenylguanidine, tetramethylguanidine, and sulfaguanidine.
  7. 7 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 3), after the condensation reflux in the step 2) is completed, the amine compound is added dropwise to the reactor, and then the reaction is conducted for 2 h to 3 h.
  8. 8 . The preparation method of the dual-anion catalyst according to claim 1 , wherein a molar ratio of the nitrogen-containing heterocyclic compound with hydroxyl or amino, the metal salt, and the amine compound is (0.3-1):(0.3-1.5):(0.5-1).
  9. 9 . The preparation method of the dual-anion catalyst according to claim 1 , wherein in the step 4), the filtrate obtained in the step 3) is treated for 1 h to 2 h in a rotary evaporator at 50° C. to 60° C.; and in the step 5), the product obtained in the step 4) is oven-dried for 12 h to 24 h in a forced air oven at 80° C. to 90° C.
  10. 10 . A use of a dual-anion catalyst prepared by the preparation method according to claim 1 in catalytic degradation of a polyurethane material.
  11. 11 . The use according to claim 10 , wherein in the step 1) of the preparation method, the metal salt is one or more of zinc acetate, magnesium acetate, zinc nitrate, cadmium nitrate, nickel nitrate, and cobalt nitrate.
  12. 12 . The use according to claim 10 , wherein in the step 2) of the preparation method, the nitrogen-containing heterocyclic compound with hydroxyl or amino is one or more of 4-(hydroxymethyl)imidazole, 2-hydroxymethyl-1-methylimidazole, 6-(hydroxymethyl)pyridin-3-ol, 3,4-bis(hydroxymethyl)furan, and 6-hydroxymethylquinoline.
  13. 13 . The use according to claim 10 , wherein in the step 2) of the preparation method, the metal salt solution is slowly added dropwise to the reactor for 20 min to 40 min.
  14. 14 . The use according to claim 10 , wherein in the step 2) of the preparation method, the condensation reflux is conducted at 100° C. to 150° C. for 1 h to 4 h.
  15. 15 . The use according to claim 10 , wherein in the step 3) of the preparation method, the amine compound is one or more of phenylethylamine, triphenylguanidine, tetramethylguanidine, and sulfaguanidine.
  16. 16 . The use according to claim 10 , wherein in the step 3) of the preparation method, after the condensation reflux in the step 2) is completed, the amine compound is added dropwise to the reactor, and then the reaction is conducted for 2 h to 3 h.
  17. 17 . The use according to claim 10 , wherein in the preparation method, a molar ratio of the nitrogen-containing heterocyclic compound with hydroxyl or amino, the metal salt, and the amine compound is (0.3-1):(0.3-1.5):(0.5-1).
  18. 18 . The use according to claim 10 , wherein in the step 4) of the preparation method, the filtrate obtained in the step 3) is treated for 1 h to 2 h in a rotary evaporator at 50° C. to 60° C.; and in the step 5), the product obtained in the step 4) is oven-dried for 12 h to 24 h in a forced air oven at 80° C. to 90° C.

Description

CROSS REFERENCE TO THE RELATED APPLICATIONS This application is a continuation application of International Application No. PCT/CN2024/126578, filed on Oct. 22, 2024, which is based upon and claims priority to Chinese Patent Application No. 202411183355.9, filed on Aug. 27, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to the field of chemical catalytic degradation and recycling of waste polyurethane materials, and specifically relates to a preparation method of a dual-anion catalyst, and a use of the dual-anion catalyst in catalytic degradation of a polyurethane material. BACKGROUND The recycling and reuse of waste polymer materials is a crucial pathway for enabling a green circular economy and achieving the goals of peak carbon dioxide emissions and carbon neutrality. The annual consumption of polyurethane products in China exceeds 15 million tons, with waste production reaching 400,000 tons per year. Polyurethane materials are widely used in aerospace, household goods, transportation, and other fields. However, polyurethane materials can hardly be recycled due to insoluble and non-melting cross-linked structures. Waste polyurethane can only be disposed of through landfill or incineration, or can only be processed into low-end products through crushing and compaction, with a recycling rate of less than 10%. This leads to severe ecological and environmental problems and significant resource waste. Additionally, common polyurethane materials are often mixtures characterized by complex structures and variable compositions, which pose significant challenges for chemical recycling. Currently, the chemical depolymerization methods for waste polyurethane primarily include alcoholysis, acidolysis, aminolysis, hydrolysis, and enzymolysis. The common goal of these methods is to depolymerize polyurethane into polymerizable polyols, thereby achieving the recycling of resources and the treatment of non-depolymerizable wastes. However, for high-volume flexible polyurethane foam that demands high-quality recycling, there is still a lack of efficient depolymerization and recycling technologies. The invention patent CN201910863314.7 discloses a method for preparing a polyether polyol through hydrothermal catalytic degradation of a waste rigid polyurethane material. In this method, the polyether polyol is prepared by a catalytic solvothermal technology. A catalyst used in this method does not need to be recovered, but can remain in a reaction product to further serve as a catalyst for synthesizing a polyurethane material. However, this method requires a relatively high temperature (180° C. to 240° C.). Most importantly, this method is limited to rigid polyurethane foam. The invention patent CN201710649420.6 discloses a method for acidolysis of a flexible polyurethane foam waste to produce a polyol. In this method, a solid acid catalyst, a liquid acid catalyst, an impregnated acid catalyst, a cation exchange resin, or a metal-salt acid catalyst is used to achieve the degradation of the flexible polyurethane foam waste. However, this method requires a reaction time of 9 h or more and a relatively high reaction temperature (230° C. to 250° C.). Moreover, the catalysts mentioned above cannot significantly enhance the reaction rate or reduce the reaction activation energy. In summary, to achieve the eco-friendly recovery of high-quality polyols, it is essential to clarify a degradation mechanism of polyurethane, develop a key degradation catalyst for polyurethane, and activate urethane bonds at the source by a catalytic technology to enhance the attack capability of a nucleophilic reagent. Consequently, the reaction temperature can be lowered, the generation of harmful by-products such as aromatic amines can be avoided, the reaction efficiency can be improved, and the quality of a recovered polyol can be enhanced. SUMMARY The present disclosure is intended to provide a preparation method of a dual-anion catalyst, and a use of the dual-anion catalyst in catalytic degradation of a polyurethane material. This catalyst plays a catalytic role through a synergistic action in the following two aspects: In a first aspect, an amine compound enhances the attack capability of a nucleophilic reagent itself. In a second aspect, a complex formed by a metal ion and a nitrogen-containing heterocyclic compound boosts the electropositivity of carbonyl carbon of a urethane bond to make it susceptible to attack by a nucleophilic reagent, thereby enhancing the degradation rate and degree. A recovered polyol obtained through the degradation with this catalyst exhibits basically the same fundamental physical properties such as hydroxyl value, amine value, and viscosity to a virgin polyol, and can partially replace the virgin polyol in the production of a flexible polyurethane foam. Technical solutions of the present disclosure are as follows: A preparation method of a dual-anio