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KR-102963043-B1 - METHOD FOR PREPARING DOUBLE METAL CYANIDE CATALYST FOR POLYMERIZATION OF CYCLIC MONOMERS

KR102963043B1KR 102963043 B1KR102963043 B1KR 102963043B1KR-102963043-B1

Abstract

A method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization having a porous structure and a high specific surface area is disclosed. The method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization according to the present invention may include the step of hydrothermally synthesizing an acid solution comprising a mixture of a metal salt, a metal cyanide, and a polymer template in a high-pressure hydrothermal reactor.

Inventors

  • 김일
  • 최하경
  • 트란호앙친

Assignees

  • 부산대학교 산학협력단

Dates

Publication Date
20260508
Application Date
20230511

Claims (13)

  1. A method for preparing a dimetallic cyanide catalyst comprising the step of hydrothermally synthesizing an acid solution containing a mixture of a metal salt, a metal cyanide, and a polymer template in a high-pressure hydrothermal reactor at 100 to 150 °C for 1 to 12 hours, The above metal salt includes ZnCl2 , and The above metal cyanide comprises H₃Co (CN) ₆ or K₃Co (CN) ₆ , and The polymer template comprises one or more selected from the group consisting of polyether, polyester, polycarbonate, polyvinylpyrrolidone, and polyvinyl alcohol having a molecular weight of 600 to 60,000; or a linear block copolymer comprising poly(ethylene glycol-b-propylene glycol-b-ethylene glycol) or poly(propylene glycol-b-ethylene glycol-b-propylene glycol) having a molecular weight of 1,000 to 100,000, and The bimetallic cyanide catalyst prepared according to the above manufacturing method has a porous structure and is characterized by having a cubic crystal structure, a hexagonal crystal structure, a monoclinic crystal structure, a rhombohedral crystal structure, or a layered structure depending on the type of added acid, the type of added polymer template, or the amount of added polymer template. Method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization.
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  5. In paragraph 1, If the above acid solution contains acetic acid ( CH₃COOH ), The bimetallic cyanide catalyst prepared by the above method has a porous structure and a layered structure. Method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization.
  6. In paragraph 1, The molar ratio of the metal salt and the metal cyanide is 2:1 to 4:1, Method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization.
  7. In paragraph 1, The acid solution comprising the mixture of the above metal salt, metal cyanide, and polymer template is, A first step of mixing a metal salt solution and a polymer template solution under acidic conditions; A second step of reacting the mixture with a metal cyanide solution; and Characterized by being prepared by including a third step of aging the reactant of the second step at room temperature for 1 to 8 hours. Method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization.
  8. As a bimetallic cyanide catalyst manufactured by a manufacturing method according to any one of claims 1 and 5 to 7, The above catalyst has a porous structure and a specific surface area of 300 to 550 m² /g, and Having a cubic crystal structure, a hexagonal crystal structure, a monoclinic crystal structure, a rhombohedral crystal structure, or a layered structure, Bimetallic cyanide catalyst for cyclic monomer polymerization.
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  10. A method for producing a polyether polyol comprising the step of ring-opening polymerizing an epoxy monomer under a bimetallic cyanide catalyst prepared according to claim 1.
  11. A method for producing a polyester polyol comprising the step of ring-opening polymerizing a lactone-based monomer under a bimetallic cyanide catalyst prepared according to claim 1.
  12. A method for producing a polycarbonate polyol comprising the step of copolymerizing an epoxy monomer and carbon dioxide under a bimetallic cyanide catalyst prepared according to claim 1.
  13. In Paragraph 12, The above epoxy monomer comprises propylene oxide or cyclohexene oxide, Method for manufacturing polycarbonate polyol.

Description

Method for Preparing Double Metal Cyanide Catalyst for Polymerization of Cyclic Monomers The present invention relates to a method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization having a porous structure and a high specific surface area. Double Metal Cyanide (DMC) complexes, or Prussian blue analogs, are well-known inorganic polymer materials made from two metal atoms connected by cyanide bridges. These complexes and analogs have been used as pigments for hundreds or years. Since the 1960s, General Tire and Rubber Co. has discovered new industrial applications for producing high-quality polyalkylene ether polyols with higher molecular weights (MW), tunable hydroxyl functional groups, and lower degrees of unsaturation than those obtained with conventional alkali catalysts. In addition to the homopolymerization of alkylene oxide, DMC catalysts were used for the copolymerization of alkylene oxide and CO₂ for the synthesis of polycarbonate polyols (US 4,500,704, WO 2013/010986, WO 2013/011015, WO 2012/136657, and WO 2012/136658) and for the ternary polymerization of alkylene oxide, CO₂ , and cyclic anhydride for the synthesis of polyether-ester-carbonate polyols (WO 2013/087582). To date, DMC catalysts have been used in carbon dioxide fixation (Green Chem. 2008, 10, pp. 678–684), esterification (J. Catal. 2006, 241, pp. 34–44), transesterification (Energy Fuels 2010, 24, pp. 2154–2161), hydroamination (ACS Catal. 2013, 3, pp. 597–607), prene condensation (J. Mol. Catal. A Chem. 2007, 273, pp. 39–47), oxidation reactions (J. Catal. 2014, 311, pp. 386–392), lactone polymerization (Giant 2020, 3, pp. 100030), and hyperbranched polymer synthesis (Macromolecules 2020, 53, pp. It has been applied to 2051-2060. A conventional method for preparing DMC catalysts for polyols or polycarbonate polyols consists of the reaction of four main compounds comprising a water-soluble metal salt (i.e., ZnCl₂ ), a water-soluble metal cyanide salt (i.e., K₃Co (CN) ₆ ), an electron donor or organic complexing agent (CA), and co-CA. The overall catalyst formula can be expressed as M₀ [M'(CN) ₆ ] ₁₀L₂c₀L'₂d₀ , where M and M' are metal elements, L and L' are CA and co-CA, respectively, and a + b + c + d₀ is equal to the sum of the electron valence of M and M', and a, b, c, and d are integers. For example, the Zn-Co DMC catalyst Zn₃ [Co(CN) ₆ ] ₂ · 5H₂O is a solid compound with a cubic structure and is a three-dimensional coordination polymer composed of small unit cells with a diameter of about 4.2 Å. Each unit cell consists of a Zn²⁺ atom connected to a cobalt atom via a cyanide bridge. Due to charge neutrality, one-third of the unit cell is missing, resulting in a substantial void space with a diameter of approximately 8.5 Å. Given the small size of the unit cell, it is difficult for monomers such as alkylene oxides to penetrate into the DMC framework. Consequently, DMC-catalyzed polymerization occurs mostly on the surface (surface area < 100 m² /g), leading to a prolonged induction period. There have been significant efforts to modify the crystal structure of DMC catalysts to improve activity and reduce the induction period. For example, the process of making nanoscopic DMC catalysts is described in Solid State Ionics 2004, 172, pages 139–144 and Polymer 2011, 52, page 5494, but it has limitations as it requires complex preparation processes and the use of surfactants. Furthermore, conventional bimetallic cyanide catalysts and protocols for their preparation have various disadvantages. Specifically, conventional methods for preparing DMC catalysts require the use of excessive amounts of metal salts and organic complexing agents, which causes environmental problems and increases the cost of the catalyst manufacturing process. In addition, as mentioned above, DMC catalysts produced according to conventional methods exhibit significantly long induction times (> 30 minutes) and side reactions. Therefore, research and development are needed on effective methods to prepare catalysts with a high surface area so that monomer penetration into the matrix facilitates rapid activation of monomer molecules and reduces induction time. FIG. 1a is a schematic diagram showing a method for preparing a bimetallic cyanide catalyst for cyclic monomer polymerization according to one embodiment of the present invention. Figure 1 shows scanning electron microscope and transmission electron microscope images of catalyst 1 having a typical cubic structure. Figure 2 shows scanning electron microscope and transmission electron microscope images of catalyst 2 in an amorphous form, in which particles of 50-200 nm are clustered or aggregated and do not have a specific crystal shape. Figure 3 shows scanning electron microscope and transmission electron microscope images of catalyst 3, which has a mixture of cubic and rhombohedral forms and a large crystal size of 0.5-1 μm. Figure 4 shows scanning electron microscope and transmission ele