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WO-2026091830-A1 - CATALYST COMPOSITION AND PREPARATION METHOD THEREFOR, AND PREPARATION METHOD FOR HIGH MELT STRENGTH POLYETHYLENE

WO2026091830A1WO 2026091830 A1WO2026091830 A1WO 2026091830A1WO-2026091830-A1

Abstract

The present invention provides a catalyst composition and a preparation method therefor, and a preparation method for high melt strength polyethylene. The catalyst composition comprises a main catalyst and a co-catalyst; the co-catalyst comprises an alkylaluminum compound and a pyridine compound; and the main catalyst is prepared by reacting a magnesium compound, a silicon compound and a titanium compound in a molar ratio of 1:0.1-10:0.05-3. When catalyzing ethylene polymerization, the catalyst composition of the present invention can significantly improve the melt strength of a polymerization product.

Inventors

  • GAO, KEJING
  • QIN, Rui
  • ZHANG, LIYANG
  • ZHU, Wenqin
  • ZHOU, Jingsheng
  • ZHU, Kaige
  • WANG, YISEN
  • LI, Shuanhong
  • LI, BING
  • REN, XIAOBING

Assignees

  • 中国石油天然气股份有限公司

Dates

Publication Date
20260507
Application Date
20250829
Priority Date
20241028

Claims (19)

  1. A catalyst composition comprising a main catalyst and a co-catalyst, the co-catalyst comprising an alkylaluminum compound and a pyridine compound, wherein the main catalyst is prepared by reacting a magnesium compound, a silicon compound, and a titanium compound in a molar ratio of 1:0.1-10:0.05-3; the molar ratio of the alkylaluminum compound to the titanium compound in the main catalyst is 10-200:1, and the molar ratio of the alkylaluminum compound to the pyridine compound is 1:1-10; The magnesium compound includes one or more combinations of compounds with the general formula Mg(OR 1 ) 2 , where R 1 is selected from saturated or unsaturated C2 - C20 hydrocarbon groups. The silicon compound includes one or more combinations of compounds with the general formula Si(OR 2 ) m Cl 2-m , where R 2 is selected from saturated or unsaturated C 2 -C 20 hydrocarbon groups, and 0 < m ≤ 2. The titanium compound includes one or more combinations of compounds with the general formula Ti(OR 3 ) n Cl 4-n , where R 3 is selected from saturated or unsaturated C 2 -C 20 hydrocarbon groups, and 0 ≤ n < 4.
  2. According to claim 1, the catalyst composition wherein R1 , R2 , and R3 are each independently selected from straight-chain hydrocarbon groups, branched-chain hydrocarbon groups, or cyclic-chain hydrocarbon groups, and each is independently selected from C2 - C20 aliphatic hydrocarbons.
  3. The catalyst composition according to claim 1, wherein R1 , R2 , and R3 are each independently selected from C2 - C20 alkyl groups.
  4. The catalyst composition according to claim 1, wherein R1 , R2 , and R3 are each independently selected from C2 - C10 alkyl groups.
  5. According to claim 1, the catalyst composition wherein R1 , R2 , and R3 are each independently selected from ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or isooctyl.
  6. According to claim 1, the catalyst composition wherein the molar ratio of magnesium compound, silicon compound and titanium compound is 1:0.5-5:0.1-2.
  7. According to claim 1, the catalyst composition wherein the magnesium compound comprises alkoxy magnesium, and the alkoxy magnesium comprises one or more of diethoxy magnesium, dibutoxy magnesium, and dipropoxy magnesium.
  8. According to claim 1, the catalyst composition wherein the magnesium compound is in particulate form with a particle size of 2-20 micrometers.
  9. According to claim 1, the catalyst composition, wherein the silicon compound comprises a mixture of the reaction products of silicon tetrachloride and C2 - C20 fatty alcohol; the reaction conditions include: a molar ratio of C2 - C20 fatty alcohol to silicon tetrachloride of 1-4:1, a reaction temperature of 20-50°C, and a reaction time of 0.5-5 h.
  10. According to claim 1, the catalyst composition, wherein the titanium compound comprises titanium tetrachloride and/or a mixture of the reaction products of titanium tetrachloride and fatty alcohols; the reaction conditions include: a molar ratio of C2 - C20 fatty alcohol to titanium tetrachloride of 0-4:1, a reaction temperature of 20-100°C, and a reaction time of 0.5-5 h.
  11. According to claim 1, the catalyst composition wherein the alkyl group in the alkylaluminum compound has 1-20 carbon atoms.
  12. The catalyst composition according to claim 11, wherein the alkylaluminum compound comprises one or more of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, and tri-n-octylaluminum.
  13. The catalyst composition according to claim 1, wherein the pyridine compound comprises one or more combinations of pyridine, 2-methylpyridine, 2-ethylpyridine, 2-isopropylpyridine, 2,4-dimethylpyridine, 2,6-dimethylpyridine, 2-methyl-6-ethylpyridine, 2,6-diethylpyridine, 2-chloro-6-methylpyridine, 2,6-dichloropyridine, 2,4,6-trimethylpyridine, 2,4,6-triethylpyridine, 2,4,6-trichloropyridine, and 2,4,6-triisopropylpyridine.
  14. A method for preparing the catalyst composition according to any one of claims 1-13, comprising the following steps: Preparation of the main catalyst: A particulate magnesium compound is dispersed in an organic solvent, and then a silicon compound and a titanium compound are slowly added at low temperature to carry out a chlorination reaction, followed by aging. The resulting particles are the main catalyst. The feeding temperature of the silicon compound is -10℃ to 100℃, and the feeding temperature of the titanium compound is -10℃ to 20℃; the feeding rate of the silicon compound and the titanium compound shall not exceed 2L/min respectively. An alkylaluminum compound and a pyridine compound are provided to form the catalyst composition with the main catalyst.
  15. According to the method for preparing the catalyst composition according to claim 14, the aging reaction temperature is 80℃-100℃ and the reaction time is 0.5-15h.
  16. According to the method for preparing the catalyst composition of claim 14, the reaction process for preparing the main catalyst is carried out in an inert dispersant, wherein the inert dispersant includes one or more of hexane, heptane, octane, toluene, xylene, 1,2-dichloroethane, chlorocyclohexane, and chlorobenzene.
  17. A method for preparing high melt strength polyethylene, comprising the following steps: The catalyst composition according to any one of claims 1-13 is uniformly dispersed in a reaction solvent, heated to the reaction temperature, and then ethylene is introduced to carry out a polymerization reaction to obtain the high melt strength polyethylene.
  18. According to the method for preparing high melt strength polyethylene according to claim 17, when dispersing the catalyst composition in the reaction solvent, the alkyl aluminum compound and pyridine compound are first added to the reaction solvent and mixed evenly, and then the main catalyst is added and dispersed evenly.
  19. According to the method for preparing high melt strength polyethylene according to claim 17, the reaction solvent includes one or a combination of two or more of propane, isobutane, isopentane, and hexane.

Description

Catalyst composition and its preparation method, and preparation method of high melt strength polyethylene Cross-reference information This application claims priority to Chinese Patent Application No. 202411515564.9, filed on October 28, 2024, entitled "Catalyst Composition and Preparation Method Thereof, and Preparation Method of High Melt Strength Polyethylene", the entire contents of which are incorporated herein by reference. Technical Field This invention relates to the field of ethylene polymerization catalyst technology, specifically to a catalyst composition and its preparation method, and a method for preparing high melt strength polyethylene. Background Technology Since the successful development of high-efficiency polyethylene catalysts, the polyethylene industry has undergone tremendous changes. In recent years, along with the development of ethylene polymerization processes, catalysts配套 (matching) these processes have also made significant progress. Among them, high-efficiency catalysts, with their excellent polymerization performance and mature application technologies, still occupy an important position in the field of polyethylene catalysts. After years of exploration and research, many high-efficiency Ziegler-Natt catalysts have been prepared, many of which are used to produce high-density polyethylene. High-density polyethylene (HDPE) has a high density, a good balance of rigidity and toughness, excellent resistance to chemical corrosion, is non-hygroscopic, and has good water resistance. It can be used to produce large bulk containers, automotive fuel tanks, fruit and milk bottles, and various other hollow containers. Currently, HDPE large and hollow containers are widely used for containing various hazardous and non-hazardous chemicals, oils, and other liquids, gradually replacing metal containers and becoming the main form of liquid packaging in some industries. High-density polyethylene (HDPE) used in hollow container manufacturing primarily utilizes chromium-based catalysts. Chromium-based catalysts can produce HDPE with a broad molecular weight distribution, containing a certain amount of high molecular weight components. This meets the melt strength requirements and environmental stress cracking (ESCR) resistance requirements during hollow container blow molding. Furthermore, chromium-based catalysts can form a small amount of long-chain branches online during ethylene polymerization. The presence of these long branches is beneficial to the blow molding process of hollow containers and the final mechanical properties of the finished products. Currently, polyethylene manufacturers primarily use chromium-based catalysts for the production of materials specifically for large and hollow containers. Compared to chromium-based catalysts, titanium-based catalysts cannot produce polyethylene with a wide molecular weight distribution. To achieve a wider molecular weight distribution, a two-reactor series reactor approach is generally used for the production of bimodal polyethylene. The low molecular weight fraction is produced in the first reactor, while the high molecular weight fraction is produced in the second reactor, thus meeting the requirement for a wide molecular weight distribution in hollow containers. However, polyethylene produced by titanium-based catalysts typically has lower melt strength and insufficient melt tensile strength, making it unsuitable for blow molding processes in the production of hollow blow-molded products. Summary of the Invention To solve the above-mentioned technical problems, the present invention aims to provide a catalyst composition and its preparation method, as well as a method for preparing high melt strength polyethylene, which catalyzes the preparation of high melt strength polyethylene through a specific combination of catalysts. To achieve the above objectives, the present invention provides a catalyst composition comprising a main catalyst and a co-catalyst, wherein the co-catalyst comprises an alkylaluminum compound and a pyridine compound, and the main catalyst is prepared by reacting a magnesium compound, a silicon compound, and a titanium compound in a molar ratio of 1:0.1-10:0.05-3; the molar ratio of the alkylaluminum compound to the titanium compound in the main catalyst is 10-200:1, and the molar ratio of the alkylaluminum compound to the pyridine compound is 1:1-10; The magnesium compound includes one or more combinations of compounds with the general formula Mg(OR 1 ) 2 , where R 1 is selected from saturated or unsaturated C 2 -C 20 hydrocarbon groups. The silicon compound includes one or more combinations of compounds with the general formula Si(OR 2 ) m Cl 2-m , where R 2 is selected from saturated or unsaturated C 2 -C 20 hydrocarbon groups, and 0 < m ≤ 2. The titanium compound includes one or more combinations of compounds with the general formula Ti(OR 3 ) n Cl 4-n , where R 3 is selected from saturated or unsaturated C 2 -C 20