US-12617882-B2 - Homogeneous rare earth catalyst and preparation method and use thereof

US12617882B2US 12617882 B2US12617882 B2US 12617882B2US-12617882-B2

Abstract

The present disclosure provides a preparation method of a homogeneous rare earth catalyst. In the present disclosure, a depolymerizing agent is introduced into the homogeneous rare earth catalyst to promote complete depolymerization of an alkyl aluminum trimer into monomolecular alkyl aluminum. As a result, there is an increase in the number of the alkyl aluminum which serves as an effective chain transfer agent, resulting in a greatly improved chain transfer rate, such that a polymerization system has completed the chain transfer in an early stage of the reaction. Accordingly, an aluminum terminal molecular chain has an increased concentration, leading to an accelerated exchange with an active center propagating chain and a decreased influence caused by an increased viscosity of the system, maintaining living polymerization of the system.

Inventors

Feng Wang
Xuequan Zhang
Heng Liu
Chunyu Zhang

Assignees

QINGDAO UNIVERSITY OF SCIENCE & TECHNOLOGY

Dates

Publication Date: 20260505
Application Date: 20221213

Claims (16)

1 . A preparation method of a homogeneous rare earth catalyst, the preparation method comprising: in a dry inert atmosphere, adding an electron donor, alkyl aluminum, and a depolymerizing agent sequentially into a rare earth neodymium-based organic compound to conduct alkylation, and adding a chloride to conduct chlorination to obtain the homogeneous rare earth catalyst; wherein the rare earth neodymium-based organic compound, the electron donor, the alkyl aluminum, the depolymerizing agent, and the chloride are in a molar ratio of 1:(4-22):(8-42):(2-14):(0.8-4); the depolymerizing agent is one selected from the group consisting of an alkyl boron compound, a phosphate compound, and a nitrogen-containing compound without active hydrogen; and the alkyl boron compound is one selected from the group consisting of triethyl borane, triallylborane, and tri-n-butyl borane; the phosphate compound is one selected from the group consisting of triethyl phosphate, tributyl phosphate, and triphenyl phosphate; and the nitrogen-containing compound without active hydrogen is one selected from the group consisting of triethylamine, tri-n-butylamine, trioctylamine, pyridine, and 2,6-dibromopyridine.
2 . The preparation method according to claim 1 , wherein the rare earth neodymium-based organic compound is one selected from the group consisting of neodymium neodecanoate, neodymium isooctanoate, neodymium naphthenate, neodymium isopropoxide, neodymium isobutoxide, neodymium (2-ethylhexyl) phosphonate, and neodymium mono-2-ethylhexyl (2-ethylhexyl) phosphonate.
3 . The preparation method according to claim 1 , wherein the electron donor is one selected from the group consisting of butadiene, isoprene, piperylene, 1,3,5-hexatriene, and myrcene.
4 . The preparation method according to claim 1 , wherein the alkyl aluminum is selected from the group consisting of diisobutylaluminum hydride and diethylaluminum hydride.
5 . The preparation method according to claim 1 , wherein the alkylation is conducted at 30° C. to 85° C. for 5 minutes to 40 minutes.
6 . The preparation method according to claim 1 , wherein the chloride is selected from the group consisting of dichlorodimethylsilane and ethylaluminium sesquichloride.
7 . The preparation method according to claim 1 , wherein the chlorination is conducted at 30° C. to 110° C. for 10 minutes to 80 minutes.
8 . A homogeneous rare earth catalyst prepared in a dry inert atmosphere, wherein a preparation of the homogeneous rare earth catalyst comprises: adding an electron donor, alkyl aluminum, and a depolymerizing agent sequentially into a rare earth neodymium-based organic compound to conduct alkylation, and adding a chloride to conduct chlorination to obtain the homogeneous rare earth catalyst; wherein the rare earth neodymium-based organic compound, the electron donor, the alkyl aluminum, the depolymerizing agent, and the chloride are in a molar ratio of 1:(4-22):(8-42):(2-14):(0.8-4); the depolymerizing agent is one selected from the group consisting of an alkyl boron compound, a phosphate compound, and a nitrogen-containing compound without active hydrogen; and the alkyl boron compound is one selected from the group consisting of triethyl borane, triallylborane, and tri-n-butyl borane; the phosphate compound is one selected from the group consisting of triethyl phosphate, tributyl phosphate, and triphenyl phosphate; and the nitrogen-containing compound without active hydrogen is one selected from the group consisting of triethylamine, tri-n-butylamine, trioctylamine, pyridine, and 2,6-dibromopyridine.
9 . The homogeneous rare earth catalyst according to claim 8 , wherein the homogeneous rare earth catalyst is used in a process for polymerization of a conjugated diolefin, the process comprising: adding a hexane solution of a conjugated diolefin monomer and the homogeneous rare earth catalyst to a dry ampoule filled with nitrogen, and conducting polymerization at 20° C. to 80° C. for 1 hour to 12 hours; adding an ethanol solution of 2,6-di-tert-butyl-p-cresol with a mass fraction of 1% to terminate a reaction; and subjecting a polymerization product to ethanol precipitation, washing, and drying sequentially to obtain a diolefin polymer.
10 . The homogeneous rare earth catalyst according to claim 8 , wherein the rare earth neodymium-based organic compound is one selected from the group consisting of neodymium neodecanoate, neodymium isooctanoate, neodymium naphthenate, neodymium isopropoxide, neodymium isobutoxide, neodymium (2-ethylhexyl) phosphonate, and neodymium mono-2-ethylhexyl (2-ethylhexyl) phosphonate.
11 . The homogeneous rare earth catalyst according to claim 8 , wherein the electron donor is one selected from the group consisting of butadiene, isoprene, piperylene, 1,3,5-hexatriene, and myrcene.
12 . The homogeneous rare earth catalyst according to claim 8 , wherein the alkyl aluminum is selected from the group consisting of diisobutylaluminum hydride and diethylaluminum hydride.
13 . The homogeneous rare earth catalyst according to claim 8 , wherein the alkylation is conducted at 30° C. to 85° C. for 5 minutes to 40 minutes.
14 . The homogeneous rare earth catalyst according to claim 8 , wherein the chloride is selected from the group consisting of dichlorodimethylsilane and ethylaluminium sesquichloride.
15 . The homogeneous rare earth catalyst according to claim 8 , wherein the chlorination is conducted at 30° C. to 110° C. for 10 minutes to 80 minutes.
16 . The preparation method according to claim 1 , wherein the alkyl boron compound is one selected from the group consisting of triethyl borane and tri-n-butyl borane.

Description

CROSS REFERENCE TO RELATED APPLICATION This patent application claims the benefit and priority of Chinese Patent Application No. 202111527882.3, filed with the China National Intellectual Property Administration on Dec. 14, 2021, the disclosure of which is incorporated by reference herein in its entirety as part of the present application. TECHNICAL FIELD The present disclosure relates to the field of catalytic materials, in particular to a homogeneous rare earth catalyst and a preparation method and use thereof. BACKGROUND Ziegler-Natta catalysts are excellent directional polymerization catalysts commonly used in diolefin polymerization. High-cis polybutadiene rubber, polyisoprene rubber, and butadiene-isoprene copolymer rubber are basic types of rubber in the tire manufacturing industry. The industrialized rare earth cis-butadiene rubber and isoprene rubber each have a high cis-1,4-structure content, a desirable linear structure (no short-branched chain), and a regular chain structure (no head-to-head or tail-to-tail structure), as well as performances far superior to those of nickel-based butadiene rubber and cobalt-based butadiene rubber. Therefore, these types of rubber are widely used in the manufacture of high-performance green tires. For most Ziegler-Natta catalysts, chain transfer reactions are inevitable during catalytic polymerization. On the one hand, the chain transfer reaction can improve a catalytic activity by increasing the number of polymer molecular chains under a preset catalyst dosage, that is, increasing a chain transfer strength means increasing a polymerization activity, and it is difficult to realize industrialization of a coordination polymerization catalytic system without the chain transfer. On the other hand, irreversibility of the chain transfer reaction is another important reason for the uncontrollable polymerization in addition to multi-active site properties. Existing rare earth-based Ziegler-Natta catalysts still have a low activity, especially have irreversible chain transfer when catalyzing coordination polymerization, resulting in uncontrollable polymerization and a broad molecular weight distribution (greater than 2.5) of obtained polymers. Therefore, it is an urgent problem to be solved in the prior art to improve an activity of the rare earth-based Ziegler-Natta catalyst while improving a chain transfer strength of the system and reversibility of the chain transfer reaction during catalytic polymerization. SUMMARY An objective of the present disclosure is to provide a homogeneous rare earth catalyst and a preparation method and use thereof. In the present disclosure, the homogeneous rare earth catalyst belongs to a Ziegler-Natta catalyst. When being used to catalyze polymerization of conjugated diolefins, the catalyst can enhance chain transfer and make the chain transfer from irreversible to reversible, breaking through an upper limit of the number of polymer molecular chains generated by each active center (rare earth atom), and achieving unification of a high activity (ie, each active center can generate multiple polymer chains) and controlled polymerization (ie, polymers with a controlled molecular weight and a narrow molecular weight distribution) in theory and practice. Thus, a high-cis diolefin polymer is obtained with a high molecular weight and a narrow molecular weight distribution. To achieve the above objective of the present disclosure, the present disclosure provides the following technical solutions. The present disclosure provides a preparation method of a homogeneous rare earth catalyst, including the following steps: in a dry inert atmosphere, adding an electron donor, alkyl aluminum, and a depolymerizing agent sequentially into a rare earth neodymium-based organic compound to conduct alkylation, and adding a chloride to conduct chlorination to obtain the homogeneous rare earth catalyst; where the rare earth neodymium-based organic compound, the electron donor, the alkyl aluminum, the depolymerizing agent, and the chloride have a molar ratio of 1:(4-22):(8-42):(2-14):(0.8-4). Preferably, the rare earth neodymium-based organic compound is one selected from the group consisting of neodymium neodecanoate, neodymium isooctanoate, neodymium naphthenate, neodymium isopropoxide, neodymium isobutoxide, neodymium (2-ethylhexyl) phosphonate, and neodymium mono-2-ethylhexyl (2-ethylhexyl) phosphonate. Preferably, the electron donor is one selected from the group consisting of butadiene, isoprene, piperylene, 1,3,5-hexatriene, and myrcene. Preferably, the depolymerizing agent is one selected from the group consisting of an alkyl aluminum compound, an alkyl boron compound, a phosphate compound, and a nitrogen-containing compound without active hydrogen. Preferably, the alkyl aluminum is selected from the group consisting of diisobutylaluminum hydride and diethylaluminum hydride. Preferably, the alkylation is conducted at 30° C. to 85° C. for 5 min to 40 min. Pre