Process for the preparation and use of rare earth catalysts

Abstract

The application provides a preparation method and application of a rare earth catalyst, and comprises the following steps: mixing a carboxylic acid neodymium alkane solution with a high water content and a conjugated diene alkane, adding a first alkyl aluminum compound, then adding a halogen-containing compound, and finally adding a second alkyl aluminum compound to obtain the rare earth catalyst; wherein the water content of the carboxylic acid neodymium alkane solution is 2000-20000 ppm; and the molar ratio of aluminum in the first alkyl aluminum compound to aluminum in the second alkyl aluminum compound is (0.02-0.60):1.0. The rare earth catalyst prepared in this way has high activity and high orientation ability, the content of cis-1,4 structure in the rare earth isoprene rubber is improved, and the tires made of the rare earth isoprene rubber have excellent damage resistance, wear resistance and crack growth resistance.

Description

Technical Field

[0001] This invention relates to the field of rare earth catalysts, and more specifically, to a method for preparing and applying a rare earth catalyst. Background Technology

[0002] Rare earth isoprene rubber is a polyisoprene rubber with a high content of cis-1,4-structure, obtained by coordination-directional polymerization of isoprene using rare earth catalysts. Its important application is as a substitute for natural rubber in the production of automobile tires. Compared with traditional titanium-based isoprene rubber produced using titanium catalysts, rare earth isoprene rubber has a simpler production process, generates less wastewater, and produces superior overall performance, thus becoming the direction of global isoprene rubber development.

[0003] The content of cis-1,4-structure in isoprene rubber is one of the key indicators affecting its performance. Natural rubber contains almost 100% cis-1,4-structure in polyisoprene, resulting in excellent elasticity and tires made from it exhibiting superior resistance to damage, abrasion, and crack growth. Given the geographical and limited nature of natural rubber resources, developing isoprene rubber as a substitute for natural rubber has become a global consensus.

[0004] However, the cis-1,4-structure content of rare earth isoprene rubber produced by different rare earth catalysts and production processes varies. The cis-1,4-structure content of rare earth isoprene rubber prepared using a traditional three-component heterogeneous catalytic system with neodymium chloride complexes can reach over 97%. In contrast, the cis-1,4-structure content of rare earth isoprene rubber prepared using traditional three-component heterogeneous catalytic systems with carboxylic acid and four-component homogeneous catalytic systems with carboxylic acid can only reach around 96%. Given the advantages of the four-component homogeneous catalytic system with carboxylic acid, such as simple formulation, accurate metering, and stable production control, this technology is still used in production facilities worldwide, especially in China, with considerable capacity. Therefore, increasing the cis-1,4-structure content of isoprene rubber products using this technology is of practical significance.

[0005] The general method for preparing a four-component homogeneous catalytic system of neodymium carboxylate is as follows: first, neodymium carboxylate is mixed with a conjugated diene; then, alkyl aluminum is added to the mixture; and finally, a halogen-containing compound is added. An improved method to increase the cis-1,4-structure content of the isoprene polymerization product generally involves first adding a halogen-containing compound (such as alkyl aluminum chloride) to the mixture of neodymium carboxylate and the conjugated diene, and finally adding the alkyl aluminum, thus changing the order of addition of the alkyl aluminum and alkyl aluminum halide.

[0006] Patent CN103360516A discloses a neodymium-based homogeneous rare earth catalyst for the production of rare earth isoprene rubber. The catalyst contains neodymium carboxylate, alkyl aluminum and / or alkyl aluminum hydride, alkyl halides, and a polymer obtained by polymerizing a conjugated diene. The unique preparation method of this catalyst includes: under inert gas protection, a first contact of neodymium carboxylate, alkyl halides, and conjugated diene in an inert organic solvent to obtain a mixture; and then a second contact of the mixture with alkyl aluminum and / or alkyl aluminum hydride. The solvent used in the catalyst preparation process has a water content of less than 20 ppm. However, this invention does not mention the source of the alkane solution of neodymium carboxylate or its water content. Generally, the preparation of the alkane solution of neodymium carboxylate employs a neutralization extraction method, and the water content of the product is as high as approximately 10,000 ppm (mass content, the same below). When directly used in the preparation of the catalyst of this invention, the activity of the resulting catalyst is significantly reduced, and it is necessary to reduce its water content to a certain level before use.

[0007] Patent CN102532365B discloses a homogeneous neodymium carboxylate catalyst and its preparation method. The catalyst comprises neodymium carboxylate, alkylaluminum, a halogen-containing compound, and a conjugated diene, belonging to a traditional four-component homogeneous neodymium carboxylate catalytic system. The preparation method involves first mixing neodymium carboxylate with the conjugated diene, then adding the halogen-containing compound to the mixture, and finally adding the alkylaluminum; or first mixing neodymium carboxylate, the halogen-containing compound, and the conjugated diene, then adding the alkylaluminum to the mixture. However, this invention also fails to mention the source and water content of the neodymium carboxylate alkane solution. To ensure the polymerization activity of the prepared catalyst, the water content of the neodymium carboxylate alkane solution must be reduced to a certain level (e.g., less than 500 ppm). This inevitably leads to a complex production process, increased production costs, and poor storage stability of the low-water-content neodymium carboxylate alkane solution.

[0008] Therefore, how to directly prepare rare earth catalysts for the efficient production of rare earth isoprene rubber with high cis structure content using neodymium carboxylate solutions with high water content as raw materials, in order to reduce costs and simplify the process, is an urgent problem to be solved.

[0009] In view of the above, this application is hereby submitted. Summary of the Invention

[0010] The main objective of this invention is to provide a method for preparing and applying rare earth catalysts, in order to solve the problems in the prior art where a pretreatment dehydration step is required when preparing rare earth catalysts using neodymium carboxylate solutions with high water content as raw materials, resulting in complex production processes, increased production costs, and easy deterioration of neodymium carboxylate solutions with low water content during storage.

[0011] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a rare earth catalyst is provided, comprising the following steps: Step S1, mixing a neodymium carboxylate solution and a conjugated diene in an alkane to obtain a first mixture; wherein the water content of the neodymium carboxylate solution is 2000-20000 ppm; Step S2, mixing a first alkylaluminum compound with the first mixture to obtain a second mixture; Step S3, mixing a halogen-containing compound with the second mixture to obtain a third mixture; Step S4, mixing a second alkylaluminum compound with the third mixture to obtain a rare earth catalyst; wherein the molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound is (0.02-0.60):1.0.

[0012] Furthermore, the water content of the neodymium carboxylate solution is 5000-15000 ppm, and even further, 8000-11000 ppm.

[0013] Furthermore, the molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound is (0.06–0.24):1.0.

[0014] Furthermore, the molar ratio of neodymium in the carboxylic acid neodymium alkane solution, conjugated diene, aluminum in the first alkyl aluminum compound, chlorine in the halogen-containing compound, and aluminum in the second alkyl aluminum compound is 1.0:(5.0-20.0):(0.2-3.0):(2.0-3.5):(5.0-10.0).

[0015] Furthermore, the neodymium carboxylate in the neodymium carboxylate alkane solution includes at least one of neodymium naphthenate, neodymium isooctanoate, and neodymium neodecanoate, and even more specifically, neodymium neodecanoate.

[0016] Further, in step S1, the alkane includes C5-C7 alkanes and / or cycloalkanes, and more specifically, at least one of cyclohexane, n-pentane and its isomers, n-heptane and its isomers, and n-hexane and its isomers.

[0017] Furthermore, the solvent in the carboxylic acid neodymium alkane solution is an alkane, including C5-C7 alkanes and / or cycloalkanes, and more specifically, at least one of cyclohexane, n-pentane and its isomers, n-heptane and its isomers, and n-hexane and its isomers.

[0018] Furthermore, the conjugated diene includes at least one of 1,3-butadiene, isoprene, and isoprene, and even more specifically, isoprene.

[0019] Furthermore, the first alkylaluminum compound and the second alkylaluminum compound each independently include alkylaluminum compounds and / or hydrogenated alkylaluminum compounds.

[0020] Furthermore, the alkylaluminum compound includes at least one of trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0021] Furthermore, the alkylaluminum hydrogenated compounds include at least one of diisobutylaluminum hydride and diethylaluminum hydride.

[0022] Furthermore, the first alkylaluminum compound and the second alkylaluminum compound are each independently a mixture of triisobutylaluminum and diisobutylaluminum hydride, and the molar ratio of the two is 1.0:(0.05-0.50).

[0023] Furthermore, the halogenated compounds include diethylaluminum chloride and / or diethylaluminum chloride, and even more specifically, diethylaluminum chloride.

[0024] According to another aspect of the present invention, an application is provided of a rare earth catalyst obtained by the preparation method provided in the first aspect above in the preparation of rubber by conjugated diene polymerization.

[0025] Furthermore, the conjugated diene is isoprene, and the rubber is isoprene rubber.

[0026] Applying the technical solution of this invention, this application uses a neodymium carboxylate solution with a water content of 2000-20000 ppm as raw material. First, the neodymium carboxylate solution with a high water content is mixed with a conjugated diene. Then, a first alkylaluminum compound is added, followed by a halogen-containing compound, and finally a second alkylaluminum compound. The molar ratio of the first alkylaluminum compound to the second alkylaluminum compound, calculated based on aluminum element, is (0.02-0.6):1.0. The rare earth catalyst prepared in this manner exhibits high activity and high orientation ability, increasing the content of the cis-1,4-structure in rare earth isoprene rubber. Tires manufactured using this rare earth isoprene rubber exhibit excellent resistance to damage, wear, and crack growth.

[0027] The preparation method provided in this application does not require reducing the water content in a neodymium carboxylate solution with a water content of 2000-20000 ppm to below 500 ppm, and can directly prepare rare earth catalysts. Moreover, the prepared rare earth catalysts have high activity and high orientation ability. This method simplifies the production process, reduces energy consumption and production costs, improves the storage stability of neodymium carboxylate solutions, and achieves a dual improvement in industrial production efficiency and economic benefits, while also making a positive contribution to environmental protection. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0029] As analyzed in the background section of this application, existing technologies require a pretreatment dehydration step when preparing rare earth catalysts using neodymium carboxylate solutions with high water content as raw materials. This results in complex production processes, increased production costs, and the easy deterioration of neodymium carboxylate solutions with low water content during storage. To address these issues, this application provides a method for preparing and applying a rare earth catalyst.

[0030] In a first typical embodiment of this application, a method for preparing a rare earth catalyst is provided, comprising the following steps: Step S1, mixing a neodymium carboxylate solution and a conjugated diene in an alkane to obtain a first mixture; wherein the water content of the neodymium carboxylate solution is 2000-20000 ppm; Step S2, mixing a first alkylaluminum compound with the first mixture to obtain a second mixture; Step S3, mixing a halogen-containing compound with the second mixture to obtain a third mixture; Step S4, mixing a second alkylaluminum compound with the third mixture to obtain a rare earth catalyst; wherein the molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound is (0.02-0.60):1.0.

[0031] This application uses a neodymium carboxylate solution with a water content of 2000-20000 ppm as raw material. First, the neodymium carboxylate solution with high water content is mixed with a conjugated diene. Then, a first alkylaluminum compound is added, followed by a halogen-containing compound, and finally a second alkylaluminum compound. The molar ratio of the first alkylaluminum compound to the second alkylaluminum compound, based on aluminum element, is (0.02-0.6):1.0. The rare earth catalyst prepared in this manner exhibits high activity and high orientation ability, increasing the content of the cis-1,4-structure in rare earth isoprene rubber. Tires manufactured using this rare earth isoprene rubber exhibit excellent resistance to damage, abrasion, and crack growth.

[0032] The preparation method provided in this application does not require reducing the water content in a neodymium carboxylate solution with a water content of 2000-20000 ppm to below 500 ppm, and can directly prepare rare earth catalysts. Moreover, the prepared rare earth catalysts have high activity and high orientation ability. This method simplifies the production process, reduces energy consumption and production costs, improves the storage stability of neodymium carboxylate solutions, and achieves a dual improvement in industrial production efficiency and economic benefits, while also making a positive contribution to environmental protection.

[0033] Furthermore, some studies have found that when the number of coordinating atoms of neodymium carboxylate complexes is 8, coordination saturation is achieved, and the complexes exist as unimolecular molecules in alkane solutions with good solubility. During their research, the inventors of this invention unexpectedly discovered that when the water content of a neodymium carboxylate alkane solution reaches dissolution saturation (approximately 10,000 ppm at room temperature), water molecules coordinate with neodymium atoms, resulting in the number of coordinating atoms around the neodymium atoms approaching the saturation value of 8. Such neodymium carboxylate alkane solutions exhibit good stability and do not produce precipitates due to association between neodymium carboxylate molecules during long-term storage. When these solutions undergo alkylation reactions with alkylaluminum compounds, the reaction proceeds more completely, resulting in rare earth catalysts with high activity. Conversely, if the water content of the neodymium carboxylate alkane solution is reduced (e.g., below 500 ppm) through azeotropic distillation, the neodymium atoms become unsaturated due to the loss of coordinated water molecules. This makes it easy for neodymium carboxylate molecules to associate due to bridging coordination, resulting in precipitation during the storage of the neodymium carboxylate alkane solution. This, in turn, affects its application in the preparation of rare earth catalysts.

[0034] In existing technologies, the water content of neodymium carboxylate solutions prepared by neutralization extraction is generally around 10,000 ppm. However, to obtain rare earth catalysts with excellent catalytic activity and orientation using traditional methods, the water content of the neodymium carboxylate solution must first be reduced to 500 ppm before direct preparation. This process is cumbersome, has high process requirements, and consumes a significant amount of manpower and resources. This application, however, eliminates the need to reduce the water content of the high-water-content neodymium carboxylate solution to below 500 ppm, allowing direct preparation of rare earth catalysts. Furthermore, the prepared rare earth catalyst exhibits high activity and high orientation capability. This method simplifies the production process, reduces energy consumption and production costs, and improves the storage stability of the neodymium carboxylate solution, achieving a dual improvement in industrial production efficiency and economic benefits.

[0035] In this application, the alkane in step S1 is anhydrous and oxygen-free alkane.

[0036] The saturated water content of neodymium carboxylate solutions is generally around 10,000 ppm. When the water content exceeds 20,000 ppm, free water (insoluble water) will appear. The presence of free water will lead to uneven water content, inaccurate sampling and measurement of water content, and seriously affect the formulation effect of the catalyst.

[0037] Typically, but not limitingly, the water content of the neodymium carboxylate solution provided in this application may be 2000 ppm, 3000 ppm, 5000 ppm, 8000 ppm, 11000 ppm, 13000 ppm, 15000 ppm, 18000 ppm, 20000 ppm, or any range of two such values.

[0038] Typically, but not limitingly, the molar ratios of aluminum in the first alkylaluminum compound and the second alkylaluminum compound provided in this application are, for example, 0.02:1.0, 0.026:1, 0.05:1.0, 0.068:1, 0.1:1.0, 0.114:1, 0.147:1, 0.16:1, 0.164:1, 0.2:1.0, 0.238:1, 0.3:1.0, 0.4:1.0, 0.5:1.0, 0.59:1, 0.6:1.0, or any range of two such values.

[0039] To further improve the activity of the rare earth catalyst and thus further increase the content of the cis-1,4-structure in the rare earth isoprene rubber, the water content of the carboxylic acid neodymium alkane solution is preferably 5000-15000 ppm, more preferably 8000-11000 ppm.

[0040] Typically, but not limitingly, the water content of the neodymium carboxylate solution provided in this application is 5000 ppm, 6000 ppm, 8000 ppm, 9000 ppm, 11000 ppm, 13000 ppm, 15000 ppm, or any range of two such values.

[0041] To further improve the ability of rare earth catalysts to directionally generate cis-1,4-structures, the preferred molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound is (0.06–0.24):1.0.

[0042] In some embodiments, the molar ratio of neodymium in the carboxylic acid neodymium alkane solution, the conjugated diene, the aluminum in the first alkylaluminum compound, the chlorine in the halogen-containing compound, and the aluminum in the second alkylaluminum compound is 1.0:(5.0–20.0):(0.2–3.0):(2.0–3.5):(5.0–10.0). When the molar ratio of each component is within the above range, the activity and catalytic efficiency of the rare earth catalyst of this application can be further improved.

[0043] In other embodiments, the molar ratio of neodymium in the carboxylic acid neodymium alkane solution, the conjugated diene, the aluminum in the first alkylaluminum compound, the chlorine in the halogen-containing compound, and the aluminum in the second alkylaluminum compound is 1.0:(5.0–20.0):(0.5–1.7):(2.0–3.5):(6.8–7.8). This further improves the activity and catalytic efficiency of the rare earth catalyst of this application.

[0044] Typical, but not limiting, molar ratios of neodymium in the carboxylic acid neodymium alkane solution, conjugated diene, aluminum in the first alkylaluminum compound, chlorine in the halogen-containing compound, and aluminum in the second alkylaluminum compound provided in this application are, for example, 1.0:5.0:0.2:2.0:5.0, 1.0:5.0:0.5:2.0:5.0, 1.0:5.0:0.20:2.0:10.0, 1.0:9.7:1.06:2.6:7.18, 1.0:9.7:1.06:3.0:7.18, and 1.0:9.7:1.27:2.6:7.93. 1.0:9.7:0.21:2.6:8.06, 1.0:9.7:2.96:2.6:5.03, 1.0:9.7:0.53:2.6:7.77, 1.0:9.7:1.64:2.6:6.89, 1.0:9.7:0.84:2.6:7.38, 1.0:9.7:1.17:2.6:7.09, 1.0:10.0:1.0:3.0:7.0, 1.0:20.0:3.0:3.5:5.0, 1.0:20.0:3.0:3.5:10.0, or any range of two values.

[0045] In some embodiments, the neodymium carboxylate alkane solution is prepared by a neutralization extraction method, which includes the following steps: stirring and mixing an aqueous solution of neodymium chloride hexahydrate with an alkane solution of carboxylate, then adding an alkaline solution for extraction and neutralization, so that the generated neodymium carboxylate extract dissolves in the alkane oil phase, and the aqueous phase is removed to obtain the neodymium carboxylate alkane solution. The water content of the neodymium carboxylate alkane solution is determined using a Karl Fischer method in a micro-moisture analyzer.

[0046] Regarding the neodymium carboxylate alkane solution in this application, the type of neodymium carboxylate is not specifically limited; any neodymium carboxylate commonly used in the art that is readily soluble in alkane solvents is acceptable. To further improve the activity of the rare earth catalyst and to further increase the content of the cis-1,4-structure in the rare earth isoprene rubber, the neodymium carboxylate in the neodymium carboxylate alkane solution preferably includes any one or more of neodymium naphthenate, neodymium isooctanoate, and neodymium neodecanoate, more preferably neodymium neodecanoate.

[0047] In this application, the naphthenic acid in neodymium naphthenate is a byproduct of oil refining, mainly consisting of a five-membered ring carboxylic acid, which can be purchased commercially.

[0048] In some embodiments, in step S1, the alkanes include C5-C7 alkanes and / or cycloalkanes, preferably at least one of cyclohexane, n-pentane and its isomers, n-heptane and its isomers, and n-hexane and its isomers, to promote the polymerization reaction of rubber and improve reaction efficiency.

[0049] In this application, the solvent in the neodymium carboxylate alkane solution is an alkane, and the type of alkane is not specifically limited; any alkane conventionally used in the art is acceptable. To further improve the activity of the rare earth catalyst and to further increase the content of the cis-1,4-structure in the rare earth isoprene rubber, the alkane in the neodymium carboxylate alkane solution preferably includes C5-C7 alkanes and / or cycloalkanes, more preferably any one or more of n-pentane, n-hexane, cyclohexane, n-heptane, and their isomers, and even more preferably n-hexane and its isomers (commercially available industrial hexane).

[0050] The type of conjugated diene used in this application is not specifically limited; any conjugated diene conventionally used in the art is acceptable. To further improve the activity of the rare earth catalyst and to further increase the content of the cis-1,4-structure in the rare earth isoprene rubber, the conjugated diene preferably includes any one or more of 1,3-butadiene, isoprene, and isoprene, more preferably isoprene and / or isoprene, and even more preferably isoprene.

[0051] The types of the first and second alkylaluminum compounds in this application are not specifically limited, and any alkylaluminum compounds conventionally used in the art are acceptable. To further improve the activity of the rare earth catalyst and to further increase the content of the cis-1,4-structure in the rare earth isoprene rubber, it is preferred that the first and second alkylaluminum compounds each independently include an alkylaluminum compound and / or a hydrogenated alkylaluminum compound.

[0052] To further improve the activity of rare earth catalysts, alkyl aluminum compounds are preferred, including any one or more of trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0053] To further improve the activity of rare earth catalysts, preferred alkyl aluminum hydrides include any one or more of diisobutylaluminum hydride and diethylaluminum hydride.

[0054] In some embodiments, the first alkylaluminum compound and the second alkylaluminum compound are each independently a mixture of triisobutylaluminum and diisobutylaluminum hydride, and the molar ratio of the two in the mixture is 1.0:(0.05 to 0.5), so as to further improve the activity of the rare earth catalyst and the content of cis-1,4-structure in rare earth isoprene rubber.

[0055] Typically, but not limitingly, in the mixture of triisobutylaluminum and diisobutylaluminum hydride provided in this application, the molar ratio of triisobutylaluminum to diisobutylaluminum hydride is, for example, 1.0:0.05, 1.0:0.0857, 1.0:0.096, 1.0:0.1, 1.0:0.101, 1.0:0.104, 1.0:0.106, 1.0:0.107, 1.0:0.0111, 1.0:0.164, 1.0:0.2, 1.0:0.21, 1.0:0.3, 1.0:0.4, 1.0:0.5, or a range of any two values.

[0056] The types of halogen-containing compounds used in this application are not specifically limited, and any halogen-containing compounds conventionally used in the art are acceptable. In order to further improve the activity of rare earth catalysts and further increase the content of cis-1,4-structure in rare earth isoprene rubber, the halogen-containing compounds preferably include diethylaluminum chloride and / or diethylaluminum chloride, more preferably diethylaluminum chloride.

[0057] In some embodiments, the mixing conditions in step S1 are: temperature 0–40°C, time 1–10 min; the mixing conditions in step S2 are: temperature 0–40°C, time 5–20 min; the mixing conditions in step S3 are: temperature 0–40°C, time 5–20 min; and the mixing conditions in step S4 are: temperature 0–40°C, time 5–30 min. Higher mixing temperatures will lead to deactivation of the catalytic active centers, while lower temperatures will lead to a reduction in the number of generated active centers. Limiting the mixing conditions to the above ranges further improves the preparation efficiency of rare earth catalysts.

[0058] In another typical embodiment of this application, an application is provided of a rare earth catalyst obtained by the preparation method provided in the first typical embodiment above in the polymerization of conjugated diene rubber.

[0059] In some embodiments, the conjugated diene is isoprene, and the rubber is isoprene rubber.

[0060] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0061] Example 1

[0062] This embodiment provides a method for preparing a rare earth catalyst, including the following steps:

[0063] (1) In a glove box, at room temperature, add 3.7 mL of anhydrous and oxygen-free industrial hexane, 0.1 mL of anhydrous and oxygen-free isoprene (1 mmol) and 0.25 mL of neodymium hexane solution (neodymium concentration 0.411 mol / L, neodecanoic acid concentration 0.253 mol / L, water content 9000 ppm, oxygen-free, neodymium 0.103 mmol) to a 30 mL glass polymerization bottle and mix for 5 min.

[0064] (2) Under electromagnetic stirring, add 0.1 mL of industrial hexane solution of the first alkyl aluminum compound, specifically 0.1 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.099 mmol of aluminum in triisobutylaluminum and 0.01 mmol of aluminum in diisobutylaluminum hydride) and mix for 10 min.

[0065] (3) Then add 0.31 mL of industrial hexane solution of diethylaluminum chloride (0.31 mmol of chlorine) and mix for 10 min.

[0066] (4) Add 0.68 mL of industrial hexane solution of the second alkyl aluminum compound, specifically 0.68 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.67 mmol of aluminum in triisobutylaluminum and 0.07 mmol of aluminum in diisobutylaluminum hydride) and mix for 15 min. Then age at 25 °C for 24 h to obtain rare earth catalyst for later use.

[0067] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium industrial hexane solution is 1.0:9.7:1.06:3.0:7.18.

[0068] Example 2

[0069] This embodiment provides a method for preparing a rare earth catalyst, including the following steps:

[0070] (1) In a glove box, at room temperature, add 3.7 mL of anhydrous and oxygen-free industrial hexane, 0.1 mL of anhydrous and oxygen-free isoprene (1 mmol) and 0.25 mL of neodymium naphthenate industrial hexane solution (neodymium concentration 0.411 mol / L, naphthenic acid concentration 0.253 mol / L, water content 10000 ppm, oxygen-free, neodymium 0.103 mmol) to a 30 mL glass polymerization bottle and mix for 10 min.

[0071] (2) Under electromagnetic stirring, add 0.1 mL of industrial hexane solution of the first alkyl aluminum compound, specifically 0.1 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.099 mmol of aluminum in triisobutylaluminum and 0.01 mmol of aluminum in diisobutylaluminum hydride) and mix for 15 min.

[0072] (3) Then add 0.27 mL of industrial hexane solution of dichloroethylaluminum (0.27 mmol of chlorine) and mix for 10 min.

[0073] (4) Add 0.68 mL of industrial hexane solution of the second alkyl aluminum compound, specifically 0.68 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.67 mmol of aluminum in triisobutylaluminum and 0.07 mmol of aluminum in diisobutylaluminum hydride), mix for 30 min, and age at 30 °C for 24 h to obtain rare earth catalyst for later use.

[0074] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:1.06:2.6:7.18.

[0075] Example 3

[0076] This embodiment provides a method for preparing a rare earth catalyst, including the following steps:

[0077] (1) In a glove box, at room temperature, add 3.7 mL of anhydrous and oxygen-free industrial hexane, 0.1 mL of anhydrous and oxygen-free isoprene (1 mmol) and 0.24 mL of neodymium isooctanoate industrial hexane solution (neodymium concentration 0.430 mol / L, isooctanoic acid concentration 0.250 mol / L, water content 10000 ppm, oxygen-free, neodymium 0.103 mmol) to a 30 mL glass polymerization bottle and mix for 10 min.

[0078] (2) Under electromagnetic stirring, add 0.12 mL of industrial hexane solution of the first alkyl aluminum compound, specifically 0.12 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.119 mmol of aluminum in triisobutylaluminum and 0.012 mmol of aluminum in diisobutylaluminum hydride) and mix for 5 min.

[0079] (3) Then add 0.27 mL of industrial hexane solution of dichloroethylaluminum (0.27 mmol of chlorine) and mix for 10 min.

[0080] (4) Add 0.75 mL of industrial hexane solution of the second alkyl aluminum compound, specifically 0.75 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.74 mmol of aluminum in triisobutylaluminum and 0.077 mmol of aluminum in diisobutylaluminum hydride), mix for 5 min, and age at 20 °C for 24 h to obtain rare earth catalyst for later use.

[0081] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium isooctanoate industrial hexane solution is 1.0:9.7:1.27:2.6:7.93.

[0082] Example 4

[0083] The difference from Example 2 is that, in Example 4, the water content of the neodymium naphthenate industrial hexane solution was adjusted to 2000 ppm; the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.02 mL, specifically 0.02 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.020 mmol of aluminum in triisobutylaluminum and 0.002 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.76 mL, specifically 0.76 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.75 mmol of aluminum in triisobutylaluminum and 0.08 mmol of aluminum in diisobutylaluminum hydride).

[0084] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:0.21:2.6:8.06.

[0085] Example 5

[0086] The difference from Example 2 is that, in Example 5, the water content of the neodymium naphthenate industrial hexane solution was adjusted to 20,000 ppm; and the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.28 mL, specifically 0.28 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.252 mmol of aluminum in triisobutylaluminum and 0.053 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.50 mL, specifically 0.50 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.428 mmol of aluminum in triisobutylaluminum and 0.090 mmol of aluminum in diisobutylaluminum hydride).

[0087] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:2.96:2.6:5.03.

[0088] Example 6

[0089] The difference from Example 2 is that, in Example 6, the water content of the neodymium naphthenate industrial hexane solution was adjusted to 5000 ppm; and the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.05 mL, specifically 0.05 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.050 mmol of aluminum in triisobutylaluminum and 0.005 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.73 mL, specifically 0.73 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.73 mmol of aluminum in triisobutylaluminum and 0.07 mmol of aluminum in diisobutylaluminum hydride).

[0090] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:0.53:2.6:7.77.

[0091] Example 7

[0092] The difference from Example 2 is that, in Example 7, the water content of the neodymium naphthenate industrial hexane solution was adjusted to 15000 ppm; and the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.15 mL, specifically 0.15 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.145 mmol of aluminum in triisobutylaluminum and 0.024 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.63 mL, specifically 0.63 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.61 mmol of aluminum in triisobutylaluminum and 0.10 mmol of aluminum in diisobutylaluminum hydride).

[0093] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:1.64:2.6:6.89.

[0094] Example 8

[0095] The difference from Example 2 is that, in Example 8, the water content of the neodymium naphthenate industrial hexane solution was adjusted to 8000 ppm; and the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.08 mL, specifically 0.08 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.080 mmol of aluminum in triisobutylaluminum and 0.007 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.70 mL, specifically 0.70 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.70 mmol of aluminum in triisobutylaluminum and 0.06 mmol of aluminum in diisobutylaluminum hydride).

[0096] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:0.84:2.6:7.38.

[0097] Example 9

[0098] The difference from Example 2 is that, in Example 9, the water content of the neodymium naphthenate industrial hexane solution was adjusted to 11,000 ppm; and the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.11 mL, specifically 0.11 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.108 mmol of aluminum in triisobutylaluminum and 0.012 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.67 mL, specifically 0.67 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.66 mmol of aluminum in triisobutylaluminum and 0.07 mmol of aluminum in diisobutylaluminum hydride).

[0099] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:1.17:2.6:7.09.

[0100] Example 10

[0101] The difference from Example 2 is that in Example 10, the amounts of each component are adjusted so that the molar ratio of neodymium in the neodymium naphthenate industrial hexane solution, isoprene, aluminum in the first alkylaluminum compound, chlorine, and aluminum in the second alkylaluminum compound is 1.0:5.0:0.20:2.0:10.0.

[0102] Example 11

[0103] The difference from Example 2 is that in Example 11, the amounts of each component are adjusted so that the molar ratio of neodymium in the neodymium naphthenate industrial hexane solution, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound is 1.0:20.0:3.0:3.5:5.0.

[0104] Comparative Example 1

[0105] The difference between Comparative Example 1 and Example 1 is that the preparation method of the rare earth catalyst was adjusted, specifically including the following steps:

[0106] (1) In a glove box, at room temperature, add 3.7 mL of anhydrous and oxygen-free industrial hexane, 0.1 mL of anhydrous and oxygen-free isoprene (1 mmol) and 0.25 mL of neodymium hexane solution (neodymium concentration 0.411 mol / L, neodecanoic acid concentration 0.253 mol / L, water content 9000 ppm, oxygen-free, neodymium 0.103 mmol) to a 30 mL glass polymerization bottle and mix for 5 min.

[0107] (2) Add 0.31 mL of industrial hexane solution of diethylaluminum chloride (0.31 mmol of chlorine) under electromagnetic stirring and mix for 10 min.

[0108] (3) Add 0.78 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.77 mmol of aluminum in triisobutylaluminum and 0.08 mmol of aluminum in diisobutylaluminum hydride) and mix for 15 min. Then age at 25 °C for 24 h to obtain a rare earth catalyst for later use.

[0109] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L. The molar ratio of neodymium, isoprene, chlorine, and aluminum in the mixture of triisobutylaluminum and diisobutylaluminum hydride in the neodymium hexane solution of neodymium neodecanoate is 1.0:9.7:3.0:8.3.

[0110] Comparative Example 2

[0111] The difference between Comparative Example 2 and Example 1 is that the preparation method of the rare earth catalyst and the water content of the neodymium neodecanoate industrial hexane solution were adjusted, specifically including the following steps:

[0112] (1) In a glove box, at room temperature, add 3.7 mL of anhydrous and oxygen-free industrial hexane, 0.1 mL of anhydrous and oxygen-free isoprene (1 mmol), and 0.2 mL of neodymium hexane solution (neodymium concentration 0.513 mol / L, neodecanoic acid concentration 0.251 mol / L, water content 400 ppm, oxygen-free, neodymium 0.103 mmol) to a 30 mL glass polymerization bottle and mix for 5 min.

[0113] (2) Add 0.31 mL of industrial hexane solution of diethylaluminum chloride (0.31 mmol of chlorine) under electromagnetic stirring and mix for 10 min.

[0114] (3) Add 0.78 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.77 mmol of aluminum in triisobutylaluminum and 0.08 mmol of aluminum in diisobutylaluminum hydride) and mix for 15 min. Then age at 25 °C for 24 h to obtain a rare earth catalyst for later use.

[0115] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L. The molar ratio of neodymium, isoprene, chlorine, and aluminum in the mixture of triisobutylaluminum and diisobutylaluminum hydride in the neodymium hexane solution of neodymium neodecanoate is 1.0:9.7:3.0:8.3.

[0116] Comparative Example 3

[0117] The difference between Comparative Example 3 and Example 1 is that the preparation method of the rare earth catalyst was adjusted, specifically including the following steps:

[0118] (1) In a glove box, at room temperature, add 3.7 mL of anhydrous and oxygen-free industrial hexane, 0.1 mL of anhydrous and oxygen-free isoprene (1 mmol) and 0.25 mL of neodymium hexane solution (neodymium concentration 0.411 mol / L, neodecanoic acid concentration 0.253 mol / L, water content 9000 ppm, oxygen-free, neodymium 0.103 mmol) to a 30 mL glass polymerization bottle and mix for 5 min.

[0119] (2) Under electromagnetic stirring, add 0.78 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.77 mmol of aluminum in triisobutylaluminum and 0.08 mmol of aluminum in diisobutylaluminum hydride) and mix for 15 min.

[0120] (3) Add 0.31 mL of industrial hexane solution of diethylaluminum chloride (0.31 mmol of chlorine) and mix for 10 min. Then age at 25 °C for 24 h to obtain rare earth catalyst for later use.

[0121] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L. The molar ratio of neodymium, isoprene, chlorine, and aluminum in the mixture of triisobutylaluminum and diisobutylaluminum hydride in the neodymium hexane solution of neodymium neodecanoate is 1.0:9.7:3.0:8.3.

[0122] Comparative Example 4

[0123] The difference from Example 4 is that, in Comparative Example 4, the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.01 mL, specifically 0.01 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.01 mmol of aluminum in triisobutylaluminum and 0.001 mmol of aluminum in diisobutylaluminum hydride); and the amount of industrial hexane solution of the second alkyl aluminum compound added was adjusted to 0.77 mL, specifically 0.77 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.76 mmol of aluminum in triisobutylaluminum and 0.07 mmol of aluminum in diisobutylaluminum hydride).

[0124] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:0.11:2.6:8.06.

[0125] Comparative Example 5

[0126] The difference from Example 5 is that, in Comparative Example 5, the amount of industrial hexane solution of the first alkyl aluminum compound added was adjusted to 0.39 mL, specifically 0.39 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.351 mmol of aluminum in triisobutylaluminum and 0.074 mmol of aluminum in diisobutylaluminum hydride); the amount of industrial hexane solution of the second alkyl aluminum compound added was also adjusted to 0.39 mL, specifically 0.39 mL of industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.351 mmol of aluminum in triisobutylaluminum and 0.074 mmol of aluminum in diisobutylaluminum hydride).

[0127] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L. The molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the neodymium naphthenate industrial hexane solution is 1.0:9.7:4.13:2.6:4.13.

[0128] Application Test Example 1

[0129] Inside a glove box, at room temperature, 1.36 g of anhydrous and oxygen-free isoprene (0.02 mol) and 7.7 g of anhydrous and oxygen-free industrial hexane were added to a 30 mL glass polymerization flask and mixed to obtain a mixture. The mixture was then placed in a refrigerator inside the glove box and cooled to -20°C. Under electromagnetic stirring, 0.1 mL of the rare earth catalyst sample prepared in the above examples and comparative examples was added to the glass polymerization flask, and the polymerization reaction was maintained at this temperature for 2 hours. The molar ratio of isoprene to neodymium in the rare earth catalyst solution was 10000. After the reaction was completed, the glass polymerization flask was moved outside the glove box, and an ethanol solution containing antioxidant 264 was added to terminate the reaction and coagulate the gel to obtain a solid wet gel.

[0130] The solid wet glue was dried in a vacuum oven at 60℃ until constant weight to obtain solid dry glue. The mass of the solid dry glue was weighed, the isoprene conversion rate was calculated, and the cis-1,4-structure content was measured. The results are shown in Table 1.

[0131] Conversion rate = (Mass of solid dry adhesive / Mass of added isoprene) × 100%

[0132] The content of cis-1,4-structure was determined according to SH / T1832-2020 "Determination of Microstructure of Isoprene Rubber by Proton Nuclear Magnetic Resonance Spectroscopy". The determination method was liquid proton nuclear magnetic resonance spectroscopy, and the solvent used was deuterated chloroform.

[0133] Table 1

[0134]

[0135]

[0136] The experimental results from Examples 1-11, Comparative Example 1, and Comparative Example 3 show that when the water content of the neodymium carboxylate solution is 2000-20000 ppm, the rare earth catalyst prepared in this way, according to the preparation method provided in this application, firstly, the neodymium carboxylate solution with a high water content is mixed with a conjugated diene, then a first alkylaluminum compound is added, followed by a halogen-containing compound, and finally a second alkylaluminum compound is added, wherein the first alkylaluminum compound is in a small amount and the second alkylaluminum compound is in a relatively large amount. The rare earth catalyst prepared in this way exhibits a high conversion rate and a high content of cis-1,4-structure when catalyzing the preparation of isoprene rubber. However, when the preparation method in Comparative Example 1 is changed, adding the halogen-containing compound first and then all the alkylaluminum compounds results in a decrease in both the conversion rate and the content of the cis-1,4-structure. When the preparation method in Comparative Example 3 is changed, adding all the alkylaluminum compounds first and then the halogen-containing compound, although the conversion rate does not decrease significantly, the content of the cis-1,4-structure decreases significantly.

[0137] The experimental results of Example 1 and Comparative Example 2 show that when the water content in Comparative Example 2 is adjusted to a low level of 400 ppm, and the rare earth catalyst is obtained by first adding a halogen-containing compound and then adding all the alkyl aluminum compounds according to the preparation method in the prior art, the conversion rate is significantly reduced when catalyzing the preparation of isoprene rubber, although the content of the cis-1,4-structure does not change significantly.

[0138] The experimental results from Examples 2, 4-9, and Comparative Examples 4-5 show that when the water content of the neodymium carboxylate solution is 2000-20000 ppm, and the molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound is (0.02-0.60):1.0, the prepared rare earth catalyst exhibits high conversion rate and high cis-1,4-structure content in the catalytic preparation of isoprene rubber. When the molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound changes, both the conversion rate and the cis-1,4-structure content decrease significantly.

[0139] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0140] This application uses a neodymium carboxylate solution with a water content of 2000-20000 ppm as raw material. First, the neodymium carboxylate solution with high water content is mixed with a conjugated diene. Then, a first alkylaluminum compound is added, followed by a halogen-containing compound, and finally a second alkylaluminum compound. The molar ratio of the first alkylaluminum compound to the second alkylaluminum compound, based on aluminum element, is (0.02-0.6):1.0. The rare earth catalyst prepared in this manner exhibits high activity and high orientation ability, increasing the content of the cis-1,4-structure in rare earth isoprene rubber. Tires manufactured using this rare earth isoprene rubber exhibit excellent resistance to damage, abrasion, and crack growth.

[0141] The preparation method provided in this application does not require reducing the water content in a neodymium carboxylate solution with a water content of 2000-20000 ppm to below 500 ppm, and can directly prepare rare earth catalysts. Moreover, the prepared rare earth catalysts have high activity and high orientation ability. This method simplifies the production process, reduces energy consumption and production costs, improves the storage stability of neodymium carboxylate solutions, and achieves a dual improvement in industrial production efficiency and economic benefits, while also making a positive contribution to environmental protection.

[0142] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a rare earth catalyst, characterized in that, Includes the following steps: Step S1: In the alkane, a neodymium carboxylate solution and a conjugated diene are mixed to obtain a first mixture; wherein the water content of the neodymium carboxylate solution is 2000-20000 ppm; Step S2: Mix the first alkylaluminum compound with the first mixture to obtain a second mixture; Step S3: Mix the halogen-containing compound with the second mixture to obtain a third mixture; Step S4: The second alkylaluminum compound is mixed with the third mixture to obtain a rare earth catalyst; The molar ratio of aluminum in the first alkylaluminum compound to aluminum in the second alkylaluminum compound is (0.02~0.60):1.0; and the molar ratio of neodymium in the carboxylic acid neodymium alkane solution, the conjugated diene, aluminum in the first alkylaluminum compound, chlorine in the halogen-containing compound, and aluminum in the second alkylaluminum compound is 1.0:(5.0~20.0):(0.2~3.0):(2.0~3.5):(5.0~10.0).

2. The method for preparing the rare earth catalyst according to claim 1, characterized in that, The water content of the neodymium carboxylate solution is 5000-15000 ppm.

3. The method for preparing the rare earth catalyst according to claim 1, characterized in that, The water content of the neodymium carboxylate solution is 8000-11000 ppm.

4. The method for preparing the rare earth catalyst according to claim 1, characterized in that, The molar ratio of aluminum in the first alkylaluminum compound to that in the second alkylaluminum compound is (0.06~0.24):1.

0.

5. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The neodymium carboxylate in the carboxylate alkane solution includes at least one of neodymium naphthenate, neodymium isooctanoate, and neodymium neodecanoate.

6. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The neodymium carboxylate in the neodymium carboxylate alkane solution is neodymium neodecanoate.

7. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, In step S1, the alkane includes C5-C7 alkanes and / or cycloalkanes; And / or, the solvent in the carboxylic acid neodymium alkane solution is an alkane, which includes C5-C7 alkanes and / or cycloalkanes.

8. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, In step S1, the alkane is at least one of cyclohexane, n-pentane and its isomers, n-heptane and its isomers, and n-hexane and its isomers. And / or, the solvent in the carboxylic acid neodymium alkane solution is an alkane, wherein the alkane is at least one of cyclohexane, n-pentane and its isomers, n-heptane and its isomers, and n-hexane and its isomers.

9. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The conjugated diene includes at least one of 1,3-butadiene, isoprene, and isoprene.

10. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The conjugated diene is isoprene.

11. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The first alkylaluminum compound and the second alkylaluminum compound each independently comprise an alkylaluminum compound and / or a hydrogenated alkylaluminum compound.

12. The method for preparing the rare earth catalyst according to claim 11, characterized in that, The alkylaluminum compound includes at least one of trimethylaluminum, triethylaluminum, and triisobutylaluminum; And / or, the alkylaluminum hydrogenated compound includes at least one of diisobutylaluminum hydride and diethylaluminum hydride.

13. The method for preparing the rare earth catalyst according to claim 11, characterized in that, The first alkylaluminum compound and the second alkylaluminum compound are each independently a mixture of triisobutylaluminum and diisobutylaluminum hydride, and the molar ratio of the two in the mixture is 1.0:(0.05~0.50).

14. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The halogenated compounds include diethylaluminum chloride and / or diethylaluminum chloride.

15. The method for preparing the rare earth catalyst according to any one of claims 1 to 4, characterized in that, The halogen-containing compound is diethylaluminum chloride.

16. The application of a rare earth catalyst obtained by any one of claims 1 to 15 in the preparation of rubber by conjugated diene polymerization.

17. The application of the rare earth catalyst according to claim 16 in the polymerization of conjugated dienes to prepare rubber, characterized in that, The conjugated diene is isoprene, and the rubber is isoprene rubber.

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