Preparation method and application of rare earth catalyst

Abstract

The invention provides a preparation method and application of a rare earth catalyst, and the preparation method comprises the following steps: firstly mixing a carboxylic acid neodymium alkane solution with relatively high water content with conjugated diene, then 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; the molar ratio of the aluminum element in the first alkyl aluminum compound to the aluminum element in the second alkyl aluminum compound is (0.02-0.60): 1.0. The rare earth catalyst prepared by the method has higher activity and higher orientation capability, the content of cis-1, 4-structure in the rare earth isoprene rubber is increased, and a tire made of the rare earth isoprene rubber has excellent damage resistance, wear resistance and crack growth resistance.

Description

Technical Field

[0001] The present invention relates to the field of rare earth catalysts, and in particular to a preparation method and application of a rare earth catalyst. Background Art

[0002] Rare earth isoprene rubber is a polyisoprene rubber with a high cis-1,4-structure content obtained by using rare earth catalysts to coordinate and direct isoprene polymerization. Its important use is to replace natural rubber in the production of automobile tires. Compared with traditional titanium isoprene rubber produced using titanium catalysts, rare earth isoprene rubber has a simple production process, less wastewater discharge, and excellent product comprehensive performance, and is becoming the direction of global isoprene rubber development.

[0003] The cis-1,4-structure content of isoprene rubber is one of the key indicators that affect its performance. The cis-1,4-structure content of polyisoprene in natural rubber is almost 100%, so it has excellent elasticity, and tires made of it have excellent damage resistance, wear resistance and crack growth resistance. In view of the regionality and limited nature of natural rubber resources, the development and manufacture of isoprene rubber that can replace natural rubber has become a consensus worldwide.

[0004] However, the cis-1,4-structure content of rare earth isoprene rubber produced by different rare earth catalysts and production processes is different. The cis-1,4-structure content of rare earth isoprene rubber prepared by the traditional three-component heterogeneous catalytic system of neodymium chloride complex can reach more than 97%, while the cis-1,4-structure content of rare earth isoprene rubber prepared by the traditional three-component heterogeneous catalytic system of neodymium carboxylate and the four-component homogeneous catalytic system of neodymium carboxylate can only reach about 96%. In view of the advantages of simple preparation process, accurate measurement and stable production control of the four-component homogeneous catalytic system of neodymium carboxylate, the production equipment with considerable production capacity in the world, especially in China, also adopts this technology, and the improvement of the cis-1,4-structure content of its isoprene rubber products has practical significance.

[0005] The general method for preparing the neodymium carboxylate four-component homogeneous catalyst system is: first mix the neodymium carboxylate with the conjugated diene, then add the alkyl aluminum to the aforementioned mixture, and finally add the halogen-containing compound. The improved method for increasing the cis-1,4-structure content of the isoprene polymerization product is generally to first add the halogen-containing compound (such as alkyl aluminum chloride) to the mixture of neodymium carboxylate and conjugated diene, and finally add the alkyl aluminum, that is, to change the order of adding the alkyl aluminum and the alkyl aluminum halide.

[0006] Patent CN103360516A invented a neodymium homogeneous rare earth catalyst for rare earth isoprene rubber production, which contains neodymium carboxylate, alkyl aluminum and / or alkyl aluminum hydride, alkyl halide and polymer obtained by polymerization of conjugated diene. The unique preparation method of the catalyst includes: under the protection of inert gas, neodymium carboxylate, alkyl halide and conjugated diene are first contacted in an inert organic solvent to obtain a mixture, and then the mixture is secondly contacted with alkyl aluminum and / or alkyl aluminum hydride. The water content of the solvent used in the catalyst preparation process is less than 20ppm. However, the invention does not mention the source of the alkane solution of neodymium carboxylate and its water content. In general, the preparation of the alkane solution of neodymium carboxylate adopts the neutralization extraction method, and the water content of the product is as high as about 10000ppm (mass content, the same below). When it is directly used for the catalyst preparation of the invention, the activity of the obtained catalyst is significantly reduced, and it is necessary to try to reduce its water content to a certain level before it can be used.

[0007] Patent CN102532365B invented a neodymium carboxylate homogeneous catalyst and its preparation method, the catalyst composition is neodymium carboxylate, alkyl aluminum, halogen-containing compound and conjugated diene, belonging to the traditional four-component neodymium carboxylate homogeneous catalytic system. Its preparation method is: first neodymium carboxylate is mixed with conjugated diene, then the halogen-containing compound is added to the aforementioned mixed solution, and finally alkyl aluminum is added; or first neodymium carboxylate, halogen-containing compound and conjugated diene are mixed, and then alkyl aluminum is added to the aforementioned mixed solution. However, the invention also does not mention the source of the alkane solution of neodymium carboxylate and its water content. If the polymerization activity of the prepared catalyst is guaranteed, the water content of the alkane solution of neodymium carboxylate must be reduced to a certain level (such as less than 500ppm), which will inevitably cause the production process to be complicated, the production cost to increase and the storage stability of the low-water-content neodymium carboxylate alkane solution to be poor.

[0008] Therefore, how to use a carboxylic acid neodymium alkane solution with a high water content as a raw material to directly prepare a rare earth catalyst for efficiently producing rare earth isoprene rubber with a high cis structure content in order to reduce costs and simplify the process is a problem that needs to be solved urgently.

[0009] In view of this, this application is hereby filed. Summary of the invention

[0010] The main purpose of the present invention is to provide a preparation method and application of a rare earth catalyst, so as to solve the problem that in the prior art, when a rare earth catalyst is prepared using a carboxylic acid neodymium alkane solution with a higher water content as a raw material, a pretreatment dehydration step is required, resulting in a complicated production process, increased production costs and the problem that the carboxylic acid neodymium alkane solution with a low water content is easy to deteriorate during storage.

[0011] In order to achieve the above-mentioned purpose, 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 alkane solution and a conjugated diene in an alkane to obtain a first mixed solution; wherein the water content of the neodymium carboxylate alkane solution is 2000-20000ppm; step S2, mixing a first alkylaluminum compound with the first mixed solution to obtain a second mixed solution; step S3, mixing a halogen-containing compound with the second mixed solution to obtain a third mixed solution; step S4, mixing a second alkylaluminum compound with the third mixed solution to obtain a rare earth catalyst; wherein the molar ratio of the aluminum element in the first alkylaluminum compound to the aluminum element in the second alkylaluminum compound is (0.02-0.60):1.0.

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

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

[0014] Furthermore, the molar ratio of the neodymium element in the neodymium carboxylate alkane solution, the conjugated diene, the aluminum element in the first alkyl aluminum compound, the chlorine element in the halogen-containing compound and the aluminum element 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 cyclohexaneate, neodymium isooctanoate, and neodymium neodecanoate, and further includes neodymium neodecanoate.

[0016] Further, in step S1, the alkane includes C5-C7 alkane and / or cycloalkane, and further is 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 neodymium carboxylate alkane solution is an alkane, and the alkane includes C5-C7 alkanes and / or cycloalkanes, and further is 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 comprises at least one of 1,3-butadiene, isoprene and piperylene, and further is isoprene.

[0019] Furthermore, the first alkyl aluminum compound and the second alkyl aluminum compound each independently include an alkyl aluminum compound and / or a hydrogenated alkyl aluminum compound.

[0020] Furthermore, the alkyl aluminum compound includes at least one of trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum.

[0021] Further, the alkylaluminum hydride compound includes at least one of diisobutylaluminum hydride and diethylaluminum hydride.

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

[0023] Further, the halogen-containing compound includes diethylaluminum monochloride and / or ethylaluminum dichloride, and further diethylaluminum monochloride.

[0024] According to another aspect of the present invention, there is provided a use of the rare earth catalyst obtained by the preparation method provided in the first aspect in preparing rubber by polymerization of conjugated dienes.

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

[0026] The technical scheme of the present invention is applied. The present application uses a carboxylic acid neodymium alkane solution with a water content of 2000-20000ppm as a raw material, first mixes the carboxylic acid neodymium alkane solution with a high water content with a conjugated diene, then adds a first alkyl aluminum compound, then adds a halogen-containing compound, and finally adds a second alkyl aluminum compound, wherein the molar ratio of the first alkyl aluminum compound to the second alkyl aluminum compound is (0.02-0.6):1.0 based on the aluminum element. The rare earth catalyst prepared in this way has high activity and high directional ability, increases the content of cis-1,4-structure in rare earth isoprene rubber, and the tire manufactured using the rare earth isoprene rubber has excellent damage resistance, wear resistance and crack growth resistance.

[0027] The preparation method provided in the present application does not need to reduce the water content in the neodymium carboxylate alkane solution with a water content of 2000-20000ppm to less than 500ppm, and the rare earth catalyst can be directly prepared, and the prepared rare earth catalyst has high activity and high directional ability. The method simplifies the production process, reduces energy consumption and production costs, and improves the storage stability of the neodymium carboxylate alkane solution, thereby achieving a dual improvement in industrial production efficiency and economic benefits, and at the same time makes a positive contribution to environmental protection. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0029] As analyzed in the background technology of this application, in the prior art, when a rare earth catalyst is prepared using a carboxylic acid neodymium alkane solution with a relatively high water content as a raw material, a pre-treatment dehydration step is required, resulting in a complex production process, increased production costs, and the low-water-content carboxylic acid neodymium alkane solution is prone to deterioration during storage. In order to solve the above problems, this application provides a preparation method and application of a rare earth catalyst.

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

[0031] The present application uses a carboxylic acid neodymium alkane solution with a water content of 2000-20000ppm as a raw material, first mixes the carboxylic acid neodymium alkane solution with a high water content with a conjugated diene, then adds a first alkyl aluminum compound, then adds a halogen-containing compound, and finally adds a second alkyl aluminum compound, wherein the molar ratio of the first alkyl aluminum compound to the second alkyl aluminum compound is (0.02-0.6):1.0 in terms of aluminum element. The rare earth catalyst prepared in this way has high activity and high directional ability, increases the content of cis-1,4-structure in rare earth isoprene rubber, and the tire manufactured using the rare earth isoprene rubber has excellent damage resistance, wear resistance and crack growth resistance.

[0032] The preparation method provided in the present application does not need to reduce the water content in the neodymium carboxylate alkane solution with a water content of 2000-20000ppm to less than 500ppm, and the rare earth catalyst can be directly prepared, and the prepared rare earth catalyst has high activity and high directional ability. The method simplifies the production process, reduces energy consumption and production costs, improves the storage stability of the neodymium carboxylate alkane solution, achieves a dual improvement in industrial production efficiency and economic benefits, and also makes a positive contribution to environmental protection.

[0033] In addition, some studies have found that when the number of coordinated atoms of neodymium atoms in the neodymium carboxylate complex is 8, the coordination reaches saturation, and the complex exists in a single molecule form in an alkane solution with good solubility. The inventor of the present invention unexpectedly discovered during the research process that when the water content of the neodymium carboxylate alkane solution reaches dissolution saturation (the saturated water content is about 10000ppm at room temperature), the water molecules therein coordinate with the neodymium atoms, so that the number of coordinated atoms around the neodymium atoms is close to the saturation value of 8. Such a neodymium carboxylate alkane solution has good stability, and will not produce precipitates due to the association between neodymium carboxylate molecules during long-term storage. When it is subjected to an alkylation reaction with an alkyl aluminum compound, the reaction proceeds more completely, and the prepared rare earth catalyst has high activity. On the contrary, if the water content of the neodymium carboxylate alkane solution is reduced by azeotropic distillation (e.g., below 500 ppm), the coordination number of the neodymium atoms becomes unsaturated due to the loss of coordinated water molecules, and the neodymium carboxylate molecules are easily associated due to bridging coordination, resulting in precipitation during the storage of the neodymium carboxylate alkane solution, thereby affecting its application effect in the preparation of rare earth catalysts.

[0034] The water content of the neodymium carboxylate alkane solution prepared by the neutralization extraction method in the prior art is generally about 10000ppm. According to the traditional preparation method, the water content of the neodymium carboxylate alkane solution needs to be reduced to 500ppm before direct preparation. The steps are complicated, the process requirements are high, and a large amount of manpower and material resources are required. However, the present application does not need to reduce the water content in the neodymium carboxylate alkane solution with a high water content to less than 500ppm, and the rare earth catalyst can be directly prepared. The prepared rare earth catalyst has high activity and high directional ability. This method simplifies the production process, reduces energy consumption and production costs, and improves the storage stability of the neodymium carboxylate alkane solution, achieving a double improvement in industrial production efficiency and economic benefits.

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

[0036] The saturated water content of neodymium carboxylate alkane solution 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 preparation effect of the catalyst.

[0037] Typically but not limiting, the water content of the neodymium carboxylate alkane solution provided in the present application is 2000 ppm, 3000 ppm, 5000 ppm, 8000 ppm, 11000 ppm, 13000 ppm, 15000 ppm, 18000 ppm, 20000 ppm or a range consisting of any two values.

[0038] Typically but not limiting, the molar ratio of the aluminum element in the first alkyl aluminum compound and the aluminum element in the second alkyl aluminum compound provided in the present application is 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 a range consisting of any two values.

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

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

[0041] In order to further improve the ability of the rare earth catalyst to form cis-1,4-structure in a directional manner, the molar ratio of the aluminum element in the first alkyl aluminum compound to the aluminum element in the second alkyl aluminum compound is preferably (0.06-0.24):1.0.

[0042] In some embodiments, the molar ratio of the neodymium element in the neodymium carboxylate alkane solution, the conjugated diene, the aluminum element in the first alkyl aluminum compound, the chlorine element in the halogen-containing compound, and the aluminum element 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). When the molar ratio of each component is within the above range, the activity and catalytic efficiency of the rare earth catalyst of the present application can be further improved.

[0043] In other embodiments, the molar ratio of the neodymium element in the carboxylate neodymium alkane solution, the conjugated diene, the aluminum element in the first alkyl aluminum compound, the chlorine element in the halogen-containing compound, and the aluminum element in the second alkyl aluminum compound is 1.0: (5.0-20.0): (0.5-1.7): (2.0-3.5): (6.8-7.8), so as to further improve the activity and catalytic efficiency of the rare earth catalyst of the present application.

[0044] Typically but not limiting, the molar ratios of neodymium, conjugated diene, aluminum in the first alkyl aluminum compound, chlorine in the halogen-containing compound, and aluminum in the second alkyl aluminum compound in the neodymium carboxylate alkane solution provided in the present application are 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, 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 a range of any two values.

[0045] In some embodiments, the neodymium carboxylate alkane solution is prepared by a neutralization extraction method, which comprises the following steps: stirring and mixing an aqueous solution of neodymium chloride hexahydrate and an alkane solution of carboxylic acid, then adding an alkaline solution for extraction and neutralization, extracting and dissolving the generated neodymium carboxylate in an alkane oil phase, removing the aqueous phase, and obtaining a neodymium carboxylate alkane solution. The water content of the neodymium carboxylate alkane solution is measured in a trace moisture meter using the Karl Fischer method.

[0046] Regarding the neodymium carboxylate alkane solution in the present application, the type of neodymium carboxylate therein is not specifically limited, and any neodymium carboxylate that is conventionally used in the art and is easily soluble in an alkane solvent can be used. In order to further improve the activity of the rare earth catalyst and 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 cyclohexaneate, neodymium isooctanoate, and neodymium neodecanoate, and more preferably neodymium neodecanoate.

[0047] In the present application, the cyclopentane acid in the neodymium cyclopentaneate is a by-product of oil refining, mainly comprising a five-membered ring carboxylic acid, and can be purchased commercially.

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

[0049] The solvent in the neodymium carboxylate alkane solution in the present application is an alkane, and the type of the alkane is not specifically limited, and any alkane conventionally used in the art can be used. In order to further improve the activity of the rare earth catalyst and 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 isomers thereof, and further preferably n-hexane and isomers thereof (commercially available industrial hexane).

[0050] The types of conjugated dienes in the present application are not specifically limited, and any conjugated dienes conventionally used in the art may be used. In order to further improve the activity of the rare earth catalyst and further increase the content of cis-1,4-structure in the rare earth isoprene rubber, the conjugated dienes preferably include any one or more of 1,3-butadiene, isoprene, and piperylene, more preferably isoprene and / or piperylene, and even more preferably isoprene.

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

[0052] In order to further improve the activity of the rare earth catalyst, the alkyl aluminum compound preferably includes any one or more of trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum.

[0053] In order to further improve the activity of the rare earth catalyst, the alkylaluminum hydride compound preferably includes any one or more of diisobutylaluminum hydride and diethylaluminum hydride.

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

[0055] Typically, but not limiting, in the mixture of triisobutylaluminum and diisobutylaluminum hydride provided herein, the molar ratio of triisobutylaluminum to diisobutylaluminum hydride is 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 consisting of any two values.

[0056] The types of halogen-containing compounds in the present application are not specifically limited, and any halogen-containing compound conventionally used in the art can be used. In order to further improve the activity of the rare earth catalyst and further increase the content of cis-1,4-structure in the rare earth isoprene rubber, the halogen-containing compound preferably includes diethylaluminum monochloride and / or diethylaluminum dichloride, and more preferably diethylaluminum monochloride.

[0057] In some embodiments, the mixing conditions in step S1 are: temperature of 0-40°C, time of 1-10 min; the mixing conditions in step S2 are: temperature of 0-40°C, time of 5-20 min; the mixing conditions in step S3 are: temperature of 0-40°C, time of 5-20 min; the mixing conditions in step S4 are: temperature of 0-40°C, time of 5-30 min; when the mixing temperature is higher, the catalytic active centers will be deactivated, and when the temperature is lower, the number of active centers generated will be reduced. The mixing conditions are limited to the above range to further improve the preparation efficiency of the rare earth catalyst.

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

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

[0060] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.

[0061] Example 1

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

[0063] (1) In a glove box, 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 neodecanoate industrial hexane solution (neodymium element concentration 0.411 mol / L, neodecanoic acid concentration 0.253 mol / L, water content 9000 ppm, oxygen-free, neodymium element 0.103 mmol) were added to a 30 mL glass polymerization bottle at room temperature and mixed for 5 min.

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

[0065] (3) Then, add 0.31 mL of industrial hexane solution of diethylaluminum monochloride (0.31 mmol of chlorine element) and mix for 10 minutes.

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

[0067] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium neodecanoate 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, comprising the following steps:

[0070] (1) In a glove box, 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 industrial hexane solution of neodymium cyclohexane acid (neodymium element concentration 0.411 mol / L, cyclohexane acid concentration 0.253 mol / L, water content 10000 ppm, oxygen-free, neodymium element 0.103 mmol) were added to a 30 mL glass polymerization bottle at room temperature and mixed for 10 min.

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

[0072] (3) Then, add 0.27 mL of industrial hexane solution of ethylaluminum dichloride (0.27 mmol of chlorine element) and mix for 10 minutes.

[0073] (4) Add 0.68 mL of an industrial hexane solution of a second alkyl aluminum compound, specifically 0.68 mL of an industrial hexane solution of a mixture of triisobutyl aluminum and diisobutyl aluminum hydride (0.67 mmol of aluminum in triisobutyl aluminum and 0.07 mmol of aluminum in diisobutyl aluminum hydride), mix for 30 minutes, and age at 30° C. for 24 hours to obtain a rare earth catalyst for standby use.

[0074] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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, comprising the following steps:

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

[0078] (2) Under electromagnetic stirring, 0.12 mL of an industrial hexane solution of a first alkyl aluminum compound, specifically 0.12 mL of an industrial hexane solution of a mixture of triisobutyl aluminum and diisobutyl aluminum hydride (0.119 mmol of aluminum in triisobutyl aluminum and 0.012 mmol of aluminum in diisobutyl aluminum hydride) was added and mixed for 5 min.

[0079] (3) Then, add 0.27 mL of industrial hexane solution of ethylaluminum dichloride (0.27 mmol of chlorine element) and mix for 10 minutes.

[0080] (4) Add 0.75 mL of an industrial hexane solution of a second alkyl aluminum compound, specifically 0.75 mL of an industrial hexane solution of a mixture of triisobutyl aluminum and diisobutyl aluminum hydride (0.74 mmol of aluminum in triisobutyl aluminum and 0.077 mmol of aluminum in diisobutyl aluminum hydride), mix for 5 minutes, and age at 20° C. for 24 hours to obtain a rare earth catalyst for standby use.

[0081] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium isooctanoate 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 industrial hexane solution of neodymium cyclohexane acid is adjusted to 2000ppm; and the amount of the industrial hexane solution of the first alkyl aluminum compound added is adjusted to 0.02mL, specifically 0.02mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.020mmol of aluminum element in triisobutylaluminum, 0.002mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is adjusted to 0.76mL, specifically 0.76mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.75mmol of aluminum element in triisobutylaluminum, 0.08mmol of aluminum element in diisobutylaluminum hydride).

[0084] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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 industrial hexane solution of neodymium cyclohexaneate is adjusted to 20000 ppm; and the amount of the industrial hexane solution of the first alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.053 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.090 mmol of aluminum element in diisobutylaluminum hydride).

[0087] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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 industrial hexane solution of neodymium cyclohexaneate is adjusted to 5000 ppm; and the amount of the industrial hexane solution of the first alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.005 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.07 mmol of aluminum element in diisobutylaluminum hydride).

[0090] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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 industrial hexane solution of neodymium cyclohexaneate is adjusted to 15000 ppm; and the amount of the industrial hexane solution of the first alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.024 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.10 mmol of aluminum element in diisobutylaluminum hydride).

[0093] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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 industrial hexane solution of neodymium cyclohexaneate is adjusted to 8000 ppm; and the amount of the industrial hexane solution of the first alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.007 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.06 mmol of aluminum element in diisobutylaluminum hydride).

[0096] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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 industrial hexane solution of neodymium cyclohexaneate is adjusted to 11000 ppm; and the amount of the industrial hexane solution of the first alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.012 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is 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 element in triisobutylaluminum, 0.07 mmol of aluminum element in diisobutylaluminum hydride).

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

[0100] Example 10

[0101] The difference from Example 2 is that Example 10 adjusts the dosage of each component so that the molar ratio of neodymium element in the industrial hexane solution of neodymium cyclohexaneate, isoprene, aluminum element in the first alkyl aluminum compound, chlorine element, and aluminum element in the second alkyl aluminum compound is 1.0:5.0:0.20:2.0:10.0.

[0102] Embodiment 11

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

[0104] Comparative Example 1

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

[0106] (1) In a glove box, 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 neodecanoate industrial hexane solution (neodymium element concentration 0.411 mol / L, neodecanoic acid concentration 0.253 mol / L, water content 9000 ppm, oxygen-free, neodymium element 0.103 mmol) were added to a 30 mL glass polymerization bottle at room temperature and mixed for 5 min.

[0107] (2) Under electromagnetic stirring, add 0.31 mL of industrial hexane solution of diethylaluminum monochloride (0.31 mmol of chlorine element) and mix for 10 minutes.

[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. Aged at 25° C. for 24 h to obtain a rare earth catalyst for standby use.

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

[0110] Comparative Example 2

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

[0112] (1) In a glove box, 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 neodecanoate industrial hexane solution (neodymium element concentration 0.513 mol / L, neodecanoic acid concentration 0.251 mol / L, water content 400 ppm, oxygen-free, neodymium element 0.103 mmol) were added to a 30 mL glass polymerization bottle at room temperature and mixed for 5 min.

[0113] (2) Under electromagnetic stirring, add 0.31 mL of industrial hexane solution of diethylaluminum monochloride (0.31 mmol of chlorine element) and mix for 10 minutes.

[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. Aged at 25° C. for 24 h to obtain a rare earth catalyst for standby use.

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

[0116] Comparative Example 3

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

[0118] (1) In a glove box, 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 neodecanoate industrial hexane solution (neodymium element concentration 0.411 mol / L, neodecanoic acid concentration 0.253 mol / L, water content 9000 ppm, oxygen-free, neodymium element 0.103 mmol) were added to a 30 mL glass polymerization bottle at room temperature and mixed 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 monochloride (0.31 mmol of chlorine element) and mix for 10 minutes. Then age at 25° C. for 24 hours to obtain a rare earth catalyst for standby use.

[0121] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.020 mol / L, and the molar ratio of neodymium, isoprene, chlorine, triisobutylaluminum and aluminum in the mixture of diisobutylaluminum hydride in the industrial 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 the industrial hexane solution of the first alkyl aluminum compound added is adjusted to 0.01 mL, specifically 0.01 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.01 mmol of aluminum element in triisobutylaluminum, 0.001 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is adjusted to 0.77 mL, specifically 0.77 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.76 mmol of aluminum element in triisobutylaluminum, 0.07 mmol of aluminum element in diisobutylaluminum hydride).

[0124] The concentration of neodymium in the rare earth catalyst solution obtained above is 0.02 mol / L, and the molar ratio of neodymium, isoprene, aluminum in the first alkyl aluminum compound, chlorine, and aluminum in the second alkyl aluminum compound in the industrial hexane solution of neodymium cyclohexane 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 the industrial hexane solution of the first alkyl aluminum compound added is adjusted to 0.39 mL, specifically 0.39 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.351 mmol of aluminum element in triisobutylaluminum, 0.074 mmol of aluminum element in diisobutylaluminum hydride); the amount of the industrial hexane solution of the second alkyl aluminum compound added is adjusted to 0.39 mL, specifically 0.39 mL of an industrial hexane solution of a mixture of triisobutylaluminum and diisobutylaluminum hydride (0.351 mmol of aluminum element in triisobutylaluminum, 0.074 mmol of aluminum element in diisobutylaluminum hydride).

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

[0128] Application Test Example 1

[0129] In a glove box, 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 bottle at room temperature to mix and obtain a mixture, and the mixture was placed in a refrigerator in the glove box and cooled to -20°C. Under electromagnetic stirring, 0.1 mL of the rare earth catalyst sample prepared in the above embodiment and comparative example was added to the glass polymerization bottle, and the polymerization reaction was kept warm for 2 hours, wherein the molar ratio of isoprene to the neodymium element in the rare earth catalyst solution was 10000. After the reaction was completed, the glass polymerization bottle was moved outside the glove box, and an ethanol solution containing antioxidant 264 was added to terminate the reaction and condense the glue liquid to obtain a solid wet glue.

[0130] The solid wet gel was placed in a vacuum oven at 60°C and dried to constant weight to obtain a solid dry gel. The mass of the solid dry gel was weighed, the isoprene conversion rate was calculated, and samples were taken to determine the cis-1,4-structure content. The results are shown in Table 1.

[0131] Conversion rate = solid dry gum mass / added isoprene mass × 100%

[0132] The content of cis-1,4-structure is determined in accordance with SH / T1832-2020 "Determination of the Microstructure of Isoprene Rubber by Nuclear Magnetic Resonance Hydrogen Spectroscopy", where the determination method is liquid nuclear magnetic resonance hydrogen spectroscopy and the determination solvent used is deuterated chloroform.

[0133] Table 1

[0134]

[0135]

[0136] It can be seen from the experimental results of Examples 1-11, Comparative Example 1, and Comparative Example 3 that when the water content of the neodymium carboxylate alkane solution is 2000-20000 ppm, according to the preparation method provided in this application: first mix the neodymium carboxylate alkane solution with a higher water content with the conjugated diene, then add the first alkyl aluminum compound, then add the halogen-containing compound, and finally add the second alkyl aluminum compound, wherein the first alkyl aluminum compound is a small amount and the second alkyl aluminum compound is a larger amount. The rare earth catalyst prepared in this way has a higher conversion rate and a higher content of cis-1,4-structure when catalyzing the preparation of isoprene rubber. When the preparation method in Comparative Example 1 changes, the halogen-containing compound is added first and then all the alkyl aluminum compounds are added, resulting 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 changes, all the alkyl aluminum compounds are added first and then the halogen-containing compound is added. Although the conversion rate is not significantly reduced, the content of the cis-1,4-structure is significantly reduced.

[0137] It can be seen from the experimental results of Example 1 and Comparative Example 2 that when the water content in Comparative Example 2 is adjusted to a lower content of 400 ppm, and at the same time, according to the preparation method in the prior art, a halogen-containing compound is first added and then all the alkyl aluminum compounds are added to obtain a rare earth catalyst. When catalyzing the preparation of isoprene rubber, although the content of the cis-1,4-structure does not change significantly, the conversion rate is significantly reduced.

[0138] It can be seen from the experimental results of Example 2, Examples 4-9, and Comparative Examples 4-5 that when the water content of the neodymium carboxylate alkane solution is 2000-20000ppm, and the molar ratio of the aluminum element in the first alkyl aluminum compound to the aluminum element in the second alkyl aluminum compound is (0.02-0.60):1.0, the prepared rare earth catalyst has a higher conversion rate and a higher content of cis-1,4-structure when catalyzing the preparation of isoprene rubber. When the molar ratio of the aluminum element in the first alkyl aluminum compound to the aluminum element in the second alkyl aluminum compound changes, the conversion rate and the content of cis-1,4-structure are significantly reduced.

[0139] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0140] The present application uses a carboxylic acid neodymium alkane solution with a water content of 2000-20000ppm as a raw material, first mixes the carboxylic acid neodymium alkane solution with a high water content with a conjugated diene, then adds a first alkyl aluminum compound, then adds a halogen-containing compound, and finally adds a second alkyl aluminum compound, wherein the molar ratio of the first alkyl aluminum compound to the second alkyl aluminum compound is (0.02-0.6):1.0 in terms of aluminum element. The rare earth catalyst prepared in this way has high activity and high directional ability, increases the content of cis-1,4-structure in rare earth isoprene rubber, and the tire manufactured using the rare earth isoprene rubber has excellent damage resistance, wear resistance and crack growth resistance.

[0141] The preparation method provided in the present application does not need to reduce the water content in the neodymium carboxylate alkane solution with a water content of 2000-20000ppm to less than 500ppm, and the rare earth catalyst can be directly prepared, and the prepared rare earth catalyst has high activity and high directional ability. The method simplifies the production process, reduces energy consumption and production costs, and improves the storage stability of the neodymium carboxylate alkane solution, thereby achieving a dual improvement in industrial production efficiency and economic benefits, and at the same time makes a positive contribution to environmental protection.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a rare earth catalyst, characterized in that: The following steps are involved: Step S1, mixing a neodymium carboxylate alkane solution and a conjugated diene in an alkane to obtain a first mixed solution; wherein the water content of the neodymium carboxylate alkane solution is 2000-20000 ppm; Step S2, mixing a first alkyl aluminum compound with the first mixed solution to obtain a second mixed solution; Step S3, mixing the halogen-containing compound with the second mixed liquid to obtain a third mixed liquid; Step S4, mixing the second alkyl aluminum compound with the third mixed solution to obtain a rare earth catalyst; The molar ratio of the aluminum element in the first alkyl aluminum compound to the aluminum element in the second alkyl aluminum compound is (0.02-0.60):1.

0.

2. The method for preparing a rare earth catalyst according to claim 1, characterized in that: The water content of the neodymium carboxylate alkane solution is 5000-15000 ppm, preferably 8000-11000 ppm.

3. The method for preparing a rare earth catalyst according to claim 1, characterized in that: The molar ratio of the aluminum element in the first alkyl aluminum compound to the aluminum element in the second alkyl aluminum compound is (0.06-0.24):1.

0.

4. The method for preparing a rare earth catalyst according to claim 1, characterized in that: The molar ratio of the neodymium element in the neodymium carboxylate alkane solution, the conjugated diene, the aluminum element in the first alkyl aluminum compound, the chlorine element in the halogen-containing compound and the aluminum element 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)。 5. The method for preparing a rare earth catalyst according to any one of claims 1 to 4, characterized in that: The neodymium carboxylate in the neodymium carboxylate alkane solution includes at least one of neodymium cyclohexaneate, neodymium isooctanoate and neodymium neodecanoate, preferably neodymium neodecanoate.

6. The method for preparing a rare earth catalyst according to any one of claims 1 to 4, characterized in that: In step S1, the alkane includes C5-C7 alkane and / or cycloalkane, preferably 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 neodymium carboxylate alkane solution is an alkane, and the alkane includes C5-C7 alkane and / or cycloalkane, preferably at least one of cyclohexane, n-pentane and its isomers, n-heptane and its isomers, and n-hexane and its isomers.

7. The method for preparing a rare earth catalyst according to any one of claims 1 to 4, characterized in that: The conjugated diene comprises at least one of 1,3-butadiene, isoprene and piperylene, preferably isoprene.

8. The method for preparing a rare earth catalyst according to any one of claims 1 to 4, characterized in that: The first alkyl aluminum compound and the second alkyl aluminum compound each independently include an alkyl aluminum compound and / or a hydrogenated alkyl aluminum compound; Preferably, the alkyl aluminum compound includes at least one of trimethyl aluminum, triethyl aluminum, and triisobutyl aluminum; Preferably, the alkylaluminum hydride compound comprises at least one of diisobutylaluminum hydride and diethylaluminum hydride; Preferably, the first alkyl aluminum compound and the second alkyl aluminum compound are each independently a mixture of triisobutyl aluminum and diisobutyl aluminum hydride, and the molar ratio of the two in the mixture is 1.0:(0.05-0.50).

9. The method for preparing a rare earth catalyst according to any one of claims 1 to 4, characterized in that: The halogen-containing compound includes diethylaluminum monochloride and / or monoethylaluminum dichloride, preferably diethylaluminum monochloride.

10. Use of the rare earth catalyst obtained by the preparation method according to any one of claims 1 to 9 in the preparation of rubber by polymerization of conjugated dienes; Preferably, the conjugated diene is isoprene, and the rubber is isoprene rubber.

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