Catalyst and preparation method of 1-hexene

Abstract

The invention belongs to the technical field of olefin polymerization, and particularly relates to a catalyst and a preparation method of 1-hexene. The catalyst provided by the invention comprises a ligand, a chromium-containing compound and an aluminum-containing promoter, wherein the ligand is prepared from at least one of amantadine compounds; the molar ratio of the ligand to the chromium-containing compound is 0.6 to 1.8; the molar ratio of the aluminum element in the aluminum-containing cocatalyst to the chromium element in the chromium-containing compound is 200-1500. According to the present invention, the ligand, the chromium-containing compound and the aluminum-containing co-catalyst are matched, particularly the amantadine compound with the simple structure is adopted as the ligand, and the molar ratio of the ligand to the chromium-containing compound to the molar ratio of Al to the molar ratio of Cr are regulated so as to highly selectively catalyze ethylene to generate the product 1-hexene through the oligomerization reaction, and the catalyst has higher reaction activity and lower polyethylene (PE) selectivity, and can effectively prevent polymer accumulation from influencing the operation of the device when in use.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of olefin polymerization, and particularly relates to a catalyst and a preparation method of 1-hexene. BACKGROUND

[0002] Linear 1-hexene is a kind of basic chemical raw material, and its oligomers are widely used in the synthesis of bulk chemical products such as lubricants and plasticizers and various fine chemical products. The demand for such substances in related industries is very large. 1-hexene itself is an important alpha-olefin oligomer product, which can be used as a monomer for ethylene copolymerization to synthesize resin materials, and can also be used as a raw material for manufacturing dyes, detergents, pharmaceuticals and pesticides, and can also be used as an oil additive to improve oil performance. 1-hexene has a very wide range of uses and a huge market demand, and is in short supply.

[0003] 1-hexene can be produced by ethylene oligomerization process, including ethylene full distribution oligomerization and selective trimerization technology. The mixture obtained by non-selective oligomerization process is a mixture of various ethylene oligomers, which is complex and difficult to separate and purify. The selective oligomerization production process can overcome the above shortcomings and can selectively generate target product 1-hexene. Therefore, it is necessary to develop an ethylene selective trimerization catalyst. In the current ethylene selective trimerization technology, the selectivity of 1-hexene is low, and the selectivity of polyethylene (PE) is high. During production, polymer accumulation can cause heat exchange difficulties or adhesion on the stirring paddle, affecting mixing effect, so it is urgent to develop a catalyst with high 1-hexene selectivity.

[0004] The combination of chromium salt and ligand is the most widely studied and used ethylene selective oligomerization catalyst. In this type of catalytic system, chromium salt and ligand generate metal complexes in situ and participate in the process of catalyzing ethylene oligomerization. The structure of the ligand has a crucial influence on the activity and selectivity of the reaction. The ligands reported for ethylene trimerization have defects such as multiple synthesis steps, complicated operation, use of multiple toxic and harmful substances, and difficulty in industrial large-scale synthesis. Moreover, the product is a mixture of 1-hexene and 1-octene, and the selectivity for 1-hexene is not high. Therefore, it is urgent to develop a catalyst system that can make the reaction have higher activity, better selectivity and less by-product generation. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to overcome the problems in the prior art, such as the need to further improve the selectivity of the catalyst for preparing 1-hexene by selective oligomerization of ethylene, the use of ligands with multiple synthesis steps, complicated operation, the need to use multiple toxic and harmful substances, and difficulty in industrial large-scale synthesis, so as to provide a catalyst and a preparation method of 1-hexene.

[0006] To this end, the present application provides the following technical solutions:

[0007] According to one aspect of the present application, a catalyst is provided, comprising a ligand, a chromium-containing compound and an aluminum-containing cocatalyst;

[0008] The ligand comprises at least one of adamantane amine compounds; the molar ratio of the ligand to the chromium-containing compound is 0.6-1.8;

[0009] The molar ratio of aluminum element in the aluminum-containing cocatalyst to chromium element in the chromium-containing compound is 200-1500.

[0010] For example, the molar ratio of the ligand to the chromium-containing compound can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or within a range formed by any of the above values. For example, the molar ratio of aluminum element in the aluminum-containing cocatalyst to chromium element in the chromium-containing compound can be 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, or within a range formed by any of the above values.

[0011] According to the above technical means, the present application uses a simple structure of adamantane amine compound as the ligand, and controls the molar ratio of the ligand to the chromium-containing compound and the molar ratio of aluminum element in the aluminum-containing cocatalyst to chromium element in the chromium-containing compound, so as to selectively catalyze ethylene to generate product 1-hexene through oligomerization reaction, and has high reaction activity and low polyethylene (PE) selectivity. When used, the accumulation of polymers can be effectively avoided to affect the operation of the device. If the molar ratio of the ligand to the chromium-containing compound is less than 0.6 or greater than 1.8, the coordination between the ligand and the metal will be affected, thereby affecting the activity and selectivity. If the molar ratio of Al / Cr is too low, the metal center cannot be reduced, and if the molar ratio of Al / Cr is too high, it will be excessively reduced, which will affect the trimerization activity and selectivity.

[0012] In some optional embodiments, the ligand comprises at least one of 1-adamantane amine, 1-adamantane methylamine, 1-adamantane ethylamine, N,N-dimethyl-1-adamantane amine, and N-methyl-1-adamantane amine.

[0013] In some optional embodiments, the molar ratio of the ligand to the chromium-containing compound is 1-1.5;

[0014] And / or, the molar ratio of aluminum element in the aluminum-containing cocatalyst to chromium element in the chromium-containing compound is 400-1200.

[0015] According to the above technical means, the application can further improve the activity of the catalyst and the selectivity to 1-hexene by optimizing the molar ratio of the ligand to the chromium-containing compound and the molar ratio of the aluminum element in the aluminum-containing cocatalyst to the chromium element in the chromium-containing compound.

[0016] In some alternative embodiments, the chromium-containing compound comprises at least one of a chromium-containing inorganic salt or a chromium-containing organic compound.

[0017] In some alternative embodiments, the chromium-containing compound comprises one of chromium acetylacetonate, chromium acetate, chromium trichloride, chromium dichloride, trichlorotri(tetrahydrofuran) chromium, chromium 2-ethylhexanoate, chromium octanoate, chromium hexacarbonyl, chromium benzene tricarbonyl, and chromium diphenyl.

[0018] In some alternative embodiments, the aluminum-containing cocatalyst comprises at least one of an alkyl aluminum or an alkoxy aluminum.

[0019] In some alternative embodiments, the alkyl aluminum comprises at least one of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, trioctyl aluminum, chlorodiethyl aluminum, dichloroethyl aluminum, and hemiethyl aluminum.

[0020] In some alternative embodiments, the alkoxy aluminum comprises at least one of methylaluminoxane (MAO), modified methylaluminoxane (including but not limited to at least one of MMAO-3A, MMAO-7, MMAO-12), isobutylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane, butylaluminoxane, n-pentylaluminoxane, neopentylaluminoxane, n-hexylaluminoxane, n-octylaluminoxane, 2-ethylhexylaluminoxane, cyclohexylaluminoxane, 1-methylcyclopentylaluminoxane, phenylaluminoxane, 2,6-dimethylphenylaluminoxane, or naphthylaluminoxane.

[0021] In the application, the preparation method or mixing method of the catalyst is not particularly required, as long as it can be added to the reaction kettle to contact with the raw materials; for the convenience of addition, it can be added in the form of a solution.

[0022] According to another aspect of the application, a preparation method of 1-hexene is also provided, which comprises catalyzing the oligomerization reaction of ethylene in the presence of the above catalyst.

[0023] The preparation method of 1-hexene provided by the application has the same advantages as the above catalyst, and will not be described here.

[0024] In some alternative embodiments, the oligomerization reaction temperature is 80-140℃, and the total pressure of the oligomerization reaction is 2-7 MPa.

[0025] As an example, the temperature of the oligomerization reaction can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, or within a range consisting of any of the above values; the total pressure of the oligomerization reaction can be 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, 5MPa, 5.5MPa, 6MPa, 6.5MPa, 7MPa, or within a range consisting of any of the above values.

[0026] In some alternative embodiments, the contact time of the oligomerization reaction is 5min-3h. As an example, the contact time can be 5min, 10min, 30min, 45min, 1h, 1.5h, 2h, 2.5h, 3h, or within a range consisting of any of the above values.

[0027] In some alternative embodiments, the oligomerization reaction is carried out in the presence of a chain transfer agent, which optionally includes hydrogen.

[0028] According to the above technical means, the chain transfer agent can significantly improve the catalyst activity, while reducing the amount of PE generated or changing the morphology of PE, avoiding the accumulation of polymers, and further reducing the impact on the stable operation of the device.

[0029] In some alternative embodiments, the partial pressure ratio of the chain transfer agent to ethylene is 0-2.

[0030] As an example, the partial pressure ratio of the chain transfer agent to ethylene can be 0, 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, or within a range consisting of any of the above values. It should be noted that when the partial pressure ratio of the two is 0, it means that no chain transfer agent is used during the oligomerization reaction.

[0031] Specifically, the preparation method of the 1-hexene includes the following steps: under the condition of with or without a chain transfer agent, ethylene is subjected to oligomerization reaction in the presence of a solvent and a catalyst to generate 1-hexene.

[0032] In some alternative embodiments, the solvent is at least one of C3-C20 alkanes or substituted alkanes, C6-C26 aromatic hydrocarbons or substituted aromatic hydrocarbons; optionally, the solvent includes but is not limited to at least one of propane, butane, isobutane, pentane, isopentane, hexane, heptane, toluene, xylene, chlorobenzene, fluorobenzene, etc.

[0033] The technical solution of the present application has the following advantages:

[0034] The catalyst provided in the application comprises a ligand, a chromium-containing compound and an aluminum-containing cocatalyst; wherein the ligand comprises at least one adamantylamine compound; the molar ratio of the ligand to the chromium-containing compound is 0.6-1.8; and the molar ratio of aluminum in the aluminum-containing cocatalyst to chromium in the chromium-containing compound is 200-1500. The application uses a simple-structured adamantylamine compound as the ligand, and controls the molar ratio of the ligand to the chromium-containing compound and the molar ratio of aluminum in the aluminum-containing cocatalyst to chromium in the chromium-containing compound, so that the catalyst can selectively catalyze ethylene to generate 1-hexene through oligomerization, and has high reactivity and low polyethylene (PE) selectivity, thereby effectively avoiding the influence of polymer accumulation on device operation.

[0035] The preparation method of 1-hexene provided in the application has the same advantages as the above-mentioned catalyst due to the use of the catalyst provided in the application, and will not be described here.

[0036] The use of the chain transfer agent in the preparation method of 1-hexene provided in the application can significantly improve the activity of the catalyst, reduce the amount of PE generated or change the morphology of PE, avoid the accumulation of polymers, and further reduce the influence on the stable operation of the device.

[0037] Additional aspects and advantages of the application will be in part apparent and in part pointed out hereinafter. DETAILED DESCRIPTION

[0038] The following examples are provided to better further understand the application and are not limited to the best mode, and do not limit the content and protection scope of the application. Any person who obtains any product the same as or similar to the application under the inspiration of the application or by combining the application with other prior art features falls within the protection scope of the application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the application; the terms "include" and "have" and any variations thereof in the text of the application are intended to cover non-exclusive inclusion.

[0040] Reference to "an embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all referring to a common set of embodiments, although they can be.

[0041] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0042] The "range" disclosed in the present application is defined in the form of lower limit and upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can be inclusive or exclusive of the end value, and can be arbitrarily combined, i.e. any lower limit can be combined with any upper limit to form a range. In the present application, unless otherwise specified, the numerical range "a-b" represents a shorthand representation of any real combination between a and b, where a and b are real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been listed herein, and "0-5" is only a shorthand representation of these numerical combinations. In addition, when it is stated that a parameter is an integer ≥2, it is equivalent to disclose that the parameter can be, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the associated objects.

[0044] In the description of the embodiments of the present application, the term "at least one" refers to one or more than two (including two).

[0045] If not otherwise specified, all steps of the present application can be carried out in any order, preferably in the order as described. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in the order as described, or the method can comprise steps (b) and (a) in the order as described. For example, the method comprising step (c) means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or the method can comprise steps (a), (c) and (b), or the method can comprise steps (c), (a) and (b), etc.

[0046] When the specific experimental procedures or conditions are not mentioned in the examples, the operations or conditions can be carried out according to the conventional experimental procedures described in the literatures. When the reagents or instruments are not mentioned, they are the conventional reagents or instruments which can be obtained from the market.

[0047] The present application will be described in detail with reference to the specific examples. It should be noted that the examples are merely illustrative and are not intended to limit the present application in any way.

[0048] The source information of the main raw materials involved in the following examples and comparative examples is as follows:

[0049] Table 1 Source and specification of raw materials

[0050]

[0051]

[0052] Example 1

[0053] The present example provides a catalyst and a method for preparing 1-hexene using the catalyst. The composition of the catalyst and the method for preparing 1-hexene are as follows:

[0054] A high-pressure stainless steel reactor was heated to 120°C, vacuumized for 2h, and the heating was turned off (the purpose of preheating in this example was to dry the reactor thoroughly), and after the temperature cooled to room temperature, vacuumized and replaced with hydrogen three times. Dehydrated and deoxygenated solvent hexane 200mL was added to the reactor, followed by a certain molar amount of Cr-containing compound, a certain ligand / Cr-containing compound molar ratio of ligand was added, a certain amount of co-catalyst was added according to the Al / Cr molar ratio, and then a certain pressure of hydrogen was introduced, followed by the introduction of ethylene to the set pressure, and the reaction was carried out at the set temperature for 1h, and the temperature of the reactor was controlled by the inner coil. After the reaction was completed, the gas inlet valve was closed, and the temperature was lowered to below 20°C before slowly releasing the pressure. After the pressure was reduced to normal pressure, the product was transferred to a special container for storage and weighed in time. After weighing, the solid of the reaction solution was filtered in time, and the filtrate was analyzed by GC. The filtered solid product was dried in a vacuum oven at 80°C for 12h before weighing, and the activity and selectivity were calculated. The operating conditions and specific composition of the catalyst of each example and comparative example are shown in Table 2.

[0055] Examples 2-9

[0056] This example provides a catalyst and a method for preparing 1-hexene using the catalyst. Compared with Example 1, the composition of the catalyst and the operating parameters are different, and the specific differences are shown in Table 2. Among them, in the examples and comparative examples, the ligand used in Example 7 is 1-adamantaneamine, the ligand used in Example 8 and Example 9 is 1-adamantaneethylamine, and the ligand used in Example 10 is N-methyl-1-adamantaneamine. The ligand used in the remaining examples is 1-adamantane methylamine.

[0057] Comparative Examples 1-7

[0058] This comparative example provides a catalyst and a method for preparing 1-hexene using the catalyst. Compared with the examples, the difference lies in the composition of the catalyst and the operating parameters, and the specific differences are shown in Table 2. The ligand used in all comparative examples is 1-adamantane methylamine.

[0059] Comparative Example 8

[0060] The related operation is consistent with Example 1, and the difference lies in that acetylacetone chromium is not included in the catalyst, i.e. acetylacetone chromium is not added to the reactor. It was found that the polymerization activity was 0.

[0061] Comparative Example 9

[0062] This comparative example provides a catalyst and a method for preparing 1-hexene using the catalyst. Compared with Example 1, the difference lies in the selection of the ligand, and the ligand used in this comparative example has the following structure:

[0063]

[0064] The polymerization activity was 910 kg / g Cr, with 1-hexene selectivity of 39%, 1-octene selectivity of 48.1%, and PE selectivity of about 0.02%.

[0065] Comparative Example 10

[0066] This comparative example provides a catalyst and a method for preparing 1-hexene using the catalyst, which is different from Example 1 in that the ligand selected is different, and the ligand used in this comparative example has the following structural formula:

[0067]

[0068] The polymerization activity was 710 kg / g Cr, with 1-hexene selectivity of 30%, 1-octene selectivity of 55%, and PE selectivity of about 0.6%.

[0069] Table 2 Catalyst composition and operating parameters of each example and comparative example

[0070]

[0071]

[0072] Test Example

[0073] The sample testing method in this application is as follows:

[0074] The solid product was separated and dried by filtration, and then weighed.

[0075] The liquid product was characterized by gas chromatography to obtain the percentage of each product in the liquid phase, and then combined with the weighing result to obtain the mass of each product in the liquid phase by deducting the mass of the solid product from the net weight gain.

[0076] Gas chromatography analysis conditions: injection port temperature: 280°C; column oven temperature: 50°C; detector temperature: 280°C; gas carrier: 1.0 MPa; air: 0.3 MPa; hydrogen: 0.3 MPa.

[0077] Gas chromatography temperature program: first hold at 50°C for 4 min, then increase the temperature to 280°C at a rate of 20°C / min, then hold at 280°C for 8 min, and finally cool down to room temperature (instrument brand: Agilent Technologies 5977B MSD, serial number: CN7113080).

[0078] Activity: the net weight gain divided by the amount of chromium in the chromium compound in the reaction kettle is recorded as the activity, with the unit of kg / g Cr.

[0079] 1-hexene selectivity: 1-hexene mass determined by GC test divided by net weight gain.

[0080] PE selectivity: solid product mass divided by net weight gain.

[0081] The specific test results of each embodiment and test example are shown in the following table:

[0082] Table 3 Test results of catalytic performance of each embodiment and comparative example

[0083]

[0084] According to the test results of the above embodiments and comparative examples, it can be seen that the adamantane amine compound selected as the ligand in the embodiments of the present application can be used together with the chromium-containing compound in the presence of an alkyl aluminum and / or alkoxy aluminum cocatalyst to catalyze the trimerization of ethylene to obtain the product 1-hexene with high selectivity and low PE selectivity, which can effectively reduce the current industry problem of polymer wall sticking in the reaction kettle. As can be seen from the comparison between Example 8 and Example 9, the use of hydrogen as a chain transfer agent in the process of catalyzing the oligomerization of ethylene by the catalyst of the present application can significantly improve the reaction activity and reduce the selectivity of PE. When no ligand, alkyl aluminum reagent, or chromium-containing catalyst is added in Comparative Example 1, Comparative Example 3, and Comparative Example 8, respectively, the catalyst system with catalytic activity for the trimerization of ethylene cannot be generated, and the oligomerization reaction cannot be carried out. By comparing Comparative Example 1 with Comparative Example 9 and Comparative Example 10, it can be seen that the catalyst system described in the present application can catalyze the generation of 1-hexene with high selectivity, which is an ethylene trimerization catalyst.

[0085] Obviously, the above embodiments are merely examples for the purpose of clarity, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. Here, it is not necessary and impossible to exhaust all embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A catalyst, characterized in that, Including ligands, chromium-containing compounds, and aluminum-containing co-catalysts; The ligand includes at least one of adamantaneamine compounds, and the molar ratio of the ligand to the chromium-containing compound is 0.6 to 1.

8. The molar ratio between aluminum in the aluminum-containing co-catalyst and chromium in the chromium-containing compound is 200–1500.

2. The catalyst according to claim 1, characterized in that, The ligand includes at least one of 1-adamantaneamine, 1-adamantanemethylamine, 1-adamantaneethylamine, N,N-dimethyl-1-adamantaneamine, and N-methyl-1-adamantaneamine.

3. The catalyst according to claim 1, characterized in that, The molar ratio of the ligand to the chromium-containing compound is 1 to 1.5; And / or, the molar ratio between aluminum in the aluminum-containing cocatalyst and chromium in the chromium-containing compound is 400 to 1200.

4. The catalyst according to claim 3, characterized in that, The chromium-containing compound includes at least one of chromium-containing inorganic salts or chromium-containing organic compounds; Optionally, the chromium-containing compound includes one of chromium acetylacetonate, chromium acetate, chromium trichloride, chromium dichloride, chromium trichlorotris(tetrahydrofuran), chromium 2-ethylhexanoate, chromium octanoate, chromium hexacarbonyl, chromium triphenylcarbonyl, and diphenylchromium.

5. The catalyst according to any one of claims 1-4, characterized in that, The aluminum-containing cocatalyst includes at least one of alkylaluminum or alkoxyaluminum.

6. The catalyst according to claim 5, characterized in that, The alkylaluminum comprises at least one of trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, diethylaluminum chloride, diethylaluminum chloride, and sesquiethylaluminum. And / or, the aluminum alkoxy comprises at least one of methylaluminoxane, MMAO-3A, ​​MMAO-7, MMAO-12, isobutylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane, butylaluminoxane, n-pentylaluminoxane, neopentylaluminoxane, n-hexylaluminoxane, n-octylaluminoxane, 2-ethylhexylaluminoxane, cyclohexylaluminoxane, 1-methylcyclopentylaluminoxane, phenylaluminoxane, 2,6-dimethylphenylaluminoxane, or naphthylaluminoxane.

7. A method for preparing 1-hexene, characterized in that, The catalyst described in any one of claims 1-6 is used to catalyze the oligomerization of ethylene.

8. The method for preparing 1-hexene according to claim 7, characterized in that, The oligomerization reaction temperature is 80-140℃, and the total pressure of the oligomerization reaction is 2-7MPa.

9. The method for preparing 1-hexene according to claim 7 or 8, characterized in that, The oligomerization reaction is carried out in the presence of a chain transfer agent, which optionally includes hydrogen.

10. The method for preparing 1-hexene according to claim 9, characterized in that, The partial pressure ratio of the chain transfer agent to ethylene is 0 to 2.

Images