Catalyst system for selective oligomerization of ethylene, reaction method and application thereof
阅读说明：本技术 一种乙烯选择性齐聚的催化剂体系、反应方法及其应用 (Catalyst system for selective oligomerization of ethylene, reaction method and application thereof ) 是由 姜涛 常琪琪 翟阳 范昊男 陈延辉 曹晨刚 王亚婷 李健 于 2020-07-23 设计创作，主要内容包括：本发明提供了一种乙烯选择性齐聚的催化剂体系、反应方法及其应用,属于均相催化技术领域。该催化剂体系包括：配体a；过渡金属化合物b,过渡金属化合物b为IVB～VIII族的金属化合物；其中,配体a的结构通式如式(I)所示：<Image he="490" wi="684" file="DDA0002598900610000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>R<Sup>1</Sup>、R<Sup>2</Sup>、R<Sup>3</Sup>、R<Sup>4</Sup>、R<Sup>5</Sup>可以相同或不同,分别独立选自烷基或芳基。本发明的催化剂体系用于乙烯选择性齐聚,具有催化活性高、产物线性α-烯烃选择性高,1-丁烯含量少、1-己烯+1-辛烯选择性高、副产物少的特点。(The invention provides a catalyst system for selective oligomerization of ethylene, a reaction method and application thereof, belonging to the technical field of homogeneous catalysis. The catalyst system comprises: a ligand a; a transition metal compound b, wherein the transition metal compound b is a metal compound of IVB-VIII groups; wherein, the structural general formula of the ligand a is shown as the formula (I): R 1 、R 2 、R 3 、R 4 、R 5 which may be the same or different from each other,each independently selected from alkyl or aryl. The catalyst system is used for selective oligomerization of ethylene, and has the characteristics of high catalytic activity, high product linear alpha-olefin selectivity, low 1-butene content, high 1-hexene + 1-octene selectivity and few byproducts.)
1. A catalyst system for selective oligomerization of ethylene, comprising:
a ligand a;
a transition metal compound b, wherein the transition metal compound b is a metal compound of IVB-VIII groups;
an activator c, the activator c being a compound containing a group IIIA metal;
wherein, the structural general formula of the ligand a is shown as the formula (I):
R1、R2、R3、R4、R5may be the same or different and are each independently selected from alkyl or aryl groups.
2. The catalyst system according to claim 1,
the alkyl group is C1-C10Alkyl groups of (a);
preferably, the alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, cyclopentyl, cyclohexyl.
3. The catalyst system according to claim 1,
said aryl group is C6-C20Aryl groups of (a) and derivatives thereof;
preferably, the aryl group is selected from phenyl, substituted phenyl.
4. The catalyst system according to claim 1,
the transition metal compound b is a compound of chromium, molybdenum, tungsten, cobalt, titanium, tantalum, vanadium, zirconium, iron, nickel or palladium.
5. The catalyst system according to claim 1,
the activating agent c is one or a mixture of more than two of an alkyl aluminum compound, an alkyl aluminoxane compound and an organic boron compound; wherein the alkylaluminoxane compound comprises an alkylaluminoxane compound having a volatile component removed.
6. The catalyst system according to claim 1 or 5,
the activating agent c is a mixture of an alkyl aluminum compound and an alkyl aluminoxane compound for removing volatile components, wherein the alkyl aluminum compound is triethyl aluminum, and the aluminoxane compound is methylaluminoxane for removing volatile components.
7. The catalyst system according to claim 1,
the molar ratio of the ligand a to the transition metal compound b to the activator c is 1: 0.5-100: 0.1-5000.
8. A reaction method of ethylene selective oligomerization is characterized in that,
comprising an oligomerization of ethylene carried out in the presence of a catalyst system according to any of claims 1 to 7.
9. The method of claim 8,
the reaction is carried out in an inert solvent, wherein the inert solvent is one or a mixture of more than two of alkane, arene, alkene or ionic liquid;
the reaction temperature is 0-200 ℃;
the reaction pressure is 0.1 MPa-50 MPa.
10. Use of a catalyst system according to any one of claims 1 to 7 for the selective oligomerization of ethylene.
Technical Field
The invention belongs to the technical field of homogeneous catalysis, and particularly relates to a catalyst system for selective oligomerization of ethylene, a reaction method and application thereof.
Background
With the continuous development of global economy and the demand for high performance of synthetic materials, the application of higher linear alpha-olefins such as 1-hexene and 1-octene in the fields of high performance polyolefins, high-end synthetic lubricating oils, and the like is increasing, and the demand thereof is continuously increasing. Ethylene oligomerization is the principal process for producing high purity, linear alpha-olefins such as 1-hexene, 1-octene, 1-decene and 1-dodecene, and generally involves non-selective ethylene oligomerization and selective ethylene oligomerization.
For non-selective ethylene oligomerization technology, several novel ligand-coordinated metal chromium-based homogeneous catalysts have been reported for the synthesis of linear alpha-olefins with a broad carbon number distribution. For example, the Sasol company Overett et al reported that a chromium catalyst system of PCP framework ligands was used to catalyze the non-selective oligomerization of ethylene, and the product composition followed the Schulz-Flory distribution (. alpha. ═ 0.55) (J.mol.Catal.A: Chem,2008,283,114). Gambarotta et al reported that pyridine-backbone ligand-derived N, P-coordinated chromium catalysts catalyze ethylene oligomerization under methylaluminoxane activation, but the product distribution is different from Schulz-Flory distribution, C6-C12The mass fraction of (2) is up to 60-75%, and the linearity is high (Organometallics, 2013,32, 7107; 2014,33, 1602). Subsequently, Danopoulos et al reported that a chromium-based catalyst of similar structure catalyzed oligomerization of ethylene under activation by methylaluminoxane to yield C6-C12The mass fraction of (A) is up to 71% (Organometallics,2016,35, 4044). In addition to chromium complexes, complexes of metals such as iron, cobalt, nickel, palladium, titanium and the like can also be used for ethyleneOligomerization, such as the late transition metal iron and cobalt complex catalysts found by Brookhart, Gibson et al, have high activity for the oligomerization of ethylene and very high selectivity for linear alpha-olefins (Brookhart, M et al, J.Am.chem.Soc.1998,120, 7143; Gibson, V.C. et al, J.chem.Commun.1998,849), but have high 1-butene contents (C.E.)>10％)、C6～C12Low selectivity of linear alpha-olefins.
The ethylene selective oligomerization can generate high-grade linear alpha-olefin such as 1-hexene, 1-octene, 1-decene, 1-dodecene and the like with high selectivity, and has the advantages of good atom economy, simple process route and the like. The activity of the catalyst system and the selectivity of the desired product are key to the evaluation of the advancement of this technology, and the structure of the ligand in the catalyst system plays an important role in this. Researchers of the Sasol company in south africa in 2004 made minor changes on the basis of ethylene trimerization diphosphine amine (PNP) ligands (chem. commun.,2002,858-859) developed by professor Wass, even though the original catalytic system was changed from ethylene trimerization to ethylene tetramerization. Then, many chemical companies and scientists in the world carry out follow-up research, such as PNP ligands disclosed by Chinese patents CN1741850A (WO2004/056478A1), CN1741849A (WO2004/056479A1), CN101032695A, CN101351424A, CN101415494A, CN1651142A, CN101291734A and US2006/0128910A1, Korean SK energy companies CN201880057196.4, CN201780043063.7, CN201780032874.7, CN201380014632.7, CN201080003564.0, CN201080003564.0, CN200880002464.9, CN200880002464.9 and CN200780100280.1, and form a catalytic system with Cr and MAO for ethylene tetramerization, so that the catalytic system has high catalytic activity and long-term stability. However, the content of the byproduct methyl cyclopentane and methylene cyclopentane in the catalytic system is high, and the total selectivity of linear alpha-olefin is low.
Disclosure of Invention
The invention aims to provide high catalytic activity and high C by finely adjusting the electronic property and steric hindrance of a catalyst ligand substituent6～C8A linear alpha-olefin selective ethylene oligomerization catalyst system to solve the problem of C in ethylene oligomerization reaction6～C8Total selectivity of linear alpha-olefinsHigh problems.
The invention provides a catalyst system for selective oligomerization of ethylene, which comprises:
a ligand a;
a transition metal compound b, wherein the transition metal compound b is a metal compound of IVB-VIII groups;
an activator c, the activator c being a compound containing a group IIIA metal;
wherein, the structural general formula of the ligand a is shown as the formula (I):
R1、R2、R3、R4、R5may be the same or different and are each independently selected from alkyl or aryl groups.
Further, alkyl is C1-C10Alkyl groups of (a); preferably, the alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, cyclopentyl, cyclohexyl.
Further, aryl is C6-C20Aryl groups of (a) and derivatives thereof; preferably, aryl is selected from phenyl, substituted phenyl.
Further, the transition metal compound b is a compound of chromium, molybdenum, tungsten, cobalt, titanium, tantalum, vanadium, zirconium, iron, nickel, or palladium.
Further, the activating agent c is one or a mixture of more than two of an alkyl aluminum compound, an alkyl aluminoxane compound and an organic boron compound; wherein the alkylaluminoxane compound includes an alkylaluminoxane compound having a volatile component removed.
Further, the activator c is a mixture of an alkylaluminum compound and a volatile component-removing alkylaluminoxane compound, wherein the alkylaluminum compound is triethylaluminum, and the aluminoxane compound is volatile component-removing methylaluminoxane.
Further, the molar ratio of the ligand a, the transition metal compound b and the activator c is 1: 0.5-100: 0.1-5000.
The invention provides a reaction method for selective oligomerization of ethylene, which comprises the oligomerization of ethylene in the presence of any one of the catalyst systems.
Further, the reaction is carried out in an inert solvent, wherein the inert solvent is one or a mixture of more than two of alkane, arene, alkene or ionic liquid; the reaction temperature is 0-200 ℃; the reaction pressure is 0.1 MPa-50 MPa.
The invention also provides the use of any of the above catalyst systems in the selective oligomerization of ethylene.
The invention has the following advantages:
the catalyst system provided by the invention has high catalytic activity, the total selectivity of the target product 1-hexene + 1-octene is high, and the selectivity of the by-products methylcyclopentane and methylene cyclopentane is low.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.
The catalyst system of the present invention is described below.
Note that, in this text, "C" is used6～C12Linear alpha-olefin Total selectivity "means C6～C12The total amount of linear alpha-olefins in the total product (all linear alpha-olefins and by-products).
The embodiment of the invention provides a catalyst system for selective oligomerization of ethylene, which comprises a ligand a, a transition metal compound b and an activator c. Wherein, the structural general formula of the ligand a is shown as a formula (I) and contains a ligand of phosphorus atoms and nitrogen atoms; the transition metal compound b is a metal compound of IVB-VIII groups, and is a central metal atom; the activator c is a compound containing a group IIIA metal;
wherein, the structural general formula of the ligand a is shown as the formula (I):
R1、R2、R3、R4、R5may be the same or different and are each independently selected from alkyl or aryl groups.
In one embodiment of the present invention, the alkyl group is C1-C10Alkyl group of (1). Preferably, the alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, cyclopentyl, cyclohexyl. More preferably, the alkyl group is selected from methyl, ethyl, n-propyl, and the like.
In one embodiment of the present invention, aryl is C6-C20Aryl groups of (1) and derivatives thereof. Preferably, aryl is selected from phenyl, substituted phenyl. More preferably, aryl is selected from phenyl, 4-methylphenyl, 4-methoxyphenyl, and the like. The aryl derivatives may be selected from naphthyl, substituted naphthyl, fluorenyl and the like.
In an embodiment of the present invention, the transition metal compound b is a compound of chromium, molybdenum, tungsten, cobalt, titanium, tantalum, vanadium, zirconium, iron, nickel or palladium. Preferably, the transition metal compound b is CrCl3(THF)3、CrCl2(THF)2、CoCl3、NiBr2One kind of (1). More preferably, the transition metal compound b is a chromium-containing transition metal compound. Alternative chromium compounds include those of the formula CrRnA compound of the formula wherein RnBeing an organic negative ion or neutral molecule, RnWherein the carbon atoms are usually 1-10 carbon atoms, n is an integer of 0-6, and the valence of chromium is 0-6. Specific RnThe group is an organic matter containing carboxyl, beta-diketone group and alkyl or the group thereof. From the viewpoint of easy dissolution and easy handling, more suitable chromium compounds include chromium acetate, chromium isooctanoate, chromium n-octanoate, chromium acetylacetonate, chromium diisoprenate, chromium diphenyloxide, CrCl3(THF)3、CrCl2(THF)2One of (phenyl) chromium tricarbonyl and chromium hexacarbonyl.
Further, the activating agent c is one or a mixture of more than two of an alkyl aluminum compound, an alkyl aluminoxane compound and an organic boron compound; wherein the alkylaluminoxane compound includes an alkylaluminoxane compound having a volatile component removed.
Specifically, the activator c may be a compound containing a group IIIA metal. Such as alkylaluminum compounds, alkylaluminoxane compounds. The alkylaluminum compound can be various trialkylaluminums, such as Triethylaluminum (TEAL), triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum or tri-n-octylaluminum; the alkylaluminum compound can also be an alkylaluminum halide, alkylaluminum hydride or alkylaluminum sesquichloride, such as diethylaluminum monochloride (AlEt)2Cl) and triethylaluminum trichloride (A1)2Et3Cl3) (ii) a The alkylaluminoxane compound may be selected from Methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, modified aluminoxane, methylaluminoxane DMAO from which volatile components are removed, and the like. The activator c may be a mixture of an alkylaluminum compound and an alkylaluminoxane for removing volatile components, wherein the alkylaluminum compound is TEAL and the alkylaluminoxane compound is DMAO. Preferably, the molar ratio of TEAL to DMAO is 0.01-100, preferably 0.1-10.
In the present invention, the TEAL alkylation capacity is relatively weak, and is more adaptable to the catalyst system proposed by the present invention; and simultaneously, DMAO can shield the influence of volatile components such as toluene on the catalyst complexing process, so that the activity of the catalyst system is improved, and the dosage of the activating agent can be further reduced by mixing the DMAO and the catalyst.
Further, the activator c is a mixture of an alkylaluminum compound and a volatile component-removed alkylaluminoxane compound, wherein the alkylaluminum compound is triethylaluminum, and the aluminoxane compound is volatile component-removed methylaluminoxane; the molar ratio of triethyl aluminum to methylaluminoxane for removing volatile components is 0.01 to 100, preferably 0.1 to 10.
Further, the molar ratio of the ligand a, the transition metal compound b and the activator c is 1: 0.5-100: 0.1-5000.
Further, the molar ratio of the ligand a, the transition metal compound b and the activator c is 1: 0.5-100: 0.1-200.
Further, the molar ratio of the transition metal compound b to the activator c is 1:1 to 500.
Further, the molar ratio of the transition metal compound b to the activator c is 1: 1-200.
The preparation of the catalyst system of the present invention is further illustrated below.
In an embodiment of the present invention, the preparation method of the ligand a may include the steps of:
(1) preparation of Ph2PR1NLi
Taking a certain amount of Ph2PR1NH, adding a small amount of n-hexane, and cooling in a refrigerator for 10-20 minutes for later use. Adding a certain amount of n-BuLi into a small amount of n-hexane, cooling in a refrigerator for 10-15 min, taking out the two medicines, slowly dripping n-BuLi into the standby solution, naturally heating to room temperature, stirring for reacting for about 12-24h, filtering with a sand core funnel, washing with n-hexane for 2 times, and vacuum drying to obtain white Ph2PR1NLi solid.
(2) Preparation of Ph2PR1NPR2R3
Taking a certain amount of Ph2PR1Adding NLi into a proper amount of normal hexane, putting the mixture into a refrigerator for later use, and taking ClPNR2R3NR4R5Adding appropriate amount of n-hexane, placing in refrigerator, taking out the above solution after 15-20 min, and adding ClPNR2R3NR4R5Slowly adding into the above solution, stirring overnight, filtering, vacuum drying to obtain white or yellow oil, adding appropriate amount of n-hexane, stirring, mixing, and recrystallizing in refrigerator. Overnight, the n-hexane solvent was filtered off and dried under vacuum to give the product as a white or pale yellow solid powder.
In one embodiment of the present invention, the preparation method of the catalyst system may include the following steps:
the components a, b and c are mixed in advance or directly added into a reaction system for in-situ synthesis. That is, the catalyst is prepared by mixing the ligand a, the transition metal compound b, and the activator c in advance; or directly adding the ligand a, the transition metal compound b and the activator c into a reaction system for in-situ synthesis;
the ligand a, the transition metal compound b and the activator c in the formula (I) can be reacted in a liquid phase reaction, for example, in the presence of a solvent, and optionally a solvent such as toluene, benzene and derivatives thereof; or by solid phase reaction; the catalyst may also be generated by an in situ reaction during the oligomerization reaction. The reaction here may be a reaction between one, two or three compounds of the above-mentioned ligand, transition metal compound and metal organic activator. The course of this reaction is also the aging (pre-complexing) of the catalyst.
The method of the catalyst system of the present invention for oligomerization of ethylene is further described below.
The invention also provides an ethylene oligomerization reaction method, which comprises the ethylene oligomerization reaction carried out in the presence of the catalyst system.
In one embodiment of the present invention, the reaction is performed in an inert solvent, wherein the inert solvent is one or more than two of alkane, arene, alkene or ionic liquid. Typical solvents include, but are not limited to, benzene, toluene, xylene, cumene, n-heptane, n-hexane, methylcyclohexane, cyclohexane, 1-hexene, 1-octene, ionic liquids, and the like, with methylcyclohexane being preferred.
In one embodiment of the invention, the reaction temperature is 0-200 ℃. Preferably from 45 ℃ to 100 ℃.
In one embodiment of the present invention, the pressure of the ethylene oligomerization reaction can be performed at a pressure of 0.1MPa to 50MPa, preferably 1.0MPa to 10 MPa.
In one embodiment of the present invention, the concentration of the catalyst in the reaction system may be from 0.01. mu. mol metal/L to 1000. mu. mol metal/L, preferably from 0.1. mu. mol metal/L to 10. mu. mol metal/L. Note that the metal here is a transition metal in the transition metal compound b.
The present invention will be further illustrated with reference to the following specific examples, but the present invention is not limited to the following examples.