CN112725054A

CN112725054A - Process method for directly synthesizing high-performance high-viscosity base oil by polymerizing low-carbon olefins

Info

Publication number: CN112725054A
Application number: CN201911032644.8A
Authority: CN
Inventors: 周姣龙; 任鸿平; 朱洁; 刘加帅; 杨建华
Original assignee: Nanjing Zhongke Kangrun New Material Technology Co ltd
Current assignee: Nanjing Zhongke Kangrun New Material Technology Co ltd
Priority date: 2019-10-28
Filing date: 2019-10-28
Publication date: 2021-04-30
Anticipated expiration: 2039-10-28
Also published as: CN112725054B

Abstract

The invention relates to a process method for directly synthesizing high-performance high-viscosity base oil through low-carbon olefin polymerization. Specifically, the invention discloses a method for directly synthesizing high-performance base oil with high viscosity through low-carbon olefin, which comprises a plurality of working procedures of polymerization, hydrogenation, rectification and the like. The method has the advantages of easily available raw materials, less three wastes, reduction of pollution in the production process, good performance of the synthesized base oil and low production cost.

Description

Process method for directly synthesizing high-performance high-viscosity base oil by polymerizing low-carbon olefins

Technical Field

The invention relates to the technical field of synthetic base oil production, in particular to low-carbon olefin (C) such as ethylene₂- C₄) A process method for directly synthesizing high-performance high-viscosity base oil through polymerization.

Background

Lubricating oil is an indispensable material in industry, and has important values for saving energy, reducing consumption, protecting and ensuring long-term high-efficiency operation of equipment. It is statistically estimated that the global amount of industrial energy consumption 1/3-1/2 is caused by friction and 80% of failed parts are caused by wear, so high performance lubricating oils are of great importance for reducing wear, reducing energy consumption and sustainable development of society. The lubricating oil is composed of 70-95% of base oil and 5-30% of additives, so the performance of the base oil basically determines the quality of the lubricating oil. The current international universal base oil comprises mineral oil (API I-API III) and synthetic oil (API IV-V), wherein the fully synthetic oil PAO (API IV) has the characteristics of wide operating temperature range, good viscosity-temperature performance, high viscosity index, low pour point, small evaporation loss, good oxidation stability, environmental friendliness and the like, is a high-quality lubricating oil base oil and is applied to a plurality of high-end fields.

The existing PAO production mainly comprises the following three production processes: 1) BF (BF) generator₃+ alcohol catalytic system: mainly comprises (i) polymerization and (ii) BF₃Recovering, washing, distilling at normal pressure, adding hydrogen, vacuum rectifying, and blending; 2) AlCl₃+ alcohol catalytic system: mainly comprises polymerization, sedimentation and slag cutting, neutralization, filtration, distillation under normal pressure, hydrogenation, rectification under reduced pressure, bleaching clay refining, and adjustment of nine and 9 main processes; 3) metallocene catalyst system: the method mainly comprises polymerization, quenching-adsorption, filtration, atmospheric distillation, hydrogenation, decompression and rectification and 7 blending steps. Wherein, BF₃+ alcohol catalytic systems are mainly used for the production of PAO of low viscosity; AlCl₃+ PAO of high viscosity in the main production of alcohols; metallocene catalyst systems produce predominantly PAOs of high viscosity.

The polymerization raw material for synthesizing PAO by the three processes is mainly C₈、C₁₀And C₁₂Of alpha-olefins, especially C₁₀The best quality of (1-decene) synthesized PAO. The majority of alpha-olefin comes from ethylene oligomerization, and the carbon number of the olefin obtained by the oligomerization through the SHOP process conforms to Flory distribution, C₈、C₁₀And C₁₂The content is about 40%; oligomerizing and separating to obtain target alphaAnd the PAO is obtained by catalytic polymerization after the olefin is polymerized, so the total conversion rate of the ethylene is lower, the whole process is very complex, the process flow is longer, and the production cost of the PAO is greatly increased.

The raw materials for domestic PAO production all depend on import and the source of goods is unstable. There are also related alternative processes: 1) The mixed alpha-olefin prepared by cracking is used for polymerization, but the olefin distribution of the mixed alpha-olefin obtained by cracking is wide, and the mixed alpha-olefin contains a large amount of internal olefin and other impurities which cannot participate in polymerization, and the quality difference of the obtained PAO is obvious from that of the PAO produced by using foreign raw materials. 2) The patent CN201510439004.4 reports that the α -olefin synthesized by high temperature fischer-tropsch synthesis is then subjected to separation polymerization, but the yield of α -olefin obtained by this scheme is also low (45%), the number of olefin carbons is continuously distributed (containing both odd number carbons and even number carbons), which results in high cost of separation in the early stage, low purity of α -olefin, and especially the adjacent odd number carbons and even number carbons cannot be separated, which affects the stability and quality of product performance. In addition, the purification cost in the early stage of polymerization is high, and a potassium-sodium alloy or the like is required.

In addition to the above-mentioned raw material problems, the existing catalytic systems have several problems:

1)AlCl₃the alcohol catalytic reaction system causes wide product molecular weight distribution, the catalyst can not be recycled, and because the system has a large amount of chloride ions, the corrosion to equipment is large, the clay needs to be neutralized in the early stage, and the clay needs to be added again for refining in the later stage, so a large amount of waste residues (about 10 percent of the product) are generated in the process.

2)BF₃+ alcohol catalytic system due to BF₃The catalyst has high toxicity and strong corrosivity, and the catalyst needs to be recovered, so that the recovery cost is very high, and a large amount of wastewater is generated in the post-treatment;

3) the metallocene catalyst systems are mainly based on the fact that the cocatalyst used (MAO or perfluorophenylboron) is too costly.

4) In the above PAO production process, after the polymerization of α -olefin, poly α -olefin with different polymerization degree is first vacuum distilled and cut to obtain different fractions (for example: polymers such as dimers, trimers, tetramers and pentamers) and then through subsequent blending steps to obtain PAO products with different viscosity grades, because the poly-alpha-olefin raw material is mixed olefin and the polymerization degree is not single in most cases, the fine cutting not only increases the investment cost of equipment, but also further increases the cost through the blending after cutting.

In conclusion, the defects of high production cost, complex process flow, more three wastes, shortage of raw material sources and the like in the conventional process flow become main factors influencing the large-scale production and application of the PAO. Therefore, there is an urgent need in the art to develop new processes to achieve low cost, low pollution synthesis of high performance base oils.

Disclosure of Invention

The invention aims to provide a process route for producing fully-synthetic lubricating base oil LPE by one-step polymerization of low-carbon olefin.

The first aspect of the invention provides a process for directly preparing base oil by polymerizing low-carbon olefins, which comprises the following steps:

(1) polymerization: sequentially adding a first solvent and aluminum alkyl a into a tubular reactor or a kettle-type reactor at a set polymerization temperature, continuously introducing low-carbon olefin under a set polymerization pressure, and then adding a catalyst solution into the reactor in multiple batches to perform a polymerization reaction, thereby forming base oil before hydrogenation; wherein,

the polymerization temperature is 10-60 ℃;

the polymerization pressure is 0.7-2.0 MPa;

the polymerization reaction time is 1-24 hours;

the low-carbon olefin is selected from the following group: ethylene, propylene, or combinations thereof;

the alkyl aluminum a is selected from the following group: triethylaluminum, trimethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, or a combination thereof;

the first solvent is selected from the group consisting of: c₆～C₁₂Alkane, white oil, toluene, xylene, halogenated C₁～ C₁₂An alkane of (a);

the catalyst solution is a solution formed by the complex and alkyl aluminum b in a second solvent; wherein, the molar ratio of the alkyl aluminum b to the complex is as follows: 1 to 100/1;

the alkyl aluminum b is selected from the following group: triethylaluminum, triisobutylaluminum, diethylaluminum chloride, or a combination thereof;

the second solvent is selected from the group consisting of: toluene, halogenated C₁～C₁₂An alkane of (a);

the complex is the combination of a ligand compound I and a divalent metal salt, or the complex is a complex shown as II:

in the formula,

Y¹are respectively hydrogen and C₁-C₈Alkyl or C₁-C₈Haloalkyl, unsubstituted or substituted phenyl;

Y²are respectively CR₄R₅、NR₆O or S, R₄、R₅、R₆Each independently is H, C₁-C₄Alkyl or C₁- C₄A haloalkyl group;

is an unsubstituted or substituted 5-7 membered monocyclic ring, or a bicyclic or tricyclic group (e.g., a spirocyclic structure) containing said 5-7 membered monocyclic ring, wherein said 5-7 membered monocyclic ring contains 1-3N, O or S atoms and contains at least one N;

Y³is one or more optional substituent groups on said 5-7 membered monocyclic ring or a bicyclic or tricyclic group containing said 5-7 membered monocyclic ring, each Y³Independently of each other is hydrogen, C₁-C₈Alkyl radical, C₁-C₈Haloalkyl, C₅-C₈Cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted benzyl;

z is respectively C₁-C₈Alkyl radical, C₁-C₈Haloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl;

wherein "substituted" as recited in each of the above definitions means that the group has 1 to 5 substituents selected from the group consisting of: c₁-C₄Alkyl and C₁-C₄Haloalkyl, halogen, nitro, cyano, CF₃、-O-R₁、-N(R₂)₂、-Si(R₃)₃、 -CH₂-O-R₈、-SR₉、-CH₂-S-R₁₀、-CH-(R₁₀)₂Or phenyl which is unsubstituted or substituted with 1 to 5 substituents selected from the group consisting of: c₁-C₄Alkyl and C₁-C₄Haloalkyl, wherein R₁、R₂、R₃Each independently is C₁-C₄Alkyl or C₁-C₄A haloalkyl group; and R is₈、R₉And R₁₀Are respectively C₁-C₈Alkyl or phenyl.

The divalent metal salt is a divalent nickel metal salt;

wherein X is independently halogen, C₁-C₄Alkyl radical, C₂-C₆Alkenyl, allyl

-OAc、^-OTf or benzyl;

(2) hydrogenation: carrying out hydrogenation reaction on the base oil before hydrogenation through a fixed bed or kettle type hydrogenation reactor to obtain hydrogenated base oil;

(3) and (3) rectification: and performing molecular rectification on the hydrogenated base oil through negative pressure to obtain the base oil with high viscosity grade.

In another preferred embodiment, the halogen is preferably fluorine, chlorine and bromine.

In another preferred embodiment, the complex can be used after the ligand compound I is coordinated with the divalent metal salt and purified, or can be used after the ligand compound I is mixed with the divalent metal salt in situ and is not purified.

In another preferred embodiment, the substituted phenyl group has 1 to 3 substituents.

In another preferred example, in the step (2), the solvent used in the fixed bed hydrogenation reaction is an alkane or an alkane mixture.

In another preferred example, in the step (2), the solvent used in the fixed bed hydrogenation reaction is hexane; more preferably n-hexane, isomeric hexanes, cyclohexane or mixtures of hexanes.

In another preferred embodiment, the tubular reactor is a loop.

In another preferred embodiment, the kettle type reactor is a reaction kettle.

In another preferred embodiment, in the step (1), the alkyl aluminum a is selected from the group consisting of: triethylaluminium, diethylaluminium chloride, ethylaluminium dichloride and ethylaluminium sesquichloride

In another preferred example, in the step (1), the aluminum alkyl a is triethylaluminum.

In another preferred example, in the step (1), the alkylaluminum a is diethylaluminum chloride, ethylaluminum dichloride or ethylaluminum sesquichloride.

In another preferred example, in the step (1), when ethylene is used as a single raw material, the polymerization temperature is 40 to 60 ℃, and the polymerization pressure is 1.5 to 2.0 MPa; when propylene is used as a single raw material, the polymerization temperature is 10-30 ℃, and the polymerization pressure is 0.7-1.2 MPa.

In another preferred embodiment, the method further comprises the steps of recovering and purifying the solvent.

In another preferred example, in the step (2), the hydrogenation reaction is completed by a fixed bed hydrogenation process, wherein the fixed bed hydrogenation reaction conditions are as follows:

hydrogenation temperature: 220-300 ℃;

hydrogenation pressure: 2.0-4.0 MPa;

space velocity: 1.5 to 2.5 hours^-1；

Hydrogen-oil ratio: 200 to 300.

In another preferred embodiment, the fixed bed hydrogenation reaction conditions are as follows:

hydrogenation temperature: 220-250 ℃;

hydrogenation pressure: 3-4 MPa;

space velocity: 1.8 to 2.2 hours^-1；

Hydrogen-oil ratio: 200 to 300.

In another preferred example, in the step (2), the hydrogenation reaction is completed by a kettle type hydrogenation process, wherein the kettle type processing process is as follows:

hydrogenation temperature: 100-200 ℃;

hydrogenation pressure: 2.0-6.0 MPa;

concentration of oil: 0.2 to 1.0 Kg/L.

In another preferred example, the kettle type processing technology is as follows:

hydrogenation temperature: 100-200 ℃;

hydrogenation pressure: 2.0-6.0 MPa;

concentration of oil: 0.8-0.9 Kg/L.

In another preferred example, in the step (3), the process parameters of the negative pressure rectification are as follows: rectification temperature: 300 to 350 ℃; rectification absolute pressure: 1 to 700 Pa.

In another preferred example, in the step (3), the negative pressure distillation may be performed by using a molecular distillation device, a short path distillation device or any other device capable of achieving base oil distillation.

In another preferred embodiment, the order of the hydrogenation step and the rectification step can be interchanged.

In another preferred embodiment, the step (1) further comprises a post-treatment step after the polymerization reaction is completed: adding a quenching agent into the mixture after the polymerization reaction is finished, and filtering, recovering the solvent and decoloring to obtain clear and transparent base oil before hydrogenation; wherein the quencher is selected from the group consisting of: diatomaceous earth, alcohol, silica gel powder, water, or combinations thereof.

In another preferred embodiment, the quenching agent is an alcohol.

In another preferred embodiment, the molar ratio of the quenching agent (e.g., alcohol) to the aluminum alkyl is 2: 1-4: 1.

in another preferred embodiment, the quenching agent is methanol, ethanol, isopropanol, tert-butanol, n-butanol, isobutanol, or a combination thereof.

In another preferred embodiment, the quenching agent is water.

In another preferred embodiment, the quenching agent is wet diatomite.

In another preferred example, the filtering equipment is various filtering equipment commonly used in the market.

In another preferred example, the aperture of the filter screen used for filtering is 1-5 microns.

In another preferred example, the liquid-liquid separation equipment used for solvent recovery can be simple atmospheric distillation or rectification equipment, and can also be vacuum distillation or rectification equipment.

In another preferred example, the equipment used for decoloring is a fixed bed decoloring column.

In another preferred example, the filler of the fixed bed can be activated clay, diatomite, silica, activated carbon.

In another preferred example, the filler of the fixed bed is activated clay.

In another preferred embodiment, the temperature for decoloring is 20-50 ℃.

In another preferred example, the kinematic viscosity of the high-viscosity grade base oil at 100 ℃ is 100-300 mm²/s。

In another preferred embodiment, the high viscosity base oil has a molecular weight distribution of less than 2.0, more preferably less than 1.8.

In another preferred example, the kinematic viscosity of the high-viscosity grade base oil at 100 ℃ is 100-300 mm²Acid number less than 0.01mg KOH/g, wherein NOACK evaporation loss is less than 1%, pour point is less than-20 ℃, and viscosity index is greater than 170.

The invention provides high-viscosity base oil, and the kinematic viscosity of the high-viscosity base oil is 100-300 mm at 100 DEG C²/s。

In another preferred example, the kinematic viscosity of the high-viscosity grade base oil at 100 ℃ is 100-300 mm²Acid number less than 0.01mg KOH/g, wherein NOACK is evaporatedThe loss is less than 1 percent, the pour point is less than-20 ℃, and the viscosity index is higher than 170.

In another preferred embodiment, the base oil is prepared by the process of the first aspect.

In a third aspect of the present invention, there is provided a method for producing a mechanical lubricating oil, characterized in that a base oil is produced by the method according to the first aspect of the present invention; and

mechanical lubricating oil is prepared by using the base oil.

It is to be understood that within the scope of the present invention, the above-described features of the present invention and those specifically described below (e.g., in the examples) may be combined with each other to form new or preferred embodiments. Not to be reiterated herein, but to the extent of space.

Drawings

FIG. 1 shows a process flow diagram for the direct polymerization of ethylene to make base oils.

FIG. 2 shows the molecular weight and the molecular weight distribution (GPC) diagram of the high viscosity base oil LPE100 after molecular rectification in example 1.

FIG. 3 shows the molecular weight and molecular weight distribution (GPC) of the high viscosity base oil LPE120 after molecular rectification in example 2.

Detailed Description

The present inventors have extensively and intensively studied and found that a base oil having a high viscosity grade can be obtained by controlling the polymerization process including the formation pattern of the catalytic species, the temperature and pressure of the polymerization reaction, and after further hydrogenation, by a simple rectification process. The method can directly prepare the base oil with high performance and high viscosity from the low-carbon olefin without adopting a very complicated or high-cost separation process or a blending process (certainly, the method can be further blended with other base oil with high performance). On this basis, the inventors have completed the present invention.

Term(s) for

As used herein, the term "C₆～C₁₂The alkane of "means a straight or branched alkane having 6 to 12 carbon atoms, and includes, for example,but are not limited to: hexane, heptane, octane, and the like.

As used herein, the term "C₁～C₁₂By haloalkane "is meant a straight or branched chain haloalkane having 1 to 12 carbon atoms, for example, including, but not limited to: methylene chloride, 1, 2-dichloroethane, 1,2, 2-tetrachloroethane, and the like;

as used herein, the term "C₁-C₄Alkyl "means a straight or branched chain alkyl group having 1 to 4 carbon atoms, and includes, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl.

As used herein, the term "C₁-C₈Alkyl "refers to straight or branched chain alkyl groups having 1 to 8 carbon atoms, including, for example, but not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl. T-butyl, pentyl, hexyl and the like.

As used herein, the term "C₅-C₈Cycloalkyl "refers to cycloalkyl groups having 5 to 8 carbon atoms, including, for example, but not limited to: cyclopentyl, cyclohexyl, cycloheptyl, and the like.

As used herein, the term "halogenated" or "halo" means substituted with a halogen (e.g., fluorine, chlorine, bromine, iodine).

Low carbon olefin

The lower olefin used in the invention can be C₂-C₄Olefins, for example, ethylene, propylene, or combinations thereof.

Complexes and process for preparing same

The complexes used herein for the polymerization can be prepared by complexing the ligand compound I with a divalent metal salt in an inert solvent.

The ligand compound I has the structure:

in the formula,

or Y¹And Y²And the C-C bond to which they are attached together form an unsubstituted or substituted 5-12 membered ring; preferably, Y is¹And Y²Together with the C-C bond to which they are both attached, may form an unsubstituted or substituted C₆-C₈A membered ring;

is an unsubstituted or substituted 5-7 membered monocyclic ring, or a bicyclic or tricyclic group containing said 5-7 membered monocyclic ring, wherein the 5-7 membered monocyclic ring contains 1-3N, O or S atoms and contains at least one N;

Y³is one or more optional substituent groups on said 5-7 membered monocyclic ring or a bicyclic or tricyclic group containing said 5-7 membered monocyclic ring, each Y³Independently of each other is hydrogen, C₁-C₈Alkyl or C₁-C₈Haloalkyl, C₅-C₈Cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted benzyl;

z is selected from the group consisting of: c₁-C₈Alkyl radical, C₁-C₈Haloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl;

wherein "substituted" as recited in each of the above definitions means that the group has 1 to 5 substituents selected from the group consisting of: c₁-C₄Alkyl and C₁-C₄Haloalkyl, halogen, nitro, cyano, CF₃、-O-R₁、-N(R₂)₂、- Si(R₃)₃、-CH₂-O-R₈、-SR₉、-CH₂-S-R₁₀、-CH-(R₁₀)₂Or unsubstituted or substituted by 1 to 5Phenyl substituted with a substituent selected from the group consisting of: c₁-C₄Alkyl and C₁-C₄Haloalkyl, wherein R₁、R₂、R₃Each independently is C₁-C₄Alkyl or C₁-C₄A haloalkyl group; and R is₈、R₉And R₁₀Are respectively C₁-C₈Alkyl or phenyl.

The divalent metal salt may be a divalent nickel metal salt, for example, including but not limited to: NiCl₂、NiBr₂、 NiI₂、(DME)NiBr₂、(DME)NiCl₂、(DME)NiI₂And the like.

The inert solvent may be any solvent conventionally used without affecting the reaction, including alcohols, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, ethers, esters, nitriles, preferably halogenated hydrocarbon solvents, among which more preferable results are obtained among halogenated hydrocarbon and lipid solvents, preferred examples being dichloromethane, 1, 2-dichloroethane, ethyl acetate, tetrahydrofuran.

For example, the process or preparation of the present invention is applicable to complexes having the structure shown in formula (II):

^-OAc、^-OTf or benzyl; said C₁-C₄Alkyl is preferably methyl; the halogen is preferably bromine, chlorine or iodine.

When X is a hydrocarbyl group, for example methyl or benzyl, it is often obtained by reacting the corresponding chloride or bromide with a methyl or benzyl Grignard reagent under conventional reaction conditions similar to those of the reaction, and this catalysis can be achieved whether X is a halogen or a hydrocarbyl group or any other group capable of coordinating to nickel in the nickel complex (II), for example an oxygen-containing compound, which has the same active site in catalyzing the polymerization of ethylene and thus exhibits the same or similar properties, as long as the complex can form a Ni-C bond or a Ni-H bond under the action of an alkylaluminum.

The specific synthetic method of the complex can refer to CN 201410555078X.

The complex can be used for catalyzing low carbon (C) after being separated and purified after being coordinated by ligand compound I and metal precursor₂-C₄) The polymerization of olefin can also be carried out by directly using a complex solution obtained by mixing the ligand compound I and the metal precursor in situ to catalyze the low carbon (C)₂-C₄) The polymerization of olefins, both ways, with the rest of the polymerization process being the same, does not have a significant effect on the polymerization results and on the product properties.

Process for producing base oil (lubricating base oil)

The preparation method or the process of the base oil of the invention is to select one or a mixture of more of the complexes to be low-carbon (C)₂-C₄) One or more mixture of olefin (including ethylene and propylene) is used as raw material, and the synthetic base oil LPE with high viscosity and quality is obtained through the processes of polymerization, hydrogenation, rectification and the like.

The preparation method comprises the following steps:

(1) polymerization: at a set polymerization temperature, a first solvent and an aluminum alkyl a are sequentially added into a tubular reactor or a kettle reactor, and low carbon (for example, C) is continuously introduced at a set polymerization pressure₂-C₄) Olefins (e.g., qualified purified olefins) (e.g., ethylene, propylene, or mixtures thereof) are then polymerized by adding the catalyst solution to the reactor in multiple batches to form the pre-hydrogenated base oil.

The catalyst solution may be added in two, three or more batches.

The catalyst solution is added in portions at fixed or unfixed time intervals throughout the polymerization reaction until the reaction is complete.

In the polymerization process, the polymerization temperature can be controlled to be between 10 and 60 ℃, the polymerization pressure is controlled to be between 0.7 and 2.0MPa, the reaction is stopped after the polymerization reaction is carried out for 1 to 24 hours, and the materials are put into the next process.

In the polymerization step, the alkyl aluminum a is selected from the group consisting of: triethylaluminum, trimethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, or a combination thereof; more preferred are triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride and ethylaluminum sesquichloride.

In the polymerization step, the first solvent is an alkane (e.g., C) commonly used for polymerization₆～C₁₂Alkane of (ii), toluene, xylene or a halogenated alkane; preferably, the alkanes are hexane and white oil; the halogenated alkane may preferably be dichloromethane, 1, 2-dichloroethane or 1,1,2, 2-tetrachloroethane.

In the polymerization step, the catalyst solution is a solution of a complex and an alkylaluminum b in a second solvent; wherein, the molar ratio of the alkyl aluminum b to the complex is as follows: 1 to 100/1; the alkyl aluminum b is selected from the following group: triethylaluminum, triisobutylaluminum, diethylaluminum chloride, or a combination thereof; the second solvent is selected from the group consisting of: toluene, halogenated C₆～C₁₂Of (a) an alkane.

In the polymerization process, the structure of the reactor has certain influence on the polymerization efficiency, but the property of a polymerization product is not influenced, namely the structure of a kettle body can influence the yield, and qualified base oil can be obtained. The processes provided herein are applicable to tank reactors and tubular reactors (e.g., loops). The tank reactor can be used independently, or a plurality of tank reactors can be used in series, according to the specific yield requirement.

(2) Hydrogenation: and (3) carrying out hydrogenation reaction on the base oil before hydrogenation obtained in the polymerization process through a fixed bed or a kettle type hydrogenation reactor to obtain the hydrogenated base oil.

Wherein, the fixed bed hydrogenation process can be as follows:

hydrogenation temperature: 220-300 ℃;

hydrogenation pressure: 2.0-4.0 MPa;

space velocity: 1.5 to 2.5 hours^-1；

Hydrogen-oil ratio: 200 to 300.

Wherein, the kettle type processing technology can be as follows:

hydrogenation temperature: 100-200 ℃;

hydrogenation pressure: 2.0-6.0 MPa;

concentration of oil: 0.2 to 1.0 Kg/L.

In the hydrogenation step, the catalyst used for hydrogenation is a commonly used hydrogenation catalyst, preferably a supported hydrogenation catalyst used in petrochemical industry, such as DC series products, RIW series, supported raney nickel catalysts, aluminum nickel alloy hydrogenation catalysts, palladium carbon catalysts, and the like, but is not limited to the exemplified hydrogenation catalysts.

In the hydrogenation step, the solvent used in the hydrogenation reaction is a common solvent for hydrogenation, and includes alkanes and alkane mixtures, such as white oil, petroleum ether, hexane and the like; preferably hexane; the hexane may comprise n-hexane, isomeric hexanes, cyclohexane or mixtures of hexanes.

(3) And (3) rectification: adding argil into the reaction mixture obtained in the previous step, filtering, and performing molecular rectification on the filtrate through negative pressure to obtain the high-viscosity grade base oil.

The negative pressure distillation can use a conventional distillation tower, and can also use molecular distillation equipment or any device available on the market and capable of realizing liquid fractionation.

The preferred process parameters when using a molecular distillation apparatus are as follows: rectification temperature: 300-350 ℃; rectification absolute pressure: 1-700 Pa;

in order to ensure the long-term stable operation of the process, after the working procedure (1) is finished, the quenching reaction can be selected firstly and then the working procedure (2) is carried out, the quenching mode can be selected according to the plant environment, the requirements and the like, the method comprises the steps of directly adding a small amount of quenching agent into the materials finished in the working procedure (1), or transferring the liquid generated in the working procedure (1) into another kettle to be contacted with the quenching agent, conventional silica gel, diatomite, clay, water, steam and the like can be used as the quenching agent, the quenching agent can be used singly or in a plurality of mixtures, the dosage of the quenching agent can be adjusted according to the requirement, the quenching catalyst can be used for terminating the polymerization, more quenching effects are not influenced when more quenching agents are added, but the burden of the subsequent working procedures is possibly increased;

in addition, in order to ensure the quality, the color and the stability of the process of the oil and save the cost, auxiliary processes, such as a solvent recovery process, product decoloration, filtration and the like, can be added. All of these auxiliary processes may be used, or one or more of them may be used as necessary; the auxiliary process can be used in different process links according to requirements;

the hydrogenation of the oil product in the step (2) can be carried out before the step (3) or after the oil product is fractionated and cut according to working conditions and product requirements, so that the product quality including properties such as viscosity and viscosity index is not influenced, but the product cost is possibly influenced.

The process flow diagram for the direct polymerization of ethylene to produce base oil is now described with reference to FIG. 1 as follows:

(i) polymerization: sequentially adding a first solvent and alkyl aluminum a into a tubular reactor or a kettle-type reactor at a set polymerization temperature, continuously introducing refined qualified ethylene under a set polymerization pressure, adding a catalyst solution into the reactors in multiple batches, and carrying out polymerization reaction to form base oil before hydrogenation;

controlling the polymerization temperature at 10-60 ℃, the polymerization pressure at 0.7-2.0 MPa, and the polymerization time at 1-24 hours, stopping the reaction, and placing the materials in the next process.

The first solvent may be selected from the group consisting of: c₆～C₁₂An alkane of (a); toluene, xylene; halogen substituted C₁～C₁₂An alkane of (a); preferably selected from the group consisting of: hexane, dichloromethane, 1, 2-dichloroethane, 1,2, 2-tetrachloroethane.

The amount of the first solvent is determined depending on the reaction vessel and the reaction yield, and it is generally preferable to achieve a final product concentration of not higher than 70% (v/v).

The alkyl aluminum a is selected from the following group: triethylaluminum, trimethylaluminum, diethylaluminum chloride, ethylaluminum dichloride and ethylaluminum sesquichloride; triethylaluminium is preferred.

The catalyst solution is a solution formed by the complex and alkyl aluminum b in a second solvent; the pre-reaction of the complex and the alkyl aluminum b at room temperature before adding into a reaction system is an important step for controlling the concentration of a catalytic species, the stability of a polymerization reaction and the quality of a product, in the step, the selection of the alkyl aluminum b and a second solvent is important, the complex is ensured to generate a real active species, and simultaneously the stability of the active species under the condition of no olefin existence is ensured, the alkyl aluminum b in the catalyst solution and the alkyl aluminum a added into a polymerization reaction kettle can be the same or different, and are triethyl aluminum, triisobutyl aluminum, diethyl aluminum chloride or a mixture of two or more of the triethyl aluminum, the triisobutyl aluminum and the diethyl aluminum chloride; the molar ratio of the alkyl aluminum b to the complex is 1-100/1; the second solvent is selected from toluene or halogenated C₆～ C₁₂An alkane of (a); the concentration of the catalyst solution is preferably 0.01-0.5M.

The molar ratio of the total aluminum amount in the final polymerization reaction system to the complex is preferably 100-800/1.

The reaction temperature is preferably 40-60 ℃.

The reaction pressure is preferably 0.7-1.0 MPa.

The reaction time is preferably 6 to 10 hours.

(ii) And (3) post-treatment: adding a quenching agent into the mixture after the reaction in the step is finished, and then filtering, recovering the solvent and decoloring to obtain clear and transparent base oil before hydrogenation.

The quenching agent is diatomite, alcohol, silica gel powder and water, preferably alcohol;

the molar ratio of the quenching agent (such as alcohol)/alkyl aluminum is 2-4.

(iii) Hydrogenation: and (3) carrying out hydrogenation reaction on the base oil before hydrogenation obtained in the step (a) through a fixed bed or a kettle type hydrogenation reactor to obtain hydrogenated base oil.

The fixed bed hydrogenation process may be as follows:

hydrogenation catalyst: the load type hydrogenation catalyst used in the petrochemical industry can achieve ideal hydrogenation effect, such as DC series products, RIW series, load type Raney nickel catalyst, aluminum nickel alloy hydrogenation catalyst, palladium carbon catalyst, and the like.

Hydrogenation temperature: 220-300 ℃;

hydrogenation pressure: 2.0-4.0 MPa;

space velocity: 1.5 to 2.5 hours^-1；

Hydrogen-oil ratio: 200 to 300.

The kettle type processing technology can be as follows:

Hydrogenation temperature: 100-200 ℃;

hydrogenation pressure: 2.0-6.0 MPa;

concentration of oil: 0.2 to 1.0 Kg/L.

Solvent: hexane (C)

(iv) Negative pressure rectification: and (5) performing molecular rectification on the hydrogenated base oil obtained in the step (iii) through negative pressure rectification equipment to obtain the base oil with high viscosity grade.

The process parameters of the molecular distillation can be as follows: 300-350 ℃; rectification absolute pressure: 1 to 700 Pa.

Base oil (lubricating base oil)

The invention can prepare the product with the kinematic viscosity of 100-300 mm at 100 ℃ by the method or the process²A high viscosity base oil per second (ASTM D445-15 a). Wherein the Viscosity Index (VI) of the high viscosity base oil is higher than 170, the NOACK evaporation loss is lower than 1%, and the pour point is lower than-20 ℃; the prepared base oil has sulfur and nitrogen content lower than 5ppm, metal content lower than 5ppm, other impurity content lower than 5ppm, acid value lower than 0.01mg KOH/g, water content lower than 50ppm, and ASTM color<0.5。

The main advantages of the invention include:

(1) using low carbon (C)₂-C₄) Olefins (including ethylene, propylene or mixtures thereof) are used as feedstocks to directly make fully synthetic base oils. Because the raw materials are all polymer-grade olefins, the prepared fully synthetic base oil is clean, the sulfur and nitrogen content is usually lower than 5ppm, the content of various metals is lower than 5ppm, the content of other impurities is lower than 5ppm, the acid value is lower than 0.01mg KOH/g, the viscosity index is more than 170, the pour point is lower than-20 ℃, the water content is lower than 50ppm, and the ASTM chromaticity is lower than 50ppm<0.5。

In addition, the process route adopts C₄The olefin in the raw material is sufficient in raw material source and low in cost; avoiding the oligomerization preparation and separation of ethylene C₈-C₁₂Especially when ethylene is used as a feedstock, the efficiency of ethylene conversion to oil is high: (>80%) and the ethylene conversion rate can exceed 95% under the condition of process optimization, thus greatly reducing the cost of the base oil.

(2) The process of the invention is easy to prepare high-viscosity synthetic oil through process adjustment.

(3) The invention has safe process and small corrosion to equipment in the production process. And traditional AlCl₃+ alcohol, BF₃The production mode of alcohol cation polymerization is different, the addition amount of the complex in the process is less (less than or equal to 0.01 percent), the activity is high, the cocatalyst is easy to remove, and the system does not contain chloride ions which are strong in corrosivity and difficult to remove.

(4) The invention has simple post-treatment process and less waste water and waste residue. The post-treatment process is simple, and the oil with low acid value and low impurity content can be obtained only by filtration and fixed bed adsorption without water washing or alkali washing or adding a large amount of clay for adsorption.

(5) Gel Permeation Chromatography (GPC) analysis shows that the base oil obtained in step (1) of the present invention is a high viscosity base oil with a narrow molecular weight distribution, typically below 1.8 (e.g., as shown in fig. 2 and 3), and that the presence or absence of hydrogenation does not change the GPC results of the oil. The high-viscosity base oil can be regulated and produced through the polymerization process and the control of specific parameters of negative pressure rectification separation, the base oil produced by the method can be directly used as the base oil of synthetic lubricating oil, and can be mixed with required additives according to required proportions (100-70/0-30) according to different purposes to be used as a final product; the high-viscosity base oil produced by the process can be mixed with other base oils with different viscosities according to specific proportions, and the mixture is mixed with required additives according to required proportions and used as a final product; or may be blended with one or more of group II, group III, group IV, and group V oils (according to the American Petroleum Institute (API) classification standard) in the desired proportions and used as the final product.

The invention is further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. Unless otherwise indicated, percentages and parts are by weight. The materials and equipment used in the examples of the present invention are commercially available unless otherwise specified.

In the examples, complex a or complex B will be illustrated by way of example, but it is to be understood that the practice of the process of the present application is not limited to these two complexes as catalysts:

example 1

Adding 10L of dichloromethane and 300mmol of triethyl aluminum into a 20L reaction kettle at 40-50 ℃, continuously introducing ethylene under the condition that the polymerization pressure in the reaction kettle is controlled to be 1.0-1.2 MPa, and adding 100mL (Et) of catalyst solution in batches₃Al/Complex A: 30/l (molar ratio), solvent: hexane, concentration 0.01M) was added to the reaction vessel to start polymerization; the reaction was stopped after 6 hours of polymerization time and 3.3Kg of ethylene was consumed. Adding 600mmol of ethanol into the obtained reaction solution, filtering, decolorizing, and removing solvent under negative pressure to obtain 3.0Kg of clear and transparent base oil before hydrogenation with yield of 91%, and ethyleneThe conversion was 98.5%.

And (2) hydrogenating the obtained base oil before hydrogenation through a fixed bed, wherein the hydrogenation catalyst comprises the following components in percentage by weight: a supported catalyst RIW-2; hydrogenation temperature: 220 ℃; hydrogenation pressure: 4.0 MPa; space velocity: 2.0h^-1(ii) a Hydrogen-oil ratio: 300, obtaining hydrogenated base oil; and then performing molecular rectification on the hydrogenated base oil under negative pressure, wherein the absolute pressure of the system is 50Pa, the heating temperature is 300 ℃, and the clear and transparent base oil LPE100 with high viscosity grade is obtained, and the molecular weight distribution are shown in figure 2. The basic physical and chemical properties of the high viscosity grade base oil LPE100 obtained are as follows:

example 2

Adding 10L of dichloromethane and 300mmol of triethyl aluminum into a 20L reaction kettle at 50-60 ℃, introducing 300g of propylene and ethylene under the condition that the polymerization pressure in the reaction kettle is controlled to be 0.8-1.0 MPa, and adding 100mL ((iBu) of catalyst solution₃Al/Et₃Al) (1/1)/complex B: 40/l (molar ratio), solvent: hexane, 0.01M) was added to the reaction vessel to start polymerization, and the reaction was stopped after 10 hours of polymerization time, and 3.2Kg of ethylene was consumed. 600mmol of ethanol is added into the obtained reaction solution, and the solution is decolorized and removed to obtain 3.2Kg of clear and transparent base oil before hydrogenation, the yield is 91.5 percent, and the conversion rate is 99 percent.

And (2) hydrogenating the obtained base oil before hydrogenation through a fixed bed, wherein the hydrogenation catalyst comprises the following components in percentage by weight: a supported catalyst RIW-2; hydrogenation temperature: 220 ℃; hydrogenation pressure: 4.0 MPa; space velocity: 2.0h^-1(ii) a Hydrogen-oil ratio: 300, obtaining hydrogenated base oil; subjecting the hydrogenated base oil to molecular rectification under negative pressure at absolute pressure of 50Pa and heating temperature of 300 deg.C to obtain clear and transparent high viscosity grade base oil LPE120 with molecular weight and molecular weight distribution shown in FIG. 3. The basic physical and chemical properties of the high viscosity grade base oil LPE120 obtained are as follows:

example 3

Adding 10L of 1,1,2, 2-tetrachloroethane and 300mmol of diethyl aluminum chloride into a 20L reaction kettle at the temperature of 20-30 ℃, introducing propylene under the condition that the polymerization pressure in the reaction kettle is controlled to be 0.7-0.8 MPa, and adding 100mL (Et) of catalyst solution in batches₃Al/Complex A: 50/l (molar ratio), solvent: hexane, concentration 0.01M) was added to the reaction vessel to start polymerization; the reaction was stopped after 4 hours of polymerization time and 3.2Kg of propylene were consumed. 600mmol of ethanol is added into the obtained reaction solution, and then the solution is filtered, chromatographically decolorized and solvent is removed to obtain 2.9Kg of clear and transparent base oil before hydrogenation, the yield is 91.2 percent and the conversion rate of propylene is 98.6 percent.

And (2) hydrogenating the obtained base oil before hydrogenation through a fixed bed, wherein the hydrogenation catalyst comprises the following components in percentage by weight: a supported catalyst RIW-2; hydrogenation temperature: 220 ℃; hydrogenation pressure: 4.0 MPa; space velocity: 2.0h^-1(ii) a Hydrogen-oil ratio: 300, obtaining hydrogenated base oil; and performing molecular rectification on the hydrogenated base oil under negative pressure, wherein the absolute pressure of the system is 50Pa, and the heating temperature is 300 ℃, so as to obtain the clarified and transparent high-viscosity-grade base oil LPE 140.

The basic physical and chemical properties of the obtained high viscosity grade base oil LPE140 are as follows:

example 4

The other conditions are the same as example 1, the temperature is changed to 50-60 ℃, and 3.1Kg of high viscosity grade base oil LPE160 is obtained. The basic physical and chemical properties of the high viscosity grade base oil LPE160 obtained are as follows:

example 5

Otherwise as in example 1, the solvent was changed to heptane to yield 2.92Kg of a high viscosity grade base oil LPE 220. The basic physical and chemical properties of the obtained high viscosity grade base oil LPE220 are as follows:

example 6

The other conditions are the same as example 1, and the pressure is changed to 1.6-1.7 MPa, so that 2.9Kg of high-viscosity grade base oil LPE240 is obtained. The basic physicochemical properties of the high viscosity grade base oil LPE240 obtained are as follows:

all documents referred to herein are incorporated by reference into this application as if each were individually incorporated by reference. Furthermore, it should be understood that various changes and modifications of the present invention can be made by those skilled in the art after reading the above teachings of the present invention, and these equivalents also fall within the scope of the present invention as defined by the appended claims.

Claims

1. A process for directly preparing base oil by polymerizing low-carbon olefins is characterized by comprising the following steps:

the polymerization temperature is 10-60 ℃;

the polymerization pressure is 0.7-2.0 MPa;

the polymerization reaction time is 1-24 hours;

the first solvent is selected from the group consisting of: c₆～C₁₂Alkane, white oil, toluene, xylene, halogenated C₁～C₁₂An alkane of (a);

the complex is prepared by coordinating a ligand compound I and a divalent metal salt; wherein,

in the formula,

Y²are respectively CR₄R₅、NR₆O or S, R₄、R₅、R₆Each independently is H, C₁-C₄Alkyl or C₁-C₄A haloalkyl group;

Y³is one or more optional substituent groups on said 5-7 membered monocyclic ring, or a bicyclic or tricyclic group containing said 5-7 membered monocyclic ring, each Y³Independently of each other is hydrogen, C₁-C₈Alkyl radical, C₁-C₈Haloalkyl, C₅-C₈Cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted benzyl;

wherein "substituted" as recited in each of the above definitions means that the group has 1 to 5 substituents selected from the group consisting of: c₁-C₄Alkyl and C₁-C₄Haloalkyl, halogen, nitro, cyano, CF₃、-O-R₁、-N(R₂)₂、-Si(R₃)₃、-CH₂-O-R₈、-SR₉、-CH₂-S-R₁₀、-CH-(R₁₀)₂Or phenyl which is unsubstituted or substituted with 1 to 5 substituents selected from the group consisting of: c₁-C₄Alkyl and C₁-C₄Haloalkyl, wherein R₁、R₂、R₃Each independently is C1-C4 alkyl or C₁-C₄A haloalkyl group; and R is₈、R₉And R₁₀Are respectively C₁-C₈Alkyl or phenyl;

the divalent metal salt is a divalent nickel metal salt;

-OAc, -OTf or benzyl;

2. The process of claim 1, wherein in step (1), the aluminum alkyl a is selected from the group consisting of: triethylaluminium, diethylaluminium chloride, ethylaluminium dichloride and ethylaluminium sesquichloride.

3. The process according to claim 1, wherein in the step (1), when ethylene is used as a single raw material, the polymerization temperature is 40 to 60 ℃, and the polymerization pressure is 1.0 to 1.5 MPa; when propylene is used as a single raw material, the polymerization temperature is 10-30 ℃, and the polymerization pressure is 0.7-1.2 MPa.

4. The process of claim 1, further comprising solvent recovery and purification steps.

5. The process of claim 1, wherein in step (2), the hydrogenation reaction is carried out by a fixed bed hydrogenation process, wherein the fixed bed hydrogenation reaction conditions are as follows:

hydrogenation temperature: 220-300 ℃;

hydrogenation pressure: 2.0-4.0 MPa;

space velocity: 1.5 to 2.5 hours^-1；

Hydrogen-oil ratio: 200 to 300.

6. The process of claim 1, wherein in step (2), the hydrogenation reaction is carried out by a kettle hydrogenation process, wherein the kettle hydrogenation process comprises the following steps:

hydrogenation temperature: 100-200 ℃;

hydrogenation pressure: 2.0-6.0 MPa;

concentration of oil: 0.2 to 1.0 Kg/L.

7. The process method as claimed in claim 1, wherein in the step (3), the process parameters of the negative pressure distillation are as follows: rectification temperature: 300-350 ℃; rectification absolute pressure: 1 to 700 Pa.

8. The process of claim 1 wherein the hydrogenation and rectification steps are reversed in order.

9. The process of claim 1, wherein step (1) further comprises a post-treatment step after the polymerization reaction is completed: adding a quenching agent into the mixture after the polymerization reaction is finished, and filtering, recovering the solvent and decoloring to obtain clear and transparent base oil before hydrogenation; wherein the quencher is selected from the group consisting of: diatomaceous earth, alcohol, silica gel powder, water, or combinations thereof.

10. The process of claim 1, wherein the high viscosity grade base oil has a molecular weight distribution of less than 2.0, more preferably less than 1.8.

11. The process of claim 1, wherein the high viscosity grade base oil has a kinematic viscosity of 100 to 300mm at 100 ℃²Acid number less than 0.01mg KOH/g, wherein NOACK evaporation loss is less than 1%, pour point is less than-20 ℃, and viscosity index is greater than 170.

12. The process according to the preceding claim, wherein the high viscosity grade base oil produced is used in mechanical lubricating oils.