Nickel catalyst, preparation method thereof and method for catalytically synthesizing crude oil drag reducer polyolefin

Abstract

The invention belongs to the technical field of petrochemical engineering, and provides a nickel catalyst, a preparation method thereof and a method for catalytically synthesizing a crude oil drag reducer polyolefin, the structural formula of the nickel catalyst is shown in the specification, a chiral environment is constructed in a ligand of an alpha-diimine Ni (II) catalyst based on an acenaphthequinone structure, a chiral alpha-diimine / Ni (II) catalytic system is formed, and the chiral alpha-diimine / Ni (II) catalytic system is used for catalyzing the crude oil drag reducer polyolefin. The chiral configuration in the catalyst can control the spatial configuration of carbon atoms in the carbon chain unit of the long-chain polymer, so that the catalyst provided by the invention can be used for catalytically synthesizing the crude oil drag reducer poly-alpha-olefin with an isotactic configuration.

Description

TECHNICAL FIELD

[0001] The present application relates to a nickel catalyst, a preparation method thereof and a method for catalytically synthesizing a crude oil drag reducing agent polyolefin, and belongs to the technical field of petroleum chemical industry. BACKGROUND

[0002] The transportation of fluid is an important link in industrial production. Compared with the material transportation modes such as railway, waterway, highway and air transportation, the pipeline transportation has the advantages of safety, airtightness, short construction period, low construction cost, safe and reliable transportation, low energy consumption, low cost, good benefit, small restriction by geographical and climatic conditions, etc., and thus becomes the main transportation mode for crude oil production. As of the end of 2016, more than 95% of the crude oil and refined oil in the world was transported by pipeline.

[0003] In the process of oil exploration and development, it is very difficult to accurately predict the reserves of oil. The oil field also has the production law of development period, peak production period and decline period. After the oil pipeline is built, the working condition of the oil pipeline is fluctuant. The time when the oil pipeline actually operates under the design condition is limited. In addition, the oil pipeline still needs to ensure the delivery capacity after aging and reduction of pressure resistance. When the oil pipeline is maintained and repaired, the oil pipeline has an accident, and the like, the oil pipeline requires certain adjustment capacity for the delivery capacity.

[0004] The uncontrolled vortex formed by the chaotic and disordered flow direction of fluid in the pipeline flow process makes the liquid delivery pump lose in all directions along with the vortex, and increases the delivery resistance. How to increase the flow rate of fluid without increasing the energy consumption of the pump or reduce the energy consumption of the pump to reduce the energy consumption cost while maintaining the flow rate is also concerned by the operators of the oil pipeline.

[0005] The drag reducing agent is an additive that can increase the deliverability of fluid. The drag reducing agent added to the oil pipeline can adjust the delivery capacity of the oil pipeline and reduce the energy of the delivery pump. The drag reducing agent can be divided into two categories of water-soluble and oil-soluble. The main agent of the oil-soluble drag reducing agent is usually poly-long-chain α-olefin with a number average molecular weight of more than one million. In industry, the synthesis of this kind of compound usually adopts the Ziegler-Natta catalyst system, and the reaction equation is shown as formula (1):

[0006]

[0007] For example, in 1992, Yang Shilin et al. of Zhejiang University used the complex II type TiCl3 catalyst produced by Beijing Chemical Research Institute and the AlEt2Cl catalyst system, adopted the prepolymerization process, that is, the catalyst was pre-complexed in the presence of a small amount of monomer, and then the polymerization (post-polymerization) was continued in the presence of a large amount of monomer, to treat the C9-C 14The mixed α-olefins with different carbon numbers as raw materials, under lower catalyst concentration and prepolymerization temperature, can obtain oil-soluble drag reducer with higher molecular weight and higher drag reduction rate. The chain segment composition of the polymer is close to the raw material composition, which is a random flexible comb-like structure polymer. The drag reduction test shows that when 10 ppm of the polymer is added in Daqing crude oil, the drag reduction rate can reach more than 10%, which meets the requirements of drag reduction and increased transmission in industrial crude oil pipeline transportation.

[0008] Guangzhong Yuan et al. reported in Chinese patent document CN1530377A that α-olefins with 2-20 carbons were used to produce a pipeline oil poly-α-olefin drag reducer in a Ziegler-Natta catalytic system. Specifically, the α-olefins were added to a sealed reaction vessel, and a catalyst was added under air isolation and stirring. Within 20 hours of the start of the reaction, a reaction base liquid that was oil-soluble but not soluble in the α-olefin polymer was slowly added while stirring, and the reaction was carried out at a temperature of -50 to 20°C under normal or low pressure for 3 to 10 days. This method has the advantages of simple production device and process, easy control, high molecular weight of the polymer, low viscosity of the reaction mixture, good drag reduction effect, good static stability, and no need for stirring for direct use in oil transportation.

[0009] Konoco Philips Corporation abroad has applied for a mixed drag reducer with high polymer content (CN101848966B), which discloses a drag reduction composition comprising particles of at least two different drag reducing polymers. The different drag reducing polymers can be formed by different methods such as bulk polymerization or emulsion polymerization, and the particles of the different drag reducing polymers can have different average particle sizes. The drag reduction composition can be added to a hydrocarbon-containing fluid to reduce the pressure drop associated with turbulent flow of the hydrocarbon-containing fluid through a conduit.

[0010] The poly-α-olefin obtained by the polymerization of α-olefins (CH=CHR) catalyzed by transition metal complexes has chiral carbon atoms in the carbon chain structure unit. The chiral carbon atom is connected with H atom, substituent group R and two polymer chain segments, and each chiral center is a stereogenic point. When the main chain connected by carbon-carbon single bond is in the same plane, if the substituents are on the same side of the plane, it is isotactic polymer (also known as isotactic polymer). If the substituents are alternately arranged on both sides of the plane, it is syndiotactic polymer (also known as syndiotactic polymer). If the substituents are randomly arranged on both sides of the plane, it is atactic polymer (also known as atactic polymer). In addition, it is also possible to form heterotactic polymer, hemi-isotactic polymer and stereoblock polymer (as shown in the following structural formula).

[0011]

[0012] Poly-α-olefin structure

[0013] In 1954, Natta discovered that the heterogeneous organometallic catalyst could be used to synthesize crystalline "isotactic" polypropylene, but the synthesis of poly-alpha-olefin drag reducing agent main agent by using higher carbon number alpha-olefin in the Ziegler-Natta catalyst system was less concerned about the configuration of carbon chain unit in poly-alpha-olefin. The crystallization performance of "isotactic" poly-alpha-olefin is better than that of random structure poly-alpha-olefin, and the glass transition temperature is high. In the subsequent refrigeration and crushing production process of drag reducing agent, the cooling temperature is high, which can reduce the process difficulty and save the refrigeration cost. Due to the fluctuation of reaction conditions during the polymerization of alpha-olefin, the structure and composition of poly-alpha-olefin obtained from different batches may change, thereby affecting the stability of the drag reducing performance. The isotactic poly-alpha-olefin structure is regular, which can avoid various permutations and combinations of each chiral carbon atom in a single carbon chain of random structure poly-alpha-olefin, facilitate the analysis and control of poly-alpha-olefin structure, and is beneficial to the stability of product performance.

[0014] In the 1990s, Brookhart successfully realized the goal of promoting chain growth by using bulky alpha-diimine ligands to coordinate to Ni(II) and Pd(II) centers, becoming the first post-transition metal catalyst system capable of producing high relative molecular mass poly-alpha-olefin. Killian reported an alpha-diimine Ni(II) catalyst based on acenaphthenequinone structure in 1996, and the complex can catalyze the active polymerization of alpha-olefin to obtain diblock and triblock polymers. The above two types of catalyst systems solve the problem of alpha-diimine ligand / transition metal catalyzed olefin polymerization, but cannot control the configuration of carbon atoms in the carbon chain structural unit.

[0015]

[0016] Nickel catalyst containing acenaphthenequinone structure ligand SUMMARY

[0017] In order to solve the above problems of the prior art, the present application provides a nickel catalyst, a preparation method thereof and a method for catalytically synthesizing crude oil drag reducing agent polyolefin, which can catalyze the synthesis of high molecular weight poly-alpha-olefin with "isotactic" configuration for crude oil transportation.

[0018] The present application is realized by the following technical solutions:

[0019] The present application provides a nickel catalyst, and the structural formula is shown as formula 4:

[0020]

[0021] In the formula, R1 is hydrogen, aryl, alkyl, ester group, ether group or halogen group.

[0022] Preferably, the alkyl group is methyl, the ether group is methoxy, and the halogen group is bromine.

[0023] The present application provides a preparation method of the nickel catalyst, comprising:

[0024] S1, acenaphthenequinone shown in formula 1 is dehydrated and condensed with a spirochiral aromatic amine shown in formula 2 to generate a chiral α-diimine ligand shown in formula 3;

[0025] S2, the chiral α-diimine ligand is reacted with dibromo(1,2-dimethoxyethane) nickel to generate a nickel catalyst shown in formula 4;

[0026]

[0027] Preferably, S1 specifically comprises: mixing acenaphthenequinone and a spirochiral aromatic amine in a solvent, adding formic acid, stirring at room temperature for reaction, separating the solid after the reaction is completed, and obtaining the chiral α-diimine ligand through recrystallization and washing of the obtained solid.

[0028] Preferably, S2 specifically comprises: under the protection of an inert gas, the chiral α-diimine ligand and dibromo(1,2-dimethoxyethane) nickel are added into a solvent, stirring at room temperature under the protection of the inert gas for reaction, and obtaining the nickel catalyst through recrystallization and washing of the obtained solid after the reaction is completed.

[0029] The present application provides a catalyst paraffin capsule, comprising a paraffin shell and a paraffin core in the paraffin shell, and the paraffin core is distributed with the nickel catalyst as described above.

[0030] The present application provides a preparation method of the catalyst paraffin capsule, comprising:

[0031] Step 1, under an anaerobic condition, paraffin is melted, the nickel catalyst powder is added, and stirring is performed to obtain a catalyst paraffin suspension;

[0032] Step 2, the catalyst paraffin suspension is poured into a mold while hot, and cooling and solidification are performed to obtain a paraffin core;

[0033] Step 3, the paraffin core is immersed in melted paraffin for a preset time, taken out, and after the surface paraffin is solidified again, step 3 is repeated for several times to obtain the catalyst paraffin capsule.

[0034] The present application provides a method for catalytically synthesizing a crude oil drag reducing agent polyolefin, comprising:

[0035] α-olefin is added into a solvent, stirring and heating to a reaction temperature, a main catalyst and a cocatalyst are added, and reaction is performed, and after the reaction is completed, a precipitate is separated and washed to obtain poly-α-olefin; wherein the main catalyst is the nickel catalyst according to claim 1 or 2 or the catalyst paraffin capsule according to claim 6.

[0036] Preferably, the reaction temperature is 30-60℃, and the reaction time is 0.5-2h.

[0037] Preferably, the molar ratio of the nickel catalyst to the alpha-olefin is (0.05-0.15):200.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] The present application constructs a chiral environment in the ligand of the alpha-diamine Ni(II) catalyst based on acenaphthenequinone structure, forms a chiral alpha-diamine / Ni(II) catalytic system, and the chiral configuration of the catalyst can control the stereoscopic configuration of the carbon atoms in the carbon chain unit of the long-chain polymer molecular structure, so that the catalyst described in the present application can be used to catalytically synthesize high molecular weight poly-alpha-olefin for crude oil transportation with a "isotactic" configuration.

[0040] The present application uses the easily available acenaphthenequinone and the spirochetal amine to synthesize the chiral alpha-diamine ligand, and then performs complexing with the divalent bromide salt of the later transition metal nickel to prepare the chiral alpha-diamine / Ni(II) catalytic system for catalytically synthesizing "isotactic" poly-alpha-olefin, and the preparation method is simple, low in cost, and suitable for industrial production.

[0041] In order to make the nickel catalyst uniformly distributed in the reactor in the pilot test and industrial production, and avoid the influence of water and oxygen, the nickel catalyst is prepared into a catalyst paraffin capsule, that is, the nickel catalyst is encapsulated in paraffin, so that the influence of water and oxygen can be avoided, and when the catalyst paraffin capsule is added into the reactor, the paraffin melts and the nickel catalyst is released as the temperature rises, so that the uniformity of the nickel catalyst in the reactor is ensured, and the paraffin does not affect the reaction.

[0042] The nickel catalyst described in the present application is used to catalytically synthesize drag-reducing agent poly-alpha-olefin, and the chiral configuration of the nickel catalyst can control the stereoscopic configuration of the carbon atoms in the carbon chain unit of the long-chain polymer molecular structure, so that the catalytically synthesized poly-alpha-olefin has an "isotactic" configuration, high isotacticity, high molecular weight, and high drag reduction rate, and is a drag-reducing agent with excellent performance. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0044] Figure 1 The preparation flowchart of the chiral alpha-diamine / Ni(II) catalyst paraffin capsule for pilot test is shown in the figure. DETAILED DESCRIPTION

[0045] The present application is described in greater detail by the following specific examples, and other advantages and benefits of the present application will become apparent to those skilled in the art from this disclosure. The present application can be implemented or performed in other different ways, and the details in the present description can be modified in various ways without departing from the spirit of the present application.

[0046] It should be noted that the process equipment or devices not specifically mentioned in the following examples are all conventional equipment or devices in the art.

[0047] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or apparatus that includes a list of steps or units not necessarily limited to those clearly listed, but can include other steps or units not clearly listed or inherent to such processes, methods, products or apparatus. Moreover, unless otherwise specified, the numbering of the method steps is only a convenient tool for identifying the method steps, and is not intended to limit the arrangement order of the method steps or to limit the scope of the present application, and changes or adjustments of the relative relationship, without substantial changes in the technical content, are also considered to be within the scope of the present application.

[0048] The nickel catalyst described in the present application has a structural formula as shown in formula 4:

[0049]

[0050] wherein R1 is hydrogen, aryl, alkyl, ester, ether or halogen, the alkyl is preferably methyl, the ether is preferably methoxy, and the halogen is preferably bromine.

[0051] The present application constructs a chiral environment in the ligand of the nickel catalyst, and when the nickel catalyst is used to catalyze the synthesis of polyolefin, the chiral environment in the nickel catalyst can control the configuration of carbon atoms in the structural unit of the long-chain polymer carbon chain, and the preparation of the "isotactic" configuration of the drag-reducing agent poly-alpha-olefin for crude oil transportation is realized.

[0052] The preparation method of the nickel catalyst described in the present application comprises:

[0053] S1, acenaphthenequinone shown in formula 1 is subjected to dehydration condensation reaction with a spirochiral aromatic amine shown in formula 2 to generate a chiral α-diamine ligand shown in formula 3;

[0054] S2, the chiral α-diamine ligand is subjected to reaction with dibromo(1,2-dimethoxyethane)nickel ((DME)NiBr2) to generate the nickel catalyst shown in formula 4.

[0055] In some specific embodiments of the present application, the specific scheme adopted by S1 is as follows: mixing acenaphthenequinone and a spirochiral arylamine in a solvent, adding formic acid, stirring at room temperature, separating the solid after the reaction is completed, and washing and recrystallizing the obtained solid to obtain a chiral α-diimine ligand.

[0056] In some specific embodiments of the present application, the specific scheme adopted by S2 is as follows: under the protection of an inert gas, a chiral α-diimine ligand and (DME)NiBr2 are added into a solvent, and the reaction is stirred at room temperature under the protection of an inert gas; the solid is separated after the reaction is completed, and the obtained solid is washed, recrystallized and washed to obtain a nickel catalyst.

[0057] In the present application, the synthesis reaction formula of the nickel catalyst is as follows:

[0058]

[0059] The method for catalytically synthesizing a crude oil drag-reducing agent polyolefin by using the nickel catalyst prepared by the present application comprises the following steps:

[0060] The α-olefin is added into a solvent, stirred and heated to a reaction temperature, the nickel catalyst (as a main catalyst) and a cocatalyst are added, and the reaction is carried out; after the reaction is completed, the precipitate is separated and washed to obtain a poly-α-olefin.

[0061] In some specific embodiments of the present application, the cocatalyst is preferably methylaluminoxane (MAO).

[0062] In some specific embodiments of the present application, the reaction temperature is 30-60℃, and the reaction time is 0.5-2h.

[0063] In some specific embodiments of the present application, the solvent is n-hexane, toluene or cyclohexane.

[0064] In some specific embodiments of the present application, the ratio of the nickel catalyst to the cocatalyst is n MAO / n Ni = 500-1500; and the molar ratio of the nickel catalyst to the α-olefin is (0.05-0.15):200.

[0065] In a pilot test and industrial production, whether the catalyst can be uniformly distributed in a reactor has a great influence on the catalytic effect of the catalyst and the distribution of the reaction product, and the chiral α-diimine / Ni(II) catalyst prepared in the present application is sensitive to water and oxygen. In order to overcome the above problems, the catalyst is prepared into a catalyst paraffin capsule in the present application.

[0066] The catalyst paraffin capsule of the present application comprises a paraffin shell and a paraffin core located in the paraffin shell, and the nickel catalyst is distributed in the paraffin core.

[0067] The preparation method of the catalyst paraffin capsule is: under anaerobic conditions, melt the paraffin particles, add the chiral α-diimine / Ni(II) catalyst powder into the melted paraffin, stir until the catalyst powder is uniformly dispersed, pour the catalyst paraffin suspension into a mold while hot, cool to room temperature, take out the solidified paraffin core from the mold, immerse it in another prepared melted paraffin, quickly take it out, after the surface paraffin solidifies again, repeat the above steps several times, and obtain the chiral α-diimine / Ni(II) catalyst paraffin capsule for pilot production of poly-α-olefins.

[0068] Example 1 Synthesis of chiral α-diimine / Ni(II) catalyst 4d

[0069] Put 1.184 g (6.5 mmol) of acenaphthenequinone into a 100 mL round-bottom flask, add 15 mL of anhydrous methanol and stir to dissolve, dissolve 4.171 g (13.325 mmol) of (S)-7'-bromo-2,2',3,3'-tetrahydro-1,1'-spirobisanthracene-7-amine in 15 mL of methanol, mix the (S)-7'-bromo-2,2',3,3'-tetrahydro-1,1'-spirobisanthracene-7-amine methanol solution with the acenaphthenequinone methanol solution, then add one milliliter of formic acid to the mixture, stir with a magnetic rotor at room temperature for 2 days, filter the solid, add the obtained solid to 15 mL of anhydrous methanol, heat to dissolve, and recrystallize in a -20°C refrigerator, filter the solid, wash the filter cake with cold methanol (8 mL*3), pump dry the solvent, and obtain orange-yellow solid powder chiral α-diimine ligand with a mass of 4.265 g and a yield of 85%.

[0070] Under nitrogen protection, add 30 mL of anhydrous dichloromethane as a solvent into a 100 mL round-bottom flask, add 0.772 g (1.0 mmol) of chiral α-diimine ligand and 0.325 g (1.05 mmol) of (DME)NiBr2, stir overnight at room temperature under nitrogen protection, filter with diatomite, pump dry the solvent, wash the obtained solid with ether (10 mL*3), recrystallize in a dichloromethane / n-hexane system, suck out the solvent, wash the solid with n-hexane (5 mL*3), pump dry the solvent, weigh, and obtain bright red needle-shaped solid 0.823 g with a yield of 83%.

[0071] Example 2 Synthesis of chiral α-diimine / Ni(II) catalyst 4d catalyzing "isotactic" poly-α-olefins

[0072] The "isotactic" poly-α-olefins were synthesized in the laboratory, and all polymerization reactions were carried out under strictly anhydrous and anaerobic conditions. The α-olefins were dried with anhydrous CaH2, distilled under reduced pressure, and then sealed with nitrogen and stored in a glove box before use. The solvents, n-hexane, cyclohexane and toluene, were used after being treated by a solvent purification system. The co-catalyst MAO was a 10% mass concentration toluene solution. All glassware and metal needles were dried at 110°C for 2 h and cooled under a nitrogen atmosphere before use.

[0073] A 250 mL thick-walled two-necked round-bottom flask was dried in an oven at 110°C for 3 h, and vacuum-nitrogen replacement was performed three times using a Schlenk double-tube. Under nitrogen protection, the freshly distilled reaction solvent and the dehydrated and deoxygenated α-olefin were added to the flask, and the temperature of the reaction flask was balanced with the set metal sand bath temperature under magnetic stirring. Then, the main catalyst, a toluene solution of MAO, was added under nitrogen protection, and the reaction was terminated after a specified time with an excess of 4% hydrochloric acid-ethanol solution. The precipitate was allowed to stand for 24 h, filtered, washed thoroughly with ethanol, and dried to a constant weight at 60°C under vacuum.

[0074] The boundary conditions, such as the type of main catalyst, the molar ratio of main catalyst (Ni) to co-catalyst (MAO), the catalyst dosage, the reaction solvent, the reaction temperature, and the reaction time, were experimentally determined using α-octene as a template substrate. After the experiment was stopped, the poly-α-olefin yield, the catalyst catalytic activity, the number average molecular weight (Mn), the isotacticity, and the drag reduction rate were calculated and analyzed, and relatively optimal reaction conditions for the nickel-catalyzed synthesis of "isotactic" α-octene were obtained. Under the optimized reaction conditions, nickel-catalyzed homopolymerization reactions of α-hexene, α-decene, and α-dodecene were also experimentally determined. The specific conditions are shown in Table 1. n

[0075] Table 1 Nickel-catalyzed α-olefin polymerization reaction using chiral α-diimine / Ni(II)

[0076]

[0077]

[0078] ​For example, the preparation method of experiment 13 is as follows: a 250 mL thick-wall two-port round-bottom flask is dried in an oven at 110°C for 3 h, and vacuumized by an oil pump until the flask cools down, and vacuum-nitrogen replacement is performed for 3 times by using a Schlenk double-tube. Under the protection of nitrogen, freshly distilled anhydrous cyclohexane 90 mL and dehydrated and deoxygenated α-octene 200 mmol are added into the flask, and after the temperature in the reaction flask balances with the set metal sand bath temperature (50°C), 0.010 mmol of the main catalyst 4d and 10 mmol (calculated by MAO) of a toluene solution of the cocatalyst MAO are added under the protection of nitrogen, and the reaction is performed for 1.0 h, and then the reaction is terminated by using an excess amount of 4% hydrochloric acid-ethanol solution, and the precipitate is allowed to stand for 24 h, and then filtered and washed with ethanol, and dried at 60°C under vacuum until the weight is constant, and then weighed to obtain poly-α-octene 20.3 g.

[0079]

[0080] The calculation method of the catalytic activity (Act.) of the α-olefin polymerization catalyst in Table 1 is: the poly-α-octene yield (m) / [the catalyst amount (n Cat. ) * the reaction time (t)], and the unit is 10 6 g·mol -1 ·h -1 ; n Cat. represents the number of moles of the chiral α-diimine / Ni(II) catalyst (Cat. 4).

[0081] The number average molecular weight (M n ) is measured by a gel permeation chromatograph (GPC) and polystyrene is used as an internal standard.

[0082] The isotacticity (I.I.) is measured by determining the poly-α-octene product 13 C NMR (deuterated tetrachloroethane as a solvent, 120°C), and the integral calculation is performed on specific carbon peaks in the spectrum.

[0083] The drag reduction rate (DR) is measured by a rotating disc drag reduction test device, and diesel oil is used as a test solvent and the mass concentration of the poly-α-octene is 30 ppm.

[0084] As can be seen from experiments 1-4 in Table 1, when R1 of the main catalyst is bromine, the catalytic activity of the main catalyst is the highest, and the poly-α-octene yield, the number average molecular weight, the isotacticity and the drag reduction rate are all optimal, which can indicate that the performance of the main catalyst with R1 being bromine is optimal.

[0085] As can be seen from experiments 4-6 in Table 1, when the reaction solvent is cyclohexane, the catalytic activity of the main catalyst is the highest, and the poly-α-octene yield, the number average molecular weight, the isotacticity and the drag reduction rate are all optimal, which can indicate that the optimal reaction solvent is cyclohexane.

[0086] From experiments 6-8 in Table 1, it can be seen that when the ratio of solvent to α-olefin is 90 mL:200 mmol, the performance is best in all aspects.

[0087] From experiments 7, 9-11 in Table 1, it can be seen that when the reaction temperature is between 30-60℃, as the reaction temperature increases, the catalytic activity of the main catalyst and the parameters of the poly-α-olefin in all aspects increase, but when the temperature exceeds 50℃, as the temperature increases, the performance in all aspects decreases, indicating that the optimal reaction temperature is 50℃.

[0088] From experiments 10, 12-14 in Table 1, it can be seen that as the ratio of co-catalyst increases, the catalytic activity of the main catalyst first increases and then decreases, and the optimal ratio is n MAO / n Ni =1000.

[0089] From experiments 13, 15-16 in Table 1, it can be seen that as the amount of main catalyst increases, the yield of poly-α-olefin increases continuously, but the catalytic activity of the main catalyst first increases and then decreases, so in summary, the optimal molar ratio of catalyst to α-olefin is 0.01:200.

[0090] From experiments 13, 15-16 in Table 1, it can be seen that when the reaction time is less than 1h, as the reaction time increases, the yield of poly-α-olefin increases continuously, and when it exceeds 1h, as the reaction time increases, the yield of poly-α-olefin, number average molecular weight, isotacticity and drag reduction rate hardly change, and the catalytic activity of the main catalyst decreases significantly, therefore, the optimal reaction time is 1h.

[0091] From experiments 13, 19-21 in Table 1, it can be seen that α-hexene, α-decene and α-dodecene can all obtain poly-α-olefin with high isotacticity under this reaction condition. As the number of carbon atoms in α-olefin increases, the yield and number average molecular weight of poly-α-olefin increase continuously, and the catalytic activity of the main catalyst increases continuously, but the isotacticity changes little, and when α-olefin is α-octene, the drag reduction rate is the highest, indicating that the performance of poly-α-olefin synthesized from α-octene is the best.

[0092] Example 3 Preparation of chiral α-diimine / Ni(II) catalyst 4d paraffin capsules

[0093] As Figure 1As shown, about 20.000 g of No. 60 paraffin wax particles were added into a thick-walled beaker and melted in a metal sand bath with a set temperature of 80°C, about 1.000 g of chiral α-diimine / Ni(II) catalyst 4d powder was weighed and added into the melted paraffin wax, and stirred rapidly until the catalyst particles were uniformly suspended, then poured into a pre-prepared aluminum mold while hot, and after natural cooling, the solidified paraffin wax core was taken out of the mold, and then immersed in a pre-prepared No. 60 paraffin wax liquid, quickly taken out, and after the surface paraffin wax liquid solidified, the above operation was repeated three times to complete the preparation of the catalyst 4d paraffin wax capsule, which was sealed with a plastic bag and stored in a cool, dry and dark place for standby use.

[0094] The above is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A nickel catalyst characterized in that, The structural formula is shown as formula 4: Wherein, R1 is hydrogen, aryl, alkyl, ester, ether or halogen.

2. The nickel catalyst according to claim 1, characterized in that, The alkyl is methyl, the ether is methoxy, and the halogen is bromine.

3. The process for the preparation of a nickel catalyst as claimed in claim 1 or 2, characterized in that, The method comprises the following steps: S1, acenaphthenequinone shown in formula 1 is subjected to dehydration condensation reaction with a spirochiral aromatic amine shown in formula 2 to generate a chiral alpha-diimine ligand shown in formula 3; S2, the chiral alpha-diimine ligand is subjected to reaction with dibromo(1,2-dimethoxyethane) nickel to generate a nickel catalyst shown in formula 4; 4. The method of producing a nickel catalyst according to claim 3, characterized by, S1 specifically comprises: mixing acenaphthenequinone and the spirochiral aromatic amine in a solvent, adding formic acid, stirring at room temperature, separating the solid after the reaction is completed, and recrystallizing and washing the obtained solid to obtain the chiral alpha-diimine ligand.

5. The method of preparing a nickel catalyst according to claim 3, characterized by, S2 specifically comprises: under the protection of inert gas, the chiral alpha-diimine ligand and dibromo(1,2-dimethoxyethane) nickel are added into a solvent, stirring at room temperature under the protection of inert gas, separating the solid after the reaction is completed, and recrystallizing and washing the obtained solid to obtain the nickel catalyst.

6. A catalyst paraffin capsule characterized by, The method comprises the following steps:

7. The process for the preparation of catalyst paraffin wax capsules according to claim 6, characterized in that, The method comprises the following steps: Step 1, under anaerobic conditions, melt the paraffin, add the nickel catalyst powder according to claim 1 or 2, stir to obtain a catalyst paraffin suspension; Step 2, pour the catalyst paraffin suspension into a mold while hot, cool and solidify to obtain a paraffin inner core; Step 3, immerse the paraffin inner core in molten paraffin for a predetermined time, take it out, and repeat step 3 several times after the surface paraffin solidifies again to obtain a catalyst paraffin capsule.

8. A process for the catalytic synthesis of a polyolefin drag reducing agent for crude oil, characterized in that, The method comprises the following steps: Add the alpha-olefin to the solvent, stir and heat to the reaction temperature, add the main catalyst and the cocatalyst, and carry out the reaction, separate the precipitate and wash after the reaction is completed to obtain the poly-alpha-olefin; wherein the main catalyst is the nickel catalyst according to claim 1 or 2 or the catalyst paraffin capsule according to claim 6.

9. The catalytic synthesis of a drag reducing agent polyolefin crude oil according to claim 8, characterized in that, The reaction temperature is 30-60 DEG C, and the reaction time is 0.5-2 h.

10. The process for catalytic synthesis of drag reducing agent polyolefins according to claim 8, characterized in that, The molar ratio of the nickel catalyst to the alpha-olefin is (0.05-0.15):200.

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