CN112898460A - Novel ethylene polymerization process - Google Patents
Novel ethylene polymerization process Download PDFInfo
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- CN112898460A CN112898460A CN202110080140.4A CN202110080140A CN112898460A CN 112898460 A CN112898460 A CN 112898460A CN 202110080140 A CN202110080140 A CN 202110080140A CN 112898460 A CN112898460 A CN 112898460A
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Abstract
The application provides a polymerization method of a high-branching low-molecular-weight ethylene oligomer, which comprises the steps of injecting ethylene into a solvent in which a polymerization catalyst is dissolved by using an injection device, and carrying out polymerization reaction on a reaction system to obtain the high-branching low-molecular-weight ethylene oligomer; wherein the method is performed in an aggregation system comprising: a spray reactor in which the spray device is disposed, the solvent in which the catalyst is dissolved being contained in the interior of the spray reactor; a circulation pump and a heat exchanger located outside the injection reactor. The method for preparing the high-branched low-molecular-weight ethylene oligomer has the advantages of high reaction speed, high catalyst efficiency, stable and controlled temperature and pressure, few byproducts and low energy consumption.
Description
Technical Field
The present application relates to a new ethylene polymerization process, in particular, it relates to a polymerization method of high-branched low-molecular weight ethylene oligomer.
Background
The traditional ethylene polymerization process adopts solution method, slurry method and gas phase method polymerization process, and can produce various grades of polyethylene products such as linear low density polyethylene, high density polyethylene and the like. The reactor is a stirred bed or kettle, fluidized bed or pipeline reactor. Under the reaction process conditions of the solution method and the slurry method, the ethylene is in a gas state and must be dissolved in a solvent to be contacted with the active center of the catalyst for reaction.
In the traditional stirred tank type solution polymerization reaction, the ethylene dissolution speed is low, and the normal reaction can be ensured only by strong stirring. In addition, the ethylene is gaseous under the conditions of reaction pressure and temperature, and can contact and react with the catalyst in the solvent only through a dissolving process, so that a phase interface is limited, the dissolving speed is limited, and the reaction rate is low; and the reaction needs to be carried out under a large reaction pressure, and the energy consumption in the reaction process is high.
Disclosure of Invention
Therefore, the traditional solution polymerization process is combined with the spray reaction, a proper solvent is selected to dissolve the catalyst for polymerization, and the rapid and efficient polymerization reaction is realized by strengthening the mass transfer in the reaction process.
The application provides a polymerization method of a high-branching low-molecular-weight ethylene oligomer, which comprises the steps of injecting ethylene into a solvent in which a polymerization catalyst is dissolved by using an injection device, and carrying out polymerization reaction on a reaction system to obtain the high-branching low-molecular-weight ethylene oligomer;
wherein the method is performed in an aggregation system comprising:
a spray reactor in which the spray device is disposed, the solvent in which the catalyst is dissolved being contained in the interior of the spray reactor;
the circulating pump and the heat exchanger are positioned outside the jet reactor, wherein the circulating pump conveys circulating materials from the jet reactor to the heat exchanger for heat exchange;
and conveying the circulating material subjected to heat exchange by the heat exchanger back to the inside of the injection reactor through the injection device, injecting the ethylene into the inside of the injection reactor through the injection device, and polymerizing to obtain the high-branching low-molecular-weight ethylene oligomer.
In one embodiment, the flow rate of the recycled material is between 10 and 50V/h with respect to the total volume V of the injection reactor.
In one embodiment, the ethylene is sprayed into the solvent in which the polymerization catalyst is dissolved using a spraying device to form bubbles having a diameter of 10 to 200 microns.
In one embodiment, compared to m3The volume of solvent in which the polymerization catalyst is dissolved V1, the feed rate of ethylene in kg/h S/V1 is from 3 to 65kg/m3·h。
In one embodiment, the pressure of the polymerization reaction is from 0.1 to 1.0MPa and the temperature of the polymerization reaction is from 20 ℃ to 100 ℃.
In one embodiment, the solvent is selected from one or more of linear alkanes, halogenated alkanes, alkylbenzenes, and halogenated compounds thereof.
In one embodiment, the polymerization catalyst is present in an amount of 0.01 wt% to 2.0 wt% of the solvent.
In one embodiment, the weight average molecular weight of the highly branched low molecular weight ethylene oligomer is 1000-10000, Mw/Mn is 1.1-2.0, and the branching degree is 130-190 branches/1000 carbon atoms.
The method applies the jet reactor to the ethylene homogeneous polymerization reaction process, the polymerization catalyst can be well dissolved in the reaction system, and the high-branched low-molecular-weight ethylene oligomer can be well dissolved in the reaction system, so that the whole reaction system is homogeneous. The method for preparing the high-branched low-molecular-weight ethylene oligomer has the advantages of high reaction speed, high catalyst efficiency, stable and controlled temperature and pressure, few byproducts and low energy consumption.
Drawings
FIG. 1 shows a polymerization system used in the process of the present invention.
Detailed Description
The technical solution of the present invention is further explained below according to specific embodiments. The scope of protection of the invention is not limited to the following examples, which are set forth for illustrative purposes only and are not intended to limit the invention in any way.
The application provides an ethylene polymerization method, in particular to a polymerization method of a high-branching low-molecular-weight ethylene oligomer, which comprises the steps of injecting ethylene into a solvent dissolved with a polymerization catalyst by using an injection device, and carrying out polymerization reaction on a reaction system to obtain the high-branching low-molecular-weight ethylene oligomer;
wherein the method is performed in an aggregation system comprising:
a spray reactor in which the spray device is disposed, the solvent in which the catalyst is dissolved being contained in the interior of the spray reactor;
a circulation pump and heat exchanger located outside the injection reactor; wherein the circulating pump conveys the circulating material from the jet reactor to the heat exchanger for heat exchange;
and conveying the circulating material subjected to heat exchange by the heat exchanger back to the inside of the injection reactor through the injection device, injecting the ethylene into the inside of the injection reactor through the injection device, and polymerizing to obtain the high-branching low-molecular-weight ethylene oligomer.
The method is an intermittent solution polymerization method, and takes ethylene as a main raw material to react under the action of a catalyst to synthesize the polyethylene. The polymerization reaction may be carried out in a polymerization system.
Fig. 1 shows the polymerization system, including a spray reactor 1, a liquid phase circulation pump (liquid phase pump) 2, a heat exchanger 3, a gas feed control 4, and the like.
The spray reactor 1 is internally provided with a spray device 11, and the solvent in which the catalyst is dissolved is contained inside the spray reactor 1. The gas feed control 4 is used for feeding ethylene and is in communication with the injection device 11. The injection device 11 can inject ethylene into the solvent in which the polymerization catalyst is dissolved to form bubbles with smaller particle sizes, thereby increasing the contact area with the solution, improving the reaction efficiency, accelerating the reaction speed and shortening the reaction time. The circulating pump 2 conveys the circulating material from the jet reactor 1 to the heat exchanger 3 for heat exchange, and the circulating material subjected to heat exchange by the heat exchanger 3 is also conveyed back to the interior of the jet reactor 1. The external circulation is carried out by the circulating pump 2, and the reaction heat is removed through the external circulation heat exchanger, so that the temperature of the reaction system is easier to control. The circulating pump 2 can be a gear pump or a centrifugal pump capable of conveying gas-liquid mixture, the heat exchanger can be a tubular heat exchanger, and the heat exchange medium can be water or oil and the like. The flow rate of the recycled material is 10-50V/h relative to the total volume V of the injection reactor. Alternatively, the flow rate of the recycled material is 10-125V1/h compared to the volume of solvent dissolved with the polymerization catalyst, V1. With such a circulation flow rate the following advantages can be achieved: the method has the advantages of high reaction speed, high catalyst efficiency, stable and controlled temperature and pressure, few byproducts and low energy consumption.
In one embodiment, ethylene is added at the feed port of the recycle stream, enabling the formation of more stable small bubbles. In one embodiment, the bubbles have a diameter of 30 to 50 microns. The bubble diameter can be controlled by the ethylene feed rate, etc. Compared with m3The volume of solvent in which the polymerization catalyst is dissolved V1, the feed rate of ethylene in kg/h S/V1 is from 3 to 65kg/m3H. In this case, the following advantages can be achieved: the method has the advantages of high reaction speed, high catalyst efficiency, stable and controlled temperature and pressure, few byproducts and low energy consumption.
The ethylene polymerization process of the present invention can be carried out under relatively low temperature and pressure conditions. In one embodiment, the reaction pressure is 0.1 to 0.5MPa and the reaction temperature is 20 ℃ to 60 ℃. The method has low energy consumption due to the mild reaction conditions.
In one embodiment, the solvent is selected from one or more of linear alkanes and alkylbenzene compounds. For example, the solvent may be a linear alkane such as hexane or gasoline, or an alkylbenzene compound such as toluene or ethylbenzene. In the present invention, the solvent and the reaction system are anhydrous and anaerobic conditions.
In one embodiment, the polymerization catalyst used herein may be a conventional catalyst system for catalyzing the polymerization of ethylene, such as a Ziegler-Natta catalyst system, a metallocene catalyst system, and the like, preferably a Ziegler-Natta catalyst system. In the Ziegler-Natta catalyst system, for example, a Ti-containing procatalyst and a cocatalyst which is an aluminum alkyl compound or an aluminum alkoxy compound may be included. In one embodiment, the polymerization catalyst is present in an amount of 0.1 wt% to 1.0 wt% of the solvent.
The method can be carried out in a short time, for example, the polymerization time can be 0.5h-2.0h, and the reaction efficiency is high. After the reaction is stopped, the product polyethylene can be obtained through conventional steps of separation, washing and the like. The obtained polyethylene product is a highly branched low molecular weight ethylene oligomer, the weight average molecular weight of the polyethylene product is 1000-10000, the Mw/Mn is 1.1-2.0, and the branching degree is 130-190 branched chains/1000 carbon atoms. Wherein the degree of branching may be determined by1H NMR measurement; the molecular weight can be determined by the GPC method.
The method applies the jet reactor to the ethylene homogeneous polymerization reaction process, the polymerization catalyst can be well dissolved in the reaction system, and the high-branched low-molecular-weight ethylene oligomer can be well dissolved in the reaction system, so that the whole reaction system is homogeneous.
Example 1
The polymerization system used is shown in FIG. 1, and the volume V of the spray reactor was 200L. A spray reactor was charged with 1000 grams of hexane solvent, followed by 20 grams of a co-catalyst aluminum alkyl, and then 1 gram of a rigid, large skeletal alpha-nickel diimine procatalyst (synthesized according to example 21 of patent application No. CN 201811633475.9).
Starting the external circulating pump, and adding ethylene into the circulating liquid inlet of the reactor. The circulation rate of the reactant stream was 6 cubic meters per hour. Ethylene was injected into the solution system of the injection reactor through the injection device of the injection reactor at an ethylene feed rate of 2.2kg/h and formed bubbles having a diameter of 60 μm.
The reaction pressure is kept between 0.3MPa, the reaction temperature is 80 ℃, and the fluctuation range is controlled within 5 ℃. When the reaction temperature begins to decrease, the ethylene feeding is stopped, the heat preservation is continued for 0.5 hour, and the polyethylene is obtained after discharging, wherein the weight average molecular weight of the polyethylene is 5100, the Mw/Mn is 1.13, and the branching degree is 153 branches/1000 carbon atoms.
Measurement results of properties of the obtained polyethylene:
the kinematic viscosity of the product at different temperatures is tested according to national standards GB/T265-88 and GB/T1995-88, and the viscosity index is calculated, so that the lubricating property of the product is evaluated; the pour point of the product is determined according to GB/T3535-; the evaporation loss and the flash point of the product are determined according to the petrochemical industry standard SH/T0731-2004 and the national standard GB/T3536-2008, and the stability and the safety of the product are further evaluated. The performance test results of the polyethylene base oil obtained in the inventive example are shown in table 1.
Example 2
The polymerization system used is shown in FIG. 1, and the volume V of the spray reactor was 200L. A spray reactor was charged with 1000 grams of hexane solvent, followed by 25 grams of a co-catalyst aluminum alkyl, and then 1.1 grams of a rigid, large skeletal alpha-nickel diimine procatalyst (synthesized according to example 21 of patent application No. CN 201811633475.9).
Starting the external circulating pump, and adding ethylene into the circulating liquid inlet of the reactor. The circulation rate of the reactant stream was 5.5 cubic meters per hour. Ethylene was injected into the solution system of the injection reactor through the injection device of the injection reactor at an ethylene feed rate of 2.5kg/h, and formed bubbles having a diameter of 65 μm.
The reaction pressure is kept at 0.32MPa, the reaction temperature is 85 ℃, and the fluctuation range is controlled within 5 ℃. And when the reaction temperature begins to decrease, stopping feeding ethylene, continuing keeping the temperature for 0.5 hour, and discharging to obtain the polyethylene, wherein the weight average molecular weight of the polyethylene is 7300, the Mw/Mn is 1.45, and the branching degree is 161 branches/1000 carbon atoms.
Measurement results of properties of the obtained polyethylene:
the kinematic viscosity of the product at different temperatures is tested according to national standards GB/T265-88 and GB/T1995-88, and the viscosity index is calculated, so that the lubricating property of the product is evaluated; the pour point of the product is determined according to GB/T3535-; the evaporation loss and the flash point of the product are determined according to the petrochemical industry standard SH/T0731-2004 and the national standard GB/T3536-2008, and the stability and the safety of the product are further evaluated. The performance test results of the polyethylene base oil obtained in the inventive example are shown in table 1.
TABLE 1 Properties of the polyethylene base oils obtained according to the invention.
Comparative example 1
A conventional stirred reactor having a volume V of 200 liters was charged with 100 liters of hexane solvent, followed by 20 grams of aluminum alkyl co-catalyst and 1 gram of nickel alpha-diimine procatalyst with a rigid large backbone (synthesized according to example 21 of patent application No. CN 201811633475.9).
Starting the external circulating pump, and adding ethylene into the circulating liquid inlet of the reactor. The recycle rate of the reactant stream was 6 cubic meters per hour and the feed rate of ethylene was 2.5kg per hour. The reaction pressure is kept between 0.3MPa, the reaction temperature is 80 ℃, and the fluctuation range is controlled within 5 ℃. And when the reaction temperature begins to decrease, stopping feeding ethylene, continuing keeping the temperature for 0.5 hour, and discharging to obtain the polyethylene, wherein the weight average molecular weight of the polyethylene is 4800, the Mw/Mn is 1.12, and the branching degree is 143 branches/1000 carbon atoms.
Comparative example 2
A conventional stirred reactor having a volume V of 200 liters was charged with 100 liters of hexane solvent, followed by the addition of 25 grams of a cocatalyst of aluminum alkyl and the addition of 1.1 grams of a nickel alpha-diimine procatalyst with a rigid large backbone (synthesized according to example 4980 of patent application No. CN 201811633475.9).
Starting the external circulating pump, and adding ethylene into the circulating liquid inlet of the reactor. The recycle rate of the reactant stream was 5.5 cubic meters per hour and the feed rate of ethylene was 2.2kg per hour. The reaction pressure is kept between 0.32MPa, the reaction temperature is 85 ℃, and the fluctuation range is controlled within 5 ℃. When the reaction temperature begins to decrease, the ethylene feeding is stopped, the heat preservation is continued for 0.5 hour, and the polyethylene is obtained after discharging, wherein the weight average molecular weight of the polyethylene is 5200, the Mw/Mn is 1.13, and the branching degree is 137 branches/1000 carbon atoms.
Measurement results of properties of the obtained polyethylene:
the kinematic viscosity of the product at different temperatures is tested according to national standards GB/T265-88 and GB/T1995-88, and the viscosity index is calculated, so that the lubricating property of the product is evaluated; the pour point of the product is determined according to GB/T3535-; the evaporation loss and the flash point of the product are determined according to the petrochemical industry standard SH/T0731-2004 and the national standard GB/T3536-2008, and the stability and the safety of the product are further evaluated. The performance test results of the polyethylene base oil obtained in the inventive example are shown in table 2.
TABLE 2 Properties of the polyethylene base oils obtained in comparative examples 1 and 2.
Comparing the results of table 1 and table 2, it can be found that: the method has the advantages of high reaction speed, high catalyst efficiency, stable and controlled temperature and pressure, few byproducts and low energy consumption.
The embodiment 1-2 adopting the method of the application can ensure that reactants are contacted more fully and continuously react, and has the advantages of high reaction speed, high catalyst efficiency, stable and controlled temperature and pressure, less byproducts and low energy consumption;
the comparative examples 1 to 2, which were not the process of the present application, had low productivity per unit time, insufficient reaction, low conversion rate, low catalyst utilization rate and high energy consumption.
It should be noted by those skilled in the art that the described embodiments of the present invention are merely exemplary and that various other substitutions, alterations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the above-described embodiments, but is only limited by the claims.
Claims (8)
1. A polymerization method of a highly branched low molecular weight ethylene oligomer comprises the steps of injecting ethylene into a solvent in which a polymerization catalyst is dissolved by using an injection device, and carrying out polymerization reaction on a reaction system to obtain the highly branched low molecular weight ethylene oligomer;
wherein the method is performed in an aggregation system comprising:
a spray reactor in which the spray device is disposed, the solvent in which the catalyst is dissolved being contained in the interior of the spray reactor;
the circulating pump and the heat exchanger are positioned outside the jet reactor, wherein the circulating pump conveys circulating materials from the jet reactor to the heat exchanger for heat exchange;
and conveying the circulating material subjected to heat exchange by the heat exchanger back to the inside of the injection reactor through the injection device, injecting the ethylene into the inside of the injection reactor through the injection device, and polymerizing to obtain the high-branching low-molecular-weight ethylene oligomer.
2. A process for the polymerization of highly branched low molecular weight ethylene oligomers according to claim 1 wherein the flow rate of said recycled material is comprised between 10 and 50V/h with respect to the total volume V of said jet reactor.
3. A process for the polymerization of highly branched low molecular weight ethylene oligomers as claimed in claim 1 wherein ethylene is injected into the solvent in which the polymerization catalyst is dissolved using an injection device to form gas bubbles having a diameter of 10 to 200 microns.
4. The process for the polymerization of highly branched low molecular weight ethylene oligomers as claimed in claim 1, wherein said polymerization is carried out in comparison with m3The volume of solvent in which the polymerization catalyst is dissolved V1, the feed rate of ethylene in kg/h S/V1 is from 3 to 65kg/m3·h。
5. The process for polymerizing highly branched low molecular weight ethylene oligomers as claimed in claim 1, wherein the polymerization pressure is between 0.1 and 1.0MPa and the polymerization temperature is between 20 ℃ and 100 ℃.
6. The process for polymerizing highly branched low molecular weight ethylene oligomers as claimed in claim 1 wherein said solvent is selected from the group consisting of linear alkanes, halogenated alkanes, alkylbenzenes and halogenated compounds thereof.
7. The process for polymerizing highly branched low molecular weight ethylene oligomers as claimed in claim 1 wherein said polymerization catalyst is present in an amount of from 0.01 to 2.0% by weight based on the amount of solvent.
8. The method for polymerizing the highly branched low molecular weight ethylene oligomer as claimed in claim 1, wherein the weight average molecular weight of the highly branched low molecular weight ethylene oligomer is 1000-10000, the Mw/Mn is 1.1-2.0, and the branching degree is 130-190 branches/1000 carbon atoms.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1490290A (en) * | 2003-09-19 | 2004-04-21 | 中国石油天然气股份有限公司 | Method for preparing 1-ethene under ethene oligomerizating catalyst system |
| CN110639459A (en) * | 2019-10-10 | 2020-01-03 | 万华化学集团股份有限公司 | Device and method for preparing 1-octene by ethylene selective oligomerization |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1490290A (en) * | 2003-09-19 | 2004-04-21 | 中国石油天然气股份有限公司 | Method for preparing 1-ethene under ethene oligomerizating catalyst system |
| CN110639459A (en) * | 2019-10-10 | 2020-01-03 | 万华化学集团股份有限公司 | Device and method for preparing 1-octene by ethylene selective oligomerization |
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