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INVENTION
Patent of the Russian Federation RU2171816
METHOD FOR PRODUCING LOW-MOLECULAR POLYOLEPHINES
Applicant's name: Timur K. Plaksunov
The name of the patent holder: Kokorev Evgeniy Mikhailovich; Plaksunov Timur Kasimovich; Konshin Gennady Vasilyevich; Mokhnachev Stanislav Fedorovich; Yetmanov Yetmanovich
Address for correspondence: 423550, Tatarstan, Nizhnekamsk, Chemikov Ave., 51, Apt. 43, SF Mokhnachevu
Date of commencement of the patent: 1999.06.16
The invention relates to the preparation of polymeric additives and additives of various functional purposes used in oil refining and petrochemistry, in particular depressant additives for diesel fuels with mol. 800-3000 or viscous additives to lubricating oils with a mol. 8000-100000, based on low molecular weight polyolefins. Low molecular weight polyolefins are obtained by thermal destruction of high molecular weight polyolefin-elastomer rubber EPDM - copolymer of ethylene with propylene and dienes during depolymerization at 300-370 ° C in two stages. The first step is carried out by heating the EPDM in the entire volume gradientlessly to the depolymerization temperature in 1-6 min. In the second stage, the depolymerizate is removed and maintained at a depolymerization temperature of 15-30 minutes. Both steps are carried out in an inert gas atmosphere, for example nitrogen. Thermal destruction is carried out in a tubular reactor having heating, depolymerization and aging sections of depolymerization.
DESCRIPTION OF THE INVENTION
The invention relates to the field of oil refining and petrochemistry and can be used to produce polymeric additives and additives of various functional purposes, mainly to petroleum products.
A method for the thermal destruction of ethylene-propylene rubbers with a molecular weight of 300-500,000 is known, in that the finely chopped rubber is loaded into an autoclave with a stirrer, the air is evacuated from it, heated to a temperature of 250-300 ° C, the stirrer is turned on and the temperature is raised to 370-400 O C (copyright certificate of the USSR 765307, MCI C 08 F 23/16). The process is carried out at a residual pressure of 20-760 mm Hg. The resulting product has a molecular weight of 400-3000 and can be used as an adhesive additive to the rubber compound.
A method for the continuous thermal degradation of a polyethylene with a molecular weight of 10,000-200,000 is known, which consists in the fact that the polyethylene is loaded into an extruder, melted, heated to a temperature of 250 ° C., continuously pushed through a destructor made as a heated tube with two heating zones with different specific thermal Loads in zones of homogeneous and heterogeneous state of the reaction medium that are maintained in the required places by varying the pressure at the output of the destructor (USSR copyright certificate N 665 681, MKI 08 F 8/50, 30.11.1983). The pressure of the process varies within 2-6 atm, the temperature is 350-500 ° C. The resulting product has a molecular mass within the limits of 600-4500 and can be used as a substitute for natural waxes.
The closest to the claimed invention is a process for producing low molecular weight polyolefins, according to which the thermal degradation of polyolefins and elastomers is proposed to be carried out in a thin layer in a plant comprising a combination of a heated screw feeder, for example an extruder, preheating the destructate to a temperature of 250-300 ° C for 5-10 min and a tubeless gradient destructor with adjustable two-way heat input to the destructate at a temperature of 350-450 ° C for 10-30 minutes (published application of the Russian Federation No. 97114180 A1 to the "Method for producing low molecular weight polyolefins" in the volume of the formula.) 10.06.1999.
In the process of thermal destruction by known methods, including the nearest analog, a large number of different polymer fragments are formed "according to the law of the case". The resulting low molecular weight polyolefins have a molecular weight distribution (MWD) greater than 3, a reproducibility of physicomechanical properties of not more than 60-65%, and because of such characteristics can not be used as additives and additives to petroleum products, since they do not ensure the performance properties of petroleum products, respectively Known world level.
In addition, the known methods are not universal, that is, each known method is suitable for obtaining a specific product.
At the same time, as a result of our studies, it was found that low molecular weight polyolefins with a molecular weight in the range from 800 to 1,000,000 are suitable for the preparation of polymeric additives and additives of various functional purposes for petroleum products by thermal destruction of high molecular weight polyolefins and elastomers. For example, it has been found that the molecular weight of low molecular weight polyolefins suitable for the preparation of depressant additives for diesel fuels is 800 to 3000, and that of MMP is 1.5 to 3, the molecular weight of low molecular weight polyolefins suitable for obtaining viscous additives to lubricating oils is 80,000 - 100000, and MMP - from 2 to 4. At the same time, to ensure the operational properties of petroleum products according to the world level, the reproducibility of the above characteristics of low molecular weight polyolefins should be not less than 80%. This makes it possible to ensure the reproducibility of physico-mechanical properties of petroleum products with these additives and not less than 80%.
It is an object of the present invention to provide a method for producing low molecular weight polyolefins by thermal degradation of high molecular weight polyolefins and elastomers that is universal, i.e., suitable for the preparation of polymeric additives and additives for petroleum products of various functional purposes, enabling the production of low molecular weight polyolefins of certain molecular weight characteristics Molecular weight m and MWD) with a reproducibility of at least 80%.
This problem is solved by the fact that in the process for obtaining molecular-weight polyolefins by thermal destruction of high molecular weight polyolefins at a depolymerization temperature of 320 to 370 ° C in two stages, the first stage of thermal degradation is carried out by heating as a high-molecular polyolefin elastomer-EPDM rubber, a copolymer of ethylene with propylene And the diene in the entire volume gradientlessly to the depolymerization temperature in a time of 1 to 6 minutes, the resulting depolymerization in the second stage is withdrawn and maintained at a depolymerization temperature for 15 to 30 minutes, both steps are carried out under an inert gas atmosphere, the final product being a depressant additive Diesel fuels with a molecular weight of 800 - 3000 or viscous additive to lubricating oils with a molecular weight of 8000 - 100000.
It is expedient that the thermal degradation is carried out in a tubular reactor having a heating and depolymerization section and a depolymerization holding section, the diameters of the first section and the second having a ratio of 2 and the heating systems being autonomous.
It is expedient that the heating system of the depolymerization section be made in the form of a rotor apparatus.
It is expedient to obtain depressant additives for diesel fuels having the following molecular weight characteristics: a molecular weight of 800-3000 and a molecular weight distribution of 1.5-3; a first stage, heating and depolymerization, was carried out at thermal annealing at 355-365 ° C for The time is 2-5 minutes.
It is expedient to obtain viscous additives for lubricating oils having the following molecular weight characteristics: molecular weight 8000-100000 and molecular weight distribution 2-4, the first stage - heating and depolymerization - was carried out at thermal annealing at 330-350 ° C during 2 -6 minutes.
It is expedient to carry out both stages of the process in a nitrogen atmosphere.
The method is carried out as follows
A high molecular weight polyolefin or an elastomer with a molecular weight (300-1000) of 10 3 is ground on a mechanical crusher to obtain pellets of 3-10 mm. The resulting granules are loaded into a feed hopper in an inert gas environment, for example nitrogen. The pellets are then introduced into the reactor in an atmosphere of the same inert gas, for example nitrogen. Thermal destruction is carried out in a reactor where, in the first section of the reactor, the depolymerization sections, the entire volume of the incoming destructant is heated incontinently to a depolymerization temperature in the range of 320-370 ° C. for a time of 1-6 minutes. The depolymerization temperature is determined from the tables compiled on the basis of theoretical and experimental studies, respectively, the molecular weight characteristics of the resulting low molecular weight polyolefins. The resulting depolymerizate flows to the second section of the reactor, the stabilization section, where it is stabilized by maintaining it at the temperature of stabilization in the atmosphere of the same inert gas, for example nitrogen. This stabilization is carried out for 15-30 minutes.
The reactor sections have autonomous heating systems. The heating system of the depolymerization section ensures rapid heating of the destructate without gradient throughout the entire volume. Such a heating system can be realized with a rotary device with a variable speed. Such a heating system can be implemented in another manner, for example, by a laser or ultrasonic device.
Exemplary embodiments of the method.
Example 1 . High-molecular elastomer - EPDM rubber, with a molecular weight of 500 × 10 3, is crushed on a mechanical crusher to obtain pellets of 3-10 mm. The resulting granules (destruktat) are loaded into a feed hopper in a nitrogen medium. The pellets are then fed to the reactor in an atmosphere of the same nitrogen. The reactor is made in two sections. The first section of the reactor, the depolymerization section, is equipped with a rotary apparatus with a variable speed set inside the section. The second section of the reactor - the stabilization section - has an autonomous heating system (here electric heating) and temperature control. In general, the reactor is a pipe of variable cross-section, the diameter of the first section being referred to as the diameter of the second section as 2: 1. A nitrogen atmosphere is created in the reactor. The residual pressure is 10-100 mm Hg. Set the required number of rotations of the rotor, which ensures the heating of the destructate to a temperature of 355 - 360 ° C for a time of 5 minutes. Heating occurs without gradient in the entire volume of incoming destructate. The resulting depolymerizate flows to the second section of the reactor, where it is kept at a depolymerization temperature of 360 ° C for 25 minutes.
The resulting low molecular weight polyolefin was analyzed by gel chromatography. The data and results of Example 1a and performed similarly to Examples 2-7 are summarized in Table
Table 1 presents data and results of experiments performed according to the method adopted for the closest analogue (N 8-10)
Low molecular weight polyolefins, suitable for the preparation of depressant additives for diesel fuels, have molecular mass characteristics: a molecular weight of 800-3000, a molecular weight distribution (MWD) of 1.5-3.
Example 2 . Example 2 was carried out analogously to Example 1, on the same reactor with the same destructate. The number of revolutions of the rotor apparatus is changed, the required rotational speed is set, which ensures the heating of the destructate to a temperature of 330-350 ° C for a time of 6 minutes.
The resulting low molecular weight polyolefin was analyzed by gel chromatography. The data and results of Example 2a, and similarly to Examples 12-20, are summarized in Table 2. Low molecular weight polyolefins suitable for the production of viscous additives for lubricating oils have molecular weight characteristics: a molecular weight of 8000-100000, a molecular weight distribution of 2-4 .
The proposed method avoids the formation of polymer fragments destructed at various time intervals in a rather narrow temperature range, due to rapid heating, temperature equalization throughout the volume, minimization of oxygen-oxidizing processes.
The method makes it possible to arrange the arrangement of polymer molecules and obtain low molecular weight polyolefins with specified molecular mass characteristics, and, most importantly, reproducible physico-mechanical and consumer properties.
CLAIM
1. A process for the preparation of low molecular weight polyolefins by thermally degrading high molecular weight polyolefins at a depolymerization temperature of 320-370 ° C in two stages, characterized in that the first step of thermal degradation is carried out by heating as a high molecular weight polyolefin elastomer-EPDM rubber, a copolymer of ethylene with propylene and Diene in the entire volume gradientlessly to the depolymerization temperature in a time of 1 to 6 minutes, the resulting depolymerization in the second stage is withdrawn and maintained at the depolymerization temperature for 15-30 minutes, both steps are carried out under an inert gas atmosphere, the final product being a depressant additive to diesel Fuels with mol. 800-3000 or viscous additive to lubricating oils with a mol. 8000-100000.
2. A process according to claim 1, characterized in that both process steps are carried out in a nitrogen atmosphere.
3. The method of claim 1, wherein the thermal degradation is carried out in a tubular reactor having a heating and depolymerization section and a depolymerization holding section, the diameters of the first section and the second having a ratio of 2 and the heating systems of both sections being autonomous.
4. Method according to claim 2, characterized in that the heating system of the depolymerization section is made in the form of a rotary apparatus.
5. A method according to any one of claims 1 to 4, characterized in that for depressant additives to diesel fuels having the following molecular weight characteristics: a molecular weight of 800-3000 and a molecular weight distribution of 1.5-3, the first stage is heating And depolymerization during thermal degradation is carried out at 355-365 ° C in 2-5 minutes.
6. A method according to any one of claims 1 to 4, characterized in that for the resulting viscous additives to lubricating oils having the following molecular weight characteristics: a molecular weight of 8000-100000 and a molecular weight distribution of 2-4, the first stage is heating and Depolymerization during thermal degradation is carried out at 330-350 ° C during 2-6 min.
print version
Date of publication 07.04.2007gg
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