CS225984B1 - Apparatus for determining polymerization activity of catalysts - Google Patents

Description

The invention relates to a device for determining the activity of catalysts in the gas phase polymerization of olefins.

In the study of polymerization catalysts, polymerization tests are used, among other methods, in which polymerization of the selected monomer by the studied catalyst is carried out under defined conditions (pressure, temperature, monomer and catalyst concentration). From the polymerization process, the amount of polymer formed and the evaluation of the properties of the obtained polymer, the properties of the catalyst system are judged.

The most studied parameters of polymerization catalysts are their activity and productivity depending on the reaction conditions and the composition of the polymerization system. To measure these parameters, many methods and devices have been proposed that use different principles. Most often, the polymerization is carried out in a glass or metal reactor under selected constant conditions. After some time the polymerization is interrupted, the polymer is isolated and weighed. From the known mass of catalyst and from the mass of polymer isolated, the average activity, which can be expressed, for example, in moles of polymerized monomer per g of catalyst per hour, is determined, or the amount of polymer per unit mass of active catalyst component Me is determined:

í ^ at. ^{= mo1} ^ ^M / S Cat.

. = moles M / g Me.

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The advantage of this method is that a sufficient amount of polymer can be prepared to permit a basic evaluation of the physical and mechanical properties of the polymer. The disadvantage is that the measured constant or Κ ^ θ characterizing the activity of the catalyst is an average value which does not say anything about the kinetic course of the polymerization.

Equipment used to study polymerization catalysts such as the dilatometric method described in Collection Czech. Chem. Conr. 24, 3703 (1959), although it allows the measurement of polymerization clutter, but is limited to liquid phase polymerization and provides only a small amount of a polymer that is not sufficient to evaluate mechanical properties.

The introduction of a fluidized bed gas phase alpha-olefin polymerization process into industrial production has led to the requirement to test catalysts by a gas phase polymerization test. The total lab instability was overcome by solving a special reactor, which is the subject of CS 178207 and CS 178250. Despite the considerable predicative ability of the polymerization test with the reactor according to the above-mentioned author's certificates, this procedure did not allow measurement of polymerization kinetics in one experiment. Kinetic data could be obtained on this reactor only by a series of β measurements of different length of polymerization time.

It has now been possible to obtain not only the average polymerization constant in a single polymerization test, but also to record the kinetic curve of the polymerization throughout the experiment in a single polymerization test. This means not only an increase in the informative ability of the polymerization test, but also a considerable saving of time, chemicals and energy and a reduction in the variance of the measured values.

SUMMARY OF THE INVENTION The present invention provides a device for determining the polymerization activity of catalysts from the monomer consumption time during a polymerization in a pressurized reactor, wherein the polymerization reactor is equipped with a contact pressure gauge, gas flow control solenoid valve, switching relay and electronic control and registration device.

The device according to the invention is shown in the drawing, wherein 1 is a polymerization reactor for olefin polymerization, 2 contact pressure gauge, 2 solenoid valve, gas flow control, 2 switching relays and 6 electronic control and registration devices.

The principle of operation of the device according to the invention is that when the monomer pressure decreases in the polymerization reactor 1 connected to the contact pressure gauge 2. The contact pressure gauge 2 gives an impulse * via the switching relay 2 and the electronic control and registration device 6 which opens the solenoid valve 2. at the same time it records the number of impulses to open the solenoid valve 2 at a specified time interval. The control and registration device 6 then records, according to the set code, the number of pulses at individual time intervals, with the differential and integral kinetic curve of monomer consumption throughout the polymerization being displayed directly on the recorder.

From the total polymerization yield or the known flow through the flow control γ and the known number of valve openings 2, the kinetic curve of the polymerization in mole monomer / g cat. Versus reaction time can be calculated.

The polymerization reactor 1 is a pressure vessel with a stirrer and a heating cooling jacket, preferably a laboratory reactor for the gas phase olefin polymerization according to Cs 178207 or CS 178250,

225 984 contact pressure gauge 2 has a range of 4 MPa and an accuracy class of at least 2.5%, solenoid valve 2 ^and switching relay 2 Commercial products are common. Various known elements controlling the gas flow at a certain pressure drop such as nozzles, orifices or control valves may be used as gas flow control 6. The control and registration electronic device 6 must allow regulation of the opening of the solenoid valve 2 during pressure drop and rise in polymerization reactor 1 a contact pressure gauge 2 and the register number of the solenoid valve 2 during ^the polymerization.

The control and registration device 6 need not be permanently connected to the polymerization reactor 1, so that it can also be used for other purposes. It can also advantageously include a switching relay 2 ·

The invention will be illustrated by the following examples in which one possible embodiment of the apparatus and its use for determining the kinetics of ethylene gas-phase polymerization is described.

Example 1

To evaluate the polymerization activity of a Davison 952 silica-based catalyst containing 0.3 wt. The stainless steel reactor, designed to a pressure of 2.5 MPa, at a volume of 1.5 liters, is equipped with a device for feeding the catalyst and allowing forced circulation of the gaseous monomer, catalyst and polymer formed.

The reactor, free of traces of oxygen and moisture by heating to 90 ° C with a stream of pure nitrogen, is charged with ethylene at a pressure of 20 bar.

The polymerization is initiated by introducing 0.120 g of catalyst. As a result of the polymerization, the ethylene pressure in the reactor decreases until the contact pressure gauge 2 sends an electrical pulse to the relay 2 which, in cooperation with the electronic control device 6, opens the solenoid valve 2. of monomer, the monomer flows into the reactor until a pressure is reached at which the manometer contacts open. The size of the nozzle is chosen such that the feed rate of ethylene relative to its consumption in polymerization is 10 to 10,000 times, preferably 20 to 1,000 times higher. After 240 minutes, the polymerization was terminated by withdrawing the monomer and polymer accumulated in the reactor and removing it. During the polymerization, the number of openings of the solenoid valve is read at 10 minute intervals by the device described. The activity of the catalyst expressed by the polymerization constant is calculated from the total weight of the polymer obtained, ^{and the} kinetic curve of the ethylene polymerization on the catalyst expressed in Table 1 is determined at ten minute intervals.

Example 2

Using the apparatus described in Example 1, except that a needle control valve was used as the ethylene flow regulator (4) and the ethylene pulse size was kept constant by setting a stable opening time of the solenoid valve (3) by the electronic regulator (6). The catalyst prepared by depositing 1% Cr on silica Davison 952 was evaluated. It was polymerized under the same conditions as in Example 1 for 180 minutes.

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Table 1 Kinetic curve of ethylene polymerization

Catalyst weight: 0.120 g

Polymer weight: 63.0 g «cat. = ^{135 '4} interval pulse number of moles CGH ^ / g catalyst moles CGH ^

1 - - - 2 - - - 3 6 0.73 0.73 4 7 0.86 1.59 5 8 0.98 2.57 6 8 O _ř 98 3.55 7 8 0.98 4.53 8 8 0.98 5,51 9 7 0.86 6.36 10 8 0.98 7.34 11 7 0.86 8.20 12 7 0.86 9.06 13 8 0.98 10,04 14 7 0.86 10.89 15 Dec 7 0.86 11.75 16 7 0.86 12.61 17 7 0.86 13.46 18 7 0.86 14.32 ^{19 Dec} 7 0.86 15.18 20 May 8 0.98 16.16 21 7 0.86 17.01 22nd 7 0.86 17.87 23 7 0.86 18.73 24 5 0.61 19.34

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Table 2 Kinetic polymerization curve

Catalyst weight: 0.120 g

Polymer weight: 44.0 g

Skat. = ¹²⁰ > ⁷ interval number of pulses moles CgH4 / g catalyst moles

1 2 - - - 3 13 0.98 0.98 4 23 1.73 2.71 5 30 2.26 4.96 6 25 1.88 6.84 7 17 1,23 8.12 8 12 0.90 9.02 9 10 0.75 9.78 10 8 0.80 10.38 11 7 0.53 10.90 12 5 0.38 11.28 13 4 0.30 11.58 14 5 0.38 11.96 15 Dec 3 0.23 12.18 18 5 0.38 12.56 17 3 0.23 12.78 18 2 0.15 12.93

SUBJECT OF THE INVENTION

Claims (1)

Apparatus for determining the polymerization activity of catalysts from the time of monomer consumption during polymerization in a pressure reactor, characterized in that the polymerization reactor (1) is equipped with a contact pressure gauge (2), a solenoid valve (3) with gas flow control (4), switching relay (5) and electronic control and registration equipment (6).