Method for producing an olefin polymerization catalyst
The present invention is directed to a process for producing a solid olefin polymerization catalyst component from an emulsion wherein the particle size of the solid catalyst or the droplet size of the emulsion is controlled. The actual size of the droplets or the solid catalyst particles is measured, or alternatively, both are measured. Then a difference between the actual size and the set point is calculated and the process is controlled based on the difference.
1. A process for producing a solid olefin polymerization catalyst component from an emulsion comprising the steps of:
(i) providing a set point for a particle size of the solid olefin polymerization catalyst component to a first controller;
(ii) producing in an emulsification stage an emulsion comprising droplets of a dispersed phase in a continuous phase, the droplets comprising a transition metal compound, wherein the production of the emulsification stage is controlled by a second controller, and wherein the second controller controls at least one manipulated variable;
(iii) solidifying the droplets to produce the solid olefin polymerization catalyst component in a solidification stage;
(iv) measuring the particle size of the solid olefin polymerization catalyst component in or after said solidification stage and determining a measured size for the particles from said measurement;
(v) calculating a difference between said set point for the particle size of the solid olefin polymerization catalyst and said measured size for the particles of the solid olefin polymerization catalyst; and
(vi) establishing a control signal based on said difference and using said control signal for adjusting at least one manipulated variable via the second controller, wherein the at least one manipulated variable is a process variable which influences the droplet size of the emulsion.
2. The process according to claim 1 wherein the process is conducted continuously by introducing a stream comprising the starting materials into the emulsification stage, withdrawing a stream comprising the emulsion from the emulsification stage, passing the stream comprising the emulsion into the solidification stage, and withdrawing a stream comprising solid catalyst particles from the solidification stage.
3. The process according to claim 1 wherein the emulsification stage is conducted in an agitated vessel comprising an agitator.
4. The process according to claim 3 wherein the at least one manipulated variable comprises the rotation speed of the agitator.
5. The process according to claim 1 wherein the emulsification stage is conducted in rotor-stator equipment.
6. The process according to claim 5 wherein the at least one manipulated variable comprises the rotation speed of the rotor.
7. The process according to claim 1 wherein the emulsification stage is conducted in a static mixer.
8. The process according to claim 7 wherein the at least one manipulated variable comprises the flow rate of the emulsion through the static mixer.
9. The process according to claim 1 wherein the step of measuring the particle or droplet size comprises a step of photographing the particles or the droplets, or determining the size by laser diffraction, laser backscattering or by ultrasonic extinction.
10. The process according to claim 1 comprising the additional steps of:
providing a signal corresponding to the set point to the first controller;
establishing a signal proportional to the measured size for the particles or droplets;
directing the signal proportional to the measured size of particles or droplets to the first controller;
calculating the difference between the signal proportional to the set point and the signal proportional to the measured size of particles or droplets;
establishing the control signal based on said difference.
11. The process according to claim 1 comprising the step of recovering the solid olefin polymerization catalyst component.
12. The process according to claim 1 comprising repeating steps (ii)-(vi) until the measured particle size for the solid olefin polymerization catalyst is equal to the set point for the particle size of the solid olefin polymerization catalyst.