Removal of catalyst and/or cocatalyst residues in a polyolefin manufacturing process
View Patent ↗The invention relates to an improved process for the manufacture of an olefin polymer composition in which corrosive trace cocatalyst and catalyst residues are removed from the hydrocarbon gas recycle stream prior to compression and re-use in the polymerization zone(s).
1. A process for treating an effluent stream from an olefin polymerization reactor, said effluent stream comprising a polymer component and a non-polymer component, the non-polymer component containing one or more catalysts and/or aluminum alkyl cocatalysts, the process comprising the step of scrubbing at least part of the non-polymer component with an oleic acid and light-oil mixture in order to reduce the concentration of catalysts and/or aluminum alkyl cocatalysts and produce a purified stream, wherein the olefin polymerization reactor produces more than 16,000 pounds of polymerized olefin per hour.
2. A process according to claim 1 wherein the step of scrubbing is performed at a pressure ranging from 1 to 20 psig.
3. A process according to claim 1 wherein the purified stream contains less than 0.5 parts per million of catalysts and less than 0.5 parts per million of cocatalysts.
4. A process according to claim 1 wherein the concentration of catalyst in the non-polymer component in the scrubbing step is greater than 0.55 parts per million and the concentration of cocatalyst is greater than 0.53 parts per million.
5. A process according to claim 1 wherein the purified stream is compressed to greater than 150 psig.
6. A process according to claim 3 further comprising the step of recycling the purified stream to one or more polymerization reactors.
7. A process according to claim 6 further comprising the step of compressing the purified stream in a compressor before the step of recycling, wherein the temperature within the compressor is between 100 and 250 degrees Fahrenheit.
8. A process according to claim 1 wherein the catalyst is a Ziegler catalyst and the cocatalyst is a triethylaluminuin compound.
9. A process according to claim 1 , wherein the step of scrubbing is carried out in a scrubbing column having one or more stages and wherein the mixture of light oil and oleic acid is circulated through the stages of the column.
10. A process according to claim 1 , wherein the light oil is a mixture of oils having a viscosity ranging from 1 to 13 centipoise and a flash point of greater than 175° F.