Polypropylene PGC Applications

Polypropylene Plant A mixture of propylene plus a second compound called a co-monomer Chemical used for the co-monomer varies depending on the desired properties Ethylene, butene, or hexene Typical polypropylene plant design with the chemical reactions are done in two stages

Reactors 1st Stage – Slurry Reactor 2nd Stage – Co-monomer Reactor Polymer-grade propylene enters the first reactor along with the catalyst Hydrogen is also added to control the size of the polymer molecule and sets the overall melting point of the final product Slurry – an inert diluent compound such as hexane or butane is added 2nd Stage – Co-monomer Reactor Chemically-active mixture leaves the first reactor and enters the second reactor Fresh propylene and the co-monomer are added to finish the reaction process

Flash Tank Finished polymer leaves the second reactor, along with the diluent and any unreacted components and enters a flash tank Unreacted monomers and diluent vaporizes and leaves the top of the vessel The polymer settles out the bottom to be extruded into plastic sheets or pellets

Diluent Recovery System and Stripper Separate the diluent from any unreacted monomers The diluent is recycled back to the feed of the reactor The unreacted propylene and co-monomer enter a stripper where they are separated from each other The propylene is recycled to the feed of the first reactor and the co-monomer is recycled to the feed of the second reactor

Typical Polypropylene Plant GC #7 GC #6 GC #5 GC #1 GC #2 GC #3 GC #4

Improving Polypropylene Performance with PGC’s It is critical that the quality of the plastic be high and consistent To insure this high quality, it is important that the ingredients fed into the polymer reactor be tightly controlled GC #1, GC #2, GC #3, and GC #4 are used to provide live feedback on the quality of the feed streams GC #1 – Propylene feed quality GC #2 – Diluent feed impurities GC #3 – Hydrogen feed impurities GC #4 – Propylene / Co-monomer feed impurities

Additional Measurements Flash Tank Measurements Feedback to the control system on how the reactions are progressing in the reactors is common through measuring the flash tank off-gases Unreacted components can indicate the quality of reactions occuring Monitor the recycle streams Diluent recycle stream Propylene recycle stream

PGC Analysis Summary GC # Stream Components Measured Measurement Objective 1 Propylene Feed C2, C3, MA, PD Propylene feed purity 2 Diluent feed Hydrocarbons Diluent feed purity; exact components vary with diluent used 3 Hydrogen feed Hydrogen feed purity 4 Co-monomer feed Co-monomer feed purity; exact components vary with co-monomer used 5 Flash tank off-gas H2, C3=, comonomer Feedback to control system on reaction kinetics 6 Diluent recycle Monitor impurities recycled with the diluent 7 Propylene recycle H2, comonomer Monitor impurities recycled with the propylene

GC #1 and GC #4 – Example 1

GC #1 and GC #4 – Chromatogram

GC #1 and GC #4 – Example 2

GC #1 and GC #4 – Chromatogram 1

GC #1 and GC #4 – Chromatogram 2

GC #1 and GC #4 – Chromatogram 3

GC #5 – Example

GC #5 – Chromatogram

GC #6 and GC #7 – Example

GC #6 and GC #7 – FID, Stream 1

GC #6 and GC #7 – FID, Stream 2

GC #6 and GC #7 – FID, Stream 3

GC #6 and GC #7 – TCD, Stream 1

GC #6 and GC #7 – TCD, Stream 2