Propylene/butene interpolymer production system and method
View Patent ↗The present disclosure provides a process. In an embodiment, the process includes producing a propylene-based polymer in a gas-phase polymerization reactor ( 10 ) under polymerization conditions. The polymerization conditions include a combined propylene-plus-propane partial pressure from 290 psia to 450 psia. The process further includes maintaining the combined propylene-plus-propane partial pressure in the range from 290 psia to 450 psia while simultaneously: (i) reducing propylene partial pressure in the gas-phase polymerization reactor; (ii) adding propane to the gas-phase polymerization reactor; (iii) introducing at least one C4-C10 comonomer into the gas-phase polymerization reactor ( 26 ); and forming a propylene/C4-C10 interpolymer in the gas-phase polymerization reactor ( 44 ).
1. A process comprising:
(A) producing a propylene-based polymer in a gas-phase polymerization reactor under polymerization conditions comprising a combined propylene-plus-propane partial pressure from 290 psia to 450 psia;
(B) maintaining the combined propylene-plus-propane partial pressure in the range from 290 psia to 450 psia while simultaneously:
(i) reducing propylene partial pressure in the gas-phase polymerization reactor;
(ii) adding propane to the gas-phase polymerization reactor;
(iii) introducing at least one C 4 -C 10 comonomer into the gas-phase polymerization reactor; and
(C) forming a propylene/C 4 -C 10 interpolymer in the gas-phase polymerization reactor.
2. The process of claim 1 comprising maintaining the combined propylene-plus-propane partial pressure from 290 psia to 450 psia during the forming of the propylene/C 4 -C 10 interpolymer.
3. The process of claim 1 comprising collecting propane during the producing step and adding the collected propane to the gas-phase polymerization reactor during the adding step (ii).
4. The process of claim 1 comprising performing the forming step within 30 seconds to 48 hours after reducing the propylene partial pressure.
5. The process of claim 1 , comprising producing the propylene-based polymer at a rate from 60% to at least 100% of nameplate rate.
6. The process of claim 1 comprising producing the propylene/C 4 -C 10 interpolymer at greater than 60% of nameplate rate.
7. The process of claim 1 wherein the introducing step comprises introducing butene comonomer into the gas-phase polymerization reactor and forming a propylene/butene copolymer.
8. The process of claim 1 wherein the introducing step comprises introducing ethylene comonomer and butene comonomer in the gas-phase polymerization reactor and forming a propylene/ethylene/butene terpolymer.
9. The process of claim 8 comprising forming propylene/ethylene/butene terpolymer at a rate from 60% to at least 100% of nameplate within 1 hour to 20 hours from performance of the introducing step.