Polyisobutylene prepared at high velocity and circulation rate
View Patent ↗A method of making a polyisobutylene polymer in a recirculating loop reactor with one or more reaction tubes in contact with a heat transfer medium includes controlling the delta P and polymerization reaction to provide a linear velocity of the reaction mixture of at least 11 ft/sec in the one or more tubes of the loop reactor and/or controlling the delta P and polymerization reaction of steps (b) and (c) to provide a recirculation ratio of the recirculation rate to the feed rate of at least 30:1. Typically, the process utilizes a recirculating pump operating at a pressure differential of from 35 psi to 70 psi.
1. A method of making a polyisobutylene polymer in a recirculating loop reactor with one or more reaction tubes in contact with a heat transfer medium comprising:
(a) feeding isobutylene, catalyst and optionally other feed components to a residual reactor stream at a feed rate to form a reaction mixture;
(b) recirculating the reaction mixture in the one or more reaction tubes of the loop reactor at a recirculation rate utilizing a recirculating pump operating at a pressure differential, delta P, of from 35 psi to 70 psi;
(c) polymerizing the reaction mixture in the one or more tubes of the loop reactor to convert isobutylene to polyisobutylene polymer at a conversion rate expressed in %, w/w, while cooling the one or more tubes of the loop reactor with the heat transfer medium;
(d) controlling the recirculation rate, the delta P and polymerization reaction of steps (b) and (c) to provide polyisobutylene polymer at a particular molecular weight having a lower polydispersity as compared to polyisobutylene polymer produced in the reactor operated with a Delta P lower than 35 psi at substantially the same reactor temperature and diluent level, wherein substantially the same reactor temperature means the reactor temperatures are within 5° F. and substantially the same diluent level means within 1 wt %; and
(e) withdrawing polyisobutylene polymer from the loop reactor.
2. The method according to claim 1 , wherein the conversion of isobutylene to polymer is from 50% to 80%.
3. The method according to claim 2 , wherein the conversion of isobutylene to polymer is at least 55%.
4. The method according to claim 2 , wherein the conversion of isobutylene to polymer is at least 65%.
5. The method according to claim 2 , wherein the conversion of isobutylene to polymer is at least 75%.
6. The method according to claim 1 , wherein the delta P of the recirculating pump is at least 40 psi.
7. The method according to claim 1 , wherein the delta P of the recirculating pump is at least 50 psi.
8. The method according to claim 1 , operated at a recirculation ratio of from 30:1 to 50:1.
9. The method according to claim 8 , operated at a recirculation ratio of at least 35:1.
10. The method according to claim 9 , operated at a recirculation ratio of at least 45:1.
11. A method of making a polyisobutylene polymer in a recirculating loop reactor with one or more reaction tubes in contact with a heat transfer medium comprising:
(a) feeding isobutylene, catalyst and optionally other feed components to a residual reactor stream at a feed rate to form a reaction mixture;
(b) recirculating the reaction mixture in the one or more reaction tubes of the loop reactor at a recirculation rate greater than the feed rate utilizing a recirculating pump operating at a pressure differential, delta P, of from 35 psi to 70 psi;
(c) polymerizing the reaction mixture in the one or more tubes of the loop reactor to convert isobutylene to polyisobutylene polymer at a conversion rate expressed in %, w/w, while cooling the one or more tubes of the loop reactor with the heat transfer medium;
(d) controlling the recirculation rate, the delta P and polymerization reaction of steps (b) and (c) to provide a linear velocity of the reaction mixture of at least 11 ft/sec in the one or more tubes of the loop reactor with the proviso that if the conversion of isobutylene is less than 55%, the recirculation rate, the delta P and the polymerization reaction of steps (b) and (c) are controlled to provide a linear velocity of the reaction mixture in the one or more reaction tubes of at least 13.5 ft/sec; and
(e) withdrawing polyisobutylene polymer from the loop reactor.
12. The method according to claim 11 , wherein the delta P of the recirculating pump is at least 40 psi.
13. The method according to claim 11 , wherein the delta P of the recirculating pump is at least 50 psi.
14. A method of making a polyisobutylene polymer in a recirculating loop reactor with one or more reaction tubes in contact with a heat transfer medium comprising:
(a) feeding isobutylene, catalyst and optionally other feed components to a residual reactor stream at a feed rate to form a reaction mixture;
(b) recirculating the reaction mixture in the one or more reaction tubes of the loop reactor at a recirculation rate greater than the feed rate utilizing a recirculating pump operating at a pressure differential, delta P, of from 35 psi to 70 psi;
(c) polymerizing the reaction mixture in the one or more tubes of the loop reactor to convert isobutylene to polyisobutylene polymer at a conversion rate expressed in %, w/w, while cooling the one or more tubes of the loop reactor with the heat transfer medium;
(d) controlling the recirculation rate, the delta P and polymerization reaction of steps (b) and (c) to provide a linear velocity of the reaction mixture of at least 11 ft/sec in the one or more tubes of the loop reactor with the proviso that if the conversion of isobutylene is less than 55%, the recirculation rate, the delta P and the polymerization reaction of steps (b) and (c) are controlled to provide a linear velocity of the reaction mixture in the one or more reaction tubes of at least 13.5 ft/sec and wherein further, there is provided a recirculation ratio of the recirculation rate to the feed rate of at least 30:1; and
(e) withdrawing polyisobutylene polymer from the loop reactor.
15. The method according to claim 14 , wherein the ratio of the recirculation rate to the feed rate is from 30:1 to 50:1.
16. The method according to claim 14 , wherein the delta P of the recirculating pump is at least 40 psi.
17. The method according to claim 14 , wherein the delta P of the recirculating pump is at least 50 psi.
18. The method according to claim 14 , wherein the delta P of the recirculating pump is at least 55 psi.
19. The method according to claim 14 , operated continuously at a residence time of from 1 to 10 minutes.
20. The method according to claim 14 , operated continuously at a residence time of from 3 to 6 minutes.