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 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 greater than the feed rate utilizing a recirculating pump operating at a pressure differential, delta P, corresponding to a recirculating flow;
(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, 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.
2. The method according to claim 1 , wherein the delta P and polymerization reaction are controlled to provide a linear velocity of the reaction mixture of from 11 ft/sec to 20 ft/sec in the one or more reaction tubes of the loop reactor.
3. The method according to claim 2 , wherein the delta P and polymerization reaction are controlled to provide a linear velocity of the reaction mixture of at least 12 ft/sec in the one or more reaction tubes of the loop reactor.
4. The method according to claim 2 , wherein the delta P and polymerization reaction are controlled to provide a linear velocity of the reaction mixture of at least 13 ft/sec in the one or more reaction tubes of the loop reactor.
5. The method according to claim 2 , wherein the delta P and polymerization reaction are controlled to provide a linear velocity of the reaction mixture of at least 14 ft/sec in the one or more reaction tubes of the loop reactor.
6. The method according to claim 2 , wherein the delta P and polymerization reaction are controlled to provide a linear velocity of the reaction mixture of at least 15 ft/sec in the one or more reaction tubes of the loop reactor.
7. The method according to claim 1 , with the further proviso that if the conversion rate of isobutylene is less than 55%, the pressure delta and the polymerization of the reaction mixture in the one or more reaction tubes is at least 14 ft/sec.
8. The method according to claim 1 , with the further proviso that if the conversion rate of isobutylene is less than 55%, the delta P and the polymerization of the reaction mixture in the one or more reaction tubes is at least 15 ft/sec.
9. The method according to claim 1 , wherein the heat transfer coefficient between the reaction mixture and the heat transfer medium is from 50 BTU/hr ft 2 ° F. to 150 BTU/hr ft 2 ° F.
10. The method according to claim 9 , wherein the heat transfer coefficient between the reaction mixture and the heat transfer medium is at least 55 BTU/hr ft 2 ° F.
11. The method according to claim 9 , wherein the heat transfer coefficient between the reaction mixture and the heat transfer medium is at least 60 BTU/hr ft 2 ° F.
12. The method according to claim 9 , wherein the heat transfer coefficient between the reaction mixture and the heat transfer medium is at least 70 BTU/hr ft 2 ° F.
13. The method according to claim 1 , wherein the polyisobutylene withdrawn from the loop reactor is a highly reactive polyisobutylene with a number average molecular weight of from 500 to 4000 Daltons.
14. The method according to claim 13 , wherein the loop reactor is operated with a catalyst complex turnover number of from 650 to 1350 lbs. polymer/lbs. catalyst when the polyisobutylene withdrawn from the loop reactor is a highly reactive polyisobutylene with a number average molecular weight of from 1500 to 4000 Daltons.
15. The method according to claim 13 , wherein the loop reactor is operated with a catalyst complex turnover number of from 800 to 1500 lbs. polymer/lbs. catalyst complex when the polyisobutylene withdrawn from the loop reactor is a highly reactive polyisobutylene with a number average molecular weight of from 500 to 1500 Daltons.
16. The method according to claim 15 , wherein the loop reactor is operated with a catalyst complex turnover number of at least 900 lbs. polymer/lbs. catalyst complex.
17. The method according to claim 1 , wherein the polymer withdrawn from the loop reactor is a mid-range vinylidene polyisobutylene polymer with a number average molecular weight of from 500 Daltons to 4000 Daltons.
18. The method according to claim 17 , wherein the loop reactor is operated with a catalyst complex turnover number of from 1600 lbs. polymer/lbs. catalyst complex to 3000 lbs. polymer/lbs. catalyst complex.
19. The method according to claim 17 , wherein the loop reactor is operated with a catalyst complex turnover number of at least 1800 lbs. polymer/lbs. catalyst.
20. The method according to claim 1 , wherein the loop reactor has a plurality of reaction tubes.