Process and system for production of polypropiolactone

1. A continuous method for producing polypropiolactone (PPL), comprising:

providing feedstock streams of ethylene oxide (EO) and carbon monoxide, wherein the feedstock streams are optionally combined;

directing the feedstock streams to a first reaction zone;

contacting the feedstock streams with a carbonylation catalyst in the presence of a carbonylation solvent in the first reaction zone to convert at least a portion of the EO to a beta propiolactone (BPL) product stream, wherein the BPL product stream comprises BPL, carbonylation catalyst, and carbonylation solvent;

separating at least a portion of carbonylation catalyst from the BPL product stream to produce a carbonylation catalyst recycling stream and a processed BPL product stream, wherein the processed BPL product stream comprises BPL and carbonylation solvent;

directing the processed BPL product stream to a carbonylation solvent removal zone;

removing at least a portion of the carbonylation solvent from the processed BPL product stream to produce a polymerization feed stream, wherein the polymerization feed stream comprises BPL;

directing the polymerization feed stream to a second reaction zone;

introducing a polymerization solvent into the polymerization feed stream, prior to contacting the polymerization feed stream with a polymerization catalyst in the second reaction zone, wherein the polymerization solvent is different from the carbonylation solvent; and

contacting BPL in the polymerization feed stream with the polymerization catalyst in the second reaction zone to produce PPL.

2. The method of claim 1 , wherein the removing of at least a portion of the carbonylation solvent from the processed BPL product stream comprises distilling at least a portion of the carbonylation solvent and withdrawing a distillation stream of the carbonylation solvent.

3. The method of claim 1 , wherein the carbonylation solvent has a boiling point below 160° C. at 1 atm.

4. The method of claim 1 , wherein the second reaction zone is a reactive extruder.

5. The method of claim 1 , wherein the separating of at least a portion of carbonylation catalyst from the BPL product stream comprises nanofiltration on a nanofiltration membrane.

6. The method of claim 1 , further comprising returning the carbonylation catalyst recycling stream returned to the first reaction zone.

7. The method of claim 1 , wherein heat is generated from contacting of the BPL in the polymerization feed stream with the polymerization catalyst, wherein at least a portion of the heat is used to maintain a temperature of the second reaction zone.

8. The method of claim 1 , wherein heat is generated from contacting of the BPL in the polymerization feed stream with the polymerization catalyst, and the method further comprises capturing at least a portion of the heat, and directing the captured heat to other processes.

9. The method of claim 8 , wherein the heat is directed to the distillation of the carbonylation solvent.

10. The method of claim 1 , wherein the polymerization feed stream is neat when introduced into the second reaction zone.

11. The method of claim 1 , wherein the polymerization catalyst is a salt of a compound of formula:

wherein p is 0 to 9.

12. The method of claim 1 , wherein the polymerization catalyst is a salt of a compound of formula:

wherein p is from 0 to 9, and R a is a non-volatile moiety.

13. The method of claim 1 , wherein the carbonylation catalyst comprises a metal carbonyl.

14. The method of claim 1 , wherein the carbonylation solvent comprises a polar donating solvent.

15. The method of claim 1 , wherein the polymerization solvent is less polar than the carbonylation solvent as measured by dielectric constant.

16. The method of claim 1 , wherein the polymerization solvent has a dielectric constant at 20° C. of less than about 13.6.

17. The method of claim 1 , wherein the polymerization solvent comprises a Lewis base and is less polar than 1,3-dioxane, ortho-difluorobenzene, or metadifluorobenzene.

18. The method of claim 1 , wherein the polymerization solvent comprises a Lewis base with substantially a same polarity as 1,4-dioxane.