Distillation process for production of acrylic acid

1. A method for producing acrylic acid, comprising:

(a) providing a feedstock stream comprising beta propiolactone and a solvent;

(b) directing the feedstock stream to a reaction zone, wherein the feedstock stream is contacted with a polymerization catalyst and wherein at least a portion of the beta propiolactone is converted to poly(propiolactone);

(c) maintaining the reaction zone at a temperature at or above the pyrolysis temperature of poly(propiolactone);

(d) thermal decomposing the poly(propiolactone) in the reaction zone to produce acrylic acid;

(e) withdrawing a distillation stream of the solvent from the reaction zone; and

(f) withdrawing an acrylic acid product stream from the reaction zone; wherein steps (b) to (d) occur in the same reaction zone.

2. The method of claim 1 , wherein the solvent has a boiling point below 160° C.

3. The method of claim 1 , wherein the solvent is tetrahydrofuran.

4. The method of claim 1 , further comprising providing a second solvent and directing a second solvent stream to the reaction zone.

5. The method of claim 4 , wherein the second solvent stream comprises the second solvent and the polymerization catalyst.

6. The method of claim 4 , further comprising withdrawing a distillation stream of the second solvent from the reaction zone.

7. The method of claim 1 , further comprising directing the distillation stream of the first solvent to a carbonylation reactor used to provide the beta propiolactone.

8. The method of claim 1 , further comprising withdrawing a recycling stream of the polymerization catalyst from the reaction zone.

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

wherein p is 0 to 9.

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

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

11. The method of claim 1 , wherein the polymerization catalyst is a heterogenous catalyst.

12. The method of claim 11 , wherein the polymerization catalyst is provided as a fixed bed of polymerization catalyst.

13. The method of claim 1 , further comprising withdrawing a distillation stream of the second solvent.

14. The method of claim 1 , wherein heat is generated in the reaction zone, and the method further comprises capturing at least a portion of the heat generated and directing the captured heat to other processes.

15. The method of claim 14 , wherein the captured heat is directed to a carbonylation reaction used to provide the beta propiolactone.

16. The method of claim 1 , further comprising using low grade heat to maintain temperature of the acrylic acid product stream above its boiling point.