Process for removal of acrolein from acrylonitrile product streams
View Patent ↗Acrolein is removed from a process stream such as a process stream generated in the manufacture of acrylonitrile. The process includes reacting the acrolein with a compound containing a reactable thiol or hydroxyl moiety in the presence of an acid catalyst. The present process provides for a refined process stream that contains no more than 5 ppm by weight unreacted acrolein.
1. A method for removing acrolein from an acrylonitrile process stream containing acrolein comprising
(a) providing an acrylonitrile process stream comprising acrolein; and
(b) reacting said acrolein in the presence of an acid catalyst with a scavenger compound containing a reactable thiol or hydroxyl moiety to form an acrolein derivative in a refined process stream.
2. The method of claim 1 wherein said acid catalyst is a solid acid catalyst.
3. The method of claim 1 wherein said process stream further comprises said acid catalyst.
4. The method of claim 1 further comprising adding said acid catalyst to said process stream prior to said reaction step (b).
5. The method of claim 4 wherein said acid catalyst is selected from the group consisting of glycolic acid and acetic acid.
6. The method claim 1 wherein said process stream further comprises water.
7. The method of claim 6 wherein said process stream includes 2.0% to 3.0% by weight water at commencement of said reaction step (b).
8. The method of claim 1 further comprising the step of reducing the water content of said process stream to no more than 0.5% water.
9. The method of claim 1 further comprising separating said acrolein derivative from said refined process stream.
10. The method of claim 9 comprising distillation of said refined process stream.
11. The method of claim 1 wherein said reaction step (b) is conducted at a pH of between 3.0 and 7.0.
12. The method of claim 1 wherein said acrolein derivative is an acrolein acetal.
13. The method of claim 1 wherein said scavenger compound contains a reactable thiol moiety.
14. The method of claim 13 wherein said scavenger compound is selected from the group consisting of mercaptoacetic acid, 2-mercaptoethanol, 2-aminoethanethiol and ethylene glycol bisthioglycolate.
15. The method of claim 1 wherein said acrolein derivative is an acrolein thioacetal.
16. The method of claim 1 wherein said reacting step is performed in the substantial absence of a cyanide compound.
17. The method of claim 1 wherein said process stream further comprises acrylic acid.
18. The method of claim 1 wherein said scavenger compound contains a reactable hydroxyl moiety.
19. A method of removing acrolein from an acrylonitrile process stream comprising
(a) providing an acrylonitrile process stream comprising acrolein; and
(b) reacting said acrolein with a scavenger compound containing a reactable thiol or hydroxyl moiety at a pH of between 3.0 and 7.0 to form an acrolein derivative in a refined process stream.