Process for preparing neopentyl glycol by cracking high boilers occurring in the production process

1. A process for obtaining neopentyl glycol from the high boilers formed in the reaction of formaldehyde with isobutyraldehyde, characterized in that the high boilers are separated off from the process for preparing neopentyl glycol and treated in the liquid phase with hydrogen in the absence of solvent and in the presence of a copper-chromite catalyst at a temperature of from 140 to 200° C. and a pressure of from 7 to 28 MPa in a separate hydrogenation reactor and the cracking products obtained are worked up by distillation.

2. The process as claimed in claim 1 , characterized in that the cracking products obtained are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

3. The process as claimed in claim 1 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

4. The process as claimed in claim 1 , characterized in that the treatment with hydrogen is carried out at a temperature of from 160 to 200° C. and a pressure of from 7 to 20 MPa.

5. The process as claimed in claim 4 , characterized in that the cracking products obtained are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

6. The process as claimed in claim 4 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

7. The process as claimed in claim 6 , characterized in that the cracking products obtained are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

8. In a process for preparing neopentyl glycol by reaction of formaldehyde with isobutyraldehyde and hydrogenation of the reaction products in a first reactor whereby high boilers are formed, the improvement comprising obtaining neopentyl glycol from the high boilers by:

a.) separating the high boilers from said process for preparing neopentyl glycol; and

b.) thereafter cracking and hydrogenating said high boilers in the liquid phase in the absence of solvent and in the presence of a copper-chromite catalyst at a temperature of from 140 to 200° C. and a pressure of from 7 to 28 MPa in a hydrogenation reactor separate from said first reactor; and

c.) thereafter recovering neopentyl glycol obtained by cracking and hydrogenation of said high boilers.

9. The process as claimed in claim 8 , characterized in that the products obtained by cracking and hydrogenation of said high boilers are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

10. The process as claimed in claim 8 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

11. The process as claimed in claim 8 , characterized in that the treatment with hydrogen is carried out at a temperature of from 160 to 200° C. and a pressure of from 7 to 20 MPa.

12. The process as claimed in claim 11 , characterized in that the products obtained by cracking and hydrogenation of said high boilers are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

13. The process as claimed in claim 11 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

14. The process as claimed in claim 13 , characterized in that the products obtained by cracking and hydrogenation of said high boilers are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

15. In a process for reacting formaldehyde with isobutyraldehyde in a first reactor wherein high boiling by-products are formed, the improvement comprising the steps of:

a.) separating the reaction products into products enriched in said high boiling by-products and products depleted in said high boiling by-products;

b.) cracking and hydrogenating said separated products enriched in high-boiling by-products in the liquid phase with hydrogen in the absence of solvent and in the presence of a copper-chromite catalyst at a temperature of from 140 to 200° C. and a pressure of from 7 to 28 MPa in a second reactor and thereby forming neopentyl glycol; and

c.) thereafter recovering neopentyl glycol from the products obtained in step b.).

16. The process as claimed in claim 15 , characterized in that the products obtained from step b.) are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

17. The process as claimed in claim 15 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

18. The process as claimed in claim 15 , characterized in that the treatment with hydrogen is carried out at a temperature of from 160 to 200° C. and a pressure of from 7 to 20 MPa.

19. The process as claimed in claim 18 , characterized in that the products obtained from step b.) are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

20. The process as claimed in claim 18 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

21. The process as claimed in claim 20 , characterized in that the products obtained from step b.) are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

22. In a process for producing neopentyl glycol by reacting formaldehyde with isobutyraldehyde in an aldolization reactor thereby forming hydroxypivalaldehyde and thereafter reducing said hydroxypivalaldehyde to neopentyl glycol in a reduction reactor, wherein by-products comprising high boiling acetals and esters are formed, the improvement comprising the steps of:

a.) separating reaction products from at least one of said steps of reacting formaldehyde with isobutyraldehyde and reducing said hydroxypivalaldehyde to neopentyl glycol into products enriched in said high boiling by-products and products depleted in said high boiling by-products;

b.) cracking and hydrogenating said products enriched in high-boiling by-products in the liquid phase with hydrogen in the absence of solvent and in the presence of a copper-chromite catalyst at a temperature of from 140 to 200° C. and a pressure of from 7 to 28 MPa in a reactor separate from both said aldolization reactor and said reduction reactor; and

c.) distilling the products obtained from step b.).

23. The process as claimed in claim 22 , characterized in that the products obtained from step b.) are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

24. The process as claimed in claim 22 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

25. The process as claimed in claim 22 , characterized in that the treatment with hydrogen is carried out at a temperature of from 160 to 200° C. and a pressure of from 7 to 20 MPa.

26. The process as claimed in claim 25 , characterized in that the products obtained from step b.) are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.

27. The process as claimed in claim 25 , characterized in that the copper-chromite catalyst further comprises barium, magnesium or manganese or a combination thereof as activator.

28. The process as claimed in claim 27 , characterized in that the products obtained from step b.) are mixed with crude neopentyl glycol and the mixture is distilled to give purified neopentyl glycol.