Industrial process for production of high-purity diol
The invention provides an apparatus and process for producing high-purity diol by taking cyclic carbonate and aliphatic monohydric alcohol as starting materials, continuously feeding the starting materials into column A, carrying out reactive distillation in column A, continuously withdrawing a low boiling point reaction mixture containing a produced dialkyl carbonate and the aliphatic monohydric alcohol from an upper portion of column A, continuously withdrawing a high boiling point reaction mixture containing a produced diol from a lower portion of column A, continuously feeding the high boiling point reaction mixture into distillation column C, distilling off material having a lower boiling point than that of the diol contained in the high boiling point reaction mixture A B as a column top component and/or a side cut component so as to obtain a column bottom component, continuously feeding the column bottom component into distillation column E, and obtaining the diol.
1. An industrial process for the production of a high-purity diol in which a high-purity diol is produced by taking a cyclic carbonate and an aliphatic monohydric alcohol as starting materials, continuously feeding the starting materials into a continuous multi-stage distillation column A in which a catalyst is present, carrying out reactive distillation in said column A, continuously withdrawing a low boiling point reaction mixture A T containing a produced dialkyl carbonate and the aliphatic monohydric alcohol from an upper portion of the column A in a gaseous form, continuously withdrawing a high boiling point reaction mixture A B containing a produced diol from a lower portion of the column A in a liquid form, continuously feeding said high boiling point reaction mixture A B into a continuous multi-stage distillation column C, distilling off material having a lower boiling point than the diol contained in said high boiling point reaction mixture A B as a column top component C T and/or a side cut component C S so as to obtain a column bottom component C B , continuously feeding the column bottom component C B into a continuous multi-stage distillation column E, and obtaining the diol as a side cut component E S from a side cut outlet of the continuous multi-stage distillation column E, wherein:
(a) said continuous multi-stage distillation column E comprises a distillation column comprising a stripping section having a length L 1 (cm), an inside diameter D 1 (cm) and an internal with a number of stages n 1 thereinside, and an enrichment section having a length L 2 (cm), an inside diameter D 2 (cm) and an internal with a number of stages n 2 thereinside, wherein L 1 , D 1 , n 1 , L 2 , D 2 , and n 2 satisfy the following formulae (1) to (9):
400≦L 1 ≦3000 (1)
50≦D 1 ≦700 (2)
2 ≦L 1 /D 1 ≦50 (3)
3≦n 1 ≦30 (4)
600≦L 2 ≦4000 (5)
100≦D 2 ≦1000 (6)
2 ≦L 2 /D 2 ≦30 (7)
5≦n 2 ≦50 (8) and
D 1 ≦D 2 (9);
(b) the enrichment section of said continuous multi-stage distillation column E has at least one chimney tray as an internal installed therein, said chimney tray having installed therein at least two chimneys each having an opening having a cross-sectional area S (cm 2 ) satisfying the formula (10):
50≦S≦2000 (10),
and each of the chimneys being such that a height h (cm) from the opening of the chimney to a gas outlet of the chimney satisfies the formula (11):
20≦h≦100 (11); and
(c) the diol is continuously withdrawn in a liquid form from the side cut outlet, which is connected to a liquid collecting section of said chimney tray of said continuous multi-stage distillation column E.
2. The process according to claim 1 , wherein a produced amount of the high-purity diol is not less than 1 ton/hr.
3. The process according to claim 1 or 2 , wherein L 1 , D 1 , L 1 /D 1 , n 1 , L 2 , D 2 , L 2 /D 2 , and n 2 for said continuous multi-stage distillation column E satisfy 500≦L 1 ≦2000, 100≦D 1 ≦500, 3≦L 1 /D 1 ≦20, 5≦n 1 ≦20, 700≦L 2 ≦3000, 120≦D 2 ≦800, 3≦L 2 /D 2 ≦20, 7≦n 2 ≦30, and D 1 <D 2 .
4. The process according to claim 1 , wherein an internal excluding the chimney tray in each of the stripping section and the enrichment section of said continuous multi-stage distillation column E is a tray and/or a packing.
5. The process according to claim 4 , wherein the internal excluding the chimney tray in each of the stripping section and the enrichment section of said continuous multi-stage distillation column E is the tray.
6. The process according to claim 5 , wherein said tray is a sieve tray.
7. The process according to claim 6 , wherein said sieve tray has 150 to 1200 holes/m 2 in a sieve portion thereof, and a cross-sectional area per hole in a range of from 0.5 to 5 cm 2 .
8. The process according to claim 6 , wherein said sieve tray has 200 to 1100 holes/m 2 in a sieve portion thereof, and a cross-sectional area per hole in a range of from 0.7 to 4 cm 2 .
9. The process according to claim 6 , wherein said sieve tray has 250 to 1000 holes/m 2 in a sieve portion thereof, and a cross-sectional area per hole in a range of from 0.9 to 3 cm 2 .
10. The process according to claim 6 , wherein an aperture ratio (a ratio of a total cross-sectional area of the hole in one tray stage to an area of the tray) of said sieve tray in the stripping section of said continuous multi-stage distillation column E is in a range of from 3 to 25%.
11. The process according to claim 6 , wherein an aperture ratio (a ratio of a total cross-sectional area of the hole in one tray stage to an area of the tray) of said sieve trays in the enrichment of said continuous multi-stage distillation column E is in a range of from 2 to 20%.
12. The process according to claim 1 , wherein an aperture ratio (a ratio of a total cross-sectional area of the opening in the chimney to an area of the chimney tray including the total cross-sectional area of the opening) of the chimney tray is in a range of from 5 to 40%.
13. The process according to claim 1 , wherein a column bottom temperature of said continuous multi-stage distillation column E is in a range of from 110 to 210° C.
14. The process according to claim 1 , wherein a reflux ratio of said continuous multi-stage distillation column E is in a range of from 6 to 100.
15. The process according to claim 1 , wherein a purity of the diol in said side cut component E S is not less than 99%.
16. The process according to claim 1 , wherein a purity of the diol in said side cut component E S is not less than 99.9%.
17. The process according to claim 1 , wherein the high-purity diol produced comprises a content of high boiling point impurities such as a dialkylene glycol of not more than 200 ppm, and a halogen content of not more than 0.1 ppm.
18. The process according to claim 1 , wherein the high-purity diol produced comprises a content of high boiling point impurities such as a dialkylene glycol of not more than 100 ppm, and a halogen content of not more than 1 ppb.
19. A continuous multi-stage distillation column being a continuous multi-stage distillation column E for producing a high-purity diol, wherein:
(a) said continuous multi-stage distillation column E comprises a distillation column comprising a stripping section having a length L 1 (cm), an inside diameter D 1 (cm) and an internal with a number of stages n 1 thereinside, and an enrichment section having a length L 2 (cm), an inside diameter D 2 (cm) and an internal with a number of stages n 2 thereinside, wherein L 1 , D 1 , n 1 , L 2 , D 2 , and n 2 satisfy the following formulae (1) to (9):
400≦L 1 ≦3000 (1)
50≦D 1 ≦700 (2)
2 ≦L 1 /D 1 ≦50 (3)
3≦n 1 ≦30 (4)
600≦L 2 ≦4000 (5)
100≦D 2 ≦1000 (6)
2 ≦L 2 /D 2 ≦30 (7)
5≦n 2 ≦50 (8) and
D 1 ≦D 2 (9);
(b) the enrichment section of said continuous multi-stage distillation column E has at least one chimney tray as an internal installed therein, said chimney tray having installed therein at least two chimneys each having an opening having a cross-sectional area S (cm 2 ) satisfying the formula (10):
50≦S≦2000 (10),
and each of the chimneys being such that a height h (cm) from the opening of the chimney to a gas outlet of the chimney satisfies the formula (11):
20≦h≦100 (11); and
(c) said multi-stage distillation column E comprises a side cut outlet installed for continuously withdrawing the high-purity diol in a liquid form from said continuous multi-stage distillation column E is connected to a liquid collecting section of said chimney tray.
20. The continuous multi-stage distillation column according to claim 19 , wherein L 1 , D 1 , L 1 /D 1 , n 1 , L 2 , D 2 , L 2 /D 2 , and n 2 satisfy 500≦L 1 ≦2000, 100≦D 1 ≦500, 3≦L 1 /D 1 ≦20, 5≦n 1 ≦20, 700≦L 2 ≦3000, 120≦D 2 ≦800, 3≦L 2 /D 2 ≦20, 7≦n 2 ≦30, and D 1 <D 2 .
21. The continuous multi-stage distillation column according to claim 19 or 20 , wherein an internal excluding the chimney tray in each of the stripping section and the enrichment section is a tray and/or a packing.
22. The continuous multi-stage distillation column according to claim 21 , wherein the internal excluding the chimney tray in each of the stripping section and the enrichment section is the tray.
23. The continuous multi-stage distillation column according to claim 22 , wherein said tray is a sieve tray.
24. The continuous multi-stage distillation column according to claim 23 , wherein said sieve trays has 150 to 1200 holes/m 2 in a sieve portion thereof, and a cross-sectional area per hole in a range of from 0.5 to 5 cm 2 .
25. The continuous multi-stage distillation column according to claim 23 , wherein said sieve trays has 200 to 1100 holes/m 2 in a sieve portion thereof, and a cross-sectional area per hole in a range of from 0.7 to 4 cm 2 .
26. The continuous multi-stage distillation column according to claim 23 , wherein said sieve trays has 250 to 1000 holes/m 2 in a sieve portion thereof, and a cross-sectional area per hole in a range of from 0.9 to 3 cm 2 .
27. The continuous multi-stage distillation column according to claim 23 , wherein an aperture ratio (a ratio of a total cross-sectional area of the hole in one tray stage to an area of the tray) of said sieve tray in the stripping section is in a range of from 3 to 25%.
28. The continuous multi-stage distillation column according to claim 23 , wherein an aperture ratio (a ratio of a total cross-sectional area of the hole in one tray stage to an area of the tray) of said sieve tray in the enrichment section is in a range of from 2 to 20%.
29. The continuous multi-stage distillation column according to claim 23 , wherein an aperture ratio (a ratio of a total cross-sectional area of the opening in the chimney to an area of the chimney tray including the total cross-sectional area of the opening) of the chimney tray is in a range of from 5 to 40%.