Tricyanohexane purification methods
View Patent ↗Provided herein are processes for purifying TCH in a feed stream, such as an adiponitrile process stream. The processes include a first separating step of separating the adiponitrile process stream to form a first overhead stream comprising low-boiling components and high-boiling components and a first bottoms stream comprising high-boiling components. The processes also include a second separating step of separating the first overhead stream in one or more distillation columns to form a lights stream comprising low-boiling components, a heavies stream comprising high-boiling components, and a TCH stream.
1. A process for purifying TCH, the process comprising:
a first separating step of flashing an adiponitrile process stream to form a first overhead stream comprising low-boiling components and high-boiling components, and a first bottoms stream comprising high-boiling components and solid impurities;
a second separating step of distilling the first overhead stream to form a second overhead stream comprising low-boiling components, and a second bottoms stream comprising TCH and heavies;
a third separating step of distilling the second bottoms stream to form a third distillate comprising TCH and less than 5 wt. % impurities, the impurities comprising the following:
from 0 wt. % to 0.05 wt. % adiponitrile,
from 0 wt. % to 0.1 wt. % di(2-cyanoethyl) amine,
from 0 wt. % to 0.05 wt. % cyanovaleramide, and
from 0 wt. % to 0.05 wt. % tri (2-cyanoethyl) amine, and
a third bottoms stream comprising heavies;
wherein the residence time in the second or third separating step is less than 8 hours.
2. The process of claim 1 , wherein at least a portion of third bottoms stream and/or the second bottoms stream is recycled.
3. The process of claim 2 , wherein the recycled stream comprises from 0 wt. % to 40 wt. % heavies.
4. A process for purifying TCH, the process comprising
a first separating step of flashing an adiponitrile process stream to form a first overhead stream comprising low-boiling components and high-boiling components, and a first bottoms stream comprising high-boiling components;
a second separating step of distilling the first overhead stream to form a second overhead stream comprising low-boiling components, a second bottoms stream comprising heavies, and a side draw comprising TCH and lights;
a third separating step of flashing the side draw in a second flash vessel to form a third bottoms stream comprising TCH and less than 5 wt % impurities, the impurities comprising the following:
from 0 wt. % to 0.05 wt. % adiponitrile,
from 0 wt. % to 0.1 wt. % di(2-cyanoethyl) amine,
from 0 wt. % to 0.05 wt. % cyanovaleramide, and
from 0 wt. % to 0.05 wt. % tri (2-cyanoethyl) amine; and
wherein the residence time in the second or third separating step is less than 8 hours.
5. The process of claim 4 , wherein at least a portion of the second bottoms stream is recycled.
6. The process of claim 5 , wherein the recycled stream comprises from 0 wt % to 40 wt % heavies.
7. A process for purifying TCH, the process comprising:
a first separating step of flashing an adiponitrile process stream to form a first overhead stream comprising low-boiling components and high-boiling components, and a first bottoms stream comprising high-boiling components;
a second separating step of distilling the first overhead stream to form a second overhead stream comprising low-boiling components, and a second bottoms stream comprising TCH and heavies;
a third separating step of distilling the second bottoms stream to form a third distillate comprising TCH and impurities, and a third bottoms stream comprising heavies; and
a fourth separating step of distilling the third distillate to form a fourth overhead stream comprising low-boiling components, and a fourth bottoms stream comprising TCH and less than 5 wt. % impurities, the impurities comprising the following:
from 0 wt. % to 0.05 wt. % adiponitrile,
from 0 wt. % to 0.1 wt. % di(2-cyanoethyl) amine,
from 0 wt. % to 0.05 wt. % cyanovaleramide, and
from 0 wt. % to 0.05 wt. % tri (2-cyanoethyl) amine; and
wherein the residence time in the second, third, or fourth separating step is less than 8 hours.
8. The process of claim 7 , wherein the fourth overhead stream comprises low-boiling components formed by the decomposition of high-boiling components during the second separating step.
9. The process of claim 7 , wherein at least a portion of the second, third, or fourth bottoms stream is recycled.
10. The process of claim 9 , wherein the recycled stream comprises from 0 wt % to 40 wt % heavies.
11. A process for purifying TCH, the process comprising:
a first separating step of separating an adiponitrile process stream to form a first overhead stream comprising low-boiling components and high-boiling components, and a first bottoms stream comprising high-boiling components;
a second separating step of distilling the first overhead stream to form a second overhead stream comprising low-boiling components, and a second bottoms stream comprising TCH and heavies;
third separating step of distilling the second bottoms stream to form a third distillate comprising TCH and impurities, and a third bottoms stream comprising heavies; and
a fourth separating step of flashing the third distillate in a second flash vessel to form a fourth overhead stream comprising low-boiling components, and a fourth bottoms stream comprising TCH and less than 5 wt. % impurities, the impurities comprising the following:
from 0 wt. % to 0.05 wt. % adiponitrile,
from 0 wt. % to 0.1 wt. % di(2-cyanoethyl) amine,
from 0 wt. % to 0.05 wt. % cyanovaleramide, and
from 0 wt. % to 0.05 wt. % tri (2-cyanoethyl) amine;
wherein the residence time in the second or third separating step is less than 8 hours.
12. The process of claim 11 , wherein the fourth overhead stream comprises low-boiling components formed by the decomposition of high-boiling components during the second and/or third separating step.
13. The process of claim 11 , wherein at least a portion of the second or third bottoms stream is recycled.
14. The process of claim 13 , wherein the recycled stream comprises from 0 wt. % to 40 wt. % heavies.
15. The process of claim 1 , further comprising a treating step of treating the TCH stream to form a purified TCH stream comprising less than 0.1 wt. % impurities, less than 20 ppm water, and/or less than 5 ppm metals.
16. The process of claim 4 , further comprising a treating step of treating the TCH stream to form a purified TCH stream comprising less than 0.1 wt. % impurities, less than 20 ppm water, and/or less than 5 ppm metals.
17. The process of claim 7 , further comprising a treating step of treating the TCH stream to form a purified TCH stream comprising less than 0.1 wt. % impurities, less than 20 ppm water, and/or less than 5 ppm metals.
18. The process of claim 11 , further comprising a treating step of treating the TCH stream to form a purified TCH stream comprising less than 0.1 wt. % impurities, less than 20 ppm water, and/or less than 5 ppm metals.