Apparatus and process for using a nitroalkane as an entrainer for azeotropic removal of water from aqueous acid solution
View Patent ↗Disclosed are a process and an apparatus for concentrating an organic acid by using a nitroalkane as an entrainer for the azeotropic removal of water from an aqueous organic acid solution. The nitroalkane may be the same as a nitroalkane that is the product of a high pressure nitration process that produces nitroalkanes and aqueous organic acid.
1. A process comprising:
supplying a feed stream to an azeotropic distillation column, wherein the feed stream comprises water and an organic acid;
using a nitroalkane as an entrainer in the azeotropic distillation column, such that the feed stream is separated into at least a top stream and a bottom stream, wherein the top stream comprises the nitroalkane and water and wherein the bottom stream comprises the organic acid;
separating the top stream into an organic phase and an aqueous phase, the organic phase comprising the nitroalkane; and
returning at least a portion of the organic phase to the azeotropic distillation column.
2. A process according to claim 1 , wherein the nitroalkane is selected from the group consisting of 1-nitropropane and 2-nitropropane.
3. A process according to claim 1 , wherein the bottom stream is at least 90 weight percent of the organic acid.
4. A process according to claim 1 , wherein the azeotropic distillation column comprises at least forty stages.
5. A process according to claim 1 , wherein the organic acid is present in the bottom stream in a higher concentration than in the feed stream.
6. A process according to claim 1 , further comprising returning at least a portion of the aqueous phase to the azeotropic distillation column.
7. A process comprising:
reacting a hydrocarbon feedstock with aqueous nitric acid in a reactor to produce a product stream comprising a product nitroalkane and byproducts;
degassing the product stream to produce a liquid stream;
separating the liquid stream in a stripping apparatus into a first top stream and a first bottom stream, wherein the first top stream comprises the product nitroalkane and the first bottom stream comprises at least one organic acid and water;
supplying the first bottom stream to an azeotropic distillation column;
using a working nitroalkane as an entrainer in the azeotropic distillation column, such that the first bottom stream is separated into at least a second top stream and a second bottom stream, wherein the second top stream comprises the working nitroalkane and water and wherein the second bottom stream comprises the at least one organic acid;
separating the second top stream in a phase separator into an organic phase and an aqueous phase, the organic phase comprising the working nitroalkane; and
returning at least a portion of the organic phase and at least a portion of the aqueous phase to the azeotropic distillation column.
8. A process according to claim 7 , wherein the at least one organic acid is selected from the group consisting of acetic acid, propanoic acid, butanoic acid, and any combination thereof.
9. A process according to claim 7 , wherein the working nitroalkane is selected from the group 1-nitropropane.
10. A process according to claim 7 , wherein the product nitroalkane is selected from the group consisting of 1-nitropropane, 2-nitropropane, and nitromethane.
11. A process according to claim 7 , further comprising returning at least a portion of the second bottom stream to the reactor.
12. A process according to claim 1 , wherein the organic acid is selected from the group consisting of acetic acid, propanoic acid, butanoic acid, and any combination thereof.
13. A process according to claim 1 , wherein the organic acid is acetic acid.
14. A process according to claim 1 , wherein the azeotropic distillation operates at a pressure of about 1 atm.
15. A process according to claim 7 , wherein the at least one organic acid is acetic acid.
16. A process according to claim 7 , wherein the reactor is at a pressure of at least about 3.4×10 6 Pa.
17. A process according to claim 7 , wherein the reactor is at a pressure range of about 6.8×10 6 Pa to about 9.7×10 6 Pa.
18. A process according to claim 7 , wherein the reactor is at a temperature range of about 140° C. to about 325° C.
19. A process according to claim 7 , wherein the azeotropic distillation operates at a pressure of about 1 atm.
20. A process according to claim 7 , wherein the second bottom stream comprises about 70 wt % or greater of the organic acid.