Process for nitroalkane recovery by aqueous phase recycle to nitration reactor
View Patent ↗Disclosed are a process and an apparatus for synthesizing nitroalkanes by reaction of a hydrocarbon feedstock with aqueous nitric acid. Energy and capital costs may be reduced by recycling a majority of the aqueous phase back to the reactor.
1. A process for synthesizing at least one nitroalkane, the process comprising:
reacting a hydrocarbon feedstock with aqueous nitric acid in a reactor at a reactor pressure and a reaction temperature, such that a product stream comprising nitrated compounds and byproducts is formed;
separating the product stream into at least an oil phase, a gas phase, and an aqueous phase, wherein the oil phase and the aqueous phase contain nitrated compounds;
dividing the aqueous phase into a first aqueous stream and a second aqueous stream upstream of an absorber;
returning the first aqueous stream to the reactor;
supplying the second aqueous stream to the absorber; and
recovering the at least one nitroalkane from at least one of the oil phase and the second aqueous stream.
2. A process according to claim 1 further comprising:
absorbing water-soluble and oil-soluble components from the gas phase to form a gas-recovered mixture;
separating a gas-recovered aqueous phase from the gas-recovered mixture; and
introducing the gas-recovered aqueous phase to a stripping apparatus to recover the at least one nitroalkane.
3. A process according to claim 1 wherein between about 65 and 85 percent of the aqueous phase is divided into the first aqueous stream.
4. A process according to claim 1 wherein the aqueous nitric acid is added to the reactor at a 10 to 50 weight percent solution.
5. A process according to claim 4 wherein the aqueous nitric acid is added to the reactor at a 15 to 40 weight percent solution.
6. A process according to claim 5 wherein the aqueous nitric acid is added to the reactor at a 18 to 35 weight percent solution.
7. A process according to claim 1 wherein the molar ratio of hydrocarbon to nitric acid is at least about 1.2:1.
8. A process according to claim 1 wherein the reactor pressure is at least about 1000 psi.
9. A process according to claim 1 wherein the reaction temperature is between about 215 and 325 degrees Celsius.
10. A process according to claim 1 wherein the reaction temperature is greater than 230 degrees Celsius.
11. A process according to claim 1 wherein the reaction temperature is 290 degrees Celsius or less.
12. A process according to claim 1 wherein the reactor is a downflow configured reactor.
13. A process according to claim 1 wherein the reactor is a packed reactor.
14. A process according to claim 1 wherein the reactor is an un-packed reactor.
15. The process according to claim 1 , wherein the at least one nitroalkane is 2-nitropropane.
16. The process according to claim 1 , wherein the at least one nitroalkane is 2,2-nitropropane.
17. A process for synthesizing at least one nitroalkane, the process comprising:
reacting a hydrocarbon feedstock with aqueous nitric acid in a reactor at a reactor pressure and a reaction temperature, such that a product stream of nitrated compounds and byproducts is formed;
quenching the product stream to separate the product stream into at least an oil phase, a gas phase, and an aqueous phase;
dividing the aqueous phase into a first aqueous stream and a second aqueous stream upstream of an absorber;
returning the first aqueous stream to the reactor;
supplying the second aqueous stream to the absorber;
combining the oil phase, the gas phase, and the second aqueous stream in the absorber;
absorbing water-soluble and oil-soluble components from the gas phase into the oil phase and the second aqueous stream to form a gas-recovered mixture;
separating a gas-recovered aqueous phase from the gas-recovered mixture; and
recovering the at least one nitroalkane from at least one of the oil phase and the second aqueous stream.