Granted Patent B2

US 8,207,382 · App. 12/934,803 · Granted Jun 26, 2012

Abstract

Claims (13)

1. A method for stabilizing liquid nitro compounds against discoloration, the method comprising:

(a) reacting in a reactor a mixture comprising a liquid nitro compound containing color-forming impurities together with aqueous nitric acid, at a temperature of about 100 to 225 degrees centigrade and a pressure of about 150 and 1200 psi, wherein sufficient aqueous nitric acid is used to provide a nitric acid concentration of about 0.5 to 5 weight percent based on total weight of the mixture;

(b) neutralizing the mixture of step (a) with a neutralizing agent and washing the neutralized mixture with water to remove residual salts; and

(c) distilling the nitro compound from the mixture of step (b).

2. The method of claim 1 wherein the liquid nitro compound is mixed with the nitric acid prior to introduction into the reactor.

3. The method of claim 2 wherein the mixture of nitro compound and nitric acid is pre-heated to between about 160 and 180 degrees centigrade.

4. The method of claim 1 wherein the nitro compound is a nitroparaffin or mixture of nitroparaffins.

5. The method of claim 1 wherein the nitro compound is nitroparaffins selected from nitromethane, nitroethane, 1-nitropropane, 2-nitropropane and mixtures of two or more thereof.

6. The method of claim 1 wherein the nitro compound and nitric acid are reacted in the reactor for a residence time of at least about 30 seconds.

7. The method of claim 1 wherein the pressure is between about 300 psi and 500 psi.

8. The method of claim 1 wherein the temperature is between about 150 and 200 degrees centigrade.

9. The method of claim 1 wherein the neutralizing agent is selected from alkali metal carbonates, bicarbonates, hydroxides, and combinations of two or more thereof.

10. The method of claim 1 wherein the neutralizing agent is sodium bicarbonate.

Assignments (9)