METHOD FOR PREPARING HYDROXYLAMINE

Abstract

A method for preparing hydroxylamine by reducing nitric acid or its salt with hydrogen gas in an aqueous medium in the presence of a catalyst, wherein reduction of nitric acid or its salt is performed in a reactor comprising a reaction section, a cooler disposed at the lower portion of the reactor, and a middle gas distributor and a lower gas distributor respectively disposed above and below the cooler for introducing hydrogen gas into the reaction section. According to the present invention, gas distribution become more uniform by disposing the gas distributors at different positions of the reactor, which results in higher yield of hydroxylamine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional reactor for production of hydroxylamine;

FIG. 2 is a schematic diagram of a reactor according to the first embodiment of the present invention;

FIG. 3 is a schematic diagram of a reactor according to the second embodiment of the present invention; and

FIG. 4 is a schematic diagram of a reactor according to the third embodiment of the present invention.

Claims

1. A method for preparing hydroxylamine by reducing nitric acid or its salt with hydrogen gas in an aqueous medium in the presence of a catalyst, wherein the reduction of nitric acid or its salt is performed in a reactor comprising a reaction section, a cooler disposed at a lower portion of the reactor, and a middle gas distributor and a lower gas distributor respectively disposed above and below the cooler for introducing hydrogen gas into the reaction section.

2. The method according to claim 1, wherein the unreacted hydrogen gas is recovered front the top of the reactor and circulated back to the reaction section.

3. The method according to claim 2, wherein fresh hydrogen gas is introduced into the reaction section through the lower gas distributor and the circulated hydrogen gas is introduced into the reaction section through the middle gas distributor.

4. The method according to claim 2, wherein the circulated hydrogen gas, after mixed with part of fresh air, is introduced into the reaction section through the middle gas distributor, and the rest part of fresh hydrogen gas is introduced into the reaction section through the lower gas distributor.

5. A method according to claim 1, wherein an upper gas distributor is further disposed in the reaction section.

6. A method according to claim 5, wherein fresh hydrogen gas is introduced into the reaction section through the lower gas distributor and into the reaction section through the middle gas distributor.

7. A method according to claim 1, wherein reduction of nitric acid or its salt is performed at a temperature from 20° C. to 100° C.

8. A method according to claim 1, wherein the catalyst is palladium/carbon catalyst.

9. A method according to claim 1, wherein the aqueous medium is a phosphate-buffered aqueous medium.