Patent ID: 7396519

Claim:
A process for preparing a high purity and high concentration hydroxylamine product, the process comprises a. feeding an aqueous feed solution containing a hydroxylammonium salt at a maximum concentration and a stabilizer into a reactor at a low temperature; b. neutralizing the aqueous feed solution with a base to form a slurry until the pH of the resulting slurry reaches in a range of from about 9.0 to about 12.0; c. adding an additional amount of solid of the hydroxylammonium salt to increase the total amount of the hydroxylammonium salt in the reactor before or during neutralization of step b; d. separating the resulting slurry into an aqueous solution phase and a solid phase at a temperature between about −20° C. to about 20° C.; e. treating the aqueous solution phase in at least one ion exchange column containing at least one ion exchange resin to produce a high purity hydroxylamine solution thereby the resistivity is not lower than about 10 Megohms-cm; and f. concentrating the high purity hydroxylamine solution at a sub-atmospheric pressure to form the high purity and high concentration hydroxylamine product.