Preparation of a high purity and high concentration hydroxylamine free base
AssigneeSan Fu Chemical Co., Ltd.
InventorsKaung-Far Lin, Jin-Fu Chen, Wei Te Lin, Ruey-Shing Chen, Kung-Chin Kuo
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Abstract
A high purity aqueous solution of hydroxylamine product is prepared by treating an aqueous solution of hydroxylammonium salt with a base like ammonia at low temperatures. A novel process can be carried out by separating the ammonium salt side product from hydroxylamine with a low temperature filtration and a resin-exchange process. The concentration of the hydroxylamine product is further improved by a safe distillation process that produces a high purity and high concentration hydroxylamine product with reduced risks of explosion.
Claims31
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;
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- f. concentrating the high purity hydroxylamine solution at a sub-atmospheric pressure to form the high purity and high concentration hydroxylamine product.
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 consisting essentially of hydroxylammonium sulfate at a maximum concentration and a stabilizer consisting essentially of cyclohexanediaminetetraacetic acid into a reactor at a low temperature;
- b. neutralizing the aqueous feed solution at a temperature in the range of from about 15° C. to 45° C. 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 hydroxylammonium sulfate wherein the ratio of the additional amount of solid added to the amount of hydroxylammonium sulfate in the aqueous feeding solution is in the range of from 0.6 to 4.5 on a weight to weight basis to increase the total amount of hydroxylammonium sulfate in the reactor before or during neutralization of step b;
- d. separating the resulting slurry by centrifugation and filtration into an aqueous solution phase and a solid phase at a temperature between about 5° C. to about 15° C.;
- e. treating the aqueous solution phase in a first column containing anion exchange resin to form an effluent followed by treating the effluent from the first column in a second column containing a cation exchange resin to produce a high purity hydroxylamine solution thereby the resistivity is in the range of from about 10 Megohms-cm to about 50 Megohms-cm;
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- f. concentrating the high purity hydroxylamine solution at a sub-atmospheric pressure in the range of from about 10 torrs to about 60 torrs [about 1.33 kPa to about 8.0 kPa] and a temperature in the range of from about 35° C. to about 45° C. to form the high purity and high concentration hydroxylamine product.
Dependencies are inferred from the claim text.