Process for the preparation of a hydroxylamine salt
AssigneeStamicarbon B.V.
InventorsAbraham H. De Rooij, Jozef M. G. Prop, Willem J. Wassen
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Abstract
An improved process for preparing a hydroxyl-amine salt by reduction of a solution of nitrate ions or nitrogen monoxide. Dissolved molybdenum in amounts as low as about two milligrams per liter of nitrate/nitrogen monoxide solution are known to interfere with the reduction reaction. The present invention provides a simple method of reducing molybdenum contamination, and hence enhancing the efficiency of the reduction reaction. Dissolved molybdenum is removed from the nitrate/nitrogen monoxide solution by coprecipitation with a complex iron-ammonium phosphate. If chromium is present, it will also be removed by this coprecipitation.
Claims8
An improved process for preparing hydroxyl-amine salts by reduction of nitrate ions or nitrogen monoxide by means of hydrogen in the presence of a noble metal catalyst in an aqueous reaction medium containing from about 2 to about 6 milligrams of molybdenum per liter by forming a complex iron-ammonium phosphate/molybdenum coprecipitate, comprising:
- reducing hydroxyl amine concentration in said reaction medium to less than 0.2 mole of hydroxyl amine per kilogram prior to removing said molybdenum,
- removing said 2 to 6 milligrams of molybdenum per liter from said reaction medium by adding an effective amount of iron, ammonium and phosphate salts to form a complex iron-ammonium phosphate/molybdenum coprecipitate in said reaction medium, stirring said reaction medium for a period of at least 15 minutes, forming a complex iron-ammonium phosphate/molybdenum coprecipitate in said reaction medium at a pH of over 3.5 and a temperature between 20.degree. and 80.degree. C., separating said complex iron-ammonium phosphate/molybdenum coprecipitate from said reaction medium,
- reducing nitrate ions or nitrogen monoxide with hydrogen in the presence of a noble metal catalyst in said reaction medium to form a hydroxyl-amine salt, and
- removing said hydroxyl-amine salt and reusing the residual reaction medium,
- whereby the selectivity of said reduction of nitrate ions or nitrogen monoxide is enhanced.
Dependencies are inferred from the claim text.