PROCESS FOR PREPARING A HYDROGENATION CATALYST.

摘要

The invention relates to a hydrogenation catalyst by the reduction from platinum in the stage of oxidation of +4 (Pt (IV)) with a selective reducing agent in an acidic aqueous medium in the presence of a carbon-containing carrier to platinum in the stage of oxidation +2 (Pt (II)), subsequent poisoning of the platinum thus obtained with a sulphur-containing selective reducing agent, and subsequent reduction of the platinum thus partially poisoned to form metallic platinum (Pt(0)) and subsequent processing as known per se in that (a) Pt (II) is partially poisoned with a sulphur-containing selective reducing agent, wherein the sulphur-containing selective reduction agent is used in an amount which corresponds to from 15 to 70 mol % of the amount of the sulphur-containing selective reducing agent which might be needed to reduce Pt(IV) to Pt (II), provided that the amount of Pt (IV) corresponds to the amount of Pt (II) used and to be poisoned, and subsequently the partially poisoned Pt (II) is reduced with an alkali metal formate to Pt (0); or (b) platinum in the stage of oxidation of greater than +2 is partially poisoned and subsequently or simultaneously reduced with an alkali metal formate to Pt (0). The invention also relates to a hydrogenation catalyst, use of the hydrogenation catalyst for preparing hydroxylammonium salts, a process for the preparation of hydroxylammonium salts, and a process for regenerating platinum-containing hydrogenation catalysts.