| abstract |
Process for the preparation of chromium (III) oxide, comprising the steps: a) reaction of sodium monochromate with gaseous ammonia, in particular at a temperature of 200 to 800 ° C, b) hydrolysis of the reaction product obtained according to step a), wherein the pH of the water for hydrolysis before the hydrolysis or the alkaline mother liquor during or after the hydrolysis to a value of 4 to 11, preferably from 5 to 10, by means of a Acid lowers, c) separation of the precipitated after step b) hydrolysis, preferably at a pH of 4 to 11, in particular from 5 to 10, and optionally washing and optionally drying and d) calcining the hydrolysis product obtained after step c) at a temperature of 700 to 1400 ° C, in particular from 800 to 1300 ° C. |