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Abstract

Process for preparing chromium(III) oxide, which comprises the steps:

a) reaction of sodium monochromate with gaseous ammonia, in particular at a temperature of from 200 to 800° C.,b) hydrolysis of the reaction product obtained in step a) with the pH of the water for the hydrolysis being reduced before the hydrolysis or that of the alkaline mother liquor being reduced during or after the hydrolysis, to a value of from 4 to 11, preferably from 5 to 10, by means of an acid,c) isolation of the hydrolysis product which has precipitated in step b), preferably at a pH of from 4 to 11, in particular from 5 to 10, and optionally washing and optionally drying andd) calcination of the hydrolysis product obtained in step c) at a temperature of from 700 to 1400° C., in particular from 800 to 1300° C.

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First Claim