Abstract: The present invention relates to a process for preparing chromium(III) oxide by reaction of alkali metal chromate with gaseous ammonia, subsequent hydrolysis, isolation of the hydrolysis product and calcination.

Abstract: The present invention relates to a process for preparing chromium(III) oxide by reaction of alkali metal chromate with gaseous ammonia, subsequent hydrolysis, isolation of the hydrolysis product and calcination.

Abstract: Process for preparing ammonium dichromate, comprising the steps of c) thermally decomposing an alkali metal ammonium chromate double salt, especially a sodium ammonium chromate double salt or hydrates thereof, at a temperature up to 200° C., especially of 75 to 190° C., to form ammonium dichromate and d) removing the ammonium dichromate from the decomposition product obtained after step c), by crystallization, characterized in that the alkali metal ammonium chromate double salt corresponds to the formula Mx(NH4)yCrO4 or hydrates thereof, in which M is Na or K, particular preference being given to Na, x is from 0.1 to 0.9, preferably from 0.4 to 0.7, y is from 1.1 to 1.9, preferably from 1.3 to 1.6, and the sum of x and y is 2.

Abstract: Process for preparing chromium(III) oxide, comprising the steps of: a) Decomposing an alkali metal ammonium chromate double salt at a temperature of 200 to 650° C., especially of 250 to 550° C., b) washing the decomposition product obtained after a) and c) calcining the product obtained after b) at a temperature of 700 to 1400° C., especially of 800 to 1300° C.

Abstract: Apparatus for maintaining a predefined pressure in one or more reactors to which pressures from 1 to 500 bar can be applied, with simultaneous measurement of the gas mass flow, comprising at least one buffer container (A) which is equipped with a pressure gauge (B) and can be filled with gas via at least one valve (C), and the buffer container (A) being connected to at least one reactor (F) which is likewise equipped with a pressure gauge (B′), characterized in that the connection between buffer container and reactor contains a restrictor (D) and a valve (E) which is controlled via a control unit (H) which is connected to the pressure gauges of the reactor (F) and of the buffer container (A) via control lines.

Abstract: A method and a device for gentle continuous mixing of a droplet dispersion with a liquid are described, wherein the liquid is injected into the droplet dispersion in the form of a plurality of fine liquid jets, such that the kinetic energy of the liquid jets is dissipated at a short distance from the injection point and further mixing is effected by circulating flow generated in the vessel and exhibiting shear rates of less than 20/s.

Abstract: A method and a device for gentle continuous mixing of a droplet dispersion with a liquid are described, wherein the liquid is injected into the droplet dispersion in the form of a plurality of fine liquid jets, such that the kinetic energy of the liquid jets is dissipated at a short distance from the injection point and further mixing is effected by circulating flow generated in the vessel and exhibiting shear rates of less than 20/s.

Abstract: It has been found that cyclopentene and hydrogen bromide can be continuously reacted in a simple manner to give cyclopentyl bromide in good yields and good selectivities if the reaction is carried out in the presence of a heterogeneous catalyst. The reaction can be carried out continuously and unreacted cyclopentene and possibly other constituents can be recirculated to the reaction.

Abstract: The present invention relates to a process for the treatment of waste gas discharged from a cyclohexane oxidation reactor used in the manufacture of adipic acid, said waste gas containing mainly nitrogen, oxygen, carbon monoxide, carbon dioxide, acetic acid, and up to 10% by weight cyclohexane, as well as other gases or vapors, by (a) scrubbing the waste gas from the cyclohexane oxidation reactor with acetic acid in a first absorption step to reduce the amount of cyclohexane to a residual content of less than about 1% by weight, (b) scrubbing the waste gas from the first absorption step with water in a second absorption step to reduce the amount of acetic acid to a residual content of less than about 1% by weight, and (c) subjecting the scrubbed waste gas from the second absorption step to an oxidation step to oxidize carbon monoxide and other oxidizable components of the waste gas to carbon dioxide and water.