Buerger,Pawelke

, p. 517 (1979)

Copper-Substituted Chromium Oxide Compositions, Their Preparation, and Their Use as Catalysts and Catalyst Precursors

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Page/Page column 12, (2010/06/22)

A crystalline alpha-chromium oxide where from about 0.05 atom % to about 5 atom % of the chromium atoms in the alpha-chromium oxide lattice are replaced by divalent copper (Cu+2) atoms is disclosed. Also disclosed is a chromium-containing catalyst composition comprising as a chromium-containing component the crystalline copper-substituted alpha-chromium oxide; and methods for preparing a composition comprising the crystalline copper-substituted alpha-chromium oxide. One method involves (a) co-precipitating a solid by adding ammonium hydroxide to an aqueous solution of a soluble copper salt and a soluble trivalent chromium salt that contains at least three moles of nitrate per mole of chromium in the solution and has a copper concentration of from about 0.05 atom % to about 5 atom % of the total concentration of copper and chromium in the solution; and after at least three moles of ammonium per mole of chromium in the solution has been added to the solution, (b) collecting the co-precipitated solid formed in (a); (c) drying the collected solid; and (d) calcining the dried solid. Another method involves (a) preparing an aqueous solution of a soluble copper salt and a soluble trivalent chromium salt that contains a copper concentration of from about 0.05 atom % to about 5 atom % of the total concentration of copper and chromium in the solution, (b) evaporating the solution to dryness, and (c) calcining the dried solid. Also disclosed is a chromium-containing catalyst composition comprising a chromium-containing component prepared by treating the crystalline copper-substituted alpha-chromium oxide with a fluorinating agent; and a process for changing the fluorine distribution (i.e., content and/or arrangement) in a hydrocarbon or halogenated hydrocarbon in the presence of a catalyst. The process involves using as the catalyst a composition comprising the crystalline copper-substituted alpha-chromium oxide and/or the treated copper-substituted alpha-chromium oxide.

Preparation of composition containing chromium, oxygen, and either silver or palladium, and their use as catalysts and catalyst precursors

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Page/Page column 8-9, (2008/12/08)

A method for preparing a catalyst composition suitable for increasing the fluorine content in a hydrocarbon or a halogenated hydrocarbon is disclosed. The method involves (a) co-precipitating a solid by adding ammonium hydroxide to an aqueous solution of a soluble trivalent chromium salt and a soluble salt of a modifier metal selected from silver and palladium, that contains at least three moles of nitrate (i.e., NO3?) per mole of chromium (i.e., Cr+3) in the solution and has a modifier metal concentration of from about 0.05 atom % to about 10 atom % of the total concentration of modifier metal and chromium in the solution to form an aqueous mixture containing co-precipitated solid and dissolved ammonium nitrate; and after at least three moles of ammonium hydroxide per mole of chromium in the solution has been added to the solution, (b) drying said aqueous mixture formed in (a); and (c) calcining the dried solid formed in (b) in an atmosphere containing at least 10% oxygen by volume (e.g., air). Also disclosed is a catalyst composition comprising alpha-chromium oxide and a modifier metal selected from silver and palladium prepared by the above method. Also disclosed is a process for increasing the fluorine content in a hydrocarbon or halogenated hydrocarbon in the presence of a catalyst; and processes using a catalyst composition comprising chromium, oxygen and a modifier metal selected from siver and palladium as essential constituent elements (e.g., a catalyst composition prepared by the above process). An azeotropic composition involving CF3CCl═CF2 and HF is also disclosed.