- Preparation of composition containing chromium, oxygen, and either silver or palladium, and their use as catalysts and catalyst precursors
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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.
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Page/Page column 8-9
(2008/12/08)
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- Compositions containing chromium, oxygen, and at least two modifier metals selected the group consisting of gold, silver, and palladium, their preparation, and their use as catalysts and catalyst precursors
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A catalyst composition is disclosed that includes chromium, oxygen, and at least two of gold, silver, and palladium as essential constituent elements. The amount of modifier metals (gold, silver, and/or palladium) in the composition is from about 0.05 atom % to about 10 atom % based on the total amount of chromium and modifier metals. Also disclosed is a process for changing the fluorine distribution (i.e., content and/or arrangement) in a hydrocarbon or halogenated hydrocarbon in the presence of the catalyst composition; and methods for preparing said catalyst composition. One preparation method involves (a) co-precipitating a solid by adding ammonium hydroxide (aqueous ammonia) to an aqueous solution of soluble salts of modifier metals and a soluble chromium salt that contains at least three moles of nitrate per mole of chromium in the solution and has a modifier metal content of from about 0.05 atom % to about 10 atom % of the total content of modifier metals and chromium in the solution to form an aqueous mixture containing co-precipitated solid; (b) drying the co-precipitated solid formed in (a); and (c) calcining the dried solid formed in (b) in an atmosphere containing at least 10% oxygen by volume. Another preparation method involves (a) impregnating solid chromium oxide with a solution of a soluble modifier metal salts; (b) drying the impregnated chromium oxide prepared in (a); and optionally; (c) calcining the dried solid. Yet another preparation method involves mixing multiple compositions, each comprising chromium, oxygen, and at least one modifier metal.
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- PROCESSES FOR THE PREPARATION OF 2-CHLORO-1,1,1,2,3,3,3-HEPTAFLUOROPROPANE, HEXAFLUOROPROPENE AND 1,1,1,2,3,3,3-HEPTAFLUOROPROPANE
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A process for the preparation of 2-chloro-1,1,1,3,3,3-heptafluoropropane is disclosed which involves (a) contacting a mixture comprising hydrogen fluoride, chlorine, and at least one starting material selected from the group consisting of halopropenes of the formula CX3CCl=CX2 and halopropanes of the formula the CX3CClYCX3, wherein each X is independently F or Cl, and Y is H, Cl or F (provided that the number of X and Y which are F totals no more than six) with a chlorofluorination catalyst in a reaction zone to produce a product mixture comprising CF3CClFCF3, HCl, HF, and underfluorinated halogenated hydrocarbon intermediates. The process is characterized by said chlorofluorination catalyst comprising at least one chromium-containing component selected from (i) a crystalline alpha-chromium oxide where at least 0.05 atom % of the chromium atoms in the alpha-chromium oxide lattice are replaced by nickel, trivalent cobalt or both nickel and trivalent cobalt, provided that no more than 2 atom % of the chromium atoms in the alpha-chromium oxide lattice are replaced by nickel and that the total amount of chromium atoms in the alpha-chromium oxide lattice that are replaced by nickel and trivalent cobalt is no more than 6 atom % , and (ii) a fluorinated crystalline oxide of (i).Also disclosed is a process for the manufacture of a mixture of HFC-227ea and hexafluoropropene by reacting a starting mixture comprising CFC-217ba and hydrogen in the vapor phase at an elevated temperature, optionally in the presence of a hydrogenation catalyst. This process involves preparing the CFC-217ba by the process described above.
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