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

摘要

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.