Copper-Substituted Chromium Oxide Compositions, Their Preparation, and Their Use as Catalysts and Catalyst Precursors
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.
1 . 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 atoms.
2 . A chromium-containing catalyst composition comprising as a chromium-containing component the crystalline copper-substituted alpha-chromium oxide of claim 1 .
3 . A chromium-containing catalyst composition comprising a chromium-containing component prepared by treating the crystalline copper-substituted alpha-chromium oxide of claim 1 with a fluorinating agent.
4 . A process for changing the fluorine distribution in a hydrocarbon or a halogenated hydrocarbon in the presence of a catalyst, characterized by:
using as the catalyst a composition comprising at least one chromium-containing component selected from the group consisting of the crystalline copper-substituted alpha-chromium oxide of claim 1 and a crystalline copper-substituted alpha-chromium oxide of claim 1 which has been treated with a fluorinating agent.
5 . The process of claim 4 wherein the fluorine content of a halogenated hydrocarbon compound or an unsaturated hydrocarbon compound is increased by reacting said compound with hydrogen fluoride in the vapor phase in the presence of said catalyst composition.
6 . The process of claim 4 wherein the fluorine content of a halogenated hydrocarbon compound or a hydrocarbon compound is increased by reacting said compound with HF and Cl 2 in the vapor phase in the presence of said catalyst composition.
7 . The process of claim 4 wherein the fluorine distribution in a halogenated hydrocarbon compound is changed by isomerizing said halogenated hydrocarbon compound in the presence of said catalyst composition.
8 . The process of claim 4 wherein the fluorine distribution in a halogenated hydrocarbon compound is changed by disproportionating said halogenated hydrocarbon compound in the vapor phase in the presence of said catalyst composition.
9 . The process of claim 4 wherein the fluorine content of a halogenated hydrocarbon compound is decreased by dehydrofluorinating said halogenated hydrocarbon compound in the presence of said catalyst composition.
10 . The process of claim 4 wherein the fluorine content of a halogenated hydrocarbon compound is decreased by reacting said halogenated hydrocarbon compound with hydrogen chloride in the vapor phase in the presence of said catalyst composition.
11 . A method for preparing a composition comprising the crystalline copper-substituted alpha-chromium oxide of claim 1 , comprising:
(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 co-precipitated solid formed in (a);
(c) drying the collected solid; and
(d) calcining the dried solid.
12 . The method of claim 11 wherein the soluble copper salt is a divalent copper salt.
13 . The method of claim 12 wherein the soluble copper and chromium salts are nitrates or hydrated nitrates
14 . The method of claim 12 wherein more than three moles of ammonium nitrate per mole of chromium is present in the aqueous solution.
15 . A method for preparing a composition comprising the crystalline copper-substituted alpha-chromium oxide of claim 1 , comprising:
(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.