Cobalt-substituted chromium oxide compositions, their preparation, and their use as catalysts and catalyst precursors
View Patent ↗A crystalline alpha-chromium oxide where from about 0.05 atom % to about 6 atom % of the chromium atoms in the alpha-chromium oxide lattice are replaced by trivalent cobalt (Co +3 ) atoms is disclosed. Also disclosed is a chromium-containing catalyst composition comprising as a chromium-containing component the crystalline cobalt-substituted alpha-chromium oxide; and a method for preparing a composition comprising the crystalline cobalt-substituted alpha-chromium oxide. The method involves (a) co-precipitating a solid by adding ammonium hydroxide to an aqueous solution of a soluble cobalt 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 cobalt concentration of from about 0.05 mole % to about 6 mole % of the total concentration of cobalt and chromium in the solution; and after at least three moles E 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. Also disclosed is a chromium-containing catalyst composition comprising a chromium-containing component prepared by treating the crystalline cobalt-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 cobalt-substituted alpha-chromium oxide and/or the treated cobalt-substituted alpha-chromium oxide.
1. A crystalline colbalt-substituted alpha-chromium oxide where from about 0.05 atom % to about 6 atom % of the chromium atoms in the alpha-chromium oxide lattice are replaced by trivalent cobalt atoms.
2. A chromium-containing catalyst composition comprising as a chromium-containing component the crystalline cobalt-substituted alpha-chromium oxide of claim 1 .
3. A chromium-containing catalyst composition comprising a chromium-containing component prepared by treating the crystalline cobalt-substituted alpha-chromium oxide of claim 1 with a fluorinating agent.
4. A method for preparing a composition comprising the crystalline cobalt-substituted alpha-chromium oxide of claim 1 , comprising:
(a) co-precipitating a solid by adding ammonium hydroxide to an aqueous solution of a soluble cobalt 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 cobalt concentration of from about 0.05 mole % to about 6 mole % of the total concentration of cobalt and chromium in the solution; and after at east 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 in the presence of oxygen.
5. The method of claim 4 wherein the soluble cobalt salt is a divalent cobalt salt.
6. The method of claim 5 wherein the soluble cobalt and chromium salts are nitrates or hydrated nitrates.
7. The method of claim 6 wherein more than three moles of ammonium nitrate per mole of chromium is present in the aqueous solution.
8. The method of claim 4 wherein a mixture comprising co-precipitated solid and ammonium nitrate from (a) is dried and calcined.
9. The method of claim 8 wherein the dried solid is calcined in air.
10. The method of claim 4 wherein the dried solid is calcined in air.
11. A process for changing the fluorine distribution in a hydrocarbon or a halogenated hydrocarbon, characterized by:
bringing said hydrocarbon or a halogenated hydrocarbon into the presence of a catalyst composition comprising at least one chromium-containing component selected from the group consisting of the crystalline cobalt-substituted alpha-chromium oxide of claim 1 and a crystalline cobalt-substituted alpha-chromium oxide of claim 1 which has been treated with a fluorinating agent.
12. The process of claim 11 wherein the fluorine distribution in a halogenated hydrocarbon compound is changed by isomerizing said halogenated hydrocarbon compound in the presence of said catalyst composition.
13. The process of claim 11 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.
14. A process for increasing the fluorine content of a halogenated hydrocarbon compound or an unsaturated hydrocarbon compound comprising:
reacting said compound with hydrogen fluoride in the vapor phase in the presence of a catalyst composition comprising at least one chromium-containing component selected from the group consisting of the crystalline cobalt-substituted alpha-chromium oxide of claim 1 and a crystalline cobalt-substituted alpha-chromium oxide of claim 1 which has been treated with a fluorinating agent.
15. A process for increasing the fluorine content of a halogenated hydrocarbon compound or a hydrocarbon compound comprising:
reacting said compound with HF and Cl 2 in the vapor phase in the presence of a catalyst composition comprising at least one chromium-containing component selected from the group consisting of the crystalline cobalt-substituted alpha-chromium oxide of claim 1 and a crystalline cobalt-substituted alpha-chromium oxide of claim 1 which has been treated with a fluorinating agent.
16. A process for decreasing the fluorine content of a halogenated hydrocarbon compound:
dehydrofluorinating said halogenated hydrocarbon compound in the presence of a catalyst composition comprising at least one chromium-containing component selected from the group consisting of the crystalline cobalt-substituted alpha-chromium oxide of claim 1 and a crystalline cobalt-substituted alpha-chromium oxide of claim 1 which has been treated with a fluorinating agent.
17. The A process for decreasing the fluorine content of a halogenated hydrocarbon compound comprising:
reacting said halogenated hydrocarbon compound with hydrogen chloride in the vapor phase in the presence of a catalyst composition comprising at least one chromium-containing component selected from the group consisting of the crystalline cobalt-substituted alpha-chromium oxide of claim 1 and a crystalline cobalt-substituted alpha-chromium oxide of claim 1 which has been treated with a fluorinating agent.