Dehydrochlorination of hydrochlorofluorocarbons using pre-treated activated carbon catalysts
View Patent ↗The present disclosure provides methods for pre-treating activated carbon before it is used in a dehydrochlorination process. The methods can comprise mixing the activated carbon with an acid, an oxidizing agent in a liquid phase, or an oxidizing agent in a gas phase. Activated carbons undergoing one or more of these methods can exhibit improved stability during the dehydrochlorination process.
1. A method for producing a fluorinated alkene comprising:
dehydrochlorinating a hydrofluorochloroalkane in the presence of a stabilized demineralized activated carbon which catalyzes dehydrochlorinating the hydrofluorochloroalkane, wherein said hydrochlorofluoroalkane is selected from the group consisting of 1,1,1,2-tetrafluoro-2-chloropropane, 1,1,1,2-tetrafluoro-3-chloropropane, 1,1,1,3-tetrafluoro-3-chloropropane, 1,1,1,3-tetrafluoro-2-chloropropane, 1,1,1,2,3-pentafluoro-2-chloropropane, 1,1,1,2,3-pentafluoro-3-chloropropane, 1,1,1,3,3-pentafluoro-3-chloropropane, 1,1,1,3,3-pentafluoro-2-chloropropane, 1,1,1,2,3,3-hexafluoropropane-2-chloropropane, and 1,1,1,2,3,3-hexafluoro-3-chloropropane.
2. The method of claim 1 wherein said hydrochlorofluoroalkane is 1,1,1,2-tetrafluoro-2-chloropropane.
3. The method of claim 1 wherein said fluorinated alkene is selected from the group consisting of: 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1,2,3,3,3-pentafluoropropene, 1,1,3,3,3-pentafluoropropene, and 1,1,2,3,3,3-hexafluoropropene.
4. The method of claim 2 wherein said fluorinated alkene is 2,3,3,3-tetrafluoropropene.
5. The method of claim 1 wherein said stabilized catalyst is activated carbon that has been demineralized in the presence of at least one acid selected from the group consisting of hydrochloric acid and hydrofluoric acid.
6. The method of claim 5 wherein said acid is hydrochloric acid.
7. The method of claim 1 wherein said stabilized catalyst is activated carbon that has been subjected to a demineralization process comprising the following:
forming a suspension comprising said activated carbon and at least one acid selected from the group consisting of hydrochloric acid and hydrofluoric acid;
stirring said suspension at a temperature of at least about 22° C. for a first period of time from about 0.5 to about 24 hours;
filtering said suspension, to separate said activated carbon catalyst from said acid;
washing said catalyst to remove substantially all free ions from said activated carbon catalyst; and
drying said catalyst at a temperature of at least about 50° C. for a second period of time from about 0.5 to about 24 hours.
8. A method for producing a fluorinated alkene comprising:
dehydrochlorinating a hydrofluorochloroalkane in the presence of an activated carbon catalyst, which is both demineralized and oxidized, which catalyzes dehydrochlorinating the hydrofluorochloroalkane, wherein said hydrochlorofluoroalkane is selected from the group consisting of 1,1,1,2-tetrafluoro-2 chloropropane, 1,1,1,2-tetrafluoro-3-chloropropane, 1,1,1,3 tetrafluoro-3-chloropropane, 1,1,1,3 tetrafluoro-2-chloropropane, 1,1,1,2,3-pentafluoro-2-chloropropane, 1,1,1,2,3-pentafluoro-3 chloropropane, 1,1,1,3,3-pentafluoro-3-chloropropane, 1,1,1,3,3-pentafluoro-2-chloropropane, 1,1,1,2,3,3-hexafluoropropane-2-chloropropane, and 1,1,1,2,3,3-hexafluoro-3-chloropropane.
9. The method of claim 8 wherein the activated carbon catalyst is demineralized in the presence of at least one acid selected from the group consisting of hydrochloric acid and hydrofluoric acid and is oxidized in the presence of at least one liquid phase oxidizing agent selected from the group consisting of nitric acid and hydrogen peroxide.
10. The method of claim 8 wherein the activated carbon catalyst is demineralized in the presence of at least one acid selected from the group consisting of hydrochloric acid and hydrofluoric acid and is oxidized in the presence of at least one vapor phase oxidizing agent selected from the group consisting of O 2 and CO 2 .