| 摘要 |
A method for detoxification of spent catalyst from a fluorination process includes the step of hydrolyzing such spent catalyst in the presence of aqueous calcium chloride to produce insoluble compounds which are separable from the aqueous medium. The spent catalyst is one which includes at least one antimony halide, such as SbCl5, SbF5, SbCl3 and/or SbF3, usually with some halogenated hydrocarbons, such as partially chlorinated methane, partially chlorinated ethane and/or chlorofluorocarbons of 1 to 5 carbon atoms, often in the presence of arsenic compounds, such as AsCl3, hydrofluoric acid, and antimony chlorofluoride, such as SbCl4F. The spent catalyst may be directly treated with the aqueous calcium chloride solution, very preferably with such solution containing small amounts of a transition metal ion, such as Fe++ or Fe+++, or aluminum ion, e.g., Al+++, after which volatile gases emitted are treated, an organic liquid phase is separated from an aqueous liquid phase containing dispersed precipitated insoluble compounds of antimony and arsenic (when arsenic is present), such as calcium salts of acids thereof, oxides, hydroxides and/or oxyhalides thereof resulting from the hydrolysis reaction, such insolubles are separated from the aqueous liquid medium, as by filtration, and the filtrate is neutralized with lime. The neutralized filtrate, containing calcium chloride resulting from the neutralization reaction, may be returned to the hydrolysis step and/or may be further treated by a sulfide or hydrosulfide and a water soluble iron salt, such as aqueous solutions of sodium sulfide or sodium hydrosulfide, and ferric chloride, to co-precipitate compounds of antimony and arsenic, which may be removed from the aqueous medium, together with precipitated compounds of heavy metals which may be present, after which the filtrate may be discharged to a sewer after suitable monitoring to ensure that the contents of toxic materials are within permissible ranges for such discharge. The antimony compounds removed during the process may be recovered and converted to useful form, as for reuse as fluorination catalysts, and other removed materials may also be recovered, regenerated and/or reused.
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