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AssigneeCelanese Corporation
InventorJames D. Fruge'
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The solid oxalate of a catalytic metal such as cobalt, typically formed as an undesired and useless by-product during the liquid-phase oxidation of an organic compound, typically a hydrocarbon, in the presence of a homogeneous catalyst comprising said metal, is treated to convert the metal moiety to a reusable form by a process comprising leaching the metal oxalate with an aqueous solution of a soluble salt of ethylenediaminetetraacetic acid (EDTA). The resulting solution of EDTA-metal complex or chelate is then mixed with a soluble calcium salt to precipitate the oxalate moiety as insoluble calcium oxalate leaving the metal-EDTA complex in solution. After removing the resulting solid calcium oxalate, the remaining filtrate is acidified to convert the metal moiety to a simple salt which can be recycled to the liquid-phase oxidation, while the EDTA is precipitated as a solid which can also be recovered and re-used in the complexation step of the process.
In a process for treating a solid comprising the oxalate of a metal of the group consisting of cobalt, copper, and manganese to recover therefrom an aqueous solution containing a water-soluble salt of said metal substantially free from oxalate moiety, the improvement which comprises:
In a process for oxidizing an organic feedstock with a catalyst comprising cobalt in a liquid phase comprising a carboxylic acid to produce a liquid oxidate comprising a carboxylic acid and wherein cobalt initially contained in said catalyst is converted to cobalt oxalate, in which process said cobalt oxalate is separated as a solid from said oxidate and converted to a cobalt salt which can be re-used as catalyst in said process, the improvement which comprises;
Dependencies are inferred from the claim text.