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Abstract

The present invention provides a process for recovering boron trifluoride from an impure gaseous boron trifluoride residue. The process comprises: (a) feeding an impure gaseous boron trifluoride residue containing sulfur dioxide as an impurity into a mixture of boric and sulfuric acids wherein the acid mixture absorbs boron trifluoride from the impure boron trifluoride residue and slightly absorbs or does not absorb sulfur dioxide from the impure gaseous boron trifluoride residue; and (b) removing the unabsorbed sulfur dioxide from the acid mixture. The present invention also provides a boron trifluoride preparation and purification process. The process comprises the steps of (a) reacting boric acid and fluorosulfuric acid in surfuric acid to form a product; (b) distilling the product from step (a) to yield pure boron trifluoride and impure gaseous boron trifluoride; (c) feeding the impure gaseous boron trifluoride residue containing sulfur dioxide as an impurity into a mixture of boric and sulfuric acids wherein the acid mixture absorbs boron trifluoride from the impure gaseous boron trifluoride residue and only slightly absorbs sulfur dioxide from the impure gaseous boron trifluoride residue; and (d) removing the unabsorbed sulfur dioxide from the acid mixture. The recovered boron trifluoride may be used as a catalyst.

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First Claim