Method for producing tetrafluoroborate
View Patent ↗An object of the invention is to provide a tetrafluoroborate producing method that allows high-yield, high-efficiency production of a tetrafluoroborate by a continuous process, a tetrafluoroborate-containing electrolyte, and an electrical storage device including such an electrolyte. The invention provides a method for producing a tetrafluoroborate, which includes: a first step including dissolving boron trifluoride gas in an organic solvent; a second step including adding, to the organic solvent, a fluoride (MF n , wherein M represents a metal or NH 4 , and 1≦n≦3) in an amount stoichiometrically equivalent to or less than the amount of the boron trifluoride so that a tetrafluoroborate solution is produced; and a third step including circulating the tetrafluoroborate solution through the first step so that the boron trifluoride gas is dissolved in the tetrafluoroborate solution instead of the organic solvent.
1. A method for producing a tetrafluoroborate, comprising:
a first step comprising dissolving boron trifluoride gas in an organic solvent at an absorption tower;
a second step comprising adding at a tank separate from the absorption tower, to the organic solvent from the absorption tower, a fluoride represented by MF n in an amount stoichiometrically equivalent to or less than the amount of the boron trifluoride so that a tetrafluoroborate solution is produced, M representing a metal or NH 4 and 1≦n≦3; and
a third step comprising circulating a portion of the tetrafluoroborate solution back to the absorption tower from the tank so that the boron trifluoride gas is dissolved in the tetrafluoroborate solution.
2. The method for producing a tetrafluoroborate according to claim 1 , wherein the organic solvent is at least one of a non-aqueous organic solvent or a non-aqueous ionic liquid.
3. The method for producing a tetrafluoroborate according to claim 1 , wherein the organic solvent used has a water content of 100 ppmw or less.
4. The method for producing a tetrafluoroborate according to claim 1 , wherein in the first step, the boron trifluoride gas is brought into gas-liquid contact with the organic solvent at a temperature of −40 to 100° C.
5. The method for producing a tetrafluoroborate according to claim 1 , wherein in the third step, the boron trifluoride gas is brought into gas-liquid contact with the tetrafluoroborate solution at a temperature of −40 to 100° C.
6. The method for producing a tetrafluoroborate according to claim 1 , wherein in the first step, the concentration of the boron trifluoride in the organic solvent is 15% by weight or less.
7. The method for producing a tetrafluoroborate according to claim 1 , wherein in the third step, the concentration of the boron trifluoride in the tetrafluoroborate solution is 15% by weight or less.