Vanadium iii sulfate, also known as V 2 SO 4, is a transition metal sulfate. It is used as an additive in the production of steel. It is also used as an alloy in titanium-6AL-4V, the most common commercially available titanium alloy.
The present invention relates to a method for producing a vanadium (III) sulfate aqueous sulfuric acid solution of high quality, which is useful as an electrolyte for a vanadium redox flow battery. This method includes the following steps:
Heating a vanadium (III) oxide in sulfuric acid having a concentration of 80% or more at 140 to 260 deg C to form solid vanadium (III) sulfate.
Alternatively, the reaction solution may be cooled to 30 deg C or lower and filtered through an acid-resistant filter such as a # 4 glass filter. The filtrate may be washed with water, distilled water or other aqueous solutions, and the residue removed.
The resulting dried cake is then analyzed by powder X-ray diffraction to confirm that it is composed of vanadium (III) sulfate. It was then further analyzed by an elemental analysis method to confirm the composition of the dried cake and determine the concentration of the elements.
Moreover, the present invention provides a method for producing a sulfuric acid aqueous solution of vanadium (III) sulfate of high quality, which is useful as an electrode electrolyte for a vanadium (III) redox flow battery. This method includes heating a vanadium (III) oxide solution in sulfuric acid having a concentration of 80 percent or more at 140 to 260 degC, removing the generated hydrogen chloride and adjusting the sulfate content of the solution by adding fuming sulfuric acid or stabilized SO 3 to adjust the sulfate content of the reaction solution.