The recovery of molybdenum and vanadium from acid leaching solutions of spent catalysts using solvent extraction has been
investigated. Among various acid leaching solutions, sulfuric acid solution is found to be adequate for the recovery of these two
metals. The extraction and stripping behavior of the two metals in the absence and presence of other impurity metals by various
types of extractants such as cationic, solvating, amine and a mixture of cationic and solvating extractants was discussed. Each
type of extractants has advantage and disadvantage in terms of the possibility of separation and of forming a third phase. Among
the various types of extractants, a mixture of cationic and solvating extractants seems to be the most promising extractant system
for the separation of Mo and V from the acid leaching solutions of spent catalysts.