Method for selectively extracting and separating molybdenum in spent catalyst leaching solution by utilizing benzyl quaternary ammonium salt deep-eutectic solvent

The invention relates to a method for selectively extracting and separating molybdenum in a spent catalyst leaching solution by utilizing a benzyl quaternary ammonium salt deep-eutectic solvent. The method comprises the following steps of: (1) synthesis of the benzyl quaternary ammonium salt deep-eutectic solvent: mixing a hydrogen bond donor and a hydrogen bond acceptor according to a molar ratioof (1-4): 1, stirring and mixing uniformly at 30-80 DEG C, wherein the stirring time is 10-60 minutes, and vacuumizing and drying a sample after reaction to obtain the deep-eutectic solvent; and (2)extraction and separation of molybdenum: fully mixing an extracted organic phase with the spent catalyst leaching solution to be treated for reaction, and performing phase-splitting reverse extractionafter reaction to obtain a molybdenum product. In the extraction and separation process, the extracted organic phase containing the deep-eutectic solvent is added into the molybdenum-containing acidic leaching solution, the two phases are fully mixed for reaction, and phase splitting is performed after reaction to obtain a loaded organic phase; and after phase-splitting reverse extraction, efficient separation of molybdenum and other metal ions is realized, so that the extraction selectivity and the purity of molybdenum are improved.