Selectively stepwise separation and recovery of molybdenum and vanadium from simulated leaching solution of spent hydrodesulfurization catalysts

Selective separation of molybdenum(Mo) and vanadium(V) from hazardous secondary resources containing Mo and V has become a technical bottleneck of its resource utilization. In this work, the selective separation of Mo and efficient recovery of V from simulated leaching solutions of spent hydrodesulfurization (HDS) catalysts were investigated via solvent extraction and chemical precipitation . The result indicates that the D 2 EHPA(P204) exhibits higher selectivity for Mo in strongly acidic conditions. Under optimum experimental conditions of hydrochloric acid of 1 mol/L, extractant concentration of 20 % (v/v), O/A ratio of 1:3 and contact time of 50 min, the single-stage extraction ratio of Mo reached 98.63 %, meanwhile, the co-extraction ratio of vanadium was less than 5 %. Additionally, over 97 % of Mo could be stripped from loaded organic phase at O/A ratio of 1 with 50 g/L NH 4 HCO 3 . The mechanism analysis revealed that selective extraction of Mo was mainly through the cation exchange mechanism. Moreover, the enthalpy changes in the molybdenum extraction were 44.1 kJ mol −1 , which demonstrated that was an endothermic reaction . Furthermore, the Fe(III) was adopted to fabricate FeVO 4 by precipitating vanadium from raffinate, and the precipitation efficiency of vanadium reached 97.71 % at a Fe/V molar ratio of 5/2, meanwhile, the precipitation product was further confirmed by XRD, XPS and SEM-EDS. Ultimately, a conceptual flowsheet for recovering completely Mo and V from simulated leaching solutions of spent HDS catalysts was proposed, which provides theoretical guidance for the resource utilization of containing molybdenum and vanadium secondary resources.