In order to recover and recycle the valuable metals, such as Mo, Ni and V on γ-Al2O3 supported catalyst, which has been used for desulfurization in petroleum refining process, three step process, i.e. air-oxidation roasting step at temperatures from 400 to 900°C, alkaline leaching step using sodium hydroxide and carbonate solution and hydrogen reduction-hydrochloric acid leaching step, has been experimentally conducted for its process feasibility. It has been known that NiAl2O4 spinel compound formation in the roasting step hinders the leaching of Ni, which leads us to the reducing-acid leaching step of the alkaline leach residue. It has been shown that (1) in the roasting step, better elimination of hydrocarbon and sulfur constituents is attained at temperature at temperatures, 700 to 900°C, with resultant formation of Mo and V oxides and Ni spinel compound, (2) better leaching rate of Mo and V, 97% and 89% respectively, and the least leaching rate of Al (around, 0.6%) using sodium carbonate solution and (3) high Ni leaching rate of 80% has been attained in the final step. Thus, using this three step process, reasonable rate recovery of Mo, V and Ni has been shown feasible and this process scheme could be applicable for recovery Mo, Co and V in desulfurization catalysis.
