Faezeh Godarrzi - Department of Chemistry, Faculty of Science, Arak University, ۳۸۱۵۶-۸-۸۳۴۹, Arak, Iran
Vahid Mahdavi - Department of Chemistry, Faculty of Science, Arak University, ۳۸۱۵۶-۸-۸۳۴۹, Arak, Iran

Petroleum refineries must pay attention to spent hydroprocessing catalysts particularly since they arehazardous toxic wastes. This review focuses on the progress in metal reclamation and disposal methodsused for dealing with the environmental problem ofspent hydroprocessing catalysts. Studies have beenconducted with the aim either to increase the efficiency of metals recovery using established methodsor to develop novelmethods. Leaching studies used inorganic agents such as solutions of strongacidsandbases, alumina containing compounds and water soluble organic acids.The extracted metals were impregnated on recovered alumina to synthesize fresh catalyst. Structural analysis of spentcatalyst, recovered support material, and synthesized catalyst from extracted metals suggested successful recovery and recycling ofmetals. This work offers an incentive to the industrial practice for waste minimization, recycling of the extracted metals, and thenoncorrosive, ecofriendly approach for metal extraction from spent catalyst.Hydro desulphurisation is a non-homogeneous catalytic reaction. Sulfide-based metals have been proven to be base. Molybdenum and tungsten sulfide Both HDS catalysts are the best catalysts for reactive reactivity for hydro-desulphurisation. Molybdenum is often used as a catalyst in sulfur removal processes.