A leaching agent composition, and a method of using the leaching acid composition to remove metal from catalyst material, are provided in which the leaching agent composition comprises oxidized disulfide oil (ODSO). Active phase metals and/or contaminant metals are removed, for example after typical oil removal and drying steps. Advantageously, ODSO, which is derived from a refinery waste stream, is used to replace and/or supplement commonly used leaching acid such as sulfuric or nitric acid to remove metals used in catalyst preparation or contaminant metals deposited onto the catalyst surface.

The disclosure describes a method of separating and recovering valuable metals from remanufacturing solution of a spent desulfurization catalyst containing vanadium, and more particularly, to a method of separating and recovering a valuable metal from remanufacturing solution of a spent desulfurization catalyst containing vanadium, which includes: adding organic acid to a spent hydrodesulfurization catalyst after collecting the spent hydrodesulfurization catalyst in order to prepare the remanufacturing solution of the spent hydrodesulfurization catalyst; adding an extracting agent and a diluent to the remanufacturing solution to extract molybdenum and extracting vanadium from an extracted filtrate to obtain an organic phase; and adding a stripping agent to the organic phase to strip and recover vanadium.

A method for recovering valuable metals is disclosed. The method includes: a spent catalyst preparation step in which a spent catalyst is prepared; and a leaching step in which a first inorganic compound containing VO.sub.3.sup. is leached from the spent catalyst at a temperature of less than 100 C. under normal pressure.

The following invention relates to methods for reprocessing SCR catalysts. In a first embodiment, the invention relates to a method for reprocessing SCR catalysts, wherein an oxygen-containing compound of titanium and tungsten or molybdenum is removed from the catalyst and is then reacted with a vanadium compound. In a second embodiment, the invention relates to a method for removing titanium oxide and vanadium, molybdenum, and tungsten compounds from SCR catalysts and to a method for reusing these compounds in such catalysts.

The following invention relates to methods for reprocessing SCR catalysts. In a first embodiment, the invention relates to a method for reprocessing SCR catalysts, wherein an oxygen-containing compound of titanium and tungsten or molybdenum is removed from the catalyst and is then reacted with a vanadium compound. In a second embodiment, the invention relates to a method for removing titanium oxide and vanadium, molybdenum, and tungsten compounds from SCR catalysts and to a method for reusing these compounds in such catalysts.

There is a process for the selective recovery of transition metals from an organic stream containing transition metals. The organic stream and possibly a first extractor if solid, are melted up to the liquid state. The extractor consists of an ionic liquid or a mixture of two or more ionic liquids and the ionic liquid contains an ammonium salt as cation and as anion an anion with chelating properties. A melted organic stream and a first extractor, optionally melted, are fed to a first liquid-liquid extraction unit working at a temperature of at least 150 C. where the liquid-liquid extraction is carried out obtaining a liquid mixture containing an ionic liquid, or a mixture of two or more ionic liquids, and metals. After extraction, the liquid mixture is cooled at a temperature between 0 C. and 70 C. and becomes biphasic; then the cooled mixture is sent to a first separation unit, to separate a liquid phase that contains ionic liquids and metals, and a metal-depleted solid phase. After the first separation, the separated metal-depleted solid phase is optionally sent to a washing unit to which a solvent is fed, so as to eliminate the residual ionic liquid by transferring it into the solvent and obtaining a metal-depleted solid phase. Then the separate liquid phase containing ionic liquids and metals is sent into a liquid-liquid precipitation and separation unit, adding a counter-solvent, thereby obtaining a solid phase containing the metals and a liquid stream containing counter-solvent and ionic liquids.