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Ind. Eng. Chem. Res., 2013, 52 (36), pp 12794–12801.
H. Al-Sheeha , Meena Marafi , Vira Raghavan , Mohan S. Rana.
Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109 Ahmadi, Kuwait
Abstract
This study investigates the recovery of Mo, V, and Ni metals from the industrial spent hydroprocessing catalyst. These catalysts are not viable to regenerate mainly due to the metal deposition. The study was carried out on industrial spent residue hydroprocessing (ARDS) catalysts that contained high levels of metals. In the extraction process, metals were recovered through pyrometallurgical and hydrometallurgical routes. The possibility of recycling of total spent catalyst (TSC) was studied using various steps such as deoiling, drying, grinding, sieving, and decoking. In the subsequent steps, the digested spent catalysts were treated with acid–base reactions in order to separate the various components of the spent catalyst. Using various leaching reaction conditions such as acid–base concentration, reaction pH in aqueous as well as organic mediums was studied. The metals were leached out in the solution while the alumina support was recovered as bulk solid in the form of boehmite. The recovered alumina is further treated hydrothermally and recovered as boehmite. Samples were characterized by surface area, pore volume, and pore size distribution measurements. Hence, recovery of valuable metals from the spent catalysts is an attractive option for their recycling and utilization. Therefore, TSC recovery is not only important from an environmental point of view but also very vital from an economic viewpoint.
Copyright © 2013 American Chemical Society
Additional Information:
Catalyst Recycling Steps:
A. Support kneader/extruder machine: This machine is used to mix and extrude the alumina support powder into different extrudates shapes and dimensions.
B. Catalyst Development: After extrusion of the catalyst supports, prototype catalysts were prepared by impregnation of the active metals (CoMo, NiMo, NiWMo) solutions on the support materials.
C. Bench Scale Catalyst Testing Unit: A high pressure fixed bed micro reactor unit was used for testing hydrotreating and hydrocracking of various catalysts prepared in the laboratory.
D. Spent Catalyst (black color): During the residue hydroprocessing the catalyst activity decreased due to the carbon and metals (Ni and V) deposition, which require unload the spent catalyst or replace with the fresh one.
E. Alumina and metal Recovery from Spent Catalyst: The decoked/roasted spent catalyst alumina support was separated from the metals (V, and Mo). The residue containing Ni and Al2O3 was digested with caustic soda solution under pressure in an autoclave at temperatures in the range 250-300oC to dissolve the Al2O3 as sodium aluminate, and Ni was recovered from the insoluble residue by acid leaching.
F. High Purity Alumina Recovered from Spent Catalyst: Alumina powder is prepared by precipitating aluminum hydroxide by reaction of sodium aluminate and aluminum sulfate in water. The alumina recovery as boehmite, the alumina residue from the soda ash roasting process was characterized and high quality alumina is recovered from the spent catalyst.
