Abstract (EN):
Hydrodesulphurization (HDS) spent catalysts are hazardous solid wastes from petroleum refining industries that contain valuable metals in appreciable concentrations. In this work, removal of Ni from a spent Ni-Mo catalyst was studied. In order to evaluate selective extraction of Ni from Al and Mo, ethylenediaminetetracetic acid (EDTA) leaching was performed using conventional and microwave-assisted methods and compared with the sulphuric acid (H2SO4) performance. Microwave-assisted leaching with nitrilotriacetic acid (NTA) solutions was also performed. Results showed that EDTA leaching, using conventional heating, had a very restricted Ni extraction, even when time and concentration were increased. When microwave-assisted process was applied, Ni dissolution reached 80% at optimum conditions (4 heating cycles of 60 s each, 0.1 M EDTA, pH 10.8 and S/L = 50 g/L). Even though this value was lower than the results obtained with 0.8 M H2SO4 (>= 90%), both Al and Mo extractions were significantly lower, leading to a more selective extraction. Ni leaching with NTA was not as efficient as EDTA, even though Mo and Al extractions were reduced.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
8