A kinetic study on hydrochloric acid leaching of nickel from Ni–Al2O3 spent catalyst

摘要

Hydrochloric acid leaching of nickel from spent Ni-Al2O3 catalyst (12.7% Ni, 39.2% Al and 0.68% Fe) has been investigated at a range of conditions by varying particle size (50-180μm), acid concentration (0.025-2M), pulp density (0.2-0.4%, w/v) and temperature (293-353K). Nickel was selectively leached from the catalyst, irrespective of the different conditions. Under the most suitable conditions (1M HCl, 323K, stirring at 500rpm, 50-71μm particle size), the extent of leaching of Ni and Al after 2h was 99.9% and 1%, respectively. The XRD pattern of the spent catalyst corresponded to crystalline α-Al2O3 along with elemental Ni. The peak due to elemental Ni was absent in the residue sample produced at the optimum leaching conditions, confirming the complete dissolution of Ni from the spent catalyst. The leaching results were well fitted with the shrinking core model with apparent activation energy of 17kJ/mol in the temperature range of 293-353K indicating a diffusion controlled reaction.