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۱Kinetic Study of Nickel Leaching from Spent Catalyst in Sulfuric Acid solution
اطلاعات انتشار: همایش ملی یافته های نوین شیمی در صنعت و پزشکی، سال
تعداد صفحات: ۷
The kinetics of spent nickel oxide catalyst (NiO\Al2O3) leaching in sulfuric acid solution was investigated. The effects of spent catalyst particle size, acid concentration and reaction temperature on Ni extraction rate were determined. The results obtained show that extraction of about 96% is achieved using 200 mesh spent catalyst particle size at a
reaction temperature of 100C for 360 min reaction time with 60% sulfuric acid concentration. The solid\liquid ratio was maintained constant at 1:20 g\ml. Leaching kinetics are controlled either by diffusional mass transfer of either reactant or product ions through a liquid boundary layer or a product metal deposit. The leaching kinetics indicates that chemical reaction at the surface of the particles is the rate–controlling process during the reaction. The activation energy was determined as about 33.65 kJ\mol. This is consistent with values of activation energies reported for surface controlled reactions.<\div>

۲Hydrometallurgical Processing and Recovery of Nickel from Spent Catalyst with HCl and Aqua Regia
اطلاعات انتشار: همایش ملی یافته های نوین شیمی در صنعت و پزشکی، سال
تعداد صفحات: ۷
The nickel based catalysts are conventionally used in process of refinery. After periodical use of the catalysts, due to poisoning effect of foreign material and impurities, which deposit on the surface of the catalyst, they will become inactive. In such cases, fresh catalysts have to be substituted and the spent catalyst will be discarded as waste material. Spent catalysts are harmful for the environment and the nickel is a precious element, so the particular attention is paid to the recycling of spent catalyst. This study investigates the possibility of recovering nickel from the spent catalyst (NiO\Al2O3) resulting from the steam reforming in Tabriz refinery. In the extraction process, nickel is
recovered using hydrochloric acid and aqua regia as a solvent. The considered parameters effecting nickel recovery were acid concentration, temperature and time of reaction, solid : liquid ratio, particle size and stirring rate, then experimental was performed and determined optimum condition. The results obtained show that extraction of about 87.41% and 81% for HCl and aqua regia is achieved, respectively.<\div>
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