Kinetic study on the leaching of spent nickel oxide catalyst with sulfuric acid

The results of a leaching kinetics study of spent nickel oxide catalyst with sulfuric acid are presented. The effects of spent catalyst particle size, sulfuric acid concentration, and reaction temperature on Ni extraction rate were determined. The results obtained show that extraction of about 94% is achieved using -200+270 mesh spent catalyst particle size at a reaction temperature of 85 degreesC for 150 min reaction time with 50% sulfuric acid concentration. The solid/liquid ratio was maintained constant at 1:20 g/ml. The leaching kinetics indicate that chemical reaction at the surface of the particles is the rate-controlling process during the reaction. The activation energy was determined as about 9.8 kcal/mol, which is characteristic for a surface-controlled process. (C) 2004 Elsevier B.V. All rights reserved.