The kinetics of vanadium extraction from spent hydroprocessing catalyst by leaching with sulfuric acid at atmospheric pressure

The dissolution kinetics of vanadium from spent hydroprocessing catalyst was investigated by leaching with sulfuric acid at atmospheric pressure. The effects of stirring speed (400–800 rpm), initial sulfuric acid concentration (0.60–1.20 mol/l) and reaction temperature (373–423 K) on the vanadium dissolution were studied. The results showed that the vanadium dissolution ratio was practically independent of stirring speed at the investigated range, while increasing with the increases of sulfuric acid concentration and reaction temperature. The experimental data agreed quite well with the shrinking core model, with solid membrane diffusion as the rate controlling step. The apparent activation energy was calculated as 11.44 kJ/mol, and the reaction order with respect to sulfuric acid concentrations was determined to be 1.51. The kinetics equation of the leaching process was established as: 1 − 2x/3 − (1 − x) 2/3 = 0.067[H 2 SO 4 ] 1.51 exp[ − 11563/RT ]t. 1−2x/3−(1−x)2/3=0.067[H2SO4]1.51exp[−11563RT]t.