Recovery of aluminum, vanadium, and nickel from waste desulfurization catalyst residue by roasting and water leaching

Abstract

The improper disposal of hydrodesulfurization (HDS) catalysts poses significant environmental risks due to the presence of toxic materials and metals. This study investigates a method for recovering valuable resources, specifically aluminum, vanadium, and nickel, from industrial waste HDS catalyst residue. The process involves roasting the HDS residue at 300°C for 120 min with a 1:1 solid-to-liquid (S/L) ratio of residue to sodium hydroxide (NaOH). Subsequent water leaching resulted in the recovery of approximately 99% of Al(III) and V(V). The leaching kinetics of Al(III) and V(V) were found to follow the Shrinking-Core model, described by the equations X = kc.t and 1 − (1 − X)1/2 = kc.t, with activation energies (Ea) of 7.39 kJ/mol and 4.61 kJ/mol, respectively. The leach liquor containing Al(III) V(V) was treated with concentrated hydrochloric acid (HCl) at pH 9.5 to precipitate aluminum salt, while vanadium was extracted using ammonium chloride (NH4Cl) by adjusting the pH to 7.1 at 50°C for 30 min. The residual material was leached with 5% (v/v) sulfuric acid (H2SO4) in the presence of 15% (v/v) hydrogen peroxide (H2O2) to achieve maximum nickel dissolution, resulting in the recovery of 99% of aluminum as Al(OH)3 with 99.8% purity and 99% of nickel as NiSO4.6H2O.