Processing of spent NiW/Al2O3 catalysts

摘要

Spent oxidized (500 oC, 5 h) commercial NiW/Al2O3 catalysts were processed using two different routes: a) fusion with NaOH (650 oC, 1 h), the roasted mass was leached in water; b) leaching with HCl or H2SO4 (70 oC, 1-3 h). HCl was the best leachant. In both routes, soluble tungsten was extracted at pH 1 with Alamine 336 (10 vol.% in kerosene) and stripped with 2 mol L-1 NH4OH (25 oC, one stage, aqueous/organic ratio = 1 v/v). Tungsten was isolated as ammonium paratungstate at very high yield ( 97.5%). The elements were better separated using the acidic route.