METHOD OF PREPARING PALLADIUM FROM SPENT ALUMINIUM OXIDE- BASED CATALYSTS Russian patent published in 2000 - IPC

FIELD: chemical industry, more particularly preparation of noble metals. SUBSTANCE: treatment of catalyst is carried out with hydrochloric acid in four steps at S:L ratio of 1:0.6 in first two steps and S:L ratio of 1: -0.5 in subsequent steps with portionwise addition of hydrogen peroxide at H₂O₂:HC1 ratio of 1:10. In first treatment step, hydrogen peroxide is added 4 times within 10 minutes and in subsequent steps 2 times within 15-20 minutes. Carrier granules are washed with water at S:L ratio of 1:0.6 and contact time is 20 minutes. Palladium is reduced from formic acid solution with pH of 14. Method makes it possible to leach out 97- 98.8% of palladium contained in catalyst, to break granules and isolate chlorine and remove aluminium from said solution. EFFECT: more efficient preparation method. 4 cl, 15 ex, 1 tbl