METHOD FOR EXTRACTION OF PALLADIUM OF DEAD CATALYSTS ON THE BASE OF ALUMINIUM OXIDE Russian patent published in 1997 - IPC

FIELD: regeneration of palladium group metals of dead catalysts on the base of aluminium oxide, particularly, extraction of metallic palladium. SUBSTANCE: ground catalyst is mixed with powder sodium hydroxide or with potassium hydroxide at their ratio 1:1.0-1.2, respectively. Thus obtained mixture is tableted, compressing pressure being 15-25 MPa. Then caking within 0.5-1.0 h at 400-450 C is carried out and cake is leached with water, ratio of solid and liquid phases during leaching being 1:6-7. Separated palladium-containing precipitate is treated with reduction agent, allowed to stand within 0.5 h by mixing, filtered, washed and then is dried at 100-120 C. Mixture of 10 % solutions of formic and oxalic acid at their ratio 1:1 respectively, is used as said reduction agent. Thus content of palladium in precipitate is increased by 32.4 %, expense of alkaline reagent is decreased 2-2.5 times. Desired product is prepared as palladium black enamel having purity not less than 99 %. EFFECT: increased content of palladium in precipitate, decreased expense of alkaline reagent. 6 cl