Study Of Recovery And Reutilization Of Noble Metal From Spent Catalysts

Platinum has excellent catalytic activity and is widely used in industrial catalysts. Spent platinum containing catalysts are of valuable secondary resources due to its abundant resources and high grade, so the spent catalysts recycling is of great significance.In this thesis, the different kinds of alumina carrier type platinum-containing spent catalysts were studied. The current status of recovering from spent catalysts were reviewed and summarized. The process route of “Dissolve carrier-Chloride leaching of platinumChloride precipitation-Calcination” is used for the recovery of dehydroge nation spent catalysts whose carrier is γ-Al2O3 polymorph. The process conditions of Dissolve carrier and Chloride leaching of platinum were investigated. The process of “Ammonium sulfate roasting-Acid dealumination-Chloride leaching platinum-C hloride precipitation- Calcination” is used for the recovery of spent reforming catalysts whose carrier is γ-Al2O3 and α-Al2O3. The process conditions of Ammonium sulfate roasting-Acid dealumination were investigated. These process routes realized a comprehensive reco very of platinum and aluminum from spent catalysts.In the experiment of dehydrogenation spent catalysts, optimum process conditions for Dissolving carrier were listed as follows: for H2SO4 of 6mol/L, the liquid-solid ratio is 6:1, the temperature is 110℃, and the reaction time is 4h. Under these conditions, the dissolution rate of carrier can reach to 95%. Optimum process conditions for Chloride leaching platinum were listed as follows: Hydrochloric acid concentration is 8 mol/L, the liquid-solid ratio is 8:1, the reaction temperature is 60℃, the reaction time is 2h, the amount of sodium chlorate to 10% of the weight of aluminum dross. Under these conditions, the leaching rate of platinum can reach to 99.8%. Using this process route, the recovery rate of platinum reaches to 92%, and the recovery rate of aluminum reaches to 76%.In the processing experiment of spent reforming catalysts, optimum conditions for Ammonium sulfate calcination and acid dealumination were listed as follows: the ratio of Ammonium sulfate and spent catalyst of 4:1, the calcination temperature of 400℃, the calcination time of 2h, sulfuric acid concentration of 1mol/L, liquid-solid ratio of 9:1, leaching temperature of 110 ℃, and leaching time of 2h. Under these conditions, the dissolution rate of carrier reaches to 92%. Using this processing route, recovery rate of platinum reaches to 91%, recovery rate of aluminum reaches to 60%.