Recovery of platinum and palladium from various types of carrier waste catalysts and other waste residues Details

Various types of carrier catalysts are widely used in chemical and petrochemical industries, such as anthraquinone production of hydrogen peroxide, synthetic urea, CO removal from ammonia raw gas, benzene hydrogenation to synthesize cyclohexane, catalytic combustion of low concentration organic volatiles, reforming, isomerization, cracking, hydrogenation, dehydrogenation and other reactions in petroleum refining. Al2O3 is used as the carrier of various types, and SiO2 and CaCO3 are used as carriers. The main two metals used are platinum and palladium, forming Pt/Al2O3 and Pd/Al2O3 series, with different purposes, the platinum and palladium content of the catalyst is 0.01-0.5%, which is low-grade waste. Type a is insoluble in acid, while type y is easily soluble in acid. The composition of each type of spent catalyst is simple and involves only the recovery of individual platinum or palladium. The key to regenerative recovery technology is the effective separation of the platinum or palladium from the carrier and the extraction of the platinum-palladium enrichment or fine metal. One approach is to directly leach the platinum or palladium by stirring (or percolating or soaking) with acid or other chemical reagents, and then enrich from the solution by anion exchange, zinc (or iron or aluminum) replacement, activated carbon adsorption, sodium sulfide precipitation, and ethyl yellow drug precipitation. The opposite method is to leach the carrier to obtain the residue enriched with platinum and palladium. After the extraction of platinum and palladium enrichments or crude metals by both methods, there are no technical difficulties in further refining to pure metals.