Leaching kinetics of platinum and palladium from spent automotive catalysts.
Sep Sci Technol 1987 Sep; 22(2):1149-1167
This report describes a study into the leaching kinetics of selected metals from automotive catalysts. Empirical rate expressions for both platinum and palladium were obtained from mass balances and concentration time data in a packed bed reactor using different (hcl):(hno3) leaching solution concentration ratios. The spent catalysts used in this study (minus 60 plus 70 mesh to minus 120 plus 140 mesh) were analyzed to be 3,791 parts per million (ppm) platinum and 1,306 ppm paladium. High initial rates for both platinum and palladium were obtained for the early stages of leaching and were followed by rapid decay up to about 110 minutes and 50 minutes, respectively. Typical concentrations in the leached solution were about 40 ppm pt and 20 ppm pd after about 5 hours for the experimental conditions used. The extent of reaction for platinum was in the 90-pct range while that of the palladium was in the 70-pct range.
MIR 18-87; Contract-G1125132-1901
Separation Science and Technology
Iowa State University