Kinetics of platinum extraction from spent reforming catalysts in aqua-regia solutions

摘要: Abstract Platinum content of two commercial spent reforming catalysts were extracted in aqua-regia solutions under atmospheric pressure and at temperatures up to 100 °C. Three factors, including presence coke, catalyst particle size, impeller agitation speed first tested study the relative importance mass-transfer resistances during Pt extraction reaction. Catalyst sizes  700 rpm eliminated internal external resistances, respectively. The effect other HNO3-to-HCl volume ratio, liquid-to-solid mass reaction temperature on rate platinum then examined. was significantly increased by increasing ratio temperature. Kinetic modeling using power-law equation for revealed that increases acid concentration, as a major reactant. This quantitatively accounted rate. kinetics studied Arrhenius equation. activation energy surface dissolution calculated 72.1 kJ/mol. large value indicates solution is controlled chemical order 1.5 concentration solid 1.3 hydrogen ion molarity solution.