Résumé
Platinum deposition at ceria surfaces has been widely used for catalytic processes including automotive three-way catalysts. Each standard catalytic converter may contain from 3 to 7 g of Pt fine particles dispersed on cerium-based oxides. [1] The rising world demands of CeO 2 /Pt catalysts have contributed to the increase of Pt and Ce prices therefore allowing considering their recycling. Ceria is however difficult to dissolve and usually requires very strong conditions using concentrated acids at high temperature. Due to the highly positive redox potential of Ce IV /Ce III couple, one alternative concerns its reductive dissolution. In this work, the reductive dissolution of ceria is investigated in mild conditions at almost room temperature. The dissolution is catalyzed by the sonochemical deposition of Pt nanoparticles (NPs) at the surface of the oxide (Ar, 18 W.cm -2 , 20-40°C, 20 kHz). Typically, H 2 PtCl 6 solution (1 mL, 4.5 g.L -1 ) is injected into the sonicated mixture (50 mL) to reach a 2.5 wt.% of Pt on ceria support (180 mg). [2] Sonication is performed in HNO 3 -HCOOH-[N 2 H 5 ][NO 3 ], HNO 3 -[N 2 H 5 ][NO 3 ] or H 2 SO 4 -HCOOH mixtures. After Pt deposition, further dissolution is carried out under ultrasound or mechanical stirring. Dissolution progress is evaluated using UV-Vis spectroscopy, ICP-AES, and SEM.