Formation of Ru Shell on Co/Al2O3 by Galvanic Deposition Method and Its High Catalytic Performance for Three-Way Conversion

A supported Ru catalyst was prepared by a galvanic deposition (GD) of Ru on Co particles supported on Al2O3 (Ru/Co-GD). The structure and chemical state of Ru/Co-GD was characterized by using a pulsed CO chemisorption technique, STEM-EDS, XAFS, XPS, CO adsorption FT-IR spectroscopy, and temperature-programed reduction (TPR) method. It is indicated that Ru/Co-GD forms Ru shell on Co nanoparticles. Such a unique structure was not formed on Ru/Co/Al2O3 prepared by a conventional sequential impregnation method (Ru/Co-seq). The Ru shell of Ru/Co-GD showed higher reducibility than Ru species of Ru/Co-seq as well as higher than Ru/Al2O3. Owing to the Ru shell having high reducibility, Ru/Co-GD showed enhanced catalytic activity for NO–C3H6 reaction. In addition, Co oxide on Ru/Co-GD exhibited high catalytic activity for CO and C3H6 oxidation. As a result, Ru/Co-GD showed superior performance for NO–C3H6–CO–O2 reaction compared to the conventional catalysts. The Ru shell structure also contributed to the suppression of Ru vaporization.