High three-way catalytic activity of rhodium particles on a Y-stabilized La-containing ZrO2 support: the effect of Y on the enhanced reducibility of rhodium and self-regeneration

A novel, highly active three-way catalyst, rhodium supported on Y- and La-added zirconia (Rh/Zr-Y-La-O), was found in this study. Rh/Zr-Y-La-O showed superior performance to a previously reported Rh on La-added ZrO2 (Rh/Zr-La-O) catalyst (Kawabata et al., Chem. Commun., 2013, 49.38), 4015; Catal. Sci. Technol. 2014, 4(3), 697). (21,22) The effects of Y addition to ZrO2-based supports were investigated in detail. CO temperature-programmed reduction and in situ Fourier transform infrared spectra of adsorbed NO species indicated that Y addition to La-containing ZrO2 enhanced the reducibility of rhodium supported on the catalyst and that more metallic Rh was exposed on the surface after the oxidation of Rh/Zr-Y-La-O than of Rh/Zr-La-O. Before and after an aging treatment at 1273 K that simulated 80 000 km travelled by vehicles, Rh/Zr-Y-La-O showed high steam reforming activity. After the aging treatment, Rh/Zr-Y-La-O was deactivated using an oxidation treatment, but its three-way catalysis activity was completely regenerated after a short (5 min) exposure to steam reforming reaction conditions, demonstrating self-regeneration capability. After the aging treatment, Rh/Zr-Y-La-O showed higher rhodium dispersion than other catalysts. This was attributed to the high surface area of the support after aging and the stabilization of ZrO2 by the addition of Y. Our findings highlight the role of catalyst supports in designing effective three-way catalysts with high tolerance to the oxidative conditions in new vehicles and engines.