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

Abstract

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.