Efficient control of automotive emission by Pt-based and Rh-based three-way catalysts: The critical role of phase structure of ceria-zirconia support

Abstract

Rationally design efficient supports material is essential for heterogeneous catalysts with enhanced activity in many industrial catalytic processes, accordingly a clear understanding of the support effect is necessary. Herein, two ceria-zirconia materials without/with partial κ-Ce2Zr2O8(CZ/κCZ) structure were achieved and then employed as supports for Rh-based and Pt-based three-way catalysts (TWCs), respectively. According to the results of systematic characterizations, it has been manifested that the surface conditions of supports significantly affected the activity and stability of Rh-based and Pt-based catalysts. As κCZ exhibits an intrinsic Zr-rich surface with more oxygen vacancies with respect to CZ, Rh species supported on κCZ mainly occupy the Zr sites over the surface, thus exhibit a more electronic-rich and active state due to the decreased Rh-Ce interfaces, which weakened the undesirable electron transfer from Rh to Ce. As a result, κCZ delivered as an ideal support for improving the performance of Rh-based TWCs effectively. On contrary, comparing with Pt/CZ, more serious sintering of Pt nanoparticles and inferior activity as well as stability have been detected in Pt/κCZ due to the decreased Pt-Ce interfaces, which weakened the anchor effects of the support through Pt-O-Ce bonds. This finding enhances the understanding of support effects for the development of advanced TWCs.