Inhibition of Rh sintering and improved reducibility of Rh on ZrO2 nanocomposite with an Al2O3 diffusion barrier

Abstract To enhance the durability of Rh catalysts for vehicle emissions control, a novel support, Nd-A80ZL, was designed. This support was composed of La 2 O 3 -stabilized ZrO 2 particles that contained a Nd 2 O 3 -enriched surface layer and nanosized Al 2 O 3 particles, which acted as a diffusion barrier. Nd 2 O 3 was mainly loaded on ZrO 2 after high-temperature aging, as anticipated. Then, Rh was also mainly loaded on the ZrO 2 with the Nd 2 O 3 surface enrichment; the inhibition of Rh sintering during the aging test suggests that the surface Nd 2 O 3 functioned as anchoring sites for Rh. The results of the hydrogen temperature-programmed reduction showed that Rh on the Nd-A80ZL support was more easily reduced than that on a La 2 O 3 -stabilized ZrO 2 support with Nd 2 O 3 surface enrichment (Nd-ZL). Rh/Nd-A80ZL also had a more appropriate solid basicity than Rh/Nd-ZL. These results showed that the introduced Al 2 O 3 diffusion barrier in Nd-A80ZL controlled the basicity derived from the addition of Nd 2 O 3 and balanced the inhibition of Rh sintering and Rh reducibility.