PtRu nanoparticles partially embedded in the 3DOM Ce0.7Zr0.3O2 skeleton: Active and stable catalysts for toluene combustion

Abstract

We successfully prepared 1.98 wt% PtRu nanoparticles (NPs) partially embedded in the skeleton of three-dimensionally ordered macroporous Ce0.7Zr0.3O2 (denoted as 1.98PtRu@3DOM CZO) using the polymethyl methacrylate-templating and ethylene glycol reduction methods. For comparison purposes, we also synthesized a 3DOM CZO-supported 2.03 wt% PtRu catalyst (denoted as 2.03PtRu/3DOM CZO) via a colloidal adsorption route. The 1.98PtRu@3DOM CZO sample exhibited better performance than the Pt or Ru NPs partially embedded in the skeleton of 3DOM CZO. Ru played an important role in promoting the low-temperature reducibility and oxygen adsorption ability of the sample. The catalytic activity of 2.03PtRu/3DOM CZO was better than that of 1.98PtRu@3DOM CZO (ΔT90% = 23 °C) for toluene combustion, and the former showed lower apparent activation energy (45 kJ/mol). However, 1.98PtRu@3DOM CZO possessed excellent thermal stability, over which the activity did not change obviously, while that over 2.03PtRu/3DOM CZO decreased greatly; furthermore, the catalytic activity of the former was superior to that of the latter after calcination at 800 °C for 5 h. After high-temperature treatment, the average particle size of PtRu NPs in 1.98PtRu@3DOM CZO increased slightly from 4.2 to 6.7 nm, whereas that of PtRu NPs in 2.03PtRu/3DOM CZO increased significantly from 5.1 to 17.3 nm. It is concluded that the good performance of 1.98PtRu@3DOM CZO is associated with its highly dispersed partially embedded PtRu NPs and good toluene and oxygen adsorption ability, since the embedded structure facilitated formation of a larger amount of PtOCe-like bonds that possessed strong interaction between PtRu NPs and 3DOM CZO and hence contributed to its better thermal stability.