Catalytic decomposition of N2O over Rh/Zn–Al2O3 catalysts†
Abstract
Zn–Al2O3 supports were prepared by impregnating commercial γ-Al2O3 powders with different amounts of Zn(NO3)2, followed by calcination in air at 500 or 800 °C. Rh/Zn–Al2O3 catalysts were then prepared by impregnating Zn–Al2O3 supports with Rh(NO3)3 followed by calcination in air at 500 °C. The catalysts and/or supports were characterized by ICP-OES, XRD, N2 adsorption, Raman spectroscopy, TEM-EDX, XPS, CO2-TPD, H2-TPR, and O2-TPD, and the catalytic performance of supported Rh catalysts in N2O decomposition was tested. It is concluded that the support can be described as ZnO/Al2O3 (ZnO supported on Al2O3) when calcining Zn(NO3)2/Al2O3 at 500 °C, whereas ZnAl2O4 spinel forms on the Al2O3 surface at 800 °C. Rh/Zn–Al2O3 catalysts are much more active than Rh/Al2O3 and Rh/ZnO. The best catalyst (Rh/Zn–Al2O3-800 with 1 wt% Rh and 1 wt% Zn) has the smallest Rh2O3 particle size and can desorb O2 at lower temperature than other catalysts. Both factors may be important for achieving high activity in N2O decomposition.