Improved sulfur-resistant ability on CO oxidation of Pd/Ce0.75Zr0.25O2 over Pd/CeO2-TiO2 and Pd/CeO2

The influence of sulfation on Pd/Ce0.75Zr0.25O2, Pd/CeO2-TiO2 and Pd/CeO2 was investigated. Physical structure and chemical properties of different catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), CO chemisorption, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and X-ray fluorescence (XRF). After 10 h SO2 sulfation, it was found that the decrement on CO oxidation catalytic activity was limited on Pd/Ce0.75Zr0.25O2 compared to Pd/CeO2-TiO2 and Pd/CeO2. It demonstrated that Pd/Ce0.75Zr0.25O2 was more sulfur resistant compared to the other two catalysts. After sulfur exposure, catalyst texture was not much influenced as shown by N2 adsorption and XRD, and surface Pd atoms were poisoned indicated by CO chemisorption results. Pd/Ce0.75Zr0.25O2 and Pd/CeO2-TiO2 exhibited less sulfur accumulation compared to Pd/CeO2 in the sulfation process. Furthermore, XPS results clarified that surface sulfur amount, especially surface sulfates amount on the sulfated catalysts was more crucial for the deactivation in sulfur containing environment.

Light-off curves of different catalysts (Gas composition: 1000 ppm CO, 150 ppm C3H6, 100 ppm NO, 5% CO2, 5% H2O, 5% O2 and balanced N2. SV=240000 mL/g/h)Figure optionsDownload as PowerPoint slide