Effect of modified CeO₂ on the performance of PdCu/Ce_1-xTi_xO₂ catalyst for methanol purification

In this paper, we prepared a series of Ce_1-xTi_xO₂ (x = 0-0.20) nanorods by hydrothermal method, which were used to construct the PdCu/Ce_1-xTi_xO₂ catalysts. The Ce_1-xTi_xO₂ and PdCu/Ce_1-xTi_xO₂ samples were characterized by transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometer (ICP-OES), etc. Catalytic activity, stability, and repeatability of the catalysts for methanol oxidation were investigated. The results show that doping a proper amount of titanium could strengthen the interaction between Ce_1-xTi_xO₂ support and PdCu nanoalloy, thus increasing the oxygen vacancy concentration and promoting Pd species with a higher oxidation state. These modified properties are beneficial for the deep oxidation of methanol. The light-off temperature (T₅₀) and full-conversion temperature (T₉₀) of methanol over the PdCu/CeO₂ catalyst are 108 °C and 159 °C, respectively. The greatest activity improvement is found for PdCu/Ce_0.9Ti_0.1O₂, which shows the lowest T₅₀ of 88 °C and T₉₀ of 138 °C. Furthermore, neither PdCu/CeO₂ nor the modified PdCu/CeO₂ catalyst produces by-products and exhibit excellent stability and repeatability throughout the whole test period. This study provides a reference for in-depth understanding and designing of efficient and stable CeO₂-based oxidation catalysts.