Effect of modified CeO2 on the performance of PdCu/Ce1-xTixO2 catalyst for methanol purification.

Abstract

In this paper, we prepared a series of Ce1-xTixO2 (x = 0-0.20) nanorods by hydrothermal method, which were used to construct the PdCu/Ce1-xTixO2 catalysts. The Ce1-xTixO2 and PdCu/Ce1-xTixO2 samples were characterized by transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2adsorption-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 Ce1-xTixO2 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/Ce0.9Ti0.1O2, 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.