Effect of Pd loading on ZrO2 support resulting from pyrolysis of UiO-66: Application to CO oxidation

The effect of Pd loading (0.25, 0.5 and 1.0 wt%) and ZrO2 support calcined at diverse temperatures (600, 700 and 800 degrees C) by pyrolysis of UiO-66 was investigated for CO oxidation in this work, respectively. The physicochemical properties of the samples were characterized by various characterization methods. The XRD results exhibited that all ZrO2 support possessed mixed crystalline phase, the monoclinic ZrO2 and tetragonal ZrO2. And the calcination temperature had a big impact on the composition of ZrO2 supports. Pyrolysis of UiO-66 at high temperature was favorable for the formation of monoclinic ZrO2. Additionally, the introduction of Pd was induced the phase conversion from tetragonal to monoclinic of ZrO2. The order of catalytic efficiency was as follows: 0.5Pd/Zr-700 > 0.5Pd/Zr-600 > 0.5Pd/Zr-800. Moreover, 0.5Pd/Zr-700 presented high stability and great reusability. The good catalytic performance of 0.5Pd/Zr-700 was ascribed to the better reduction ability at low temperature and high O-ads/O-lat and Pd-0/Pd2+ on the surface. Importantly, the reaction pathway of CO oxidation over the 0.5Pd/Zr-700 was exposed. (C) 2020 Elsevier Inc. All rights reserved.