Influence of pretreatment conditions on low-temperature CO oxidation over Pd supported UiO-66 catalysts

•Pd supported on UiO-66 was pretreated under different armosphere.•Pretreatment conditions affect the physicochemical state of Pd species.•The better catalytic activity is attributed to high Pd2+/Pd0 and Olat/Oads. Polluting gas CO has attracted wide attention because of its toxicity to human health. Thus, it is urgent for the removal of CO. Herein, a series of Pd supported on UiO-66 catalysts were prepared by ethylene glycol reduction and the supported 0.5 wt% Pd on UiO-66 (0.5Pd-66) was used to investigate the influence of pretreatment conditions. It was found that the 0.5Pd-66 pretreated under O2 atmosphere (0.5Pd-66-O) possessed the better CO oxidation performance, which could completely oxide CO to CO2 at 165 °C. A series of characterization results indicated that the surface area, reduction ability at low temperature, particle size of Pd nanoparticles and surface chemical state of the catalyst were great influenced by pretreatment conditions. The better catalytic performance of 0.5Pd-66-O was ascribed to the high surface area, better reducibility at low temperature, small Pd NPs and more Pd2+ and Olat species. More importantly, the CO oxidation mechanism was proposed by in situ diffuse reflectance infrared Fourier transform spectroscopy of CO oxidation over 0.5Pd-66-O. This work has guiding significance for studying the effect of reaction atmosphere on the structure and activity of catalyst. [Display omitted]