The catalytic performances of supported Pd nanoparticles (NPs) are strongly dependent on the support materials for CO oxidative coupling to dimethyl oxalate (DMO). Herein, hierarchical flower-like ZnO microspheres composed of porous nanosheets are employed as a new support material for Pd catalyst, which exhibits excellent catalytic activity for CO oxidative coupling to DMO. The conversion of CO and the selectivity to DMO reach up to 67% and 98% at 130 °C, respectively. Unfortunately, the high activity of Pd/ZnO catalyst gradually deteriorates within 100 h. To resolve the poor stability, we further introduce Mg 2+ ions into ZnO support. It is exciting that the catalytic activity of Mg 2+ -doped ZnO supported Pd nanocatalyst (Pd/Mg-ZnO) can be maintained for at least 100 h without obvious decay. Catalytic stability is greatly improved by the doping of Mg 2+ ions. XRD, UV-DRS and HAADF-STEM-EDS characterizations demonstrate that a small portion of Mg 2+ ions are successfully incorporated into the lattice of ZnO support to form Zn-Mg oxide solid solution. XPS, in situ DR-FTIRS, and H 2 -TPR results reveal that the introduction of Mg 2+ ions into ZnO support leads to a strong metalsupport interaction caused by electron transfer from ZnO substrate to Pd NPs, which can effectively restrain the sintering of the active Pd NPs, retard the growth of Pd NPs, and thus enhance the catalytic stability.

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