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• Pd is doped into the CeMnO bulk lattice by an optimized co-precipitation (CP). • CP outperforms impregnation for CH 4 combustion and CH 4 -related three-way reactions. • Pd in PdCeMnO-CP is partially exsoluted, with lowered valence, after CH 4 combustion. • Surface oxygen vacancy is enriched after CH 4 combustion over PdCeMnO-CP. Besides the Pd/Al 2 O 3 , the Pd-CeO 2 catalysts are the indispensable and promising candidates for methane combustion. The Pd-CeO 2 composites with intimate interaction realized by elaborate methods are regarded as the most active formulations. However, more facile and cost-efficient methods are needed for industrial application. Herein, the Pd was incorporated into the lattice of the Mn-doped CeO 2 by an optimized co-precipitation method to synthesize the PdCeMnO-CP catalyst. The PdCeMnO-CP showed much higher catalytic activity with the T 10 decreased by 70 °C than that of the Pd/CeMnO-Imp prepared with impregnation. The partial exsolution of the initially doped Pd species and the lowered valence of Pd (from Pd4+ to Pdδ+, δ: 2 ∼ 4) during the reaction were confirmed by the low-temperature CO-DRIFTs, CO-pulse chemisorption, XRD and XPS, which were responsible for the activity enhancement. The undercoordinated Ce4+ species were generated during the reaction, thus improving the mobility of the lattice oxygen which is vital for the methane combustion following the MvK mechanism. The PdCeMnO-CP also showed higher activity for the complex methane-containing three-way catalytic reactions than the Pd/CeMnO-Imp, demonstrating its potential for industrial application. [ABSTRACT FROM AUTHOR]

• Pd/Ba-Al 2 O 3 is an excellent catalytic material for wet methane oxidation. • The location, size, valence and property of Pd are controlled by Ba through a two-step impregnation process. • The active metal Pd inside the porous channel makes the catalyst show superior resistance toward H 2 O. • The introduction of Ba enhances the O 2 activation ability of the catalyst. • The low temperature wet methane oxidation depends on the partial pressures of O 2 and H 2 O, but not on those of CH 4 and CO 2. Low temperature wet methane oxidation is critical for the after-treatment of exhaust from the vehicles powered with natural gas-fueled engine, which is always operated at low temperatures and with high water vapor concentrations. Herein, Pd/Ba-Al 2 O 3 catalysts were prepared, with different amount of Ba as the promoter. It was found that the Pd/Ba-Al 2 O 3 catalysts were superior to the reference Ba-free Pd/Al 2 O 3 catalyst in terms of methane conversion, intrinsic activity and hydrothermal stability. Based on the sufficient characterization results, the location, size, valence state and diverse properties of Pd regulated by Ba were revealed. The benefit from Ba addition on the catalytic performance was demonstrated to be derived from the favorable location of Pd inside the porous channel and the enhancement in the capability for O 2 activation. This work can provide insights into the effect of promoters on the catalysts, offer an avenue to designing highly efficient wet methane oxidation catalyst, and lay a foundation for the application of Pd/Ba-Al 2 O 3 in exhaust after-treatment for the natural gas-fueled vehicles. [ABSTRACT FROM AUTHOR]