Engineering of catalytic sites of Pdx-Ce1-xO2-δ for dehydrogenation, oxygen insertion and reverse water gas shift reactions during methane combustion

•Pd0.03Ce0.97O2-δ catalysts prepared by combustion synthesis via different fuels.•Fuel type in combustion synthesis affects the surface features of the materials.•Higher concentration of oxygen vacancies favours the combustion reaction.•Having in situ PdO to PdHx transition boosts catalytic performance and stability.•Catalysts with surface supported and lattice substituted PdOx gave best performance.