| Summary: | Dry reforming of methane with ratio CH<sub>4</sub>/CO<sub>2</sub> = 1 is studied using supported Ni catalysts on SBA-15 modified by CeMnO<sub>x</sub> mixed oxides with different Ce/Mn ratios (0.25, 1 and 9). The obtained samples are characterized by wide-angle XRD, SAXS, N<sub>2</sub> sorption, TPR-H<sub>2</sub>, TEM, UV–vis and Raman spectroscopies. The SBA-15 modification with CeMnO<sub>x</sub> decreases the sizes of NiO nanoparticles and enhances the NiO–support interaction. When Ce/Mn = 9, the NiO forms small particles on the surface of large CeO<sub>2</sub> particles and/or interacts with CeO<sub>2</sub>, forming mixed phases. The best catalytic performance (at 650 °C, CH<sub>4</sub> and CO<sub>2</sub> conversions are 51 and 69%, respectively) is achieved over the Ni/CeMnO<sub>x</sub>/SBA-15 (9:1) catalyst. The peculiar CeMnO<sub>x</sub> composition (Ce/Mn = 9) also improves the catalyst stability: In a 24 h stability test, the CH<sub>4</sub> conversion decreases by 18 rel.% as compared to a 30 rel.% decrease for unmodified catalyst. The enhanced catalytic stability of Ni/CeMnO<sub>x</sub>/SBA-15 (9:1) is attributed to the high concentration of reactive peroxo (O<sup>−</sup>) and superoxo (O<sub>2</sub><sup>−</sup>) species that significantly lower the amount of coke in comparison with Ni-SBA-15 unmodified catalyst (weight loss of 2.7% vs. 42.2%). Ni-SBA-15 modified with equimolar Ce/Mn ratio or Mn excess is less performing. Ni/CeMnO<sub>x</sub>/SBA-15 (1:4) with the highest content of manganese shows the minimum conversions of reagents in the entire temperature range (X(CO<sub>2</sub>) = 4–36%, X(CH<sub>4</sub>) = 8–58%). This finding is possibly attributed to the presence of manganese oxide, which decorates the Ni particles due to its redistribution at the preparation stage.
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