Limited nanospace for growth of Ni–Mn composite oxide nanocrystals with enhanced catalytic activity for deep oxidation of benzene

• Growth of Ni–Mn mixed oxide nanocrystal took place in a limited nanospaces by nanocasting method.
• The 90% conversion of 1000 ppm benzene at a space velocity of 120,000 mL g−1 h−1 can be low to 249 °C.
• The porous Ni–Mn mixed oxide exhibits higher activity than the pure oxides clearly.
• The strong synergistic effect leads to more adsorbed oxygen species and better reducibility.

A nanocasting method was applied to synthesize porous manganese oxide, nickel oxide and manganese nickel mixed oxide successfully. The growth of oxide nanocrystals took place in the limited nanospace provided by SBA-15 template and the resulted materials showed a porous structure with high specific surface area. All catalysts were characterized by XRD, SEM, TEM, BET, XPS, H2-TPR techniques and further tested for total oxidation of benzene. The mixed oxide with a higher surface area (162.6 m2 g−1) exhibited the best activity (T90% = 249 °C at a high space velocity of 120,000 mL g−1 h−1), which is much higher than that of the pure oxide. The formation of Mn–Ni solid solution oxide prevented the growth of nanocrystals and the strong synergistic effect gave rise to more adsorbed oxygen species and better low temperature reducibility, which make a great contribution to its superior activity.

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