Ni-Mn Spinel Aerogel Catalysts with Adsorption Induced Superior Activity for Low-Temperature Toluene Oxidation

The development of a highly efficient oxide catalyst is crucial for thermal and environmental catalytic reactions. Herein, a facile and eco-friendly strategy is developed to synthesize a series of Au-modified hollow Ni–Mn spinel nanospheres decorated on graphene aerogels (GAs) (termed Au y -hNi x Mn 3−x /GA z ) composite catalysts for deep catalytic oxidation of VOCs. The introduction of hollow structure leads to a larger specific surface area and more accessible active sites. The subsequent cooperation of Au further strengthens the low-temperature reducibility along with more active surface oxygen species. After being embedded into the graphene network, the composite catalyst shows an improvement in electron transfer and accessibility to active metal sites. The adsorption capacity of the catalyst for toluene is greatly improved by the above steps, thus facilitating the catalytic performance. The resulting Au 1 -hNi 1 Mn 2 /GA 0.5 composite catalyst exhibits optical activity for VOCs removal, reaching 100% toluene and benzene (500 ppm) oxidation at 155 °C and 148 °C, respectively. Meanwhile, the catalyst shows extraordinary catalytic stability, selectivity, moisture tolerance and compressibility making it a promising catalyst for industrial thermal catalysis. Moreover, an in situ DRIFTS study is carried out for the exploration of the reaction pathway and a modified MVK catalytic mechanism was proposed as well.