Structured cobalt–manganese oxides on SiC nano-whisker modified SiC foams for catalytic combustion of toluene

This work presents a two-step method for preparing structured Cobalt-Manganese Oxides nano-sheet (CMO) on SiC nano-whisker (SNW) modified SiC foam support (i.e. CMO@SNW@SiC) and its application to catalytic combustion of toluene. Firstly, SiC nano-whiskers were synthesized on the surface of SiC foam via carbothermal reduction to increase the specific surface area of the resulting structured support (SNW@SiC). Then, CMO were grown on SNW@SiC by hydrothermal synthesis. SNW@SiC provide more surface area, and the nano-sized SiO₂/SiC_xO_y layer on the surface of the SNW promotes the redox reaction of the reactants on the surface, thereby ensuring the directional growth of CMO on SNW@SiC. Compared to the bare SiC foam, CMO loading was increased 67.5% on SNW@SiC. Analysis methods such as H₂-TPR, O₂-TPD and XPS prove that the redox ability of the CMO on SNW is similar to that of the powder CMO. Toluene catalytic combustion was used as a probe reaction to evaluate catalytic activity. The results show that the CMO@SNW@SiC catalyst could lower the light-off temperature compared to the CMO supported on SiC foam catalyst, which was equivalent to the bulk catalyst (CMO-24h). At the same time, in comparison with the bulk CMO catalyst, the CMO@SNW@SiC catalyst possessed a higher geometric external surface area, which promoted complete conversion of toluene at lower temperatures. In addition, the stability test shows that the CMO@SNW@SiC catalyst also had very good thermal stability and hydrothermal stability as well. The work provided not only the highly performed catalytic oxidation catalyst, but also presented a generic strategy for improving the design of structured catalysts.