Self-Propagated Flaming Synthesis of Highly Active Layered CuO-δ-MnO2 Hybrid Composites for Catalytic Total Oxidation of Toluene Pollutant.

A new self-propagated flaming (SPF) technique was applied to the synthesis of highly active layered CuO-δ-MnO2 hybrid composites, for the de-polluting catalytic total oxidation of gaseous toluene vapor. Other transition metal oxide-doped MnO2 hybrid composites were also successfully prepared and investigated, ensuring a feasible strategy for the fabrication of various layered MOx-δ-MnO2 (M═Co, Ni, or Zn) hybrids. By changing the molar ratio of the precursors (KMnO4 and acetate salt) and the type of transition metal oxide introduced, it is possible to control the crystal structure and reducibility of the sheetlike hybrid composites as well as the catalytic activity for the total oxidation of toluene. The catalyst sample (CuO-δ-MnO2) with a Mn/Cu molar ratio of 10:1 exhibited the highest catalytic performance, with a lower reaction temperature of 300 °C for complete toluene removal, which was comparable to the reaction temperature for total toluene conversion by the Pt-based catalyst. The SPF technique provides an approach for developing highly efficient catalysts for the complete removal of volatile organic compounds, by allowing the facile and energy-saving fabrication of large quantities of layered CuO-δ-MnO2 hybrids.