Nanoporous CeO2-Decorated Cu-SmMn2O5 Composite Mullite Oxide Catalyst for Toluene Oxidation

Mullite-type AMn2O5 materials represent a group of promising candidates to substitute noble metal catalysts for the catalytic removal of volatile organic compounds (VOCs). When applied to catalytic oxidation of aromatic hydrocarbons such as toluene, AMn2O5 exhibits undesirable performance due to its poor intrinsic activity of oxygen species, leading to a light-off temperature above 250 °C. In this work, we have developed a synthesis route combining a two-step calcination and cation-exchange process to prepare a nanoporous CeO2-decorated Cu-SmMn2O5 composite mullite oxide catalyst applied in toluene oxidation. The best performing sample reached 90% toluene conversion at 190 °C, surpassing other transition metal oxide catalysts. Comprehensive characterizations reveal that Cu ion doping into the crystal lattice of the mullite phase is achieved via the cation-exchange process. In this catalyst design, surface CeO2 decoration and Cu doping promote the reduction ability and improve oxygen species activity to accelerate toluene oxidation. Overall, this work provides a strategy to prepare composite mullite oxide catalysts with high performance in the removal of VOCs, broadening the industrial application prospects of mullite-type materials.