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

Mullite-type AMn 2 O 5 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, AMn 2 O 5 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 CeO 2 -decorated Cu-SmMn 2 O 5 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 CeO 2 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.