Enhanced hydrothermal durability of Co₃O₄@CuO–CeO₂ Core-Shell catalyst for carbon monoxide and propylene oxidation

The Co₃O₄@CuO–CeO₂ catalyst with modified core–shell structure was designed to enhance hydrothermal durability and low-temperature for carbon monoxide (CO) and propylene (C₃H₆) co-oxidation. The Co₃O₄–CuO–CeO₂ (CCC) catalysts are excellent for the simultaneous low-temperature oxidation of CO and hydrocarbons (HC). However, Co₃O₄ catalysts are susceptible to water poisoning on the surface and sintering during hydrothermal treatment. Therefore, we first attempted to introduce a core–shell structure in the CCC catalysts to enhance hydrothermal durability. Cubic-shaped Co₃O₄ with excellent stability was synthesized as the core, and a shell composed of CuO and CeO₂ was formed through a coating process. The optimal shell thickness was determined considering both gas accessibility and hydrothermal durability. To further enhance the oxidation activity of the Co₃O₄@CeO₂ catalyst, varying amounts of Cu were introduced via incipient wetness impregnation. When an appropriate amount of Cu was impregnated with the Co₃O₄@CeO₂ catalyst, electron transfer was accelerated owing to the redox equilibrium of Cu²⁺ + Ce³⁺ ↔ Cu⁺ + Ce⁴⁺; thus, the oxidation activity of the catalyst was improved. The Co₃O₄@CuO–CeO₂ catalyst had excellent CO and C₃H₆ co-oxidation activities and hydrothermal durability. Thus, the developed catalyst was more advanced than the existing CCC catalysts.