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

Abstract

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 hy-drocarbons (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.