Catalytic and structural properties of oxide nanocomposites based on Ce-substituted Cu-spinel ferrite for preferential oxidation of CO in H2-rich streams

Copper-based catalysts combined with CeO 2 exhibit excellent performance in the preferential oxidation of CO (CO-PROX) in hydrogen-rich environments, a process critical for purifying hydrogen derived from hydrocarbon reforming. This study investigates nanocomposite catalysts synthesized via a sol–gel method from copper ferrite (CuFe 2 O 4 ), into which increasing amounts of cerium were incorporated to form a series of mixed oxide systems. The materials were characterized by XRD, BET surface area analysis, XPS, and TPR, while their catalytic behaviour was evaluated through CO-PROX testing and operando DRIFTS. Cerium addition significantly enhances CO-PROX activity, which closely correlates with the intensity of Cu + –carbonyl species observed during reaction. These findings suggest that the most active sites arise from copper species in contact with segregated CeO 2 domains. Copper ferrite contributes to the stabilization of finely dispersed CeO 2 particles, which in turn promotes catalytic performance. In addition, copper within the ferrite phase is implicated in water–gas shift (WGS) activity at higher temperatures, an effect that is further enhanced by cerium incorporation into the ferrite structure. • The CuFe 2 O 4 sample exhibits limited CO-PROX activity, which is significantly enhanced upon cerium doping. • The formation of specific interactions between copper and segregated CeO 2 nanoparticles markedly boosts CO-PROX performance. • Copper ferrite limits the growth of CeO 2 nanoparticles while introducing additional water-gas shift activity to the system.