Activity enhancement of Cu-doped ceria by reductive regeneration of CuO–CeO2 catalyst for preferential oxidation of CO in H2-rich streams

Effect of short periods of reduction, in CO and H2 feed, on regeneration and activity enhancement of a 5.0 wt.% CuO–CeO2 catalyst for preferential oxidation of CO in a H2-rich stream at various temperatures is investigated. The catalyst was prepared by a co-precipitation method, calcined at 450 °C for 5 h, and characterized by XRD, FESEM, EDS, BET specific surface area, H2-TPR and CO2-TPD. It was found that fine crystallites/amorphous CuO are dispersed on CeO2 particles with average size of about 33 nm. A gas mixture composed of 1% CO, 40% H2 and 1% O2 in N2 was used as the feed for measurements of the catalyst performance at various temperatures. CO2 and H2O were also added to the feed, to study their inhibitive effects on the activity of the catalyst. The activity of the catalyst for CO oxidation significantly enhances after transient reduction in CO and H2 feed. Higher activity enhancements are observed at lower temperatures and shorter reduction periods. Up to 35% enhancement is observed following 3 min reduction at 100 °C. The most reactive Cu1+ species may have formed during the reduction period and regenerates the catalyst leading to higher CO oxidation activities.