CO preferential oxidation over CuO–CeO2 catalysts synthesized by the urea thermal decomposition method

Gold supported on CuOx/CeO2 catalyst for the purification of hydrogen by the CO preferential oxidation reaction (PROX)

“…%. These observations point out the strong influence of the synthesis procedure over the crystallite domain size of the segregated copper species, as was highlighted by Mariño et al [48]. In our case, taking into account the copper loading, the absence of any copper oxide reflections, the hardly detectable modification of the CeO 2 diffraction lines, and results reported for other CuO x /CeO 2 systems, we propose the existence of highly dispersed copper oxide species over the CeO 2 surface.…”

“…Although Zhu et al [46] associated the absence of CuO XRD reflections to the high dispersion of such species in the cases of low copper content, the existence of trace copper and cerium solid solution formation was not discarded at all because of the broadening of the CeO 2 reflections. Similarly, Mariño et al [47,48] studied a series of CuO x /CeO 2 catalysts prepared by the urea thermal decomposition method with copper contents up to 60 at.% and they also indicated that the solid solution could be present even if it were hardly detectable by XRD. Moreover, a good CuO-CeO 2 interdispersion has been achieved with the preparation method, avoiding the generation of big CuO crystallites for Cu contents up to 40 at.…”

“…In the case of the CeCu sample, there are two small and broad signals with maxima at 774 °C and 897 °C which can be associated to the reduction of bulk Ce 4+ species, and an intense signal at 201 °C due principally to the reduction of the copper species [48,[57][58][59]. However, for this low temperature reduction process (LTP ~ 201 °C) the experimental H 2 consumption calculated with the area of the peak, is higher than the theoretical H 2 consumption for the complete reduction of the copper species, assuming that all of them are as Cu 2+ (see Table 3).…”

Preferential Oxidation of Carbon Monoxide in the Presence of Hydrogen (PROX) over Noble Metals and Transition Metal Oxides: Advantages and Drawbacks

“…As a result, the maximum of the curves x CO vs. T shifts to lower temperatures as copper loading increases. The same trend was observed for a series of copper-ceria catalysts prepared by coprecipitation, with copper contents up to 26.0 wt.% [81]. In a previous work [65], we have tested the activity of a series of copper catalysts prepared by impregnation over a commercial sample of low surface area ceria (25 m 2 /g).…”

3-D flower like Ce–Zr–Cu mixed oxide systems in the CO preferential oxidation (CO-PROX): Effect of catalyst composition

“…Current fundamental research for the removal of CO focuses on ceria-based catalysts such as monometallics Au [1][2][3][4][5], Pt [6][7][8], Pd [9,10], Ir [11], and copper oxide [11][12][13][14][15][16][17][18][19][20]. Although the binary CuO-CeO 2 system shows a good performance in the preferential CO oxidation process, several studies have been made with the purpose of improving their efficiency and stability by incorporation of additional components, such as activity promoters [21][22][23][24][25].…”