Preferential oxidation of CO in excess of H2 on Pt/CeO2–Nb2O5 catalysts

Abstract

A c c e p t e d M a n u s c r i p t which shows a high CO conversion (85 %) and a high yield (around 0.6) after a reduction treatment at 523 K. The effect of the presence of CO 2 and H 2 O in the feed has also been determined.

Highly dispersed Pt+ on Ti Ce(1−)O2 as an active phase in preferential oxidation of CO

“…However, the measurement of this percentage implies an intrinsic error, since Ce 4+ can easily be reduced to Ce 3+ during the measurement. Therefore, we could not find a direct correlation between the Ce 3+ /Ce 4+ atomic ratio and concentration of Ce in the catalysts [17,[36][37][38][39]. However, it is important to remark that all catalysts containing cerium contain more than 35 % of Ce 3+ .…”

WGS and CO-PrOx reactions using gold promoted copper-ceria catalysts: “Bulk CuO CeO2 vs. CuO CeO2/Al2O3 with low mixed oxide content”

“…Figure 2A shows the Raman spectra of the prepared CuCe catalysts. All samples exhibit a main band centered at about 462 cm −1 , which is assigned to Ce F2g mode due to symmetrical stretching of Ce-O vibrational unit in octahedral coordination [40,41]. As reported by Graham et al [42], broadening and shifting of this band indicates variations in ceria particle size.…”

High performance of Cu/CeO2-Nb2O5 catalysts for preferential CO oxidation and total combustion of toluene

“…2(a) and (b), respectively. The Raman spectrum of pure ceria exhibits a main peak at 462 cm −1 , which is assigned to the F 2g mode due to symmetrical stretching of Ce O vibrational unit in eightfold coordination [16,[29][30][31]. A decrease of the intensity of this band with an increase of the niobia content was evident for the supports, Fig.…”

“…This observation may be attributed either to a decrease of the ceria content or, more likely, to a decrease in the crystal size, in close agreement with textural properties described above. Only the characteristic peaks of CeO 2 are observed, suggesting the formation of a solid solution or the aggregation of small niobia particles [16]. Only for higher niobium contents (4Cu/0.4CeO 2 -0.6Nb 2 O 5 catalyst) additional peaks attributed to the hexagonal structure of niobium oxide were observed [21][22][23][24].…”

“…Previously, in our work group, we have studied the influence of Nb addition to Pt/CeO 2 catalysts in the PROX reaction [16]. The results have shown that it favors CO oxidation, although the selectivity towards CO 2 was still a little low, about 50%.…”