Preferential oxidation of CO in H2 rich stream (PROX) over gold catalysts supported on doped ceria: Effect of water and CO2

Gold catalysts on mechanochemically prepared mixed ceria supports doped with FeOx and MnOx were studied in the reaction of preferential oxidation of CO in H2 rich stream (PROX) in the presence of 20% CO2 and 10% H2O. The average size and the size distribution of gold particles were estimated by HRTEM. By means of XPS the Au XPS states at various binding energies, assigned to differently charged Au nanoparticles, were distinguished. The catalytic activity and selectivity in the oxidation of CO in dry H2-reach stream was high, however the PROX activity was significantly suppressed by the addition of high concentrations of water and CO2. The two step calcinations of catalysts, first at 400 °C and then at 550 °C, showed no better performance in PROX reaction carried out at realistic experimental conditions. However, after the two-step calcination procedure, nanosized gold particles of high thermal stability were obtained over MnOx doped ceria.

Comparison regarding the degree of CO conversion and the selectivity over gold catalysts: curve lines 1 – AuCeFeMA(400) following route (i) with gas feed 50% H2 + 0.3% CO + 0.3% O2, curve lines 2 – AuCeFeMA(400) following route (ii) with gas feed 50% H2 + 0.3% CO + 0.3% O2 + 10% H2O + 20% CO2, and curve lines 3 – AuCeFeMA(550) following route (ii).Figure optionsDownload high-quality image (136 K)Download as PowerPoint slideHighlights
► Mechanochemically prepared Au catalysts on ceria doped with FeOx and MnOx.
► High activity and selectivity in PROX using idealized gas stream.
► Activity significantly suppressed by the addition of water and CO2.
► No better PROX performance after two steps calcination (at 400, then at 550 °C).
► High thermal stability after the two steps calcination of gold on MnOx doped ceria.