Support effects in the Au-catalyzed CO oxidation – Correlation between activity, oxygen storage capacity, and support reducibility

Competition of CO and H2 for Active Oxygen Species during the Preferential CO Oxidation (PROX) on Au/TiO2 Catalysts

“…Furthermore, in agreement with previous findings, the amount of CO 2 formation in each CO/Ar sequence always equals the amount of CO consumed, indicating that there is no significant build-up of stable adsorbed, carbon containing surface species (surface carbonates, etc.) under present reaction conditions [25,41]. Finally, all CO 2 is formed during CO pulses (and not during O 2 pulses), as expected for CO weakly adsorbed on the Au NPs at 80˝C, and completely desorbed before O 2 is introduced [31].…”

“…Numerous previous studies have demonstrated that the activity for CO oxidation largely depends on the reducibility of the metal oxide support, with Au catalysts supported on reducible oxides being much more active [43,44]. Applying TAP reactor pulse experiments we could even demonstrate a quantitative relation between the catalysts reducibility (measured by its oxygen storage capacity) and its activity for CO oxidation [41]. In the presence of H 2 , however, the activity of Au catalysts supported on reducible and non-reducible metal oxides becomes very similar [10,12], reflecting a more pronounced promotional effect of H 2 on the CO oxidation activity (see above) for non-reducible than for reducible metal oxide supports.…”

Surface Composition and Catalytic Evolution of Au x Pd1−x (x = 0.25, 0.50 and 0.75) Nanoparticles Under CO/O2 Reaction in Torr Pressure Regime and at 200 °C

“…10 -5 Torr) [38]. The large particle size and gold-only catalysis explains the low turnovers in the case of Au [39,40]. Interestingly, the general catalytic trend for the equilibrium states of our Au-Pd NP system are in favor of a synergistic effect [41], that is the Au x Pd 1-x (x = 0.25-0.75) NPs have higher catalytic activities than the parent Pd and Au NPs of comparable average sizes.…”

Controlling activity and selectivity using water in the Au-catalysed preferential oxidation of CO in H2

“…1a) 7,14 . Numerous studies have searched for better catalysts, examining particle-size effects 12,15 , metal-oxide-support effects 16,17 , mixed metal oxides 15,18 and ordered mesoporous materials 19 . Bimetallic catalysts 20 , the inclusion of polyoxometallates in liquid-phase media 21 , Au-ceria nanocomposites 22 and embedded Au@CeO 2 catalysts 23 have also been examined, with limited success.…”