Influence of oxygen mobility on catalytic activity of La–Sr–Mn–O composites in the reaction of high temperature N2O decomposition

Surface oxygen dynamics and H2 oxidation on cobalt spinel surface probed by 18O/16O isotopic exchange and accounted for by DFT molecular modeling: facile interfacial oxygen atoms flipping through transient peroxy intermediate

“…The surface peroxy can undergo recombination with adjacent oxygen adatoms (both peroxy and metaloxo species), leading in both cases to formation of gas phase 16 The region below 350°C, where the isotopic exchange of dioxygen in pulse experiment is small, was additionally probed by hydrogen oxidation reaction. The TPSR profiles of H 2 oxidation by 18 O 2 (expressed as F/lmol min -1 ) are presented in Fig. 3a, where three different stages of the reaction progress may by distinguished.…”

“…The more detailed insight into water formation mechanism was provided by the p H2 (16) 18 O isotope to full coverage, making the interfacial oxygen-18 exchange into oxygen-16 less effective. This is reflected in the gradual increase of f 18/16 H2O value with the progress of the reaction (increasing temperature).…”

“…Thus, the former may operate even at relatively low temperatures (below 300-350°C). The appearance of significant amount of H 2 16 O in the reaction products is related to easy isotopic 18 O/ 16 O scrambling via transient peroxo intermediates, and is not diagnostic of direct involvement of the Mars van Krevelen mechanism.…”

“…Although it is generally accepted that both lattice oxygen and ROS species may be involved in oxidation reactions, there is still a debate about the specific role they play therein. A common method for studying oxygen dynamics in an oxide catalyst is 18 O- 16 O isotopic exchange with gas mass spectroscopic detection. In such experiments it is possible to differentiate between surface exchange, bulk diffusion, and fast diffusion along grain boundaries [18].…”

“…A common method for studying oxygen dynamics in an oxide catalyst is 18 O- 16 O isotopic exchange with gas mass spectroscopic detection. In such experiments it is possible to differentiate between surface exchange, bulk diffusion, and fast diffusion along grain boundaries [18]. From the course of the oxygen exchange reaction, the way in which oxygen takes place in the catalytic processes may also be deduced [19].…”