Ethylene Oxidation in an Oxygen‐Deficient Environment: Why Ceria is an Active Support?

Abstract

Pt/CeO2, Ru/CeO2, Ir/CeO2 and the corresponding unsupported nanoparticles (Pt, Ru and Ir) were evaluated for their performance in the complete oxidation of ethylene in the presence and absence of oxygen. The lattice oxygen and oxygen storage capacity (OSC) of CeO2 had a significant influence on the interaction with the supported metal nanoparticles, which caused different catalytic behaviours in the absence of oxygen. Overall, Ru/CeO2 was more stable than Ir/CeO2 and Pt/CeO2, which results in transient promotional rate enhancement ratio (ρMSI; MSI=metal–support interaction) values that reach 200 in the first 25 min. These results were attributed to the corresponding interaction with CeO2 and negligible carbon deposition. A proposed relationship between ρMSI and the O2− consumed from CeO2 is discussed, which was suggested as a possible tool to estimate the extent of the MSI. In general, an increase in ρMSI corresponded to an increase in O2− consumed from ceria.

Nanostructured Equimolar Ceria-Praseodymia for Total Oxidations in Low-O2 Conditions

“…abatement of these compounds is of high importance due to the fact that some of them are toxic for human health [42][43][44] and they can also foster the photochemical generation of secondary pollutants, such as ozone [45]. Since ceria-based oxides can be used as catalysts [46][47][48] or noble metals supports [29,49,50] for VOCs' oxidation, CeO2 and Ce50Pr50 are expected to affect these kinds of reactions. The catalytic tests were carried out at two different concentrations of oxygen, in order to evaluate the effect of this parameter.…”

Isotopic Oxygen Exchange Study to Unravel Noble Metal Oxide/Support Interactions: The Case of RuO2 and IrO2 Nanoparticles Supported on CeO2, TiO2 and YSZ

“…[39] Dole et al tested ethylene oxidation with and without gaseous oxygen and compared the results between Pt, RuO 2 and IrO 2 supported on CeO 2 . [36] In this work, Figure 6 shows the oxygen storage capacity of the catalysts under an oxygen deficient reaction atmosphere at 350°C. The catalysts were first stabilized under C 2 H 4 /O 2 condition before the oxygen feed was interrupted at t = 0 h. IrO 2 and RuO 2 supported on YSZ had the highest and most prolonged ability to provide oxygen for reaction with gaseous ethylene to produce CO 2 .…”

“…Four-port valves were used to switch the feed inlet to the reactor between pre-treatment conditions and reactants feed. Another four-port valve would allow the feed gas to enter the reactor or by-pass it before it continues its flow to the Hiden® quadrupole mass spectrometer where the gas composition is detected by following the masses of 18,20,28,29,32,34,36,42,44, 46 m/z.…”

“…To perform a titration of the amount of oxygen from the support engaged in the oxidation reaction when no source of gaseous oxygen is provided, an ethylene titration experiment is performed. In this experiment, and following the same conditions performed in a previous study from our previous study, [36] the catalysts were pretreated under 3 kPa of oxygen from room temperature to 400°C by a step increase of temperature of 25°C. The temperature was then dwelled at 400°C for 2 h before cooling it down to room temperature.…”

The Performance of Nickel and Nickel-Iron Catalysts Evaluated As Anodes in Anion Exchange Membrane Water Electrolysis

“…Ceria (CeO 2 ) is an ionically conducting support that has been widely studied and applied in various electrochemical applications due to the advantageous metal support interactions (MSIs) that it may provide [30][31][32]. The MSIs occur through the unique properties of CeO 2 , such as oxygen storage and release properties, and good ionic conductivity [33][34][35].…”