Transient kinetics of ethylene and carbon monoxide oxidation for automotive exhaust gas catalysis: experiments and modelling

Rate Inhibition and Enhancement on Ceria-Promoted Pd Monolith Catalysts: Oxidation of Acetylene, Ethylene, and Propylene and Their Mixtures

“…As acetylene comprises up to 20% of hydrocarbons (HCs) in engine exhaust, it is of interest to investigate its oxidation behavior relative to its more studied counterparts. − A limited number of studies of acetylene have shown it to have a strong inhibitive effect on not only its own light-off but also light-off of CO and other hydrocarbons when using precious metal catalysts. ,− Amon-Meziere et al evaluated alkanes, alkenes, alkynes, aromatics, and alcohols, and generalized oxidation trends for Pd/Rh/CeO 2 . A main finding is that for C2 to C5 hydrocarbons, alkene and alcohol reactivities are similar and easier to oxidize than alkynes, which are easier to oxidize than alkanes.…”

Global Kinetic Model of a Three-Way-Catalyst-Coated Gasoline Particulate Filter: Catalytic Effects of Soot Accumulation

“…44−50 There are two types of surface species: π-bonded ethylene, which is oxidized very fast, and di-σ ethylene, which is oxidized much more slowly. 48 π-Bonded ethylene is adsorbed on one single precious metal site, while di-σ ethylene is adsorbed on two active sites (more stable). 48 This is in agreement with the binding energies reported in the literature, where di-σ ethylene is in a range from 131 to 200 kJ/mol, 45−47 while π-bonded ethylene has been assigned from 40 to 54 kJ/ mol.…”

“…48 π-Bonded ethylene is adsorbed on one single precious metal site, while di-σ ethylene is adsorbed on two active sites (more stable). 48 This is in agreement with the binding energies reported in the literature, where di-σ ethylene is in a range from 131 to 200 kJ/mol, 45−47 while π-bonded ethylene has been assigned from 40 to 54 kJ/ mol. 44,51 It is therefore reasonable to assume, based on the high activation energy obtained, that the principal adsorption mode for C 2 H 4 in the present work is di-σ ethylene.…”

“…34 In contrast, ethylene may adsorb on sites, covered with oxygen, with the primary adsorption mode of di-σ bonding. Di-σ bonding can be initially formed from π-bonded species 48 and can be then also accompanied by the formation of other more stable and less reactive products. This is only possible when a large number of vacant sites are available at the catalyst surface.…”

“…This is only possible when a large number of vacant sites are available at the catalyst surface. 48 It is therefore reasonable to assume that the accumulation of soot on the filter reduced the number of active sites on the catalyst surface, This observation therefore indicates that the kinetic parameters of C 2 H 4 varied in the presence of soot. Using the same number of active site reductions as with CO and toluene, the kinetic parameters of C 2 H 4 oxidation were adjusted to corroborate the formation of more reactive species.…”