Modelling free and oxide-supported nanoalloy catalysts: comparison of bulk-immiscible Pd–Ir and Au–Rh systems and influence of a TiO2 support

DFT calculations on free and TiO₂-supported Pd–Ir and Au–Rh nanoalloys reveal that Janus and core–shell configurations compete on oxide supports.

Heterogeneous catalytic ignition of n-butane/air mixtures on platinum

The heterogeneous catalytic ignition of lean to stoichiometric n-butane/air mixtures were studied at various total pressures between 10 and 100 kPa and at temperatures equal to or larger than the critical ignition temperatures. The induction periods, ignition and extinction temperatures were measured under strict isothermal conditions. The discussion presented in this paper is based on several literature models. The data analysis allowed for the determination of the overall kinetic parameters. The rigorous isothermal conditions indicated that the extinction temperatures are lower than the ignition, a behavior different from the results obtained in stagnation-point flow reactors.

Kinetic hindrance during the initial oxidation of Pd(100) at ambient pressures

The oxidation of the Pd(100) surface at oxygen pressures in the 10(-6) to 10(3) mbar range and temperatures up to 1000 K has been studied in situ by surface x-ray diffraction (SXRD). The results provide direct structural information on the phases present in the surface region and on the kinetics of the oxide formation. Depending on the (T,p) environmental conditions, we observe either a thin (sqrt[5]xsqrt[5])R27 degrees surface oxide or the growth of a rough, poorly ordered bulk oxide film of PdO predominantly with (001) orientation. By either comparison to the surface phase diagram from first-principles atomistic thermodynamics or by explicit time-resolved measurements we identify a strong kinetic hindrance to the bulk oxide formation even at temperatures as high as 675 K.