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Highlights: [•] Bond breaking of general RO–H organic compounds on various metal surfaces. [•] Brønsted–Evans–Polanyi like relationships for the O–H bond break in organics. [•] Activation energy for the O–H bond break versus adsorption energy of the products. [•] Mean absolute error for the BEP is 0.13eV. [•] Good agreement between estimated and calculated data for a test set. [ABSTRACT FROM AUTHOR]

Highlights: [•] DFT calculations suggest that O2 dissociation is feasible on gold surfaces doped with transition metals. [•] Nickel is the most interesting transition metal for doping purposes. [•] BEP relationships relate the activation energy for O2 dissociation with different descriptors. [•] CO dissociation is less favorable than CO oxidation on Ni@Au model catalysts. [•] CO methanation is unlikely on Ni@Au model catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Periodic density functional theory (DFT) calculations have been used to unravel the mechanism of the NO reduction by CO (NO+CO→N2 +CO2) on clean and hydrogen covered gold based catalysts. The effects caused by the presence of low-coordinated atoms on the catalyst were taken into consideration by using the stepped Au(321) surface. A careful analysis of several reaction mechanisms was made and it is concluded that if hydrogen species are not available on the catalyst surface, the N–O bond cleavage will proceed through the ON2O and N2O intermediates while CO reacts directly with formed oxygen adatoms. If hydrogen species are available on the catalyst, the reaction will occur via the NOH and N2O intermediates. However, the reaction has to compete with a more favorable route, where NH3 instead of N2 is obtained after formation of NOH and NH x OH intermediates. The calculations agree also with the experimental observation of the NCO intermediate species which is formed without energy cost from combination of CO and N fragments. The NCO species is very probably a spectator at moderate temperatures since its evolution toward N2 and CO2 is less favorable than other possible routes studied in this work. Finally, calculated reaction rate constants at three different temperatures show that most of the reactions studied are only possible at moderately high temperature. [Copyright &y& Elsevier]

• Trimetallic Al/Zn/Cu surfaces might be high reactive for the Water Gas Shift reaction catalysis. • WGS follows an associative mechanism through the carboxyl intermediary on the (AlZn) s @Cu(1 1 1) surface. • DFT methods are very useful for the study of reactions on catalytic surfaces. • Active phase of commercial catalyst based on Cu/ZnO/Al 2 O 3 might embody a trimetallic alloy of Al/Zn/Cu. In this study, we evaluated the performance of Al/Zn/Cu trimetallic catalysts for the water gas shift (WGS) reaction by Density Functional Theory (DFT) calculations. A previous DFT-based study comparing the activity of a large series of trimetallic surfaces towards the catalysis of water dissociation showed that the (AlZn) s @Cu(1 1 1) surface is likely the most active catalysts for the WGS reaction. Note that, the water dissociation is the rate-determining step of the WGS reaction on copper surfaces. Therefore, in this work we carried out a systematic study of all possible WGS reaction steps on such catalyst model surface. The most plausible WGS reaction mechanism on the trimetallic surface was inferred by comparing the activation energies, reaction energies and rate constants computed for its different reaction steps. The latter demonstrated that the WGS evolves on this trimetallic surface following an associative mechanism through the carboxyl intermediary, which is dehydrogenated on the surface, assisted by a hydroxyl, to produce CO 2. The other WGS reaction product, this is H 2 , is obtained by the combination of hydrogen atoms from the water dissociation. The activation energy barriers obtained for the WGS reaction steps on that trimetallic surface are always lower than the adsorption energy of the correspondent reactants, indicating that desorption cannot compete with the catalytic process and also, that the trimetallic Al/Zn/Cu surface should be very reactive for the WGS reaction catalysis. Overall the results of this study allowed us to suggest that the active phase of commonly employed commercial catalyst based on Cu/ZnO/Al 2 O 3 might embody a trimetallic alloy of Al/Zn/Cu. [ABSTRACT FROM AUTHOR]