Reaction mechanism of the direct gas phase synthesis of H2O2 catalyzed by Au3

Abstract

The gas phase reaction of molecular oxygen and hydrogen catalyzed by a Au3cluster to yield H2O2 was investigated theoretically using second order Z-averaged perturbation theory, with the final energies obtained with the fully size extensive completely renormalized CR-CC(2,3) coupled clustertheory. The proposed reaction mechanism is initiated by adsorption and activation of O2 on the Au3cluster. Molecular hydrogen then binds to the Au3O2 global minimum without an energy barrier. The reaction between the activated oxygen and hydrogen molecules proceeds through formation of hydroperoxide (HO2) and a hydrogen atom, which subsequently react to form the product hydrogen peroxide. All reactants, intermediates, and product remain bound to the goldcluster throughout the course of the reaction. The steps in the proposed reaction mechanism have low activation energy barriers below 15kcal∕mol. The overall reaction is highly exothermic by ∼30kcal∕mol. KeywordsGold, Hydrogen reactions, Activation energies, Reaction mechanisms, Density functional theory Disciplines Chemistry CommentsThe following article appeared in Journal of Chemical Physics 129 (2008) The gas phase reaction of molecular oxygen and hydrogen catalyzed by a Au 3 cluster to yield H 2 O 2 was investigated theoretically using second order Z-averaged perturbation theory, with the final energies obtained with the fully size extensive completely renormalized CR-CC͑2,3͒ coupled cluster theory. The proposed reaction mechanism is initiated by adsorption and activation of O 2 on the Au 3 cluster. Molecular hydrogen then binds to the Au 3 O 2 global minimum without an energy barrier. The reaction between the activated oxygen and hydrogen molecules proceeds through formation of hydroperoxide ͑HO 2 ͒ and a hydrogen atom, which subsequently react to form the product hydrogen peroxide. All reactants, intermediates, and product remain bound to the gold cluster throughout the course of the reaction. The steps in the proposed reaction mechanism have low activation energy barriers below 15 kcal/ mol. The overall reaction is highly exothermic by ϳ30 kcal/ mol.

A Theoretical Study of the Interaction of Hydrogen and Oxygen with Palladium or Gold Adsorbed on Pyridine‐Like Nitrogen‐Doped Graphene

“…According to most quantum chemical data, OOH hydrogenation is the rate-determining step in H 2 O 2 synthesis [26][27][28][29] so that OOH (s) is the main precursor. We found that an O 2 molecule from the gas phase reacts directly with H 2(s) , forming OOH (s) .…”

“…We found that an O 2 molecule from the gas phase reacts directly with H 2(s) , forming OOH (s) . According to most quantum chemical data, OOH hydrogenation is the rate-determining step in H 2 O 2 synthesis [26][27][28][29] so that OOH (s) is the main precursor. Hence, the other reaction path is the interaction between H 2 and metal-PNG oxidized system, to obtain a molecule of hydrogen peroxide.…”

Towards an understanding of the vibrational spectrum of the neutral Au7cluster

“…9 (ii) AugSBKJC(1f) corresponding to the SBKJC(1f) basis augmented by a set of s and p diffuse functions (exponent = 0.01). 46 The (spin-corrected) Z-averaged second-order perturbation theory (ZAPT) 47,48 and spherical harmonic basis functions are used together with the augSBKJC(1f) basis, while cartesian basis functions are used together with the SBKJC(1f) basis. Geometry optimisations and Hessian calculations are performed using the GAMESS-US code.…”

Simulating periodic trends in the structure and catalytic activity of coinage metal nanoribbons

“…Perhaps more importantly, progress toward accurate simulations of nanowire catalysts requires addressing some fundamental issues. While small metal clusters [34][35][36][37] or embedded clusters [38] can often be treated with accurate ab initio methods, calculations on periodic nanowires or slabs are typically restricted to density functional theory (DFT) calculations using inexpensive generalized gradient approximations (GGAs) for the many-body exchange-correlation correction. [39] We [31,40,41] and others [42][43][44][45][46][47][48][49][50][51] have shown that GGAs' well-known systematic underestimate of chemical reaction barriers [52] transfer over to reactions on surfaces.…”