Journal ArticleDOI
First-principles study of the mechanism of ethylene epoxidation over Ag–Cu particles
TLDR
In this paper, the authors studied the mechanism of ethylene epoxidation catalyzed by the thin oxide-like surface structures and identified different reaction pathways that will compete and/or synergetically interplay in the catalysis.Abstract:
Silver–copper alloys have been proposed as catalysts for ethylene epoxidation due to their superior selectivity compared to pure silver, the predominant catalyst for this reaction. Under reaction conditions it has been previously shown that, rather than a two-dimensional (2D) Ag–Cu alloy, a thin copper oxide-like layer forms on top of silver, and several possible surface structures were identified (Phys. Rev. Lett., 2010, 104, 035503). By means of density-functional theory calculations, we study the mechanism of ethylene epoxidation catalyzed by the thin oxide-like surface structures. We identify different reaction pathways that will compete and/or synergetically interplay in the catalysis. In general, the reaction mechanism is structure-dependent and the reaction does not always proceed through the formation of (meta)stable intermediates, in contrast to clean Ag and the 2D alloy. Analyzing the competing reactions, we discuss how the addition of Cu improves the selectivity and stress the overall importance of accounting for the effect of ambient conditions.read more
Citations
More filters
Journal ArticleDOI
Alloys in catalysis: phase separation and surface segregation phenomena in response to the reactive environment
TL;DR: In this paper, the authors focus on experimental and theoretical studies related to in situ observations of surface segregation and phase separation phenomena taking place on the outermost surface layers of alloy catalysts.
Journal ArticleDOI
Defect stabilized gold atoms on graphene as potential catalysts for ethylene epoxidation: a first-principles investigation
TL;DR: In this article, the potential role of Au atoms stabilized by defects on graphene in the formation and dissociation of peroxametallacycle intermediate and regeneration of Au sites was investigated.
Journal ArticleDOI
Dipole effect on ethylene epoxidation: Influence of alkali metals and chlorine
Matej Huš,Anders Hellman +1 more
TL;DR: In this article, the authors present a first-principles explanation of the dipole effect on reaction selectivity, which could, in principle, be effected by alkali metals.
Journal Article
First-principles investigation of Ag-Cu alloy surfaces in an oxidizing environment
TL;DR: In this article, the surface of the Ag-Cu alloy was investigated by means of first-principles density functional theory calculations under varying conditions of pressure of the surrounding oxygen atmosphere and temperature.
Journal ArticleDOI
A Nanoarchitecture Based on Silver and Copper Oxide with an Exceptional Response in the Chlorine-Promoted Epoxidation of Ethylene.
Adrian Ramirez,Jose L. Hueso,Hugo Suarez,Reyes Mallada,Alfonso Ibarra,Silvia Irusta,Jesus Santamaria +6 more
TL;DR: A novel catalyst based on silver and copper oxide with an excellent response in the selective oxidation pathway towards ethylene epoxide is presented, which seems to facilitate the accommodation of chlorine promoters, leading to high yields at low reaction temperatures.
References
More filters
Journal ArticleDOI
Generalized Gradient Approximation Made Simple
TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Journal ArticleDOI
QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials
Paolo Giannozzi,Stefano Baroni,Stefano Baroni,Nicola Bonini,Matteo Calandra,Roberto Car,Carlo Cavazzoni,Davide Ceresoli,Guido L. Chiarotti,Matteo Cococcioni,Ismaila Dabo,Andrea Dal Corso,Andrea Dal Corso,Stefano de Gironcoli,Stefano de Gironcoli,Stefano Fabris,Stefano Fabris,Guido Fratesi,Ralph Gebauer,Ralph Gebauer,Uwe Gerstmann,Christos Gougoussis,Anton Kokalj,Michele Lazzeri,Layla Martin-Samos,Nicola Marzari,Francesco Mauri,Riccardo Mazzarello,Stefano Paolini,Alfredo Pasquarello,Lorenzo Paulatto,Lorenzo Paulatto,Carlo Sbraccia,Sandro Scandolo,Sandro Scandolo,Gabriele Sclauzero,Gabriele Sclauzero,Ari P. Seitsonen,Alexander Smogunov,Paolo Umari,Renata M. Wentzcovitch +40 more
TL;DR: QUANTUM ESPRESSO as discussed by the authors is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave).
Journal ArticleDOI
A climbing image nudged elastic band method for finding saddle points and minimum energy paths
TL;DR: In this article, a modification of the nudged elastic band method for finding minimum energy paths is presented, where one of the images is made to climb up along the elastic band to converge rigorously on the highest saddle point.
Journal ArticleDOI
XXV. Zur Frage der Geschwindigkeit des Wachsthums und der Auflösung der Krystallflächen
TL;DR: In der krystallographischen Literatur der letzten Zeit erscheinen mehr und mehr Arbeiten, welche dem gegenseitigen Verhältnisse des Krystalles and des Mediums, in welchem er sich bildet, gewidmet sind.
Journal ArticleDOI
Composition, structure, and stability of RuO 2 ( 110 ) as a function of oxygen pressure
TL;DR: In this article, the Gibbs free energy was calculated to determine the lowest energy structure of a transition metal oxide surface in thermodynamic equilibrium with an oxygen-rich environment, and it was shown that the commonly assumed stoichiometric termination is only favorable at low oxygen chemical potentials, i.e., low pressures and/or high temperatures.
Related Papers (5)
Selectivity driven design of bimetallic ethylene epoxidation catalysts from first principles
Generalized Gradient Approximation Made Simple
Ethylene epoxidation over silver and copper-silver bimetallic catalysts: I. Kinetics and selectivity
Jerome Jankowiak,Mark A. Barteau +1 more