Journal ArticleDOI
The Role of H+- and Cu+-Sites for N2O Formation during NH3-SCR over Cu-CHA
Yingxin Feng,Ton V. W. Janssens,Peter N. R. Vennestrøm,Jonas Jansson,Magnus Skoglundh,Henrik Grönbeck +5 more
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In this article, the authors investigated the mechanism for N2O formation over CHA and Cu-CHA zeolite catalysts during NH3-SCR using density functional theory calculations.Abstract:
The mechanism for N2O formation over CHA and Cu-CHA zeolite catalysts during NH3-SCR is investigated using density functional theory calculations. Direct NH4NO3 decomposition, which is commonly regarded as the main source of N2O, is found to be associated with high barriers in the absence of Bronsted acid sites. Although Bronsted acid sites promote NH4NO3 decomposition, it is still a highly activated process. Low-temperature N2O formation is instead found to be connected with an NO + NH3 reaction over Cu-sites. In particular, N2O can be formed from H2NNO with a low barrier over Cu-OOH-Cu complexes, which are proposed intermediates in the catalytic cycle for NH3-SCR over Cu-CHA. This finding provides an explanation for the experimentally observed low-temperature N2O formation and the relation between Cu loading and N2O formation. The proposed mechanisms open up strategies to enhance the selectivity to N2 during NH3-SCR.read more
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Analogous Mechanistic Features of NH3-SCR over Vanadium Oxide and Copper Zeolite Catalysts
Hiroe Kubota,Takashi Toyao,Takashi Toyao,Zen Maeno,Yusuke Inomata,Toru Murayama,Toru Murayama,Naoto Nakazawa,Satoshi Inagaki,Yoshihiro Kubota,Ken-ichi Shimizu,Ken-ichi Shimizu +11 more
Journal ArticleDOI
Mechanism of NH3–Selective Catalytic Reduction (SCR) of NO/NO2 (Fast SCR) over Cu-CHA Zeolites Studied by In Situ/Operando Infrared Spectroscopy and Density Functional Theory
Chong Liu,Grazia Malta,Hiroe Kubota,Takashi Toyao,Takashi Toyao,Zen Maeno,Ken-ichi Shimizu,Ken-ichi Shimizu +7 more
Journal ArticleDOI
In Situ/Operando IR and Theoretical Studies on the Mechanism of NH3–SCR of NO/NO2 over H–CHA Zeolites
Chong Liu,Grazia Malta,Hiroe Kubota,Kenichi Kon,Takashi Toyao,Takashi Toyao,Zen Maeno,Ken-ichi Shimizu,Ken-ichi Shimizu +8 more
Journal ArticleDOI
A First-Principles Microkinetic Model for Low-Temperature NH3 Assisted Selective Catalytic Reduction of NO over Cu-CHA
Yingxin Feng,Xueting Wang,Ton V. W. Janssens,Peter N. R. Vennestrøm,Jonas Jansson,Magnus Skoglundh,Henrik Grönbeck +6 more
TL;DR: In this paper, a first-principles microkinetic model was developed to investigate low-temperature ammonia assisted selective catalytic reduction (NH3-SCR) of NO over Cu-CHA.
Journal ArticleDOI
Regeneration of sulfur-poisoned Cu-SSZ-13 catalysts: Copper speciation and catalytic performance evaluation
V. V. Mesilov,Sandra Dahlin,Sandra Dahlin,Susanna L. Bergman,Shibo Xi,Joonsoo Han,Louise Olsson,Lars J. Pettersson,Steven L. Bernasek +8 more
TL;DR: In this paper, the regeneration of a sulfur-poisoned Cu-SSZ-13 catalyst via a temperature ramp in an inert atmosphere with subsequent holding under oxidizing conditions at 500°C restores significant activity for NOx conversion under standard, fast, and NO2-rich SCR conditions.
References
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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
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set.
Georg Kresse,Jürgen Furthmüller +1 more
TL;DR: An efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set is presented and the application of Pulay's DIIS method to the iterative diagonalization of large matrices will be discussed.
Journal ArticleDOI
Projector augmented-wave method
TL;DR: An approach for electronic structure calculations is described that generalizes both the pseudopotential method and the linear augmented-plane-wave (LAPW) method in a natural way and can be used to treat first-row and transition-metal elements with affordable effort and provides access to the full wave function.
Journal ArticleDOI
From ultrasoft pseudopotentials to the projector augmented-wave method
Georg Kresse,Daniel P. Joubert +1 more
TL;DR: In this paper, the formal relationship between US Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived and the Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional.
Journal ArticleDOI
Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set
Georg Kresse,Jürgen Furthmüller +1 more
TL;DR: A detailed description and comparison of algorithms for performing ab-initio quantum-mechanical calculations using pseudopotentials and a plane-wave basis set is presented in this article. But this is not a comparison of our algorithm with the one presented in this paper.