Published December 1, 2014 | Version v1
Journal article Metadata-only

A cluster DFT study of NH3 and NO adsorption on the (MoO2)2+/HZSM-5 surface: Lewis versus Brønsted acid sites

Creators

  • 1. College of Material Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)
  • 2. College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)
  • 3. Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

Description

Graphical abstract: - Highlights: • NH3 adsorption is found to be more favorable energetically than NO adsorption on both Lewis and Brønsted acid sites. • Lewis and Brønsted acid sites are competitive energetically for NH3 adsorption. • Reduced-state Mo5+ is suggested to play a key role in adsorption and activation of NOx together with the adsorbed NH4+. - Abstract: A systematic DFT study was carried out to investigate NH3 and NO adsorption on both Lewis and Brønsted acid sites of (MoO2)2+/HZSM-5 catalyst by using cluster models. The adsorption energy results indicate that NH3 could strongly adsorb on both Lewis and Brønsted acid sites in the form of coordinated NH3 and NH4+, respectively, whereas NO represents poorer adsorption ability. It is also found that Lewis and Brønsted acid sites are competitive energetically for NH3 adsorption. According to the difference in the proposed mechanisms for NH3 adsorption on different acid sites, particular attention has been focused on the first dissociation of coordinated NH3 for Lewis acid site and the effect of Mo site on the introduction of NO for Brønsted acid site. For the coordinated NH3 on Lewis acid site, the more electron donation from NH3 is, the greater its adsorption stability is and the higher active its H atoms are. In addition, DOS results show that stability of the H atoms is enhanced by interacting with framework oxygen and especially the H atoms chemical-bonded with framework oxygen. For the NH4+ on Brønsted acid site, reduced-state Mo5+ holds stronger reducibility and oxidizability than terminal oxygen, which is suggested to play a key role in adsorption and activation of NOx together with the adsorbed NH4+

Availability note (English)

Available from http://dx.doi.org/10.1016/j.apsusc.2014.10.048

Additional details

Identifiers

DOI
10.1016/j.apsusc.2014.10.048;
PII
S0169-4332(14)02285-5;

Publishing Information

Journal Title
Applied Surface Science
Journal Volume
321
Journal Page Range
p. 339-347
ISSN
0169-4332
CODEN
ASUSEE

INIS

Country of Publication
Netherlands
Country of Input or Organization
International Atomic Energy Agency (IAEA)
INIS RN
46112960
Subject category
S75: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY;
Descriptors DEI
ADSORPTION; AMMONIA; ATOMS; CATALYSTS; CHEMICAL BONDS; CLUSTER MODEL; DENSITY FUNCTIONAL METHOD; DISSOCIATION; ELECTRONS; LEWIS ACIDS; MOLYBDENUM IONS; MOLYBDENUM OXIDES; NITRIC OXIDE; OXYGEN; STABILITY; SURFACES
Descriptors DEC
CALCULATION METHODS; CHALCOGENIDES; CHARGED PARTICLES; ELEMENTARY PARTICLES; ELEMENTS; FERMIONS; HYDRIDES; HYDROGEN COMPOUNDS; INORGANIC ACIDS; INORGANIC COMPOUNDS; IONS; LEPTONS; MATHEMATICAL MODELS; MOLYBDENUM COMPOUNDS; NITROGEN COMPOUNDS; NITROGEN HYDRIDES; NITROGEN OXIDES; NONMETALS; NUCLEAR MODELS; OXIDES; OXYGEN COMPOUNDS; REFRACTORY METAL COMPOUNDS; SORPTION; TRANSITION ELEMENT COMPOUNDS; VARIATIONAL METHODS

Optional Information

Copyright
Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.