An operando DRIFTS study of the active sites and the active intermediates of the NO-SCR reaction by methane over In,H- and In,Pd,H-zeolite catalysts

F. Lónyi, Hanna E. Solt, J. Valyon, Hernán Decolatti, Laura B. Gutierrez, Eduardo Miró

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Zeolites In,H-ZSM-5 (Si/Al=29.7, 1.7wt% In) and In,H-mordenite (In,H-M, Si/Al=6.7, 3.5 wt% In) were prepared by reductive solid state ion exchange (RSSIE) method and studied in the selective catalytic reduction of NO (NO-SCR) by methane. The results suggested that the methane oxidation reactions proceed by redox type mechanisms over In+/InO+ sites. The NO reduction selectivity was shown to be related to the relative rates of In+ oxidation by NO and O2. Regarding the relative rates, the In+ density of the zeolite was the most important. Above about 673K the In,H-ZSM-5 (T-atom/In=102) had higher NO reduction selectivity than the In,H-mordenite (T-atom/In=46). The operando DRIFTS examinations suggested that NO+ and NO3- surface species were formed simultaneously on InO+Z- sites, and were consumed together in the NO-SCR reaction with methane. The reduction of the NO3- by methane gave an activated N-containing intermediate, which further reacted with the NO+ species to give N2. The NO-SCR properties could be significantly improved by adding small amount of Pd to the In,H-zeolite catalyst. The promoting effect of Pd was interpreted as a concerted action of InO+ and the Pdn+ sites. The interplay between these sites is twofold: the Pd speeds up the equilibration of the NO/O2 mixture, thereby, increases the formation rate and the steady state concentration of the activated nitrate species, whereas the In+/InO+ sites prevent the transformation of Pd-nitrosyls to less reactive isocyanate and nitrile species.

Original languageEnglish
Pages (from-to)133-142
Number of pages10
JournalApplied Catalysis B: Environmental
Volume100
Issue number1-2
DOIs
Publication statusPublished - 2010

Fingerprint

Zeolites
Methane
Thyristors
zeolite
methane
catalyst
mordenite
Catalysts
Isocyanates
oxidation
Atoms
Oxidation
Nitriles
Selective catalytic reduction
Nitrates
ion exchange
Ion exchange
nitrate
rate

Keywords

  • In,H-zeolites
  • In,Pd,H-zeolites
  • NO-SCR by CH
  • Operando DRIFTS

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology
  • Environmental Science(all)

Cite this

An operando DRIFTS study of the active sites and the active intermediates of the NO-SCR reaction by methane over In,H- and In,Pd,H-zeolite catalysts. / Lónyi, F.; Solt, Hanna E.; Valyon, J.; Decolatti, Hernán; Gutierrez, Laura B.; Miró, Eduardo.

In: Applied Catalysis B: Environmental, Vol. 100, No. 1-2, 2010, p. 133-142.

Research output: Contribution to journalArticle

@article{8c9d6ee672984c02b4acf642312377d2,
title = "An operando DRIFTS study of the active sites and the active intermediates of the NO-SCR reaction by methane over In,H- and In,Pd,H-zeolite catalysts",
abstract = "Zeolites In,H-ZSM-5 (Si/Al=29.7, 1.7wt{\%} In) and In,H-mordenite (In,H-M, Si/Al=6.7, 3.5 wt{\%} In) were prepared by reductive solid state ion exchange (RSSIE) method and studied in the selective catalytic reduction of NO (NO-SCR) by methane. The results suggested that the methane oxidation reactions proceed by redox type mechanisms over In+/InO+ sites. The NO reduction selectivity was shown to be related to the relative rates of In+ oxidation by NO and O2. Regarding the relative rates, the In+ density of the zeolite was the most important. Above about 673K the In,H-ZSM-5 (T-atom/In=102) had higher NO reduction selectivity than the In,H-mordenite (T-atom/In=46). The operando DRIFTS examinations suggested that NO+ and NO3- surface species were formed simultaneously on InO+Z- sites, and were consumed together in the NO-SCR reaction with methane. The reduction of the NO3- by methane gave an activated N-containing intermediate, which further reacted with the NO+ species to give N2. The NO-SCR properties could be significantly improved by adding small amount of Pd to the In,H-zeolite catalyst. The promoting effect of Pd was interpreted as a concerted action of InO+ and the Pdn+ sites. The interplay between these sites is twofold: the Pd speeds up the equilibration of the NO/O2 mixture, thereby, increases the formation rate and the steady state concentration of the activated nitrate species, whereas the In+/InO+ sites prevent the transformation of Pd-nitrosyls to less reactive isocyanate and nitrile species.",
keywords = "In,H-zeolites, In,Pd,H-zeolites, NO-SCR by CH, Operando DRIFTS",
author = "F. L{\'o}nyi and Solt, {Hanna E.} and J. Valyon and Hern{\'a}n Decolatti and Gutierrez, {Laura B.} and Eduardo Mir{\'o}",
year = "2010",
doi = "10.1016/j.apcatb.2010.07.023",
language = "English",
volume = "100",
pages = "133--142",
journal = "Applied Catalysis B: Environmental",
issn = "0926-3373",
publisher = "Elsevier",
number = "1-2",

}

TY - JOUR

T1 - An operando DRIFTS study of the active sites and the active intermediates of the NO-SCR reaction by methane over In,H- and In,Pd,H-zeolite catalysts

AU - Lónyi, F.

AU - Solt, Hanna E.

AU - Valyon, J.

AU - Decolatti, Hernán

AU - Gutierrez, Laura B.

AU - Miró, Eduardo

PY - 2010

Y1 - 2010

N2 - Zeolites In,H-ZSM-5 (Si/Al=29.7, 1.7wt% In) and In,H-mordenite (In,H-M, Si/Al=6.7, 3.5 wt% In) were prepared by reductive solid state ion exchange (RSSIE) method and studied in the selective catalytic reduction of NO (NO-SCR) by methane. The results suggested that the methane oxidation reactions proceed by redox type mechanisms over In+/InO+ sites. The NO reduction selectivity was shown to be related to the relative rates of In+ oxidation by NO and O2. Regarding the relative rates, the In+ density of the zeolite was the most important. Above about 673K the In,H-ZSM-5 (T-atom/In=102) had higher NO reduction selectivity than the In,H-mordenite (T-atom/In=46). The operando DRIFTS examinations suggested that NO+ and NO3- surface species were formed simultaneously on InO+Z- sites, and were consumed together in the NO-SCR reaction with methane. The reduction of the NO3- by methane gave an activated N-containing intermediate, which further reacted with the NO+ species to give N2. The NO-SCR properties could be significantly improved by adding small amount of Pd to the In,H-zeolite catalyst. The promoting effect of Pd was interpreted as a concerted action of InO+ and the Pdn+ sites. The interplay between these sites is twofold: the Pd speeds up the equilibration of the NO/O2 mixture, thereby, increases the formation rate and the steady state concentration of the activated nitrate species, whereas the In+/InO+ sites prevent the transformation of Pd-nitrosyls to less reactive isocyanate and nitrile species.

AB - Zeolites In,H-ZSM-5 (Si/Al=29.7, 1.7wt% In) and In,H-mordenite (In,H-M, Si/Al=6.7, 3.5 wt% In) were prepared by reductive solid state ion exchange (RSSIE) method and studied in the selective catalytic reduction of NO (NO-SCR) by methane. The results suggested that the methane oxidation reactions proceed by redox type mechanisms over In+/InO+ sites. The NO reduction selectivity was shown to be related to the relative rates of In+ oxidation by NO and O2. Regarding the relative rates, the In+ density of the zeolite was the most important. Above about 673K the In,H-ZSM-5 (T-atom/In=102) had higher NO reduction selectivity than the In,H-mordenite (T-atom/In=46). The operando DRIFTS examinations suggested that NO+ and NO3- surface species were formed simultaneously on InO+Z- sites, and were consumed together in the NO-SCR reaction with methane. The reduction of the NO3- by methane gave an activated N-containing intermediate, which further reacted with the NO+ species to give N2. The NO-SCR properties could be significantly improved by adding small amount of Pd to the In,H-zeolite catalyst. The promoting effect of Pd was interpreted as a concerted action of InO+ and the Pdn+ sites. The interplay between these sites is twofold: the Pd speeds up the equilibration of the NO/O2 mixture, thereby, increases the formation rate and the steady state concentration of the activated nitrate species, whereas the In+/InO+ sites prevent the transformation of Pd-nitrosyls to less reactive isocyanate and nitrile species.

KW - In,H-zeolites

KW - In,Pd,H-zeolites

KW - NO-SCR by CH

KW - Operando DRIFTS

UR - http://www.scopus.com/inward/record.url?scp=77957226223&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77957226223&partnerID=8YFLogxK

U2 - 10.1016/j.apcatb.2010.07.023

DO - 10.1016/j.apcatb.2010.07.023

M3 - Article

AN - SCOPUS:77957226223

VL - 100

SP - 133

EP - 142

JO - Applied Catalysis B: Environmental

JF - Applied Catalysis B: Environmental

SN - 0926-3373

IS - 1-2

ER -