Design of a "high-efficiency" -SCR reactor for stationary applications : a kinetic study of oxidation and -SCR over V-based catalysts

2015
journal article
article
65
dc.abstract.enIn this work, the kinetics of the NH3/NO/O2 reacting system over V2O5–WO3/TiO2 catalysts was studied under conditions of NH3/NO ratio ≥ 1 and temperature up to 400 °C, where some ammonia oxidation is expected. NH3-SCR and NH3-oxidation tests were performed over powdered catalysts, at varying V-loads. Over a high V-load home-made catalyst, NO conversion passed through a maximum at increasing temperature, as commonly observed in SCR tests at the onset of ammonia oxidation; however, since the experiments were performed under excess ammonia, the high temperature decrease of NO conversion could not be associated with a lack of surface NH3. The experiments were interpreted as the evidence of an unselective NH3-oxidation route, giving rise to some NO production. NH3-oxidation tests, though, showed low selectivity to NO (which is in line with the current literature); however, a quantitative analysis of data showed that the observed product distribution is fully in line with an indirect-consecutive reaction scheme from NH3 to N2, wherein NO is formed by NH3 oxidation and is then rapidly converted to N2 via NH3-SCR. The kinetic investigation was extended to commercial catalysts with low and medium V-loads. NH3-SCR tests showed increasing trends of NO conversion with temperature within the range 250–400 °C, thus they did not show any clear evidence for NH3 oxidation. However, NH3-oxidation tests showed that the reaction was active above 350 °C; notably, over 95% selectivity to N2 was observed. A quantitative analysis of the NH3-oxidation tests, based on the independent estimate of the intrinsic rate of NH3-SCR, showed that the observation of few ppm NO slip is fully in line with the assumption of a two-step kinetic scheme. A reaction path analysis shows that by neglecting the unselective nature of ammonia oxidation on V-catalysts the rate of this reaction is overestimated by a factor of 2. Preliminary evaluations suggest that the impact of NH3-oxidation on the integral performance of monolith reactors (operating at NH3/NO ratios close to 1) is non negligible, so that the correct identification of the reaction stoichiometry is crucial.pl
dc.affiliationWydział Chemiipl
dc.contributor.authorUsberti, Nicolapl
dc.contributor.authorDi Blasi, Miriampl
dc.contributor.authorForzatti, Piopl
dc.contributor.authorLietti, Lucapl
dc.contributor.authorBeretta, Alessandrapl
dc.contributor.authorJabłońska, Magdalena - 107656 pl
dc.date.accessioned2015-12-02T09:06:13Z
dc.date.available2015-12-02T09:06:13Z
dc.date.issued2015pl
dc.description.admin[AB] Jabłońska, Magdalena 50000141pl
dc.description.physical185-195pl
dc.description.volume179pl
dc.identifier.doi10.1016/j.apcatb.2015.05.017pl
dc.identifier.eissn1873-3883pl
dc.identifier.issn0926-3373pl
dc.identifier.urihttp://ruj.uj.edu.pl/xmlui/handle/item/17391
dc.languageengpl
dc.language.containerengpl
dc.rights.licencebez licencji
dc.subject.enV2O5/WO3/TiO2 catalystpl
dc.subject.enNH3-SCRpl
dc.subject.enNH3 oxidationpl
dc.subject.enkinetic modelingpl
dc.subject.enindirect kinetic schemepl
dc.subtypeArticlepl
dc.titleDesign of a "high-efficiency" $NH_3$-SCR reactor for stationary applications : a kinetic study of $NH_3$ oxidation and $NH_3$-SCR over V-based catalystspl
dc.title.journalApplied Catalysis. B, Environmentalpl
dc.typeJournalArticlepl
dspace.entity.typePublication
dc.abstract.enpl
In this work, the kinetics of the NH3/NO/O2 reacting system over V2O5–WO3/TiO2 catalysts was studied under conditions of NH3/NO ratio ≥ 1 and temperature up to 400 °C, where some ammonia oxidation is expected. NH3-SCR and NH3-oxidation tests were performed over powdered catalysts, at varying V-loads. Over a high V-load home-made catalyst, NO conversion passed through a maximum at increasing temperature, as commonly observed in SCR tests at the onset of ammonia oxidation; however, since the experiments were performed under excess ammonia, the high temperature decrease of NO conversion could not be associated with a lack of surface NH3. The experiments were interpreted as the evidence of an unselective NH3-oxidation route, giving rise to some NO production. NH3-oxidation tests, though, showed low selectivity to NO (which is in line with the current literature); however, a quantitative analysis of data showed that the observed product distribution is fully in line with an indirect-consecutive reaction scheme from NH3 to N2, wherein NO is formed by NH3 oxidation and is then rapidly converted to N2 via NH3-SCR. The kinetic investigation was extended to commercial catalysts with low and medium V-loads. NH3-SCR tests showed increasing trends of NO conversion with temperature within the range 250–400 °C, thus they did not show any clear evidence for NH3 oxidation. However, NH3-oxidation tests showed that the reaction was active above 350 °C; notably, over 95% selectivity to N2 was observed. A quantitative analysis of the NH3-oxidation tests, based on the independent estimate of the intrinsic rate of NH3-SCR, showed that the observation of few ppm NO slip is fully in line with the assumption of a two-step kinetic scheme. A reaction path analysis shows that by neglecting the unselective nature of ammonia oxidation on V-catalysts the rate of this reaction is overestimated by a factor of 2. Preliminary evaluations suggest that the impact of NH3-oxidation on the integral performance of monolith reactors (operating at NH3/NO ratios close to 1) is non negligible, so that the correct identification of the reaction stoichiometry is crucial.
dc.affiliationpl
Wydział Chemii
dc.contributor.authorpl
Usberti, Nicola
dc.contributor.authorpl
Di Blasi, Miriam
dc.contributor.authorpl
Forzatti, Pio
dc.contributor.authorpl
Lietti, Luca
dc.contributor.authorpl
Beretta, Alessandra
dc.contributor.authorpl
Jabłońska, Magdalena - 107656
dc.date.accessioned
2015-12-02T09:06:13Z
dc.date.available
2015-12-02T09:06:13Z
dc.date.issuedpl
2015
dc.description.adminpl
[AB] Jabłońska, Magdalena 50000141
dc.description.physicalpl
185-195
dc.description.volumepl
179
dc.identifier.doipl
10.1016/j.apcatb.2015.05.017
dc.identifier.eissnpl
1873-3883
dc.identifier.issnpl
0926-3373
dc.identifier.uri
http://ruj.uj.edu.pl/xmlui/handle/item/17391
dc.languagepl
eng
dc.language.containerpl
eng
dc.rights.licence
bez licencji
dc.subject.enpl
V2O5/WO3/TiO2 catalyst
dc.subject.enpl
NH3-SCR
dc.subject.enpl
NH3 oxidation
dc.subject.enpl
kinetic modeling
dc.subject.enpl
indirect kinetic scheme
dc.subtypepl
Article
dc.titlepl
Design of a "high-efficiency" $NH_3$-SCR reactor for stationary applications : a kinetic study of $NH_3$ oxidation and $NH_3$-SCR over V-based catalysts
dc.title.journalpl
Applied Catalysis. B, Environmental
dc.typepl
JournalArticle
dspace.entity.type
Publication
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