Low activation energy pathway for the catalyzed reduction of nitrogen oxides to N2 by ammonia

Meijun Li; Juan Henao; Younghoon Yeom; Eric Weitz; Wolfgang M.H. Sachtler

doi:10.1007/s10562-004-6441-y

Low activation energy pathway for the catalyzed reduction of nitrogen oxides to N₂ by ammonia

Meijun Li, Juan Henao, Younghoon Yeom, Eric Weitz, Wolfgang M.H. Sachtler

Research output: Contribution to journal › Article › peer-review

33 Scopus citations

Abstract

A low activation energy pathway for the catalytic reduction of nitrogen oxides to N₂, with reductants other than ammonia, consists of two sets of reaction steps. In the first set, part of the NO_x is reduced to NH₃: in the second set ammonium nitrite, NH₄NO ₂ is formed from this NH₃ and NO + NO₂. The NH₄NO₂ thus formed decomposes at ∼100°C to N ₂ + H₂O, even on an inert support, whereas ammonium nitrate, NH₄NO₃, which is also formed from NH₃ and NO₂ + O₂, (or HNO₃), decomposes only at 312°C yielding mainly N₂O. Upon applying Redhead's equations for a first order desorption to the decomposition of ammonium nitrite, an activation energiy of 22.4 is calculated which is consistent with literature data. For the reaction path via ammonium nitrite a consumption ratio of 1/1 for NO and NO₂ is predicted and confirmed experimentally by injecting NO into a mixture of NH₃ + NO₂ flowing over a BaNa/Y catalyst. This leads to a yield increase of one N₂ molecule per added molecule of NO. Little N₂ is produced from NH₃ + NO in the absence of NO₂.

Original language	English
Pages (from-to)	5-9
Number of pages	5
Journal	Catalysis Letters
Volume	98
Issue number	1
DOIs	https://doi.org/10.1007/s10562-004-6441-y
State	Published - Oct 2004
Externally published	Yes

Funding

This work was supported by the EMSI program of the U.S. Department of Energy Office of Science (CHE-9810378) at the Northwestern University Institute for Environmental Catalysis.

Funders	Funder number
U.S. Department of Energy	CHE-9810378

Keywords

Ammonium nitrite
Ba/Y-zeolite catalyst
NO reduction
NO/NO ratio

Access to Document

10.1007/s10562-004-6441-y

Cite this

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title = "Low activation energy pathway for the catalyzed reduction of nitrogen oxides to N2 by ammonia",

abstract = "A low activation energy pathway for the catalytic reduction of nitrogen oxides to N2, with reductants other than ammonia, consists of two sets of reaction steps. In the first set, part of the NOx is reduced to NH3: in the second set ammonium nitrite, NH4NO 2 is formed from this NH3 and NO + NO2. The NH4NO2 thus formed decomposes at ∼100°C to N 2 + H2O, even on an inert support, whereas ammonium nitrate, NH4NO3, which is also formed from NH3 and NO2 + O2, (or HNO3), decomposes only at 312°C yielding mainly N2O. Upon applying Redhead's equations for a first order desorption to the decomposition of ammonium nitrite, an activation energiy of 22.4 is calculated which is consistent with literature data. For the reaction path via ammonium nitrite a consumption ratio of 1/1 for NO and NO2 is predicted and confirmed experimentally by injecting NO into a mixture of NH3 + NO2 flowing over a BaNa/Y catalyst. This leads to a yield increase of one N2 molecule per added molecule of NO. Little N2 is produced from NH3 + NO in the absence of NO2.",

keywords = "Ammonium nitrite, Ba/Y-zeolite catalyst, NO reduction, NO/NO ratio",

author = "Meijun Li and Juan Henao and Younghoon Yeom and Eric Weitz and Sachtler, {Wolfgang M.H.}",

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AU - Li, Meijun

AU - Henao, Juan

AU - Yeom, Younghoon

AU - Weitz, Eric

AU - Sachtler, Wolfgang M.H.

PY - 2004/10

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N2 - A low activation energy pathway for the catalytic reduction of nitrogen oxides to N2, with reductants other than ammonia, consists of two sets of reaction steps. In the first set, part of the NOx is reduced to NH3: in the second set ammonium nitrite, NH4NO 2 is formed from this NH3 and NO + NO2. The NH4NO2 thus formed decomposes at ∼100°C to N 2 + H2O, even on an inert support, whereas ammonium nitrate, NH4NO3, which is also formed from NH3 and NO2 + O2, (or HNO3), decomposes only at 312°C yielding mainly N2O. Upon applying Redhead's equations for a first order desorption to the decomposition of ammonium nitrite, an activation energiy of 22.4 is calculated which is consistent with literature data. For the reaction path via ammonium nitrite a consumption ratio of 1/1 for NO and NO2 is predicted and confirmed experimentally by injecting NO into a mixture of NH3 + NO2 flowing over a BaNa/Y catalyst. This leads to a yield increase of one N2 molecule per added molecule of NO. Little N2 is produced from NH3 + NO in the absence of NO2.

AB - A low activation energy pathway for the catalytic reduction of nitrogen oxides to N2, with reductants other than ammonia, consists of two sets of reaction steps. In the first set, part of the NOx is reduced to NH3: in the second set ammonium nitrite, NH4NO 2 is formed from this NH3 and NO + NO2. The NH4NO2 thus formed decomposes at ∼100°C to N 2 + H2O, even on an inert support, whereas ammonium nitrate, NH4NO3, which is also formed from NH3 and NO2 + O2, (or HNO3), decomposes only at 312°C yielding mainly N2O. Upon applying Redhead's equations for a first order desorption to the decomposition of ammonium nitrite, an activation energiy of 22.4 is calculated which is consistent with literature data. For the reaction path via ammonium nitrite a consumption ratio of 1/1 for NO and NO2 is predicted and confirmed experimentally by injecting NO into a mixture of NH3 + NO2 flowing over a BaNa/Y catalyst. This leads to a yield increase of one N2 molecule per added molecule of NO. Little N2 is produced from NH3 + NO in the absence of NO2.

KW - Ammonium nitrite

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KW - NO/NO ratio

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