Hydrogen Promotion of Low-Temperature Passive Hydrocarbon-Selective Catalytic Reduction (SCR) over a Silver Catalyst

Theinnoi, Kampanart; Sitshebo, S.; Houel, Valérie; Rajaram, Raj R.; Tsolakis, Athanasios

doi:10.1021/ef8004515

Cited by 36 publications

(15 citation statements)

References 29 publications

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“…show that at higher temperatures (above 300°C), H 2 consistently loses its benefit as promoter, which supports past research papers on H 2 addition into HC-SCR catalysts [16], [22], [25], [28]. In addition…”

Section: Impact Of Hc:nox and H 2 :Nox Ratiosupporting

confidence: 88%

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Enhancing selective catalytic reduction of NOx with alternative reactants/promoters

Herreros

George

Umar

et al. 2014

Chemical Engineering Journal

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The hydrocarbon-selective catalytic reduction (HC-SCR) activity of an Ag/Al 2 O 3 catalyst was investigated. The function on catalytic NOx reduction of different fuel properties using alternative reactants such as gas-to-liquid (GTL) and butanol was studied. This work proves that such improvements are due to the high reactivity, polarity and diffusivity of butanol within the catalyst enhancing NOx conversion. Furthermore, it is suggested that HC components such butanol share some of the reaction mechanisms to hydrogen as a promoter in addition to his role as a reductant leading to improve NOx reduction. Therefore, it is proposed the simultaneous dual role of butanol as a reactant and as promoter.Catalyst performance at low temperature was further improved with the addition of hydrogen (H 2 ).However, this performance was found to degrade as temperature increases, due to H 2 reactant selectivity changing, directly being oxidised. Increased NOx conversion was dependent on HC:NOx ratio, showing at low temperature a low HC:NOx ratio is required. As temperature increases, so does the required HC:NOx ratio to compensate for hydrocarbons partial and complete oxidation. These results demonstrate a method of gaining significant NOx reduction through the combination of environmental catalysts and alternative reactants.

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Section: Impact Of Hc:nox and H 2 :Nox Ratiosupporting

confidence: 88%

“…The addition of H 2 also enables the removal of strongly adsorbed nitrates from the catalyst's active sites and support which, previously at low temperatures would have inhibited NOx conversion [27]- [28].…”

Section: ) Hc Conversion Comparing Betweenmentioning

confidence: 91%

Enhancing selective catalytic reduction of NOx with alternative reactants/promoters

Herreros

George

Umar

et al. 2014

Chemical Engineering Journal

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“…As we have previously reported (e.g. [36]) the presence of both unburned diesel fuel and solid particles in the engine exhaust can lead to the Ag/Al2O3 catalyst deactivation through partially blocked catalyst pores. This leads to increased diffusion resistance and thus a decrease in the activation energy.…”

Section: Scr Activity At Low Reaction Temperature (< 200 °C) With Incmentioning

confidence: 61%

Increased NO2 concentration in the diesel engine exhaust for improved Ag/Al2O3 catalyst NH3-SCR activity

Wang

Herreros

Tsolakis

et al. 2015

Chemical Engineering Journal

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Increasing the NO2 availability in some aftertreatment systems enhance their performance in reducing pollutants from internal combustion (IC) engines but result in significant fuel economy and CO2 emissions penalties. The presence of NO2 in the engine exhaust gas enhances the regeneration of the Diesel Particulate Filters (DPFs) and can improve the activity of the catalysts in reducing NOx emissions in the Selective Catalytic Reduction (SCRs) process. In this work the production and the role of the increased NO2 concentration in the Ag/Al2O3 catalyst for the SCR process of NOx removal at low exhaust gas temperatures under real engine operation has been investigated. We have increased the NO2 concentration available for the SCR process with i) the addition of different NH3 and H2 mixtures upstream the SCR catalyst and/or ii) by the use of a Pt based Diesel Oxidation Catalyst (DOC) in front of the Ag/Al2O3 -SCR catalyst. In the case of NH3 and H2 mixtures additions, H2 enhances the NO2 production on the Ag/Al2O3 catalyst, leading in promoting the "Fast -SCR" like reaction by utilising the available NH3 mainly at low reaction temperature. The incorporation of the DOC in front of the Ag/Al2O3 showed the same effect as it enhanced the NO2 availability for the SCR process.

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“…Therefore, an effective NO x removal method for lean-burn exhaust becomes desirable from the environmental and catalytic point of view. NO x removal technologies under the lean-burn condition include direct catalytic decomposition of NO x , catalytic NO x storage/reduction (NSR) [1,[4][5][6][7], and selective catalytic reduction of NO x with urea/NH 3 [8,9] or hydrocarbons [10][11][12].…”

Section: Introduction 1overview Of the Development On Nsr Catalystsmentioning

confidence: 99%

Ordered Nanostructure Catalysts Efficient for NOx Storage/Reduction (NSR) Processes

Naito

2021

Catalysts

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NOx emissions in the atmosphere can cause various environmental problems, which should be strictly controlled and regulated. Furthermore, because of the limited amount of crude oil resources in the world and severe global warming, the development of fuel-efficient vehicles has long been desired. Accordingly, efficient NOx storage and reduction catalysts have been developed over the decades, called NSR (NOx storage/reduction) catalysts. In the present article, recent advances in NSR catalysts which possess ordered nanostructures will be summarized, including our noble Pt/KNO3/K-titanate nanobelt (KTN), Pt-KNO3/CeO2 and Pt-KNO3/ZrO2 catalysts, as well as nanoporous Ni-phosphate (VSB-5) and Co-substituted VSB-5 catalysts.

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Hydrogen Promotion of Low-Temperature Passive Hydrocarbon-Selective Catalytic Reduction (SCR) over a Silver Catalyst

Cited by 36 publications

References 29 publications

Enhancing selective catalytic reduction of NOx with alternative reactants/promoters

Enhancing selective catalytic reduction of NOx with alternative reactants/promoters

Increased NO2 concentration in the diesel engine exhaust for improved Ag/Al2O3 catalyst NH3-SCR activity

Ordered Nanostructure Catalysts Efficient for NOx Storage/Reduction (NSR) Processes

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