Mechanochemical preparation of Ag catalysts for the n-octane-SCR de-NOx reaction: Structural and reactivity effects

Ralphs, Kathryn; Chansai, Sarayute; Hardacre, Christopher; Burch, Robbie; Taylor, S. F. Rebecca; James, Stuart L.

doi:10.1016/j.cattod.2014.10.027

Cited by 13 publications

(13 citation statements)

References 50 publications

(136 reference statements)

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“…The catalytic activity tests were performed as reported elsewhere. 27 For completeness, the essential details are also given here. Typically, the catalytic activity tests over Ag/Al 2 O 3 catalyst were carried out in a fixed-bed flow reactor system, consisting of a quartz reactor tube.…”

Section: Activity Testsmentioning

confidence: 99%

Assessing the effect of reducing agents on the selective catalytic reduction of NO_x over Ag/Al₂O₃ catalysts

D’Agostino

Chansai

Bush

et al. 2016

Catal. Sci. Technol.

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Section: Activity Testsmentioning

confidence: 99%

Assessing the effect of reducing agents on the selective catalytic reduction of NO_x over Ag/Al₂O₃ catalysts

D’Agostino

Chansai

Bush

et al. 2016

Catal. Sci. Technol.

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“…Among them, several formulations based on Ag/Al 2 O 3 catalysts have proved to be particularly active [44,[48][49][50] and although there is still some speculation about the mechanism for NO x reduction, -CN and -NCO species have been proposed as key…”

Section: Discussionmentioning

confidence: 99%

Formation of nitrile species on Ag nanostructures supported on a-Al₂O₃: a new corrosion route for silver exposed to the atmosphere

2017

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The aging of supported Ag nanostructures upon storage in ambient conditions (air and room temperature) for 20 months has been studied. The samples are produced on glass substrates by pulsed laser deposition (PLD); first a 15 nm thick buffer layer of amorphous aluminum oxide (a-AlO) is deposited, followed by PLD of Ag. The amount of deposited Ag ranges from that leading to a discontinuous layer up to an almost-percolated layer with a thickness of <6 nm. Some regions of the as-grown silver layers are converted, by laser induced dewetting, into round isolated nanoparticles (NPs) with diameters of up to ∼25 nm. The plasmonic, structural and chemical properties of both as-grown and laser exposed regions upon aging have been followed using extinction spectroscopy, scanning electron microscopy and x-ray photoelectron spectroscopy, respectively. The results show that the discontinuous as-grown regions are optically and chemically unstable and that the metal becomes oxidized faster, the smaller the amount of Ag. The corrosion leads to the formation of nitrile species due to the reaction between NO species from the atmosphere adsorbed at the surface of Ag, and hydrocarbons adsorbed in defects at the surface of the a-AlO layer during the deposition of the Ag nanostructures by PLD that migrate to the surface of the metal with time. The nitrile formation thus results in the main oxidation mechanism and inhibits almost completely the formation of sulphate/sulphide. Finally, the optical changes upon aging offer an easy-to-use tool for following the aging process. They are dominated by an enhanced absorption in the UV side of the spectrum and a blue-shift of the surface plasmon resonance that are, respectively, related to the formation of a dielectric overlayer on the Ag nanostructure and changes in the dimensions/features of the nanostructures, both due to the oxidation process.

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“…Since these pioneering works, no major improvement of the Ag/Al 2 O 3 system has been achieved up to the works of Kamolphop et al [9] and Petitto and Delahay [10] in which superior HC-SCR performance was obtained using long-chain alkanes as reductants and catalysts prepared by ball-milling compared with those synthesized by the conventional impregnation techniques reported to date. Ball-milled prepared Ag/Al 2 O 3 catalysts were also found to exhibit higher H 2 -HC-SCR activities in comparison with the conventionally prepared samples [11,12]. This was inferred to modifications of the catalyst surface and more specifically to changes in the affinity of the Al 2 O 3 surface towards water and decane [11].…”

Section: Introductionmentioning

confidence: 94%

“…This was inferred to modifications of the catalyst surface and more specifically to changes in the affinity of the Al 2 O 3 surface towards water and decane [11]. In addition, it was found that isocyanates (-NCO), which are supposed to be key intermediates of HC-SCR reactions [1], were formed quicker and had a higher surface concentration on the ball-milled catalyst compared with the conventionally prepared sample [11,12].…”

Section: Introductionmentioning

confidence: 99%

Promoting Ag/Al2O3 Performance in Low-Temperature H2-C3H6-SCR by Thermal Pretreatment of γ-Alumina in Water

et al. 2016

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International audienceThe present work highlights for the first time that a thermal treatment of γ-Al2O3 in water at 80 °C for 24 h prior to Ag deposition (Ag/Al2O3-OH) leads to a drastic enhancement of H2-C3H6-SCR performance at low temperature. This enhancement is attributed to the higher NOx coverage on Ag/Al2O3-OH compared with that of Ag/Al2O3. The higher NOx adsorption capacity of the sample prepared from the γ-Al2O3 thermally-treated in water is proposed to result from the preferential interaction of Ag with newly-created Al2O3 anchoring sites (Al(OH)3 bayerite domains), which were not available on the untreated pristine support

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Mechanochemical preparation of Ag catalysts for the n-octane-SCR de-NOx reaction: Structural and reactivity effects

Cited by 13 publications

References 50 publications

Assessing the effect of reducing agents on the selective catalytic reduction of NO_x over Ag/Al₂O₃ catalysts

Assessing the effect of reducing agents on the selective catalytic reduction of NO_x over Ag/Al₂O₃ catalysts

Formation of nitrile species on Ag nanostructures supported on a-Al₂O₃: a new corrosion route for silver exposed to the atmosphere

Promoting Ag/Al2O3 Performance in Low-Temperature H2-C3H6-SCR by Thermal Pretreatment of γ-Alumina in Water

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Mechanochemical preparation of Ag catalysts for the n-octane-SCR de-NOx reaction: Structural and reactivity effects

Cited by 13 publications

References 50 publications

Assessing the effect of reducing agents on the selective catalytic reduction of NOx over Ag/Al2O3 catalysts

Assessing the effect of reducing agents on the selective catalytic reduction of NOx over Ag/Al2O3 catalysts

Formation of nitrile species on Ag nanostructures supported on a-Al2O3: a new corrosion route for silver exposed to the atmosphere

Promoting Ag/Al2O3 Performance in Low-Temperature H2-C3H6-SCR by Thermal Pretreatment of γ-Alumina in Water

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Assessing the effect of reducing agents on the selective catalytic reduction of NO_x over Ag/Al₂O₃ catalysts

Assessing the effect of reducing agents on the selective catalytic reduction of NO_x over Ag/Al₂O₃ catalysts

Formation of nitrile species on Ag nanostructures supported on a-Al₂O₃: a new corrosion route for silver exposed to the atmosphere