Investigation of the nature of silver species on different Ag-containing NOx reduction catalysts: On the effect of the support

Bartolomeu, Rui; Azambre, B.; Westermann, Alexandre; Fernandes, Auguste; Bértolo, Raquel; Hamoud, Houeida Issa; Henriques, Carlos; Costa, Patrick Da; Ribeiro, M.F.

doi:10.1016/j.apcatb.2013.12.021

Cited by 33 publications

(34 citation statements)

References 59 publications

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“…DRIFTS of adsorbed CO revealed that Ag + cations mainly occupy sites S II in the faujasite structures and to a lesser extent sites S III [12]. As reported with more details in [32][33][34] , it is clearly evidenced by DRS-UV-Vis on Fig. 1 [27].…”

Section: Chemical and Textural Characteristics Of Exchanged Faujasitesupporting

confidence: 62%

Effects of the cation and Si/Al ratio on CH3I adsorption by faujasite zeolites

Azambre

Chebbi

Hijazi

2020

Chemical Engineering Journal

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In this study, we aimed to investigate the effects of some specific zeolitic parameters on the retention properties of metal-exchanged faujasites (X and Y) for methyl iodide. In the first part, the nature of exchangeable cation (H + , Na + , Cu + /Cu 2+ , Ag + , Pb 2+) is discussed. In order to link the materials properties with the adsorption behaviour, the state and location of the exchanged transition metals after calcination at 500°C were first investigated using N 2 sorptiometry at 77K, DRS-UV-Vis spectroscopy, XRD and FTIR of adsorbed CO and NO. Adsorption capacities at breakthrough and saturation were obtained from CH 3 I breakthrough curves obtained at 100°C, this temperature being relevant to severe nuclear accident conditions. From the I/M ratio computed at saturation of the adsorbents by CH 3 I vapors, it was found that the efficiency of iodine trapping follows the order Cu + /Cu 2+ > Ag + >> Pb 2+ > Na + > H +. This efficiency roughly followed the trend of the different cations to form stable MI x precipitates from CH 3 I. Nevertheless, for nuclear application, it was found that Ag/FAU are preferred over Cu/FAU, due to the propension of the latter to oxidize CH 3 I to I 2 , which slips out of the sorbent bed at 100°C. The effect of the preparation method (ion-exchange vs impregnation) is then discussed for Ag/Y zeolites having different Si/Al ratio (2.5 and 40) but similar silver content (23 wt%). It is found that the silver oxidation state and silver dispersion have important effects on CH 3 I adsorption/desorption.

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Section: Chemical and Textural Characteristics Of Exchanged Faujasitesupporting

confidence: 62%

Effects of the cation and Si/Al ratio on CH3I adsorption by faujasite zeolites

Azambre

Chebbi

Hijazi

2020

Chemical Engineering Journal

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“…g , respectively, when Co content increases from 1wt% to 10 wt%. Since the concentration and strength of Brönsted and Lewis acid sites play an important role in NOx reduction with hydrocarbons[35,[53][54][55], ZrSBADP2-supported cobalt catalysts possess a high potential to be applied as active catalysts in C3H8-SCR reaction.…”

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confidence: 99%

High Zr-loaded SBA-15 cobalt catalyst for efficient NOx reduction in lean-burn exhaust

Sabbaghi

Lam

2015

Applied Catalysis A: General

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“…It is important for preparation of catalytically stable bimetal Au-Ag systems. Some supports and modifying additives of transient metal oxides can stabilize the active sites both silver and gold [31][32][33][36][37][38][39][40][41][50][51][52]. At higher temperatures (>300-400°C) formation of the metal active states follows other way; in this case big metal particles, metal crystals and films can also catalyze oxidation reactions (for example, methanol selective oxidation [33,53]).…”

Section: Discussionmentioning

confidence: 97%

“…In the range of absorption bands of ions and charged clusters of silver (200-380 nm [34][35][36][37][38][39][40][41]) we observe only strong unstructured absorption. Usage of the catalysts in CO oxidation process lead to noticeable growth of the bands at 440-450 nm in all spectra except the first one and display of the pronounced signals at 250-270 nm attributed to silver charged clusters Ag n [ [34][35][36][37][38][39][40][41]. Obviously, 1% Ag/ZSM-5 sample contains too small concentration of silver; and UV-vis spectroscopy method is not sensitive enough for detection of the metal particles of such a low concentration.…”

Section: Uv-vis Spectroscopymentioning

confidence: 88%