Selective oxidation of ammonia on mixed and dual-layer Fe-ZSM-5+Pt/Al2O3 monolithic catalysts

Shrestha, Sachi; Harold, Michael P.; Kamasamudram, Krishna; Yezerets, Aleksey

doi:10.1016/j.cattod.2014.01.024

Cited by 60 publications

(53 citation statements)

References 35 publications

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“…These results show that the dual layer SCR top/oxidation catalyst bottom case gave the best N 2 selectivity at a higher temperature. Similarly, there was an experimental study that evaluated the differences observed between the dual layered Fe‐ZSM‐5 SCR/Pt‐Al 2 O 3 ASC monoliths versus a homogenous mixture of the two components . Modelling of this type of system was validated with experiments .…”

Section: Selective Catalytic Reduction (Scr) and Lean Nox Trap (Lnt) mentioning

confidence: 99%

Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Hazlett

Epling

2018

Can J Chem Eng

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There have been ongoing research efforts focused on layering or zoning different washcoats/active metals on the catalysts constituting diesel aftertreatment systems: the diesel oxidation catalyst (DOC), the selective catalytic reduction (SCR) catalyst, the lean NOX trap (LNT), the ammonia slip catalyst (ASC), and the diesel particulate filter (DPF). This review paper aims to shed insight into the state‐of‐the‐art research on catalyst design in this area and how these catalyst designs may evolve to tackle engine emission reductions in the future. First, we discuss the motivation for zoning or layering catalysts and pioneering work on three‐way catalyst (TWC) design for reducing gasoline engine emissions; then, we focus on the catalytic systems used for diesel exhaust aftertreatment. The configuration of the aftertreatment systems for diesel engines generally consist of an oxidation catalyst for hydrocarbon (HC), CO, and NO oxidation (over the DOC), a NOX reduction catalyst (over one or combined SCR/LNT/ASC catalysts), and a particulate matter (PM) filter (using a DPF). The research to date consistently demonstrates that zoning and layering catalyst regions leads to improved performance and/or smaller system volumes required.

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Section: Selective Catalytic Reduction (Scr) and Lean Nox Trap (Lnt) mentioning

confidence: 99%

Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Hazlett

Epling

2018

Can J Chem Eng

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“…Unfortunately,t he V 2 O 5 /WO 3 /TiO 2 -based catalysts that are commercially used fort his process have inadequate stabilityatthe highertemperatures encountered in heavy vehicle operation and are not suitable for systems including ap articulate filter that actively regenerates at high temperatures. [9,[20][21][22][23][24][25][26][27] Some reports have suggested that the SCR reaction over FeBEA catalysts proceeds accordingt oar edox mechanism whereby NO x and NH 3 are adsorbed on neighboring iron sites and Fe III is reduced to Fe II ÀNO. [4][5][6][7][8][9][10] Extensive studies on zeolite-based SCR catalysts have been conducted to determine the nature of active sites and their catalytic activity in SCR of NO.…”

Section: Introductionmentioning

confidence: 99%

Experimental Evidence of the Mechanism of Selective Catalytic Reduction of NO with NH₃ over Fe‐Containing BEA Zeolites

et al. 2018

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Various temperature‐programmed techniques were used as tools in mechanistic studies of selective catalytic reduction (SCR) of NO with ammonia in the presence of Fe‐containing BEA zeolites. Moreover, FTIR studies of adsorbed NH3 and NO were conducted to determine the interactions of reactants with the catalyst surface. Iron was introduced into BEA zeolite by three different methods: i) two‐step post‐synthesis; ii) conventional wet impregnation; iii) ion exchange. The catalytic activity was dependent on the method used for iron introduction. The reactivities of NH3 and NO adsorbed on iron‐modified zeolites obtained by impregnation and ion‐exchange methods were higher than those measured for the catalyst obtained by a two‐step post‐synthesis method. The activity of Fe‐containing zeolites in SCR was related to the form of deposited iron species, as well as to the nature, strength, and concentration of acid sites. Possible reaction pathways of NO reduction over the FeBEA zeolite catalysts were presented and discussed.

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“…The chemisorption energies of oxygen, carbon-, and nitrogen-containing species on differ-ent transitionm etals exchanged in ZSM-22 are also investigated. The study coverst hree different oxidation states, that is, metals include Co, [26][27][28][29] Fe, [7,18,[30][31][32][33] Ni, [34][35][36] Pd, [37] Pt, [38] and Ag. [24,39] Framework exchange of transition metalsi nz eolites has also received great attention.F or example iron, [40][41][42][43][44][45] cobalt, [46] vanadium, [47] and titanium-exchanged zeolites have been synthesized and characterized.…”

Section: Introductionmentioning

confidence: 99%

Exploring Scaling Relations for Chemisorption Energies on Transition‐Metal‐Exchanged Zeolites ZSM‐22 and ZSM‐5

et al. 2016

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Copper exchange on all the different T sites of ZSM‐22 and ZSM‐5 is considered and the chemisorption energies of dioxygen, OH, and O species are studied. We show that for different T sites the adsorption energies vary significantly. The oxygen adsorption energy on copper‐exchanged zeolites is quite similar to those of the most selective catalysts for oxidation reactions, that is, Ag and Au surfaces. The chemisorption energies of oxygen, carbon‐, and nitrogen‐containing species on different transition metals exchanged in ZSM‐22 are also investigated. The study covers three different oxidation states, that is, 1+, 2+, and 3+ for the transition‐metal exchanges. Scaling relations are presented for the corresponding species. Chemisorption of O scales with chemisorption of OH for all three considered exchanges, whereas there are essentially rough correlations for NH2 and N as well as CH3 and C.

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Selective oxidation of ammonia on mixed and dual-layer Fe-ZSM-5+Pt/Al2O3 monolithic catalysts

Cited by 60 publications

References 35 publications

Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Experimental Evidence of the Mechanism of Selective Catalytic Reduction of NO with NH₃ over Fe‐Containing BEA Zeolites

Exploring Scaling Relations for Chemisorption Energies on Transition‐Metal‐Exchanged Zeolites ZSM‐22 and ZSM‐5

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Selective oxidation of ammonia on mixed and dual-layer Fe-ZSM-5+Pt/Al2O3 monolithic catalysts

Cited by 60 publications

References 35 publications

Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Experimental Evidence of the Mechanism of Selective Catalytic Reduction of NO with NH3 over Fe‐Containing BEA Zeolites

Exploring Scaling Relations for Chemisorption Energies on Transition‐Metal‐Exchanged Zeolites ZSM‐22 and ZSM‐5

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Experimental Evidence of the Mechanism of Selective Catalytic Reduction of NO with NH₃ over Fe‐Containing BEA Zeolites