The sorption and reduction of nitrogen oxides by 12-tungstophosphoric acid and its ammonium salt

Bélanger, Raymond; Moffat, J.B.

doi:10.1016/s0920-5861(98)00059-5

Cited by 15 publications

(5 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Of the many structural types of HPAs, the majority used in catalytic applications are Keggin HPAs, such as H 3 12 O 40 because of their stronger acidity, higher thermal stability, and easier availability [11,12]. It has been reported that Keggin HPAs have excellent NO adsorption behavior and that rapid heating can cause absorbed NO to be decomposed into N 2 [13][14][15]. Other research has shown that Pt loaded on Keggin HPAs can enhance the activity of NO reduction [16].…”

Section: Introductionmentioning

confidence: 99%

The Keggin Structure: An Important Factor in Governing NH3–SCR Activity Over the V2O5–MoO3/TiO2 Catalyst

Zhang

Liu

et al. 2018

Catal Lett

View full text Add to dashboard Cite

Heteropolyacids and their salts have been effectively used in selective catalytic reduction because of the Keggin structure and extraordinarily strong acidity. Catalysts with and without the Keggin structure were synthesized to further investigate the effects of heteropolyoxometallate on low temperature NH 3 -SCR. XRD, BET, Raman, H 2 -TPR, NH 3 -TPD, FT-IR, and SO 2 -TPD techniques were used to characterize the physicochemical characteristics of the catalysts. Results indicate that catalysts with the Keggin structure had more surface Brönsted and Lewis acid sites, and these catalysts had significantly improved performances in the SCR reaction and in SO 2 poisoning resistance. Graphical AbstractKeywords SCR catalyst · Ammonium heteropolyacid salt · Keggin structure Rui Wu and Ningqiang Zhang have contributed equally.

show abstract

Section: Introductionmentioning

confidence: 99%

The Keggin Structure: An Important Factor in Governing NH3–SCR Activity Over the V2O5–MoO3/TiO2 Catalyst

Zhang

Liu

et al. 2018

Catal Lett

View full text Add to dashboard Cite

show abstract

“…These are in perfect agreement with the FTIR data reported by Belanger and Moffat. 8 An increase in the intensity of the bands with the increase in the ATPA content can be also observed from the spectral data. These results obtained by the IR analysis also confirm the formation of ATPA on the NbP support surface, further indicating the one-step synthesis of the catalysts.…”

Section: Green Contextmentioning

confidence: 68%

In situ synthesis by salt–surface interaction and the catalytic functionality of the ammonium salt of 12-tungstophosphoric acid

et al. 2002

View full text Add to dashboard Cite

show abstract

“…The Rh atom remained atom-dispersed and thermodynamically stable even at a high loading level (0.9%) in CO oxidation at 150–400 °C . Inspired by previous experimental works on POM-supported SACs, a great number of theoretical calculations have been performed systematically to study the catalysis mechanism in some classical reactions at the atom level. − In the last century, there have been reports in the literature that Keggin-type POMs can exhibit good adsorption capacity for NO and lead to the decomposition of NO into N 2 under a rapid heating condition. − Fehrmann et al prepared V 2 O 5 /TiO 2 and POM-promoted V 2 O 5 /TiO 2 catalysts, and it was found that the SCR activity on POM-promoted catalysts is much higher than on unpromoted catalysts . The same conclusion has been drawn from He’s experiments .…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects of Keggin-Type Phosphotungstic Acid-Supported Single-Atom Catalysts in a Fast NH₃-SCR Reaction

et al. 2022

View full text Add to dashboard Cite

Fast selective catalytic reduction of nitrogen oxide with ammonia (NH 3 -SCR) (2NH 3 + NO 2 + NO → 2N 2 + 3H 2 O) has aroused great interest in recent years because it is inherently faster than the standard NH 3 -SCR reaction (4NO + 4NH 3 + O 2 → 4N 2 + 6H 2 O). In the present paper, the mechanism of the fast NH 3 -SCR reaction catalyzed by a series of single-atom catalysts (SACs), M 1 / PTA SACs (PTA = Keggin-type phosphotungstic acid, M = Mn, Fe, Co, Ni, Ru, Rh, Pd, Ir, and Pt), has been systematically studied by means of density functional theory (DFT) calculations. Molecular geometry and electronic structural analysis show that Jahn−Teller distortion effects promote an electron transfer process from N−H bonding orbitals of the NH 3 molecule to the symmetry-allowed d orbitals (d xy and d xd 2 −yd 2 ) of the single metal atom, which effectively weakens the N−H bond of the adsorbed NH 3 molecule. The calculated free energy profiles along the favorable catalytic path show that decomposition of NH 3 to *NH 2 and *H species and decomposition of *NHNOH into N 2 and H 2 O have high free energy barriers in the whole fast NH 3 -SCR path. A good synergistic effect between the Brønsted acid site (surface oxygen atom in the PTA support) and the Lewis acid site (single metal atom) effectively enhances the decomposition of NH 3 to *NH 2 and *H species. M 1 /PTA SACs (M = Ru, Rh, Pd, and Pt)were found to have potential for fast NH 3 -SCR reaction because of the relatively small free energy barrier and strong thermodynamic driving forces. We hope our computational results could provide some new ideas for designing and fabricating fast NH 3 -SCR catalysts with high activity.

show abstract

The sorption and reduction of nitrogen oxides by 12-tungstophosphoric acid and its ammonium salt

Cited by 15 publications

References 11 publications

The Keggin Structure: An Important Factor in Governing NH3–SCR Activity Over the V2O5–MoO3/TiO2 Catalyst

The Keggin Structure: An Important Factor in Governing NH3–SCR Activity Over the V2O5–MoO3/TiO2 Catalyst

In situ synthesis by salt–surface interaction and the catalytic functionality of the ammonium salt of 12-tungstophosphoric acid

Synergistic Effects of Keggin-Type Phosphotungstic Acid-Supported Single-Atom Catalysts in a Fast NH₃-SCR Reaction

Contact Info

Product

Resources

About

The sorption and reduction of nitrogen oxides by 12-tungstophosphoric acid and its ammonium salt

Cited by 15 publications

References 11 publications

The Keggin Structure: An Important Factor in Governing NH3–SCR Activity Over the V2O5–MoO3/TiO2 Catalyst

The Keggin Structure: An Important Factor in Governing NH3–SCR Activity Over the V2O5–MoO3/TiO2 Catalyst

In situ synthesis by salt–surface interaction and the catalytic functionality of the ammonium salt of 12-tungstophosphoric acid

Synergistic Effects of Keggin-Type Phosphotungstic Acid-Supported Single-Atom Catalysts in a Fast NH3-SCR Reaction

Contact Info

Product

Resources

About

Synergistic Effects of Keggin-Type Phosphotungstic Acid-Supported Single-Atom Catalysts in a Fast NH₃-SCR Reaction