Ultrasmall Pd Clusters in FER Zeolite Alleviate CO Poisoning for Effective Low-Temperature Carbon Monoxide Oxidation

Song, Inhak; Koleva, Iskra Z.; Aleksandrov, Hristiyan A.; Chen, Linxiao; Heo, Jaeyoung; Li, Dongsheng; Wang, Yong; Szanyi, János; Khivantsev, Konstantin

doi:10.1021/jacs.3c08916

Cited by 5 publications

(3 citation statements)

References 23 publications

(39 reference statements)

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“…The formation of the [COOH] complex is recently reported by Song et al. in Pd/FER in the presence of H 2 O during CO oxidation . The activation barrier for the transformation of Pd–COOH to Pd +1 in the presence of H 2 O is 10 kJ/mol, which is comparable to that in its absence (20 kJ/mol, Figure ).…”

Section: Resultssupporting

confidence: 64%

“…Khivantsev et al proposed that CO stabilizes the NO bound to Pd . Also, various studies propose that CO reduces the oxidation state of Pd from +2 to +1, and a more recent study proposed the reduction to metallic Pd. ,,,, This results in the enhancement of NO adsorption on Pd/CHA even in the presence of H 2 O. ,, The adsorption of NO on reduced Pd occurs via back-donation of electrons, which increases the Pd–N bond strength . Further, it is established that NO binds strongly on the Pd +1 site in the absence as well as the presence of both H 2 O and CO. ,, Hadjiivanov and co-workers proposed the formation of a metal nitrosyl carbonyl complex [Pd(II)(NO)(CO)] on Pd +2 sites in Pd/ZSM-5 and Pd/WZ in the presence of CO and NO. , These complexes decompose to form the corresponding metal nitrosyl complex with desorption of CO.…”

Section: Introductionmentioning

confidence: 99%

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Effect of H₂O and CO on the NO Operating Cycle in Pd/CHA Passive NO_x Adsorbers

Kaushik,

Khan,

Haider

et al. 2024

J. Phys. Chem. C

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DFT simulations are performed to understand the impact of H 2 O and CO on the NO interaction with Pd sites present at various locations in Pd/CHA passive NO x adsorbers. The presence of H 2 O facilitates the reduction of [PdOH−PdOH] +2 and [Pd−O−Pd] +2 by NO in 8-membered rings (8MR) but increases the activation barrier in 6MR. Bidentate nitrates are formed in the absence of H 2 O, whereas monodentate nitrates are formed in the presence of H 2 O, which transform to bidentate nitrates upon H 2 O desorption. The detrimental effect of H 2 O on NO binding over [PdOH−PdOH] +2 and [PdOH] + is mitigated in the presence of CO. Additionally, CO preferentially reduces the Pd(II) species when both CO and NO are coadsorbed on [Pd−O−Pd] +2 , resulting in the formation of Pd +1 for further NO uptake. H 2 O does not significantly impact the reduction of Pd(II) species by CO.Pd +1 sites can also reoxidize to Pd(II) species under an oxidizing atmosphere. However, the reoxidation of Pd +1 is inhibited in the presence of H 2 O in 6MR and 8MR, which could explain the reported increase in the NO x desorption temperature. The operating cycle of NO, including the transformation of Pd species and the effect of H 2 O and CO on NO x uptake and release, is proposed.

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Section: Resultssupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Effect of H₂O and CO on the NO Operating Cycle in Pd/CHA Passive NO_x Adsorbers

Kaushik,

Khan,

Haider

et al. 2024

J. Phys. Chem. C

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“…Within the last decade, metal/zeolites system have become the front-liners of environmental catalysis [1,2]. These materials/catalysts have allowed us to tackle the most challenging environmental problems caused by pollutants emitted by vehicles [1][2][3][4][5][6][7][8]. More specifically, nitric oxide is a free-radical harmful pollutant, even more dangerous than carbon monoxide (CO).…”

Section: Introductionmentioning

confidence: 99%

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydrothermally Stable Co-, Cu- and Pd-SSZ-13 Materials

Khivantsev,

Derewinski,

Kovarik

et al. 2024

Catalysts

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Replacing alkaline for alkaline-earth metal hydroxide in the synthesis gel during the synthesis of siliceous SSZ-13 zeolite (Si/Al~10) yields SSZ-13 with novel, advantageous properties. Its NH4-form ion-exchanges higher amount of isolated divalent M(II) ions than the conventional one: this is the consequence of an increased number of Al pairs in the structure induced by the +2 charge of Sr(II) cations in the synthesis gel that force two charge-compensating AlO4− motives to reside closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and X-ray absorption spectroscopy measurements and show their utility for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more isolated cobalt(II) and, thus, perform better as ambient-air NOx adsorbers. Notably, Co(II)/SSZ-13 with an increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading Pd(II) into Co-SSZ-13(Sr) produces an active NOx adsorber (PNA) material that can be used for NOx adsorption from simulated diesel engine exhaust. The critical issue for these applications is hydrothermal stability of Pd-zeolites. Pd/SSZ-13 synthesized in the presence of Sr(OH)2 does not lose its PNA capacity after extremely harsh aging at 850 and 900 °C (10 h in 10% H2O/air flow) and loses only ~55% capacity after hydrothermal aging at 930 °C. This can be extended to other divalent metals for catalytic applications, such as copper: we show that Cu/SSZ-13 catalyst can survive hydrothermal aging at 920 °C without losing its catalytic properties, metal dispersion and crystalline structure. Thus, we provide a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications.

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Unique role of silica in MOF-Derived High-Loading Palladium-on-Ceria single atom catalysts with excellent efficiency and durability

Tang,

Wang,

Jiang

et al. 2024

Chemical Engineering Journal

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Ultrasmall Pd Clusters in FER Zeolite Alleviate CO Poisoning for Effective Low-Temperature Carbon Monoxide Oxidation

Cited by 5 publications

References 23 publications

Effect of H₂O and CO on the NO Operating Cycle in Pd/CHA Passive NO_x Adsorbers

Effect of H₂O and CO on the NO Operating Cycle in Pd/CHA Passive NO_x Adsorbers

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydrothermally Stable Co-, Cu- and Pd-SSZ-13 Materials

Unique role of silica in MOF-Derived High-Loading Palladium-on-Ceria single atom catalysts with excellent efficiency and durability

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Ultrasmall Pd Clusters in FER Zeolite Alleviate CO Poisoning for Effective Low-Temperature Carbon Monoxide Oxidation

Cited by 5 publications

References 23 publications

Effect of H2O and CO on the NO Operating Cycle in Pd/CHA Passive NOx Adsorbers

Effect of H2O and CO on the NO Operating Cycle in Pd/CHA Passive NOx Adsorbers

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydrothermally Stable Co-, Cu- and Pd-SSZ-13 Materials

Unique role of silica in MOF-Derived High-Loading Palladium-on-Ceria single atom catalysts with excellent efficiency and durability

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Effect of H₂O and CO on the NO Operating Cycle in Pd/CHA Passive NO_x Adsorbers

Effect of H₂O and CO on the NO Operating Cycle in Pd/CHA Passive NO_x Adsorbers