Deactivation and regeneration studies on Pd-containing medium pore zeolites as passive NOx adsorbers (PNAs) in cold-start applications

Bello-Jurado, Estefanía; Margarit, Vicente J.; Gallego, Eva María Martínez; Schuetze, F.-W.; Hengst, Christoph; Corma, Avelino; Moliner, Manuel

doi:10.1016/j.micromeso.2020.110222

“…Various NO 2 emission sources, such as exhaust from vehicles, flue gas from burning of fossil fuels, contribute to the accumulation of NO 2 in the atmosphere . Although the selective catalytic reduction (SCR) applicable for NO 2 conversion at high temperatures (523–873 K) has been widely used in industry, the control and abatement of ambient NO 2 emission is still an elusive challenge. The development of efficient technologies for ambient NO 2 removal is highly sought‐after.…”

Section: Figurementioning

confidence: 99%

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

Shang

¹

,

Yang

²

,

Wang

³

et al. 2020

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Mitigating ambient nitrogen dioxide (NO 2) pollution via selective adsorption on porous materials is a promising approach to tackle such an increasingly pressing environmental health issue. However, very few porous adsorbents have sufficiently high NO 2 adsorption capacity and good regenerability simultaneously. Here we attempt to address this challenge by developing p-backbonding adsorbents in the transition metal (TM) incorporated porphyrin metal-organic frameworks (PMOFs). Breakthrough experiments show that PMOFs with inserted TMs achieve appreciable NO 2 capacity and good regenerability. Combined in situ DRIFTS, synchrotron powder XRD, and DFT calculations reveal the adsorption mechanism: NO 2 partially transforms to N 2 O 4 and interacts with transition metal via p-backbonding and Al-node via hydrogen bonding. This work affords new insights for designing next-generation adsorbents for ambient NO 2 removal and presents PMOFs as a platform to tailor p-backbonding adsorbents.

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“…The main challenge for application of Metal/zeolite materials for industrial vehicle use has always been their hydrothermal stability. They may be exposed in vehicles to harsh steam treatment (during diesel particular filter regeneration, for example) [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. In general, it is desirable to develop materials that can survive hydrothermal aging at temperatures as harsh as 800 ⁰C and higher.…”

mentioning

confidence: 99%

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydro-Thermally Stable Cobalt and Pd-SSZ-13 Materials for Pollutant Abatement Applications

Khivantsev

¹

,

Derewinski²,

Nr³

et al. 2021

Preprint

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<div> We show that replacing alkaline (NaOH) for alkaline-earth metal (Sr(OH)2 as an example) in the synthesis of SSZ-13 zeolite with Si/Al~10 produces SSZ-13 zeolite material with novel, advantageous properties. Its NH4-form ion-exchanges higher amount of Co(II) ions than the conventional one: this is the consequence of 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 be closer together. We characterize the +2 state of Co(II) ions in these materials with infra-red spectroscopy and XANES measurements. They can be used for NOx pollutant adsorption from ambient air: the ones derived from SSZ-13 with higher Al pair content contain more cobalt(II) and thus, perform better as ambient-air NOx adsorbers before reaching full saturation capacity. Notably, Co(II)/SSZ-13 material with increased number of Al pairs is significantly more hydrothermally stable than its NaOH-derived analogue. Loading 1.7 wt% Pd into Co-SSZ-13 synthesized in the presence of Sr(II) produces a passive 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 NaOH media loses most of its PNA capacity after ~800 ⁰C hydrothermal aging in the flow of air and steam (10 hours in 10% H2O/air flow). The 1.7 wt% Pd/Co/SSZ-13 material with Si/Al ~10 does not lose its PNA capacity after extremely harsh aging at 850 and 900 ⁰C (10 hours in 10% H2O/Air flow) and loses only ~55% capacity after hydrothermal aging at 930 ⁰C. It shows considerably enhanced stability compared with previous record for Pd/FER, Pd/SSZ-39 and Pd/BEA materials that could survive hydrothermal aging no higher than 820 ⁰C. We herein reveal a new, simple, and scalable strategy for making remarkably (hydro)thermally stable metal-zeolite materials/catalysts with a number of useful applications. </div>

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“…[1] Various NO 2 emission sources, such as exhaust from vehicles, flue gas from burning of fossil fuels, contribute to the accumulation of NO 2 in the atmosphere. [2] Although the selective catalytic reduction (SCR) applicable for NO 2 conversion at high temperatures (523-873 K) has been widely used in industry, [3] the control and abatement of ambient NO 2 emission is still an elusive challenge. The development of efficient technologies for ambient NO 2 removal is highly sought-after.…”

mentioning

confidence: 99%

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

Shang

¹

,

Yang

²

,

Wang

³

et al. 2020

Angewandte Chemie

2

0

View full text Add to dashboard Cite

Mitigating ambient nitrogen dioxide (NO 2) pollution via selective adsorption on porous materials is a promising approach to tackle such an increasingly pressing environmental health issue. However, very few porous adsorbents have sufficiently high NO 2 adsorption capacity and good regenerability simultaneously. Here we attempt to address this challenge by developing p-backbonding adsorbents in the transition metal (TM) incorporated porphyrin metal-organic frameworks (PMOFs). Breakthrough experiments show that PMOFs with inserted TMs achieve appreciable NO 2 capacity and good regenerability. Combined in situ DRIFTS, synchrotron powder XRD, and DFT calculations reveal the adsorption mechanism: NO 2 partially transforms to N 2 O 4 and interacts with transition metal via p-backbonding and Al-node via hydrogen bonding. This work affords new insights for designing next-generation adsorbents for ambient NO 2 removal and presents PMOFs as a platform to tailor p-backbonding adsorbents.

show abstract

Deactivation and regeneration studies on Pd-containing medium pore zeolites as passive NOx adsorbers (PNAs) in cold-start applications

Cited by 50 publications

References 38 publications

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydro-Thermally Stable Cobalt and Pd-SSZ-13 Materials for Pollutant Abatement Applications

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

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Deactivation and regeneration studies on Pd-containing medium pore zeolites as passive NOx adsorbers (PNAs) in cold-start applications

Cited by 50 publications

References 38 publications

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO2 Removal

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO2 Removal

Increasing Al-Pair Abundance in SSZ-13 Zeolite via Zeolite Synthesis in the Presence of Alkaline Earth Metal Hydroxide Produces Hydro-Thermally Stable Cobalt and Pd-SSZ-13 Materials for Pollutant Abatement Applications

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO2 Removal

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Product

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About

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal

Transition‐Metal‐Containing Porphyrin Metal–Organic Frameworks as π‐Backbonding Adsorbents for NO₂ Removal