Silver as Storage Compound for NOx at Low Temperatures

Tamm, Stefanie; Andonova, Stanislava; Olsson, Louise

doi:10.1007/s10562-014-1211-y

Cited by 28 publications

(20 citation statements)

References 54 publications

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“…The bands at 1929, 2241 and 2533 cm -1 are related to three different types of NO adsorption, corresponding to mononitrosyl (NO-Al 3+ ), NO + -Al 3+ and NO --Al 3+ species, respectively [11,24]. > Pt-Al > pre-reduced Pt-Al (see insert in Fig.…”

Section: Drifts Studymentioning

confidence: 99%

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Al2O3-based passive NOx adsorbers for low temperature applications

Bai

Crocker

2015

Applied Catalysis B: Environmental

137

109

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Section: Drifts Studymentioning

confidence: 99%

“…Moreover, Olsson and co-workers [11] reported significant NOx storage capacity achieved over an Ag/Al 2 O 3 NOx adsorber system at 200 ºC.…”

Section: Introductionmentioning

confidence: 99%

Al2O3-based passive NOx adsorbers for low temperature applications

Bai

Crocker

2015

Applied Catalysis B: Environmental

137

109

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“…Due to the low temperature limitations of both the NSR and SCR techniques, the NO x species released during cold-start cannot be converted. An attractive strategy focused on the storage and reduction of NO x emissions during cold-start is the so-called passive NO x adsorber [8,9] (PNA) technology. In this concept, the NO x is stored at low temperatures and then thermally released once the SCR system reaches its operating temperature.…”

Section: Introductionmentioning

confidence: 99%

“…In early studies of passive NO x adsorbers, Pt/Al 2 O 3 [10] as well as Ag/Al 2 O 3 [9,11] were studied. However, the Pt/ Al 2 O 3 sample releases most of the NO x below 200 °C or above 350 °C, which is not in the optimum interval.…”

Section: Introductionmentioning

confidence: 99%

“…However, the Pt/ Al 2 O 3 sample releases most of the NO x below 200 °C or above 350 °C, which is not in the optimum interval. Moreover, the silver based catalysts required that small amounts of hydrogen was present, which is a limitation [9]. In a patent by Johnson Matthey [12], Pd and CeO 2 containing catalysts showed interesting properties, where NO x was stored below temperature of 200 °C and released above this temperature.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Si/Al Ratio for Pd/BEA and Pd/SSZ-13 Used as Passive NOx Adsorbers

et al. 2018

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The mitigation of cold-start emissions involves the development of passive NO x adsorbers (PNA) systems that store NO x at low temperature, being designed to release the trapped NO x at higher temperatures, where downstream NO x reduction catalysts are efficient. Pd-based zeolites (BEA, SSZ-13) with different SAR (Si-to-Al ratio) were used for PNA investigation, and Pd/Ce/Al 2 O 3 catalyst was used as a reference for comparison. In this study, NO x adsorption is investigated at low temperature (80 °C) and it is released during a temperature ramp (to 400 °C) under various gas feed composition. Moreover, detailed characterization was performed using BET, XRD, XPS, TPO, STEM and ICP-SFMS and the stored NO species was studied using in-situ DRIFTS. The addition of CO to the storage mixture resulted in that for Pd/zeolites with low and medium SAR the binding energy for NO was increased. In addition, NO was stored in larger quantities, especially for the Pd/SSZ-13 samples. However, for Pd/BEA (SAR = 300) no such stable NO species was formed and for Pd/Ce/Al 2 O 3 the CO addition was even negative. Moreover, in-situ NO DRIFTS showed that there was large amount of nitrosyls on ionic palladium for the Pd/zeolites with low and medium SAR, indicating that a significant fraction of the palladium was in ionexchanged positions, while this peak was small for the Pd/BEA (SAR = 300) and non-existing for Pd/Ce/Al 2 O 3. Thus, CO addition is beneficial for Pd species that are in ion-exchanged positions, but this is not the case for Pd particles and this can explain the observations that CO is only beneficial for Pd/zeolites with low and medium SAR. Moreover, experiments with similar SAR [Pd/BEA (SAR = 25) and Pd/SSZ-13 (SAR = 24)], showed that there is larger stability of the stored NO x in the small pore Pd/SSZ-13.

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Effect of H₂, H₂O, and CO₂ on the deNO_x characteristics of a combined passive NO_x adsorber and NO_x reduction catalyst

Khatri

Bhatia

2022

AIChE Journal

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The effect of H2, H2O, and CO2 on the NOx removal characteristics of a non‐PGM material (Ag/MgO/γ‐Al2O3) is investigated, which is shown to be active for both NOx adsorption and reduction. H2O facilitates NOx adsorption at early times but inhibits it at longer times. The inhibiting effect of CO2 is observed at low temperatures and is proposed to be due to bicarbonates. However, the inhibiting effect of both H2O and CO2 decreases at higher temperatures. The formation of NO2 at low temperatures is attributed to NO oxidation, and the contribution of stored NOx to NO2 formation increases with temperature. H2O inhibits NH3 oxidation at high temperatures as well as NOx reduction by NH3‐SCR at low temperatures. However, the NOx reduction activity is not affected by CO2. H2 significantly promotes the NH3‐SCR reactions, which is attributed to the facilitation of NOx spillover from the reduced Ag sites to the support.

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Silver as Storage Compound for NOx at Low Temperatures

Cited by 28 publications

References 54 publications

Al2O3-based passive NOx adsorbers for low temperature applications

Al2O3-based passive NOx adsorbers for low temperature applications

The Effect of Si/Al Ratio for Pd/BEA and Pd/SSZ-13 Used as Passive NOx Adsorbers

Effect of H₂, H₂O, and CO₂ on the deNO_x characteristics of a combined passive NO_x adsorber and NO_x reduction catalyst

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Silver as Storage Compound for NOx at Low Temperatures

Cited by 28 publications

References 54 publications

Al2O3-based passive NOx adsorbers for low temperature applications

Al2O3-based passive NOx adsorbers for low temperature applications

The Effect of Si/Al Ratio for Pd/BEA and Pd/SSZ-13 Used as Passive NOx Adsorbers

Effect of H2, H2O, and CO2 on the deNOx characteristics of a combined passive NOx adsorber and NOx reduction catalyst

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Effect of H₂, H₂O, and CO₂ on the deNO_x characteristics of a combined passive NO_x adsorber and NO_x reduction catalyst