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Fanson, Paul T.; Stradt, Martin W; Delgass, W. Nicholas; Lauterbach, Jochen A.

doi:10.1023/a:1012726809704

Cited by 83 publications

(119 citation statements)

References 24 publications

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“…Thus, it can be concluded by associating these results with those obtained above, that the formation of nitrate has two pathways; the oxidation of nitrites into to nitrate by reactive oxygen and the adsorption of NO 2 ; and that higher temperature is favorable for the formation of nitrate species. The corresponding changes in intensity of various bands provides evidence that nitrite species on the catalyst are being converted to nitrate species, which is consistent with previous studies [7,[32][33][34][35]. The large amount of nitrate species existing on BaAl 2 O 4 in the presence of O 2 further indicates the importance of nitrate species and the promotion effects of O 2 on simultaneous removal of soot-NO x .…”

Section: The Micro Behavior Of No (Ad) On Baal 2 O 4 In Osupporting

confidence: 90%

“…The band at 1216 cm -1 overlaps with that at 1256 cm -1 to some extent. The bands at 1908 and 1840 cm -1 are assigned to gas-phase NO, and the band at 1216 cm -1 is attributed to linear nitrite, Ba-O-N=O, by comparing with the spectrum of pure barium nitrite [7,23], in which the nitrogen atom of NO is linked to the barium via an oxygen atom. Bidentate nitrites on Ba-and Al-oxide all have bands at 1340 cm -1 and 1256 cm -1 [23,24], which are assigned to t sym (NO 2 ) and t asym (NO 2 ) vibrations.…”

Section: The Micro Behavior Of No (Ad) On Baal 2 Omentioning

confidence: 99%

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Properties of BaAl₂O₄ in the Simultaneous Removal of Soot and NO_x

Lin

Shangguan

et al. 2007

Chem Eng & Technol

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The catalytic activity of BaAl 2 O 4 in the simultaneous removal of soot and NO x was evaluated by Temperature Programmed Reaction (TPR). It was found that BaAl 2 O 4 could effectively catalyze the reaction of soot with NO x under various reaction conditions. Compared with non-catalytic combustion, ignition temperature, T ig , and maximum combustion temperature, T m , of soot decreased by more than 175°C and 240°C, respectively. Tight contact of soot with BaAl 2 O 4 , higher O 2 content and a lower flow rate of synthesized gases were beneficial to the catalytic reaction. It was confirmed by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis, that the reaction of soot with NO 2(ad) was the most important factor in simultaneous removal of soot and NO x , in which NO 2(ad) existed on BaAl 2 O 4 in the form of monodentate nitrate, bridged nitrate and ionic nitrate.

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Section: The Micro Behavior Of No (Ad) On Baal 2 O 4 In Osupporting

confidence: 90%

Section: The Micro Behavior Of No (Ad) On Baal 2 Omentioning

confidence: 99%

Properties of BaAl₂O₄ in the Simultaneous Removal of Soot and NO_x

Lin

Shangguan

et al. 2007

Chem Eng & Technol

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“…33 We also observed weak oscillations in conversions. Oscillations can be explained in terms of formation of islands of adsorbed CO and atomic oxygen, where the reaction to CO 2 takes place at the periphery.…”

Section: Influence Of No and O 2 On The Coverage Of Cosupporting

confidence: 51%

Influence of NO on the Reduction of NO₂ with CO over Pt/SiO₂ in the Presence of O₂

Seshan

Lefferts

2007

Chin. J. Chem.

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Reduction of NO 2 with CO in the presence of NO and excess oxygen, a model mixture for flue gas, over a 0.1% Pt/SiO 2 catalyst was studied. The related reaction mechanisms, such as oxidation of CO and NO, were discussed. It was found that there was a narrow temperature window (180-190 ℃) for the reduction of NO 2 by CO. When the temperature was lower than the lower limit of the window, the reduction hardly occurred, while when the temperature was higher than the upper limit of the window, the direct oxidation of CO by O 2 occurred and thereby NO 2 could not be effectively reduced by CO. The presence of NO shifted the window to higher temperatures owing to the inhibition effect of NO on the activation of O 2 on Pt, which made it possible to reduce NO 2 by CO in flue gas.

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“…[13] The effect of the carbonate species on the adsorption of NO x and NH 3 on CuSSZ13 was also examined by in situ FTIR spectroscopy, as depicted in Figure 3 b, c. Again, the spectrum of H 2 O was subtracted from the collected IR spectra to identify the specific IR bands related to the adsorbed NO x and NH 3 species under both dry and wet conditions (Figure S5 b, c). Upon the adsorption of NO and O 2 in the presence of H 2 O at 200 8C, both bidentate and unidentate nitrate bands were observed at 1608 and 1573 cm À1 , [14] respectively. The formation of these nitrate species on the catalyst surface is known to be one of the key steps in the low-temperature NH 3 /SCR reaction.…”

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confidence: 99%

Effect of CO₂ on the DeNO_x Activity of a Small Pore Zeolite Copper Catalyst for NH₃/SCR

et al. 2014

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Exposure of CuSSZ13 to CO 2 at temperatures below 300 8C can deactivate its low-temperature deNOx activity during NH 3 /SCR, with the severity of deactivation being dependent on reaction temperature. The adsorption of NO on Cu 2 + ion is inhibited by CO 2 due to its competitive adsorption, while NH 3 adsorption on acidic sites of CuSSZ13 is largely unaffected by CO 2 , as evidenced by NO-and NH 3 -TPD in the presence of CO 2 . Under O 2 -rich conditions, CO 2 forms unidentate carbonates on Cu 2 + sites suppressing the formation of nitrates, a key reaction intermediate essential for NOx reduction during the NH 3 /SCR reaction, as revealed in an in situ FTIR study.Selective catalytic reduction (SCR) of NO x by urea (urea/SCR) is one of the most efficient and reliable technologies to remove NO x from diesel engine exhaust to meet ever-tightening emission regulations including EURO VI and SULEV without any direct fuel penalty.[1] ZSM5-based catalysts, including CuZSM5 and Mn-Fe/ZSM5, have been regarded as representative urea/ SCR catalysts, mainly owing to their high deNO x activity in the low-temperature region [2] suitable for diesel exhaust temperatures of the advanced engine, for example, the homogenous charge-compression ignition engine, for high fuel efficiency. [3] However, those catalysts still suffer from hydrothermal deactivation during the regeneration of the diesel particulate filter-(>750 8C), which hampers their commercial application to the diesel after-treatment system, [4] although the addition of Er has significantly improved the hydrothermal stability of the Mn-Fe/ ZSM5 catalyst. [2b] In recent years, small-pore zeolite catalysts such as CuSSZ13 and CuSAPO34 have been touted as commercial urea/SCR catalysts owing to their robust hydrothermal stability as well as their excellent low-temperature deNO x activity.[5] Moreover, the CuSSZ13 catalyst has shown high resistance toward hydrocarbon poisoning.[6] Although extensive studies have been conducted to understand the exceptional hydrothermal stability of the CuSSZ13 catalyst, there has been no systematic investigation on the effect of CO 2 on the catalytic activity of CuSSZ13 even though CO 2 is always abundantly present in the exhaust gas stream at approximately 10 %. Indeed, Hudson et al. recently reported that CO 2 molecules are readily adsorbed on the surface of SSZ13.[7] Thus, it is highly desirable and timely to study the effect of CO 2 on the deNO x performance of CuSSZ13 for the urea/SCR, a de facto NH 3 /SCR.We examined the CO 2 -induced deactivation of Cu-(3 wt %)SSZ13 by long-term durability tests in the presence of 10 % CO 2 . To understand the deactivation mechanism of CuSSZ13, the effect of CO 2 on the adsorption of NO x and NH 3 on CuSSZ13 was also investigated by NO x and NH 3 temperature-programmed desorption (TPD) and surface IR spectroscopy studies.The deNO x performance of CuSSZ13 prepared in the present study was examined in the NH 3 /SCR, as depicted in the inset of Figure 1. In the absence of CO 2 , CuSSZ13 revealed excell...

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Untitled

Cited by 83 publications

References 24 publications

Properties of BaAl₂O₄ in the Simultaneous Removal of Soot and NO_x

Properties of BaAl₂O₄ in the Simultaneous Removal of Soot and NO_x

Influence of NO on the Reduction of NO₂ with CO over Pt/SiO₂ in the Presence of O₂

Effect of CO₂ on the DeNO_x Activity of a Small Pore Zeolite Copper Catalyst for NH₃/SCR

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Untitled

Cited by 83 publications

References 24 publications

Properties of BaAl2O4 in the Simultaneous Removal of Soot and NOx

Properties of BaAl2O4 in the Simultaneous Removal of Soot and NOx

Influence of NO on the Reduction of NO2 with CO over Pt/SiO2 in the Presence of O2

Effect of CO2 on the DeNOx Activity of a Small Pore Zeolite Copper Catalyst for NH3/SCR

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Properties of BaAl₂O₄ in the Simultaneous Removal of Soot and NO_x

Properties of BaAl₂O₄ in the Simultaneous Removal of Soot and NO_x

Influence of NO on the Reduction of NO₂ with CO over Pt/SiO₂ in the Presence of O₂

Effect of CO₂ on the DeNO_x Activity of a Small Pore Zeolite Copper Catalyst for NH₃/SCR