An alumina-supported silver catalyst with high water tolerance for H2 assisted C3H6-SCR of NOx

Xu, Guangyan; Ma, Jinzhu; He, Guo‐Zhong; Yu, Yunbo; He, Hong

doi:10.1016/j.apcatb.2017.02.001

Cited by 49 publications

(79 citation statements)

References 66 publications

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“…HC-SCR activity of Ag/Al 2 O 3 with atomically dispersed Ag. Ag/Al 2 O 3 catalysts have been extensively explored for the SCR of NO reaction, where both isolated Ag + species and Ag n δ+ clusters are generally considered as the active centers 1,[29][30][31] . We tested the 1% Ag/nano-Al 2 O 3 and 1% Ag/micro-Al 2 O 3 catalysts for C 3 H 6 -H 2 -SCR and ethanol-SCR of NO to investigate the effect of Ag dispersion on catalytic activity.…”

Section: Resultsmentioning

confidence: 99%

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

et al. 2020

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is widely used for catalyzing various reactions, and its performance depends on the valence state, morphology and dispersion of Ag species. However, detailed anchoring mechanism of Ag species on γ-Al 2 O 3 remains largely unknown. Herein, we reveal that the terminal hydroxyls on γ-Al 2 O 3 are responsible for anchoring Ag species. The abundant terminal hydroxyls existed on nanosized γ-Al 2 O 3 can lead to single-atom silver dispersion, thereby resulting in markedly enhanced performance than the Ag cluster on microsized γ-Al 2 O 3 . Density-functional-theory calculations confirm that Ag atom is mainly anchored by the terminal hydroxyls on (100) surface, forming a staple-like local structure with each Ag atom bonded with two or three terminal hydroxyls. Our finding resolves the puzzle on why the single-atom silver dispersion can be spontaneously achieved only on nanosized γ-Al 2 O 3 , but not on microsized γ-Al 2 O 3 . The obtained insight into the Ag species dispersion will benefit future design of more efficient supported Ag catalysts.

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Section: Resultsmentioning

confidence: 99%

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

et al. 2020

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“…Thomas et al [203] found that in the presence of H 2 , the stability of nitrate was greatly reduced, and H 2 greatly reduced the temperature of formation and decomposition of NO x . Xu et al [204] found that Ag/Al 2 O 3 catalyst had excellent water resistance in the whole temperature range. After introducing water vapor, especially at low temperature, the conversion of NO x was enhanced.…”

Section: Hc-scrmentioning

confidence: 99%

A Critical Review of Recent Progress and Perspective in Practical Denitration Application

Liu

et al. 2019

Catalysts

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Nitrogen oxides (NO x ) represent one of the main sources of haze and pollution of the atmosphere as well as the causes of photochemical smog and acid rain. Furthermore, it poses a serious threat to human health. With the increasing emission of NO x , it is urgent to control NO x . According to the different mechanisms of NO x removal methods, this paper elaborated on the adsorption method represented by activated carbon adsorption, analyzed the oxidation method represented by Fenton oxidation, discussed the reduction method represented by selective catalytic reduction, and summarized the plasma method represented by plasma-modified catalyst to remove NO x . At the same time, the current research status and existing problems of different NO x removal technologies were revealed and the future development prospects were forecasted.Catalysts 2019, 9, 771 2 of 39 adsorption, oxidation, reduction, and plasma methods. In view of these attentive findings, adsorption method uses recyclable solid adsorbent material to adsorb NO x from flue gas through microporous structure, remarkably, environmentally friendly, no secondary pollution, and energy-saving and -efficient features make it stand out [18][19][20]. The oxidation process is a method that oxidizes NO into NO 2 or N 2 O 3 with high solubility under the action of an oxidant that is then absorbed by water or alkali solution. The process is simple and cost-saving, and is widely used in the wet flue gas denitrification process with relatively low cost and high removal efficiency of NO x ; except that the oxidized NO and SO 2 can be removed simultaneously to produce high value-added products [21][22][23]. The reduction method has the characteristics of high efficiency, cleanliness, and mildness; NO x removal can be realized at low temperature at present [24][25][26]. The plasma method is used to modify the surface of the catalyst, the dispersion of active species can be improved by plasma treatment, and the stability and low temperature activity of catalyst can be improved [27,28].Seldom, if ever, does a comprehensive article to introduce the current situation and treatment methods of removing NO x . In this paper, we tried to renovate, classify, and summarize the significant perspectives and most relevant findings reported in recent research articles and earlier reviews generalizing the mechanism analysis and research progress of NO x removal by adsorption, oxidation, reduction, and plasma methods, which can provide means for promoting the technological progress of pollution prevention, maintaining healthy development of factories continuously, studying the methods of removing NO x deeply, and mastering different technologies of removing NO x , as well as providing guidance for controlling the emission of NO x from motor vehicles such as diesel, gasoline, and so on. In order to improve the environmental quality and save the ecological environment, this paper further provides a convenient, low-cost, efficient, and economic guidance line.

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“…The apparent activation energy (E a ) of NO x was measured in the fixed-bed reactor as described above. On the basis of our previous work, 31 catalysts with a particle size of 0.45−0.9 mm were used for kinetic measurements. The weight of catalysts was adjusted with the GHSV varying from 150 000 to 600 000 h −1 in order to keep NO x conversion below 20%.…”

Section: Activation Energy Measurementmentioning

confidence: 99%

Silver Valence State Determines the Water Tolerance of Ag/Al₂O₃ for the H₂–C₃H₆–SCR of NO_x

2017

J. Phys. Chem. C

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The influence of the silver valence state on Ag/Al2O3 on the water tolerance of H2–C3H6–SCR of NO x was investigated. The valence state of silver species on Ag/Al2O3, which was carefully characterized by XPS, UV–vis, and XANES measurements, was adjusted by varying the calcination temperature from 500 to 900 °C. Oxidized silver species were predominant on Ag/Al2O3 calcined at temperatures below 600 °C (LT-catalysts), while further increasing the calcination (temperatures above 600 °C, HT-catalysts) promoted the transformation of oxidized silver species into metallic silver clusters. The samples with higher amounts of oxidized silver species exhibited better water tolerance in the H2–C3H6–SCR. Activation energy measurements confirmed that the mechanism of NO x reduction on these catalysts was the same. In situ DRIFTS studies demonstrated that metallic silver species promoted the formation of active enolic species and the complete oxidation of formate, thus improving the low-temperature activity of HT-catalysts in the absence of water vapor. Water addition eliminated the formate, releasing the active Ag+ sites for enolic species formation, and thus promoted the low-temperature activity of LT-catalysts. From a comprehensive point of view, 60% oxidized silver species on Ag/Al2O3 catalysts is the optimal percentage for deNO x performance and water tolerance.

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An alumina-supported silver catalyst with high water tolerance for H2 assisted C3H6-SCR of NOx

Cited by 49 publications

References 66 publications

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

A Critical Review of Recent Progress and Perspective in Practical Denitration Application

Silver Valence State Determines the Water Tolerance of Ag/Al₂O₃ for the H₂–C₃H₆–SCR of NO_x

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An alumina-supported silver catalyst with high water tolerance for H2 assisted C3H6-SCR of NOx

Cited by 49 publications

References 66 publications

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

A Critical Review of Recent Progress and Perspective in Practical Denitration Application

Silver Valence State Determines the Water Tolerance of Ag/Al2O3 for the H2–C3H6–SCR of NOx

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Silver Valence State Determines the Water Tolerance of Ag/Al₂O₃ for the H₂–C₃H₆–SCR of NO_x