Pillared clays as superior catalysts for selective catalytic reduction of nitric oxide with ammonia

Yang, Ralph T.; Chen, J. P.; Kikkinides, Eustathios S.; Cheng, Linda S.; Cichanowicz, J. E.

doi:10.1021/ie00006a003

Cited by 104 publications

(39 citation statements)

References 23 publications

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“…By comparing the catalytic behaviours of the two PILCs, it is possible to observe that FAZA exhibits higher values of NO conversion than AZA at all the temperatures investigated, in agreement with the presence of a higher Fe content, mainly present in the pillars (Yang et al, 1992). However, it is worth noting that the values of NO conversion obtained with AZA are significantly higher than those observed using alumina or those previously reported in the literature for a similar AI-PILC (Yang et al, 1992).…”

Section: Activity Of Aza and Faza As Catalystssupporting

confidence: 73%

“…However, it is worth noting that the values of NO conversion obtained with AZA are significantly higher than those observed using alumina or those previously reported in the literature for a similar AI-PILC (Yang et al, 1992). Therefore, it may be hypothesized that the transition metal oxides present as impurities in the original clay (Table 1), i.e.…”

Section: Activity Of Aza and Faza As Catalystsmentioning

confidence: 59%

“…In a recent paper (Yang et al, 1992), it has been claimed that PILCs may be promising catalysts for the selective catalytic reduction (SCR) of NO by NH3, due to their high activity and potential poison resistance.…”

mentioning

confidence: 99%

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Catalysts based on pillared interlayered clays for the selective catalytic reduction of NO

Perathoner

Vaccari

1997

Clay miner.

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A B S T RA C T: The reactivity of an Al-pillared interlayered clay (PILC) (AZA) and a mixed Fe/A1-PILC (FAZA), used as references by the Concerted European Action-Pillared Layered Structure (CEA-PLS), was investigated in the selective catalytic reduction (SCR) of NO by NH 3 or propane, as either catalysts or as supports of Cu ions. Both AZA and FAZA, either with or without Cu were found to be inactive in the reduction of NO with propane and oxygen. This is different from the behaviour with alumina with or without Cu, because of the different surface acidity properties. Good NO conversions were observed for both PILCs using NH3. The best catalytic performances were shown by FAZA, but the activity of AZA was also remarkable. The addition of Cu ions to both AZA and FAZA leads to an improvment in the activity in NO conversion and a reduction in the side formation of N20. The catalytic behaviour was found to depend on the method of Cu addition, the Cu loading and the nature of the PILC. With AZA the best results were obtained for a Cu content up to 2 wt%, while further increases in the amount of Cu resulted in a considerable decrease in the conversion of NO. With FAZA, on the other hand, a high activity was observed at up to 3% of Cu introduced by ion exchange. By comparison with other Cu containing catalysts, Cu-FAZA allows operation in a wider range of reaction temperatures due to the reduced rate of side ammonia combustion. The surface acidity properties of AZA and FAZA were also characterized to interpret the above effects.Pillared interlayered clays (PILCs) are a class of two-dimensional porous and high surface area solids of scientific and industrial interest, based on their possible applications as catalysts or

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Section: Activity Of Aza and Faza As Catalystssupporting

confidence: 73%

Section: Activity Of Aza and Faza As Catalystsmentioning

confidence: 59%

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Catalysts based on pillared interlayered clays for the selective catalytic reduction of NO

Perathoner

Vaccari

1997

Clay miner.

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“…Since pillared clays have a number of attractive features such as porosity, high thermal stability and exchangeable cations, they have been widely studied as catalysts and adsorbents [59]. More specifically, the PILC based catalysts have been found to be excellent and H 2 O/SO 2 resistant catalysts for the SCR reactions by NH 3 and by hydrocarbons [60]. The PILCs alone showed NH 3 SCR activities [61], with Fe 2 O 3 -PILC exhibiting the highest activities [62].…”

Section: Introductionmentioning

confidence: 99%

“…More specifically, the PILC based catalysts have been found to be excellent and H 2 O/SO 2 resistant catalysts for the SCR reactions by NH 3 and by hydrocarbons [60]. The PILCs alone showed NH 3 SCR activities [61], with Fe 2 O 3 -PILC exhibiting the highest activities [62]. Using TiO 2 -PILC as a support, a 3/1 (molar ratio) of Fe 2 O 3 /Cr 2 O 3 (total 10% wt.)…”

Section: Introductionmentioning

confidence: 99%

Pillared Clays as Superior Catalysts for Selective Catalytic Reduction of Nitric Oxide

Long¹,

Tharappiwattananon²,

Li³

et al. 2000

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Conclusion 973 DisclaimerThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views or opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. EXECUTIVE SUMMARYRemoval of NO x (NO + NO 2 ) from exhaust gases is a challenging subject. V 2 O 5 -based catalysts are commercial catalysts for selective catalytic reduction (SCR) with NH 3 for stationary sources. However, for diesel and lean-burn gasoline engines in vehicles, hydrocarbons would be the preferred reducing agents over NH 3 because of the practical problems associated with the use of NH 3 (i.e., handling and slippage through the reactor). The noble-metal three-way catalysts are not effective under these conditions. The first catalyst found to be active for selective catalytic reduction of NO by hydrocarbons in the presence of excess oxygen was copper exchanged ZSM-5 and other zeolites, reported in 1990 by Iwamoto in Japan and Held et al. in Germany. Although Cu-ZSM-5 is very active and the most intensively studied catalyst, it suffers from severe deactivation in engine tests, mainly due to H 2 O and SO 2 .In this project, we found that ion-exchanged pillared clays and MCM-41 catalysts showed superior SCR activities of NO with hydrocarbon. All Cu 2+ -exchanged pillared clays showed higher SCR activities than Cu-ZSM-5 reported in the literature. In particular, H 2 O and SO 2 only slightly deactivated the SCR activity of Cu-TiO 2 -PILC, whereas severe deactivation was observed for Cu-ZSM-5. Moreover, Pt/MCM-41 provided the highest specific NO reduction rates as compared with other Pt doped catalysts, i.e., Pt/Al 2 O 3 , Pt/SiO 2 and Pt/ZSM-5. ThePt/MCM-41 catalyst also showed a good stability in the presence of H 2 O and SO 2 . The results are described in detail in 4 chapters. 5In Chapter 1, we report SCR of NO by C 2 H 4 on ion-exchanged pillared clays, i.e., CuTiO 2 -PILC, Cu-Al 2 O 3 -PILC, Cu-ZrO 2 -PILC, Cu-Al 2 O 3 -Laponite, Fe-TiO 2 -PILC, Ce-TiO 2 -PILC, Co-TiO 2 -PILC, Ag-TiO 2 -PILC, Ga-TiO 2 -PILC. Cu-TiO 2 -PILC showed the highest activities at temperatures below 370 o C, while Cu-Al 2 O 3 -PILC was most active at above 370 o C, and both catalysts showed higher SCR activities than Cu-ZSM-5 reported in the literature.No detectable N 2 O was formed by all of these catalysts. The catalytic activity increased wi...

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Ceria‐modified Al‐Mn‐pillared clay catalysts for the selective catalytic reduction of NO with NH₃ at low temperatures

Cheng

et al. 2020

Asia-Pacific J Chem Eng

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The yCe/Al-Mn-pillared interlayered clay (PILC, y [Ce content] = 8-9 wt%) catalysts were prepared using the impregnation method. Catalytic activities of the materials for the selective catalytic reduction (SCR) of NO with NH 3 at low temperatures were evaluated, and physicochemical properties of the samples were characterized by X-ray diffraction, N 2 adsorption-desorption, temperature-programmed reduction, ammonia temperature-programmed desorption, X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy techniques. It is found that introduction of cerium enhanced NO conversions at low temperatures, and the 8Ce/Al-Mn-pillared sample showed the highest NO conversion (92% at 300 C). The superior catalytic activity of 8Ce/Al-Mn-PILC was associated with the change in active component and increases in amounts of the surface chemisorbed oxygen species and the acid sites after ceria loading. Additionally, the SCR reaction mechanism over 8Ce/Al-Mn-PILC followed both Langmuir-Hinshelwood and Eley-Rideal mechanisms, with the former being dominant. K E Y W O R D SAl-Mn copillared clay, ceria loading, selective catalytic reduction, in situ DRIFTS | Al-Mn-PILC-supported ceria catalystsThe yCe/Al-Mn-PILC (y = 8 and 9 wt%) samples were prepared by impregnating the Al-Mn-PILC support with Ce (NO 3 ) 3 Á6H 2 O. Then, the sample was dried at 120 C for 6 hr and calcined at 400 C for 2 hr in an air atmosphere. | Al-PILC-supported Mn and claysupported Ce-Mn catalystsThe Mn/Al-PILC (Mn [i.e., Mn/{Mn + Al-PILC}] was 10 wt%, which was the same content of Mn in Al-Mn-2 of 14 CHENG ET AL.

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Pillared clays as superior catalysts for selective catalytic reduction of nitric oxide with ammonia

Cited by 104 publications

References 23 publications

Catalysts based on pillared interlayered clays for the selective catalytic reduction of NO

Catalysts based on pillared interlayered clays for the selective catalytic reduction of NO

Pillared Clays as Superior Catalysts for Selective Catalytic Reduction of Nitric Oxide

Ceria‐modified Al‐Mn‐pillared clay catalysts for the selective catalytic reduction of NO with NH₃ at low temperatures

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Pillared clays as superior catalysts for selective catalytic reduction of nitric oxide with ammonia

Cited by 104 publications

References 23 publications

Catalysts based on pillared interlayered clays for the selective catalytic reduction of NO

Catalysts based on pillared interlayered clays for the selective catalytic reduction of NO

Pillared Clays as Superior Catalysts for Selective Catalytic Reduction of Nitric Oxide

Ceria‐modified Al‐Mn‐pillared clay catalysts for the selective catalytic reduction of NO with NH3 at low temperatures

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Ceria‐modified Al‐Mn‐pillared clay catalysts for the selective catalytic reduction of NO with NH₃ at low temperatures