Model for NOx storage/reduction in the presence of CO2 on a Pt–Ba/γ-Al2O3 catalyst

Scholz, Cordula; Gangwal, V.R.; Croon, M.H.J.M. de; Schouten, J.C.

doi:10.1016/j.jcat.2006.10.011

Cited by 41 publications

(7 citation statements)

References 26 publications

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“…On one hand, too much K species may cover partial Pt sites, weakening the ability of the catalysts for NO adsorption and oxidation; on the other hand, too much K species can lead to the formation of more bulk or bulk-like carbonates (Figure ), which were harder to be transformed to nitrate species than the dispersed or surface carbonate species during NOx storage. By comparison, it can still be found that the samples with 20% or 25% K 2 CO 3 possess similar spectra intensity, while the sample Pt-30%K 2 CO 3 /K 2 Ti 8 O 17 exhibits much lower spectra intensity, which is also related to the formation of more bulk or bulk-like carbonates because the NOx storage in bulk phases is a slow surface-to-bulk diffusion process, requiring much more time. ,,,− In addition, it is noted that in Figure (e), (f), (g) the 1340 cm –1 band gradually becomes weaker until total disappearance in Figure (g), and at the same time a new weak band around 1290–1296 cm –1 appears which is attributed to chelating bidentate nitrates (−NO 2 asymmetric stretch) . Adsorption for longer time facilitates the transformation of surface-adsorbed species to bulk species, resulting in the decrease of a detectable IR signal.…”

Section: Resultsmentioning

confidence: 92%

States and Function of Potassium Carbonate Species in the Polytitanate Nanobelt Supported Catalysts Used for Efficient NOx Storage and Reduction

et al. 2013

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A series of polytitanate nanobelt supported lean-burn NOx trap catalysts Pt-xK 2 CO 3 /K 2 Ti 8 O 17 with different weight loading of K 2 CO 3 (x = 0%, 5%, 15%, 20%, 25%, or 30%) were synthesized by successive impregnation. The nanobelt support K 2 Ti 8 O 17 displays a specific surface area as high as 302 m 2 /g, and the corresponding catalysts Pt-xK 2 CO 3 /K 2 Ti 8 O 17 show excellent NOx storage performance. As K 2 CO 3 loading increases from 5% to 30%, the NOx storage capacity (NSC) exhibits a volcano-type altering tendency with the maximum appearing at 25% (2.68 mmol/g); the highest NOx reduction efficiency of 99.2% was also achieved over this catalyst in cyclic alternative lean/ rich atmospheres. Further increase of K 2 CO 3 loading induces the formation of more bulk or bulk-like K 2 CO 3 species, decreasing the performance of the catalysts for NOx storage and reduction. HR-TEM and FT-IR results indicate that the K species exist as highly dispersed phases including K 2 O, K 2 CO 3 , and −OK groups, which are undetectable by X-ray diffraction (XRD) even at the K 2 CO 3 loading of 30%. Several carbonate species with different thermal stability and reactivity are identified by FT-IR and CO 2 -TPD. In situ diffuse reflectance FT-IR (DRIFTS) reveals that at low K 2 CO 3 loading (<20%) NOx is mainly stored as monodentate nitrates and monodentate nitrites, while at higher K 2 CO 3 loading NOx is mainly stored as bidentate nitrite species, which results from the decrease of oxidation ability of the catalysts due to the potential covering of K 2 CO 3 on Pt sites.

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Section: Resultsmentioning

confidence: 92%

States and Function of Potassium Carbonate Species in the Polytitanate Nanobelt Supported Catalysts Used for Efficient NOx Storage and Reduction

et al. 2013

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“…In the literature, a significant amount of NSR catalyst models for normal lean/rich operation have been presented. 11–17 However, very few studies have focused on the development of models that take into account the sulfation and desulfation processes. For example, Dawody et al 18 have developed a model able to describe the decrease in NO x storage capacity against sulfur loading of various NSR samples, which did not contain oxygen storage components.…”

Section: Introductionmentioning

confidence: 99%

Sulfation and lean/rich desulfation of a NO_x storage reduction catalyst: Experimental and simulation study

Lafossas

Manetas

Mohammadi

et al. 2014

International Journal of Engine Research

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A detailed study of the sulfation and desulfation phenomena of a NOx storage reduction catalyst using synthetic gas bench is presented. The experimental observations and results were put together, in order to develop a model, which can simulate the NOx storage reduction catalyst behavior during the sulfation and desulfation conditions. The target is to use the model for simulation of the lean/rich desulfation strategies, in order to comprehend the complicated phenomena and ultimately predict the sulfur speciation at the outlet of the NOx storage reduction catalyst. Sulfation tests in the presence and in the absence of O2 at different temperatures were conducted, in order to identify the different sulfation sites. Desulfation tests with constantly rich conditions and lean/rich oscillation, using H2 as the reducing gas, were performed in order to investigate the reaction pathways of the decomposition of the sulfates. Additionally, some preliminary investigation was performed using CO and decane in the reducing gas mixture, in order to evaluate the NOx storage reduction behavior under more realistic gas composition for diesel exhaust gas. The important role of the accurate prediction of sulfur axial distribution at the desulfation onset was identified. It was found that cerium oxides play a critical role in the sulfation process by increasing the sulfur capacity of the NOx storage reduction catalyst. Finally, it was clarified that the oxygen stored on cerium oxides strongly affects the selectivity of the desulfation products by oxidizing H2S and controlling H2 availability.

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“…Although numerous investigations on the soot combustion catalysts have been conducted and theoretical models for NOx storage have been developed [4][5][6][7][8][9], some problems still remain. Among them, the too high temperature of soot combustion and the relatively low NOx storage capacity (NSC) are the main aspects.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous soot combustion and nitrogen oxides storage on potassium-promoted hydrotalcite-based CoMgAlO catalysts

Meng

Zou

et al. 2009

Journal of Hazardous Materials

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Model for NOx storage/reduction in the presence of CO2 on a Pt–Ba/γ-Al2O3 catalyst

Cited by 41 publications

References 26 publications

States and Function of Potassium Carbonate Species in the Polytitanate Nanobelt Supported Catalysts Used for Efficient NOx Storage and Reduction

States and Function of Potassium Carbonate Species in the Polytitanate Nanobelt Supported Catalysts Used for Efficient NOx Storage and Reduction

Sulfation and lean/rich desulfation of a NO_x storage reduction catalyst: Experimental and simulation study

Simultaneous soot combustion and nitrogen oxides storage on potassium-promoted hydrotalcite-based CoMgAlO catalysts

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Model for NOx storage/reduction in the presence of CO2 on a Pt–Ba/γ-Al2O3 catalyst

Cited by 41 publications

References 26 publications

States and Function of Potassium Carbonate Species in the Polytitanate Nanobelt Supported Catalysts Used for Efficient NOx Storage and Reduction

States and Function of Potassium Carbonate Species in the Polytitanate Nanobelt Supported Catalysts Used for Efficient NOx Storage and Reduction

Sulfation and lean/rich desulfation of a NOx storage reduction catalyst: Experimental and simulation study

Simultaneous soot combustion and nitrogen oxides storage on potassium-promoted hydrotalcite-based CoMgAlO catalysts

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Sulfation and lean/rich desulfation of a NO_x storage reduction catalyst: Experimental and simulation study