In-situ studies of oxidation/reduction of copper in Cu-CHA SCR catalysts: Comparison of fresh and SO2-poisoned catalysts

Bergman, Susanna L.; Dahlin, Sandra; Mesilov, V. V.; Xiao, Yang; Englund, Johanna; Xi, Shibo; Tang, Chunhua; Skoglundh, Magnus; Pettersson, Lars J.; Bernasek, Steven L.

doi:10.1016/j.apcatb.2020.118722

Cited by 46 publications

(31 citation statements)

References 99 publications

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“…Most of the SO x poisoning and regeneration studies solely focus on the impact of SO 2 as SO x species and thermal regeneration [3,5,[7][8][9][10][11][12], sometimes carried out under reducing atmosphere. However, the SO 2 present in the exhaust of a modern vehicle passes through an oxidation catalyst before reaching the SCR catalyst.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of SO2 and SO2/SO3 Poisoning and Regeneration of Cu/BEA and Cu/SSZ-13 for NH3 SCR

Auvray

Arvanitidou

Högström

et al. 2021

Emiss. Control Sci. Technol.

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Two copper-exchanged zeolites, Cu/SSZ-13 and Cu/BEA, were studied as catalysts for the selective reduction of NOx by NH3 (NH3-SCR). Their activities for standard SCR (NOx = NO) and fast SCR (NOx = 50% NO + 50% NO2) were measured before and after sulfur poisoning at 250 °C. The effect of 30 ppm SO2 and a mixture of 24 ppm SO3 + 6 ppm SO2 was evaluated. The repetition of subsequent activity measurements served as regeneration method in SCR conditions. SO2 deactivated Cu/SSZ-13 whereas Cu/BEA was only moderately affected. SO3 led to stronger deactivation of both catalysts than SO2. However, also for this case, the Cu/BEA was significantly less affected than Cu/SSZ-13, even though Cu/BEA contained larger amount of stored sulfur. One possible reason for this could be the large pores of Cu/BEA, where the sulfur species possibly resulted in less sterical hindrance than in the small pore SSZ-13 structure. NH3 temperature-programmed desorption (NH3-TPD) showed no loss of storage sites upon sulfur treatment and subsequent regeneration. Partial activity recovery was observed after a period in SCR conditions at 400 °C and 500 °C. Temperature at 300 °C was insufficient to regenerate the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of NO adsorption suggested that SO2 interacts with the ZCuOH sites on Cu/SSZ-13, causing the strong poisoning.

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Section: Introductionmentioning

confidence: 99%

Comparative Study of SO2 and SO2/SO3 Poisoning and Regeneration of Cu/BEA and Cu/SSZ-13 for NH3 SCR

Auvray

Arvanitidou

Högström

et al. 2021

Emiss. Control Sci. Technol.

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“…More specifically, a multivariate curve resolution-alternating least square (MCR-ALS) algorithm [15,16] was applied to the high-energy resolution-fluorescence-detected XANES (HERFD-XANES) data obtained during exposure of the Pt/CeO 2 catalysts to various model and reaction conditions. This approach, increasingly applied in heterogeneous catalysis [15,[17][18][19][20], enables us to derive minute spectral features, i.e. caused by the adsorption of different gas phase species, and is therefore ideal to identify noble metal state, abundance and evolution.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Structural Dynamics of Pt/CeO2 Single-Site Catalysts during CO Oxidation

et al. 2021

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Despite their high atomic dispersion, single site catalysts with Pt supported on CeO2 were found to have a low activity during oxidation reactions. In this study, we report the behavior of Pt/CeO2 single site catalyst under more complex gas mixtures, including CO, C3H6 and CO/C3H6 oxidation in the absence or presence of water. Our systematic operando high-energy resolution-fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) spectroscopic study combined with multivariate curve resolution with alternating least squares (MCR-ALS) analysis identified five distinct states in the Pt single site structure during CO oxidation light-off. After desorption of oxygen and autoreduction of Pt4+ to Pt2+ due to the increase of temperature, CO adsorbs and reduces Pt2+ to Ptδ+ and assists its migration with final formation of Ptx+ clusters. The derived structure–activity relationships indicate that partial reduction of Pt single sites is not sufficient to initiate the conversion of CO. The reaction proceeds only after the regrouping of several noble metal atoms in small clusters, as these entities are probably able to influence the mobility of the oxygen at the interface with ceria.

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“…Cu and Fe supported on various zeolites have been widely studied to raise, the different active sites and their potential for improving the efficiency in SCR-deNO x . In-situ spectroscopic studies of Cu and Fe for SCR-deNO x revealed in detail the different species active during the reaction ( Skarlis et al, 2014 ; Borfecchia et al, 2018 ; Negri et al, 2018 ; Fahami et al, 2019 ; Bergman et al, 2020 ; Zhang et al, 2020 ). Thus, Liu et al (2020) studied Cu-CHA catalysts for NO x reduction with in-situ spectroscopy and on-line mass-spectroscopy to analyze Cu(I)/Cu(II) redox cycles during the catalytic test.…”

Section: Catalytic Processes With Transition Metals On Zeolitesmentioning

confidence: 99%

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

et al. 2021

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This article reviews the current state and development of thermal catalytic processes using transition metals (TM) supported on zeolites (TM/Z), as well as the contribution of theoretical studies to understand the details of the catalytic processes. Structural features inherent to zeolites, and their corresponding properties such as ion exchange capacity, stable and very regular microporosity, the ability to create additional mesoporosity, as well as the potential chemical modification of their properties by isomorphic substitution of tetrahedral atoms in the crystal framework, make them unique catalyst carriers. New methods that modify zeolites, including sequential ion exchange, multiple isomorphic substitution, and the creation of hierarchically porous structures both during synthesis and in subsequent stages of post-synthetic processing, continue to be discovered. TM/Z catalysts can be applied to new processes such as CO2 capture/conversion, methane activation/conversion, selective catalytic NOx reduction (SCR-deNOx), catalytic depolymerization, biomass conversion and H2 production/storage.

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In-situ studies of oxidation/reduction of copper in Cu-CHA SCR catalysts: Comparison of fresh and SO2-poisoned catalysts

Cited by 46 publications

References 99 publications

Comparative Study of SO2 and SO2/SO3 Poisoning and Regeneration of Cu/BEA and Cu/SSZ-13 for NH3 SCR

Comparative Study of SO2 and SO2/SO3 Poisoning and Regeneration of Cu/BEA and Cu/SSZ-13 for NH3 SCR

Insights into the Structural Dynamics of Pt/CeO2 Single-Site Catalysts during CO Oxidation

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

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