Synergistic effect of Cu on a Ag-loaded CeO2 catalyst for soot oxidation with improved generation of active oxygen species and reducibility

Lee, Jae‐Hwan; Lee, Byung Jin; Lee, Dae Won; Choung, Jin Woo; Kim, Chang Hwan; Lee, Kwan Young

doi:10.1016/j.fuel.2020.117930

Cited by 28 publications

(11 citation statements)

References 58 publications

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“…The peak near 88 °C corresponds to the reduction of AgO. 51 Compared with the CeSnO x , the redox properties of the catalyst were significantly improved by the loading of Ag.…”

Section: Resultsmentioning

confidence: 99%

Elimination of NH₃ by Interfacial Charge Transfer over the Ag/CeSnO_x Tandem Catalyst

Zhang

Zang

et al. 2023

ACS Catal.

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Selective catalytic oxidation of NH3 is the most promising method for removing low-concentration NH3. However, achieving high activity and N2 selectivity remains a great challenge. A Ag/CeSnO x tandem catalyst with dual active centers was designed and synthesized, which couples the NH3 over-oxidation on the noble metal active sites with NO x reduction on the support. The tandem catalyst exhibited excellent NH3 selective catalytic oxidation (NH3–SCO) performance at 200–400 °C. Based on various characterization techniques and DFT calculations, it was identified that the silver species on the Ag/CeSnO x catalysts existed as AgO nanoparticles (AgO NPs), and the electrons on the support were more easily transferred to AgO NPs, which promoted the oxidation activity of AgO and the reduction performance of the CeSnO x support. The coupling between the AgO NPs and CeSnO x helped balance the NH3 oxidation rate and the NO x reduction rate. In addition, the uniform adsorption of gaseous NH3 on the oxidation and reduction sites was also demonstrated by theoretical calculations, which is a prerequisite for tandem catalysis. By in situ DRIFTS, we revealed that the NH3–SCO reaction over Ag/CeSnO x catalysts mainly follows the internal selective catalytic reduction mechanism. It was characterized by excessive oxidation of NH3 to NO x on AgO NPs. At a temperature lower than 200 °C, NO x was reduced to N2 by the adsorbed NH3 on the AgO. When the temperature was higher than 200 °C, NO x was reduced to N2 by NH3 or NH4 + adsorbed on the CeSnO x support. Therefore, the charge transfer at the Ag/CeSnO x catalyst interface and the coordination of atomic scale catalytic sites have realized the conversion of NH3 to N2 through NO x in a tandem catalytic mode.

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“…The peak near 88 °C corresponds to the reduction of AgO. 51 Compared with the CeSnO x , the redox properties of the catalyst were significantly improved by the loading of Ag.…”

Section: Resultsmentioning

confidence: 99%

Elimination of NH₃ by Interfacial Charge Transfer over the Ag/CeSnO_x Tandem Catalyst

Zhang

Zang

et al. 2023

ACS Catal.

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“…It could be observed that all four catalyst samples exhibited a similar H 2 consumption amount due to the fixed loading amount of metal dopants. It could be deduced that the reducibility of Mn-Co/γ-Al 2 O 3 and Mn-Cu/γ-Al 2 O 3 was much better than that of Mn-Ce/γ-Al (ad/latt) via electron gaining [34]. The O 2 desorption amount is presented in Table 1, while the peaks above 750 • C, which could be assigned to lattice oxygen, were not observed in this work.…”

Section: Textural Properties Of Mn-x/γ-al 2 O 3 Catalystsmentioning

confidence: 50%

“…The desorption peaks between 100 °C and 350 °C were attributed to the adsorbed surface oxygen species (α-O2) on oxygen vacancies, while the peaks between 350 °C and 700 °C belonged to chemically adsorbed oxygen species (β-O2) [33]. The surface oxygen species would go through the transformation process of O2(ad) → O2 − (ad) → O − (ad) → O2 − (ad/latt) via electron gaining [34]. The O2 desorption amount is presented in Table 1, while the peaks above 750 °C, which could be assigned to lattice oxygen, were not observed in this work.…”

Section: Textural Properties Of Mn-x/γ-al 2 O 3 Catalystsmentioning

confidence: 99%

Soot Oxidation over γ-Al2O3-Supported Manganese-Based Binary Catalyst in a Dielectric Barrier Discharge Reactor

Zhu

Liu

et al. 2022

Catalysts

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In this work, soot oxidation was conducted over a series of Mn-X/γ-Al2O3 (M = Ce, Co and Cu) binary catalysts in a dielectric barrier discharge reactor. The soot conversion in the plasma–catalytic system was in the order of Mn/γ-Al2O3 (57.7%) > Mn-Co/γ-Al2O3 (53.9%) > Mn-Ce/γ-Al2O3 (51.6%) > Mn-Cu/γ-Al2O3 (47.7%) during the 30 min soot oxidation process at 14 W and 150 °C. Meanwhile, the doping of Ce, Co and Cu slightly improved the CO2 selectivity of the process by 4.7% to 10.3% compared to soot oxidation over Mn/γ-Al2O3.It is worth to note that the order of CO2 selectivity was in the opposite order with soot oxidation rate. The effects of discharge power, oxygen content in the carrier gas and reaction temperature on plasma–catalytic soot oxidation was systematically analyzed. The catalyst characterizations, including N2 adsorption–desorption, X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction by H2 and temperature-programmed desorption of O2, were conducted to illustrate the reaction mechanisms of plasma–catalytic soot oxidation and reaction pathways.

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“…The relative content of adsorbed oxygen species of the used CuCo 2 O 4 -N catalysts (40.6%) was significantly decreased compared to the fresh CuCo 2 O 4 -N catalysts (46.8%), and the activity of soot conversion was also decreased. The adsorbed oxygen species played a crucial role in catalytic soot combustion, which could be transformed to active oxygen species such as O 2 ,

and O − (Reactions (10)–(12)) [ 52 ]. Moreover, some lattice oxygen species took over the oxygen vacancies and were transferred into adsorbed oxygen species.…”

Section: Reaction Mechanisms For Catalytic Soot Combustionmentioning

confidence: 99%

Soot Combustion over Cu–Co Spinel Catalysts: The Intrinsic Effects of Precursors on Catalytic Activity

Zhou

Zhu

Zhang

et al. 2022

IJERPH

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In this work, a series of CuCo2O4-x (x = N, A and C) catalysts were synthesized using different metal salt precursors by urea hydrothermal method for catalytic soot combustion. The effect of CuCo2O4-x catalysts on soot conversion and CO2 selectivity in both loose and tight contact mode was investigated. The CuCo2O4-N catalyst exhibited outstanding catalytic activity with the characteristic temperatures (T10, T50 and T90) of 451 °C, 520 °C and 558 °C, respectively, while the CO2 selectivity reached 98.8% during the reaction. With the addition of NO, the soot combustion was further accelerated over all catalysts. Compared with the loose contact mode, the soot conversion was improved in the tight contact mode. The CuCo2O4-N catalysts showed better textural properties compared to the CuCo2O4-A and CuCo2O4-C, such as higher specific surface areas and pore volumes. The XRD results confirmed that the formation of a CuCo2O4 crystal phase in all catalysts. However, the CuO crystal phase only presented in CuCo2O4-N and CuCo2O4-A. The relative contents of Cu2+, Co3+ and Oads on the surface of CuCo2O4-x (x = N, A and C) catalysts were analyzed by XPS. The CuCo2O4-N catalyst displayed the highest relative content of Cu2+, Co3+ and Oads. The activity of catalytic soot combustion showed a good correlation with the order of the relative contents of Cu2+, Co3+ and Oads. Additionally, the CuCo2O4-N catalyst exhibited lower reduction temperature compared to the CuCo2O4-A and CuCo2O4-C. The cycle tests clarified that the copper–cobalt spinel catalyst obtained good stability. In addition, based on the Mars–van Krevelen mechanism, the process of catalytic soot combustion was described combined with the electron transfer process and the role of oxygen species over CuCo2O4 spinel catalysts.

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Synergistic effect of Cu on a Ag-loaded CeO2 catalyst for soot oxidation with improved generation of active oxygen species and reducibility

Cited by 28 publications

References 58 publications

Elimination of NH₃ by Interfacial Charge Transfer over the Ag/CeSnO_x Tandem Catalyst

Elimination of NH₃ by Interfacial Charge Transfer over the Ag/CeSnO_x Tandem Catalyst

Soot Oxidation over γ-Al2O3-Supported Manganese-Based Binary Catalyst in a Dielectric Barrier Discharge Reactor

Soot Combustion over Cu–Co Spinel Catalysts: The Intrinsic Effects of Precursors on Catalytic Activity

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Synergistic effect of Cu on a Ag-loaded CeO2 catalyst for soot oxidation with improved generation of active oxygen species and reducibility

Cited by 28 publications

References 58 publications

Elimination of NH3 by Interfacial Charge Transfer over the Ag/CeSnOx Tandem Catalyst

Elimination of NH3 by Interfacial Charge Transfer over the Ag/CeSnOx Tandem Catalyst

Soot Oxidation over γ-Al2O3-Supported Manganese-Based Binary Catalyst in a Dielectric Barrier Discharge Reactor

Soot Combustion over Cu–Co Spinel Catalysts: The Intrinsic Effects of Precursors on Catalytic Activity

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Elimination of NH₃ by Interfacial Charge Transfer over the Ag/CeSnO_x Tandem Catalyst

Elimination of NH₃ by Interfacial Charge Transfer over the Ag/CeSnO_x Tandem Catalyst