Methane oxidation activity and nanoscale characterization of Pd/CeO2 catalysts prepared by dry milling Pd acetate and ceria

Danielis, Maila; Betancourt, Luís; Orozco, Ivan; Divins, Núria J.; Llorca, Jordi; Rodríguez, José A.; Senanayake, Sanjaya D.; Colussi, Sara; Trovarelli, Alessandro

doi:10.1016/j.apcatb.2020.119567

Cited by 71 publications

(75 citation statements)

References 75 publications

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“…Figure 1a shows a representative image of the sample prepared by milling CeO 2 and Pd acetate (50 Hz, 10 min, 1 wt.% Pd). As reported in a previous work [24], the mechanochemical synthesis of Pd/CeO 2 using Pd acetate creates an amorphous layer on the ceria crystallites. This shell exhibits an average thickness of about 2-3 nm.…”

Section: Characterizationsupporting

confidence: 54%

“…The Pd 3d spectra of the samples prepared by impregnation showed exactly the same pattern, independently of the Pd precursor used (Figure 3c,d). The Pd 3d 5/2 spectra contain two bands at about 336.4 and 338.0 eV, which correspond well to Pd 2+ and Pd 4+ species, respectively [21,24]. The surface atomic ratio Pd 4+ /(Pd 4+ +Pd 2+ ) in these samples prepared by impregnation is about 0.2.…”

Section: Characterizationmentioning

confidence: 71%

“…In recent years, it has been demonstrated that different architectures of the Pd-CeO 2 interface are obtained by using conventional impregnation or solution combustion synthesis or mechanochemical methods, which strongly determine the performance of the resulting Pd/CeO 2 catalysts in the total oxidation of methane [20][21][22][23]. In particular, advanced operando characterization has recently shown that catalysts prepared by mechanical milling are clearly superior because they contain very stable palladium species [24]. In this work, we study Pd/CeO 2 catalysts prepared by incipient wetness impregnation and by dry ball milling using Pd nitrate and Pd acetate for low-temperature POM.…”

Section: Introductionmentioning

confidence: 99%

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Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

2021

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The catalytic production of syngas by the partial oxidation of methane (POM) was investigated over Pd supported on ceria (0.5–2 Pd wt.%) prepared by incipient wetness impregnation and by mechanochemical methods. The performance of the Pd/CeO2 catalyst prepared by milling CeO2 and Pd acetate was superior to that prepared by milling CeO2 and Pd nitrate and to Pd/CeO2 prepared by impregnation from Pd acetate. The best catalytic activity of the Pd/CeO2 catalyst prepared from CeO2 and Pd acetate was obtained by milling at 50 Hz for 5 min. Two-step combustion and reforming reaction mechanism were identified. Remarkably, methane conversion increased progressively with Pd loading for the catalysts prepared by incipient wetness impregnation, whereas low metal loading showed better conversion of methane for the catalysts prepared by ball milling using Pd acetate. This was explained in terms of an impressive dispersion of Pd species with a strong interaction with the surface of ceria, as deduced from transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy characterization, which revealed a large quantity of highly oxidized species at the surface.

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Section: Characterizationsupporting

confidence: 54%

Section: Characterizationmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

2021

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“…180'000 h -1 . 38 Light-off profiles were recorded from room temperature to 1173 K with a heating rate of 10 K/min; three light-off cycle were normally carried out on one sample and the second cycle was taken as representative of the catalytic behavior. Reactants and products were continuously monitored with an on line ABB Uras 14 -Magnos 106 gas analyzer, and the temperature was measured with a Ktype thermocouple on top of the catalytic bed.…”

Section: Powder Samples Activity Tests Evaluation Of Catalytic Activi...mentioning

confidence: 99%

“…1-4 nm in size uniformly dispersed on the ceria surface. 38 Conversely, the milled samples were characterized by a peculiar amorphous shell on a ceria crystalline core structure, reported as responsible for an enhanced methane oxidation activity. 35 The shell structure is observed also here on 4PdCe1473M, despite the high palladium loading and low surface area.…”

Section: Characterization Ofmentioning

confidence: 99%

Pd/CeO₂ Catalysts Prepared by Solvent-free Mechanochemical Route for Methane Abatement in Natural Gas Fueled Vehicles

Danielis

Colussi

Llorca

et al. 2021

Ind. Eng. Chem. Res.

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The increasing diffusion of alternative mobility solutions, ranging from electric technologies to natural gas fueled vehicles (NGVs), has led to a progressive life-cycle analysis approach of their environmental impact in terms of greenhouse gases (GHGs) emissions. This new approach prompted a careful design of the NGVs catalytic aftertreatment system in order to minimize the catalytic converter carbon footprint as well as the unburned methane emissions at tailpipe. Here, a series of Pd/CeO2 methane oxidation catalysts were prepared by an environmentally friendly solvent-free method and compared to the commercial wet-synthesized state-of-the-art catalysts. Their application in NGVs aftertreatment systems was evaluated by testing powder catalysts and coated monolith cores for CH4 oxidation and steam reforming, which are the main methane abatement reactions occurring in a three-way catalyst (TWC) under lean and rich conditions, respectively. Pd/CeO2 catalysts prepared by mechanochemical synthesis initially displayed superior activity compared to their counterpart obtained by conventional wet impregnation, especially under lean oxidation conditions, but appeared less resistant to the industrial aging process after core washcoating. Lambda sweep experiments carried out under full gas composition proved that, despite needing further optimization in the washcoating and aging processes, the developed mild milling synthesis procedure is a viable way for the production of Pd/CeO2 based catalysts for natural gas TWCs.

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Boosting the Activity of Pd Single Atoms by Tuning Their Local Environment on Ceria for Methane Combustion

et al. 2022

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Supported Pd single atom catalysts (SACs) have triggered great research interest in methane combustion yet with contradicting views on their activity and stability. Here, we show that the Pd SAs can take different electronic structure and atomic geometry on ceria support, resulting in different catalytic properties. By a simple thermal pretreatment to ceria prior to Pd deposition, a unique anchoring site is created. The Pd SA, taking this site, can be activated to Pd δ + (0 < δ < 2) that has greatly enhanced activity for methane oxidation: T 50 lowered by up to 130 °C and almost 10 times higher turnover frequency compared to the untreated catalyst. The enhanced activity of Pd δ + site is related to its oxygen-deficient local structure and elongated interacting distance with ceria, leading to enhanced capability in delivering reactive oxygen species and decomposing reaction intermediates. This work provides insights into designing highly efficient Pd SACs for oxidation reactions.

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Methane oxidation activity and nanoscale characterization of Pd/CeO2 catalysts prepared by dry milling Pd acetate and ceria

Cited by 71 publications

References 75 publications

Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

Pd/CeO₂ Catalysts Prepared by Solvent-free Mechanochemical Route for Methane Abatement in Natural Gas Fueled Vehicles

Boosting the Activity of Pd Single Atoms by Tuning Their Local Environment on Ceria for Methane Combustion

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Methane oxidation activity and nanoscale characterization of Pd/CeO2 catalysts prepared by dry milling Pd acetate and ceria

Cited by 71 publications

References 75 publications

Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

Low-Temperature Methane Partial Oxidation over Pd Supported on CeO2: Effect of the Preparation Method and Precursors

Pd/CeO2 Catalysts Prepared by Solvent-free Mechanochemical Route for Methane Abatement in Natural Gas Fueled Vehicles

Boosting the Activity of Pd Single Atoms by Tuning Their Local Environment on Ceria for Methane Combustion

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Pd/CeO₂ Catalysts Prepared by Solvent-free Mechanochemical Route for Methane Abatement in Natural Gas Fueled Vehicles