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Poster De Conférence Année : 2023

Structural characteristics leading to a high CH4 oxidation activity for Pd/CeO2-based catalysts

D. Zengel
  • Fonction : Auteur
F. Maurer
  • Fonction : Auteur
A. Salcedo
  • Fonction : Auteur
C. Michel
  • Fonction : Auteur
D. Loffreda
  • Fonction : Auteur
M. Casapu
  • Fonction : Orateur
J.-D. Grunwaldt
  • Fonction : Auteur

Résumé

Keywords: methane oxidation, noble metal clusters, emission control Introduction. Methane/biomethane is a key energy carrier for the transition from fossil to more sustainable resources. Due to the high hydrogen-to-carbon-ratio in CH4 molecule, CO2 emissions can be significantly reduced compared to those resulting from the combustion of other hydrocarbons [1], with a major decrease recorded especially for biomethane. Nevertheless, an important drawback is the high greenhouse gas potential of methane itself. Among different catalysts tested for reducing the CH4 slip, Pd-based systems are known to show the highest efficiency. However, they still suffer from sulfur poisoning and water deactivation. Numerous attempts have been undertaken to understand the deactivation and regeneration behavior of Pd-catalysts, and a clear influence of the carrier material and gas composition was observed [2,3]. Experimental/methodology. A series of Pd-CeO2 based catalysts with different noble metal loadings (1-3 wt.%) were prepared by incipient wetness impregnation. After different pre-treatment procedures, the catalytic performance was investigated in plug-flow reactor between 100-550°C using a gas mixture containing 3200 ppm CH4, 10%O2 in N2. To obtain structure-activity correlations, the catalyst were characterized by complementary in situ and ex situ methods including: X-ray diffraction (XRD), temperature programmed reduction, electron microscopy and X-ray absorption spectroscopy (XAS). Additionally, the nature of active species was identified by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements supplemented by density functional theory (DFT) calculations. Results and discussion. The results obtained in this study indicate a strong impact of catalyst pre-treatment conditions on the activity of Pd/CeO2-catalysts. Whereas an oxidizing treatment at high temperatures results in catalyst deactivation, a significant activity gain was obtained upon reduction in CO- or H2-containing gas mixtures. In line with our previous studies [4,5], this positive effect of a reducing treatment could be correlated with the tuning of the interface between the reduced noble metal nanoparticles and ceria support. The formation or redispersion of Pd nanoparticles depending on the catalyst treatment was revealed by Environmental Transmission Electron Microscopy (ETEM) measurements. Further differences in the noble metal structure leading to a higher or lower catalyst durability were uncovered by in situ DRIFTS and operando XAS characterization, and were additionally supported by DFT calculations [6]. Acknowledgments This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation; grant No. 431423888 DYCAT project) and the Agence National de la Recherche (grant No. ANR-19-CE05-0038, PRCI DYCAT project). References [1] H. Muk Cho, B.-Q. He, Energy Convers. Manage., 2007, 48, 2, 608. [2] P. Lott et al., Appl. Catal. B 2020, 278, 119244. [3] K. Murata et al., Angew. Chem. Int. Ed., 2017, 56, 50, 15993. [4] F. Maurer et al., Nature Catal., 2020, 3, 824. [5] A.M. Gänzler et al., Angew. Chem. Int. Ed. 2017, 56,13078. [6] A. Salcedo et al., Small 2023, 2300945.
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Dates et versions

hal-04481749 , version 1 (28-02-2024)

Identifiants

  • HAL Id : hal-04481749 , version 1

Citer

D. Zengel, F. Maurer, A. Salcedo, C. Michel, D. Loffreda, et al.. Structural characteristics leading to a high CH4 oxidation activity for Pd/CeO2-based catalysts. 15th European Congress on Catalysis, EUROPACAT, Aug 2023, Prague, Czech Republic. ⟨hal-04481749⟩
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