Effect of support oxygen storage capacity on the catalytic performance of Rh nanoparticles for CO2 reforming of methane

Ioannis V. Yentekakis, Grammatiki Goula, Maria Hatzisymeon, Ioanna Betsi-argyropoulou, Georgia Botzolaki, Kalliopi Kousi, Dimitris I. Kondarides, Martin J. Taylor, Christopher M.a. Parlett, Amin Osatiashtiani, Georgios Kyriakou, Juan Pedro Holgado, Richard M. Lambert

Research output: Contribution to journalArticle

Abstract

The effects of the metal oxide support on the activity, selectivity, resistance to carbon deposition and high temperature oxidative aging on the Rh-catalyzed dry reforming of methane (DRM) were investigated. Three Rh catalysts supported on oxides characterized by very different oxygen storage capacities and labilities (γ-Al 2O 3, alumina-ceria-zirconia (ACZ) and ceria-zirconia (CZ)) were studied in the temperature interval 400–750 °C under both integral and differential reaction conditions. ACZ and CZ promoted CO 2 conversion, yielding CO-enriched synthesis gas. Detailed characterization of these materials, including state of the art XPS measurements obtained via sample transfer between reaction cell and spectrometer chamber, provided clear insight into the factors that determine catalytic performance. The principal Rh species detected by post reaction XPS was Rh 0, its relative content decreasing in the order Rh/CZ(100%)>Rh/ACZ(72%)>Rh/γ-Al 2O 3(55%). The catalytic activity followed the same order, demonstrating unambiguously that Rh 0 is indeed the key active site. Moreover, the presence of CZ in the support served to maintain Rh in the metallic state and minimize carbon deposition under reaction conditions. Carbon deposition, low in all cases, increased in the order Rh/CZ < Rh/ACZ < Rh/γ-Al 2O 3 consistent with a bi-functional reaction mechanism whereby backspillover of labile lattice O 2− contributes to carbon oxidation, stabilization of Rh 0 and modification of its surface chemistry; the resulting O vacancies in the support providing centers for dissociative adsorption of CO 2. The lower apparent activation energy observed with CZ-containing samples suggests that CZ is a promising support component for use in low temperature DRM.

Original languageEnglish
Pages (from-to)490-501
Number of pages12
JournalApplied Catalysis B: Environmental
Volume243
Early online date28 Oct 2018
DOIs
Publication statusPublished - 1 Apr 2019

Bibliographical note

© 2018, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/.

Funding: European Union and Greek national funds through the Operational Program "Competitiveness, Entrepreneurship and Innovation", under the call “RESEARCH-CREATE-INNOVATE” (project code: T1EΔK-00782), Royal Society and EPSRC (EP/M005186/2).

Keywords

  • Active sites
  • CO activation
  • Dry reforming of methane
  • Oxygen ions spillover
  • Oxygen storage capacity
  • Resistance to carbon deposition
  • Rhodium nanoparticles
  • Support effects
  • Synthesis gas

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