Mesoporous configuration effects on the physicochemical features of hierarchical ZSM-5 supported cobalt oxide as catalysts in methane partial oxidation

Irena Khatrin, Iman Abdullah, Alan J. McCue, Yuni K. Krisnandi

Research output: Contribution to journalArticlepeer-review

Abstract

Hierarchical porous system has become a prevalent method to overcome the diffusion limitation of conventional zeolites. Two types of mesopores characterized as intra-crystalline (mesopores in the zeolite pore wall) and inter-crystalline mesopores (meso-sized voids between nano-zeolite aggregates) could be formed in the synthesis of hierarchical zeolites. In an attempt to investigate the influence of mesopores structure on the physicochemical properties of hierarchical ZSM-5, specifically cobalt oxide impregnated ZSM-5 zeolite samples with intra- and inter-crystalline mesopores were synthesized through two different synthesis strategies. Analysis of the physicochemical properties of the as-modified hierarchical ZSM-5 catalysts were carried out using SEM, TEM, XPS, and H2-TPR which showed distinct features given by the two mesopores configurations. Co-oxide impregnated on ZSM-5 with inter-crystalline mesopores was dominated by Co(II) species, while Co-oxide/ZSM-5 showed a fair amount of Co(III) and Co(II). Furthermore, analysis of the catalytic activity was conducted using methane partial oxidation as a model reaction. With a variation in reaction time, various types of oxygenated products, i.e. methanol, formaldehyde, formic acid, and a small trace of carbon dioxide were observed. Catalytic results suggested that the Co-oxide/ZSM-5 material with inter-crystalline mesopores configuration is more active for the methane partial oxidation reaction compared to the Co-oxide/ZSM-5 with intracrystalline mesopores. This was confirmed by the formation of formaldehyde rather than methanol as the major product in the brief reaction time of 30 min.

Original languageEnglish
Article number112896
JournalMicroporous and Mesoporous Materials
Volume365
DOIs
Publication statusPublished - 1 Feb 2024

Keywords

  • Co-oxide ZSM-5
  • Hierarchical ZSM-5
  • Intra- and inter-crystalline mesopores
  • Mesopores configuration
  • Methane partial oxidation

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