MnO2 Nanowire-CeO2 Nanoparticle Composite Catalysts for the Selective Catalytic Reduction of NO x with NH3

Su Hyo Kim, Bum Chul Park, Yoo Sang Jeon, Young-geun Kim

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

MnOx-based catalysts have been applied to the selective catalytic reduction of NOx with ammonia (NH3) owing to their high NOx removal efficiency and catalytic stability. In general, the fabrication of a variety of nanomaterials in a complex structure requires complicated processes, including heat treatment and a series of cleaning steps. In addition, MnO2 which has diverse polymorphs, exhibits different catalytic effects depending on its crystalline structure. Among them, synthesizing the ϵ-MnO2 phase, which functions as a nanocatalyst, has been the most difficult and has hardly been reported. Here, we report the synthesis of heterostructured composite nanocatalysts consisting of ϵ-MnO2 nanowires (NWs) and CeO2 nanoparticles (NPs) by applying pulsed currents sequentially. This method drastically simplifies the overall process compared to the conventional techniques. Through X-ray diffraction and transmission electron microscopy, it was confirmed that 2-3 nm of CeO2 NPs were formed on the surfaces of the ϵ-MnO2 NWs. The de-NOx efficiency of the nanocatalysts was analyzed in terms of content variation, specific surface area, and the elemental chemical state of the surface. A ceramic filter containing the nanocatalysts shows a high catalytic activity over the broad operating temperature range 100-400 °C. In the low-temperature region, ϵ-MnO2 plays a major role in determining the catalytic property, which is consistent with the Brunauer-Emmett-Teller (BET), H2 temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) results. On the other hand, in the high-temperature region, the efficiency increases gradually as the content of CeO2 increases. The H2 TPR, NH3-temperature-programmed desorption, and XPS patterns reveal why the composite exhibits such superior characteristics in the temperature range mentioned above.

Original languageEnglish
Pages (from-to)32112-32119
Number of pages8
JournalACS Applied Materials and Interfaces
Volume10
Issue number38
DOIs
Publication statusPublished - 2018 Sep 26

Keywords

  • CeO nanoparticles
  • composite nanocatalyst
  • electrodeposition
  • MnO nanowires
  • selective catalytic reduction

ASJC Scopus subject areas

  • Materials Science(all)

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