Experimental and density functional theory studies on Cu/Ba-coimpregnated γ-Al2O3 for low-temperature NOx storage and adsorbent regeneration

Hyunwook Kim, Hyeonjung Jung, Jeong Woo Han, Ki Bong Lee

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Although the lean-NOx trap (LNT) has been used to reduce NOx emissions from diesel-powered vehicles, LNT application is limited because its performance degrades at low temperatures (e.g., during cold starting). Therefore, to enhance low-temperature NOx storage and adsorbent regeneration, γ-Al2O3 was coimpregnated with both Cu and Ba (Cu–Ba/γ-Al2O3). The experimentally measured NOx storage capacities (NSCs) and NOx storage efficiencies (NSEs) were compared. Density-functional-theory (DFT) calculations were performed to reveal the NOx storage mechanism. The Cu/Ba-coimpregnated γ-Al2O3 improved both NSC and NSE of NO storage and enhanced NSE of NO2 storage at initial stage. In addition, it desorbed NOx at lower temperatures than the conventional Ba-impregnated γ-Al2O3 (Ba/γ-Al2O3). The in-situ diffuse reflectance infrared Fourier-transform spectroscopy analysis and DFT calculations for NO storage showed that NO adsorption was superior on the Cu-compound surfaces and that stable hyponitrite was stored on the Ba-compound surfaces. In NO2 storage, Cu/Ba coimpregnation offered high preferential NO2 coverage on the CuO surface and produced the most stable ionic nitrate on the Ba-compound surfaces. The experimental and theoretical results confirmed that the Cu/Ba-coimpregnated adsorbent exhibited both superior NOx storage and adsorbent regeneration compared to the conventional Ba-containing LNT adsorbent.

Original languageEnglish
Article number132112
JournalChemical Engineering Journal
Volume429
DOIs
Publication statusPublished - 2022 Feb 1

Keywords

  • Density-functional-theory calculation
  • Lean-NO trap
  • NO
  • NO
  • NO storage–regeneration

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

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