TY - JOUR
T1 - Experimental and density functional theory studies on Cu/Ba-coimpregnated γ-Al2O3 for low-temperature NOx storage and adsorbent regeneration
AU - Kim, Hyunwook
AU - Jung, Hyeonjung
AU - Han, Jeong Woo
AU - Lee, Ki Bong
N1 - Funding Information:
This study was supported by the Super Ultra Low Energy and Emission Vehicle Engineering Research Center [NRF-2016R1A5A1009592] and the C1 Gas Refinery Program [NRF-2018M3D3A1A01055761] of the National Research Foundation (NRF) of Korea, funded by the Korean government through the Ministry of Science and ICT.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - 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.
AB - 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.
KW - Density-functional-theory calculation
KW - Lean-NO trap
KW - NO
KW - NO
KW - NO storage–regeneration
UR - http://www.scopus.com/inward/record.url?scp=85114695190&partnerID=8YFLogxK
U2 - 10.1016/j.cej.2021.132112
DO - 10.1016/j.cej.2021.132112
M3 - Article
AN - SCOPUS:85114695190
VL - 429
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
SN - 1385-8947
M1 - 132112
ER -