期刊
CATALYSIS TODAY
卷 327, 期 -, 页码 347-356出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.cattod.2018.03.022
关键词
Lean-burn; NOx; SCR; LNT; Dual-bed catalyst; Noble-metal-free
资金
- National Natural Science Foundation of China [U1232118, 21703227]
- Program of Introducing Talents of Discipline to University of China [B06006]
A dual-bed fixed-bed reactor consisting of a selective catalytic reduction (SCR) catalyst and a lean NOx trap (LNT) catalyst is designed and employed for high-concentration NOx removal under lean-burn condition. The lean NOx could be partially reduced over the upstream SCR catalyst (Cu/Al2O3) by C3H6 in the stream, greatly increasing the efficiencies of both NOx storage and NOx reduction over the downstream LNT catalyst (La0.7Sr0.3CoO3). The activity tests for individual catalyst show that the Cu/Al2O3 containing 5 wt.% Cu is the optimal SCR catalyst, which exhibits similar temperature window of activity (300-350 degrees C) as the LNT catalyst La0.7Sr0.3CoO3. The relative ratio of CuO nanoparticles to surface CuAl2O4 spinel on Cu/Al2O3 is rather important for NO-SCR due to the requirements of appropriate oxidation ability of SCR catalysts. As compared with the single SCR or LNT catalyst, the dual-bed SCR-LNT coupled system shows much lower NOx leak in both lean-and rich-burn periods, especially under the condition of high NOx concentration and high space velocity. Additionally, the NOx to N2O selectivity over this coupled system is as low as similar to 4%, showing obvious advantage over conventional noble metals-based SCR and LNT catalysts.
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