Review of Recent After-Treatment Technologies for De-NOx Process in Diesel Engines
- PDF / 1,025,293 Bytes
- 22 Pages / 595 x 842 pts (A4) Page_size
- 67 Downloads / 149 Views
ght © 2020 KSAE/ 11825 pISSN 12299138/ eISSN 19763832
REVIEW OF RECENT AFTER-TREATMENT TECHNOLOGIES FOR DE-NOx PROCESS IN DIESEL ENGINES Byungchul Choi1, 2)*, Kyungseok Lee2, 3) and Geonseog Son4) School of Mechanical Engineering, Chonnam National University, Gwangju 61186, Republic of Korea 2) Automotive Research Center, Chonnam National University, Gwangju 61186, Republic of Korea 3) University Industry Liaison Office, Chonnam National University, Gwangju 61186, Republic of Korea 4) Umicore Korea, 71-3 Gongdan 2ro, Seobuk-gu, Cheonan-si 31093, Republic of Korea
1)
(Received 25 September 2020; Revised 17 October 2020; Accepted 17 October 2020) ABSTRACTThe removal of nitrogen oxides (NOx), which are major atmospheric pollutants, in exhaust gas after-treatment systems, has been studied extensively. The catalytic reduction of NOx in lean-burn environments is challenging in diesel aftertreatment technology. The most relevant catalytic NOx reduction technologies for diesel engines are summarized in this review paper, focusing on current catalytic after-treatment systems for compliance with emission standards. Four promising after-treatment technologies for the abatement of tail-pipe NOx emissions are discussed: (i) lean NOx trap (LNT) and LNT combined with selective catalytic reduction (SCR) (LNT + SCR), (ii) Urea/NH3-SCR, (iii) Hydrocarbon-SCR (HC-SCR), and (iv) CO/H2-SCR. The relevant reaction mechanisms and current major challenges are reviewed in detail. The effects of the active phases and support modifications of the respective catalysts are examined to evaluate their contribution to the aftertreatment systems. Major issues in practical applications, such as hydrothermal aging, chemical poison, and metallic additives for improving de-NOx performance, are extensively reviewed in this paper. KEY WORDS : Diesel engine, After-treatment, Catalyst, De-NOx, LNT, SCR
NOMENCLATURE
TWC : three-way catalyst UHC : unburned hydrocarbon WGS : water-gas shift
AIE : aqueous ion exchange CDPF : catalyzed diesel particulate filter CeO2 : ceria CHA : chabazite CVD : chemical vapour deposition DME : dimethyl ether DOC : diesel oxidation catalyst DPF : diesel particulate filter HC : hydrocarbon HNCO: isocyanic acid LNT : lean NOx trap LOT : light-off temperature NH3 : ammonia NOx : nitrogen oxide NSC : NOx storage capacity PGM : precious group metal PM : particulate matter RDE : real driving emission SCR : selective catalytic reduction SDPF : SCR-catalyzed diesel particulate filter SR : steam reforming SSIE : solie-state ion exchange
1. INTRODUCTION Currently, emission reduction and fuel economy improvement are two key challenges in the use of diesel engines. Emission reduction focuses on the problem of nitrogen oxides (NOx) and particulate matter (PM) emissions. Extremely reduced NOx emissions are required to meet current and future emission regulations such as California LEV-III, US Tier 3, and Euro 7. Particularly, the importance of real driving emission (RDE) was emphasized after the VW diesel gate scandal. Aftertreatmen
Data Loading...
