Unraveling Reactive Nitrogen Emissions in Heavy-Duty Diesel Vehicles across Evolving Standards and Cheating Tactics

作者：Xiang Ding, Cheng Huang, Dan Dan Huang, Yong Hou, Qingyao Hu, Shengrong Lou, Meng Wang, Min Zhou, Jun Chen, Huinan Yang, Ru‐Jin Huang, Qingyan Fu, Hongli Wang · 发表于：Environmental Science & Technology · 年份：2024 · DOI：10.1021/acs.est.4c09377 · 被引用次数：9 · 研究领域：Vehicle emissions and performance、Catalytic Processes in Materials Science、Atmospheric chemistry and aerosols

Reactive nitrogen (Nr) emissions significantly affect air quality and the nitrogen cycle in ecosystems. Heavy-duty diesel vehicles (HDDVs), as major sources of these emissions, exhibit complex emission characteristics because of the combined effects of different driving conditions and aftertreatment technologies. This study first investigated the emission factors (EFs) of Nr species, including NO, NO 2, HONO, N 2 O, and NH 3, from HDDVs under different emission standards (China IV/V/VI) and cheating strategies, with a particular focus on the impact of selective catalytic reduction (SCR) systems. Vehicles employing water injection cheating present NO, NO 2, and HONO EFs that are consistent with the China III standards, significantly undermining the effectiveness of Nr emission control. The evolution of SCR technology in China IV, V, and VI standards has generally led to substantial reductions in NO, NO 2, and HONO emissions, yet the integration of ammonia slip catalysts (ASC) systems in China VI vehicles presents new challenges. While ASCs have successfully reduced NH 3 slip to an average of 17 ± 12 mg/km, they have also caused a 6–13-fold increase in N 2 O emissions compared with those of China IV and V vehicles, reaching levels of 205 ± 85 mg/km. Additionally, China VI vehicles exhibit a marked increase in the HONO/NOx ratio, which increases from 0.9% in China V to 4.6%. These increases are attributed to high-temperature oxidation of NH 3 within the ASC catalyst, leading to ...