Investigation of VOC emission characteristics of light-duty gasoline vehicles and combustion-side formation mechanisms of key VOC species
Year: 2026
Type: article
Abstract: Volatile organic compounds (VOCs) are important precursors of atmospheric ozone (O 3 ) and secondary organic aerosol (SOA), making their emissions an important concern for urban air quality. In this study, two light-duty gasoline vehicles (LDGVs), including one China V vehicle and one China VI vehicle, were tested over the Worldwide harmonized Light vehicles Test Cycle (WLTC) under normal TWC and simulated first-stage TWC failure conditions. VOC emissions were analyzed by driving phase, chemical group, and individual species, and their ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) were evaluated. Chemical kinetic simulations were further conducted to investigate the combustion-side formation and transformation behavior of representative aromatic VOCs under controlled conditions. Simulated first-stage TWC failure markedly increased VOC emissions from both tested vehicles, with the total VOC emission factors of the tested China VI and China V vehicles increasing from approximately 22 and 31 mg/km to 78 and 103 mg/km, respectively. For the two tested vehicles, the low-speed phase was the dominant contributor to VOC emissions under normal TWC conditions, whereas the contribution of the extra-high-speed phase became more important following simulated first-stage TWC failure. The VOC profile shifted toward higher contributions of alkanes, alkenes/alkynes, and aromatics. OFP was dominated by oxygenated VOCs (OVOCs) under normal TWC conditions but by aromatics and alkenes/alkynes under the simulated first-stage TWC failure condition, whereas SOAFP was primarily controlled by aromatic species. Under the controlled simulation conditions, xylene isomers mainly accumulated at 800-850 K through side-chain oxidation and HCO-elimination pathways, while toluene peaked at around 900 K and was related to the secondary conversion of xylene-derived intermediates. Increasing equivalence ratio enhanced H-assisted aromatic conversion and weakened oxidative consumption, thereby promoting the accumulation of toluene and xylene isomers.
Source: Atmospheric Environment X
Language: English
Subfield: Automotive Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,860
OpenAlex ID: W7223051008