| The vehicle fuel quality has an important role in motor vehicle exhaust emissions, while the sulfur, olefins and polycyclic aromatic hydrocarbons(PAHs) contents in vehicle fuel are the key indicators of impact on exhaust emissions. The emissions of carbon monoxide(CO), nitrogen oxide(NOX), hydrocarbon(HC) and particulate matter(PM) can effective decreased with the reduction of sulfur and olefins contents in gasoline oil or sulfur and PAHs contents in diesel oil. In order to investigate the real vehicle fuel quality in China and the differences of vehicle fuel quality between China and abroad, commercial available gasoline and diesel oil samples were collected at gas stations in 8 Chinese cities and in California, USA during July-September 2013. Determine the sulfur content in vehicle fuel by Oxygen Bomb Combustion-Ion Chromatography(OBC-IC) method, determine the olefins content in gasoline oil by Gas Chromatography-Mass Spectrometer(GC-MS) method, and determine the aromatics content in diesel oil by Mass Spectrometry(SH/T 0606-2005) method. Analysis of the contents and distribution characteristics of the above important components in vehicle fuel samples of different cities, different brands and different standards in China and compare those results to the fuel quality of California USA and previous research results. The main results are listed below:1)The mean sulfur contents were 72.8±47.2, 25.9±8.7 and 8.3±1.3 ppm in the China Ⅲ, Ⅳ and Ⅴ gasoline oil samples, and were 146.4±48.8, 60.6±77.8 and 7.9±1.3 ppm in the China Ⅲ, Ⅳ and Ⅴ diesel oil samples, respectively; while mean sulfur contents were 11.6±3.0 and 11.4±2.8 mg/kg in California’s gasoline and diesel oil samples, respectively. 3.7 % of the China Ⅲ and 13.3 % of the ChinaⅤgasoline oil samples, as well as 28.6 % of the China Ⅳ diesel oils, had sulfur contents beyond the criteria limits, while other oil samples had sulfur contents within the criteria limits. The average sulfur contents were lower in oil samples from Beijing than from California, and were also much lower in oil samples from Shanghai and Guangzhou than from other five cities. The sulfur contents in gasoline oil samples from Chongqing, Xi’an, Changchun and Urumqi, and the sulfur contents in diesel oil samples from Guangzhou, Chongqing, Wuhan and Changchun all had strong brand differentiations.2)The mean olefins contents were 10.2±3.1, 7.4±1.9 and 5.0±1.8 vol% in the China Ⅲ, Ⅳ and Ⅴ gasoline oil samples, respectively. All olefins contents in gasoline oil samples were below the relevant limits in China III, IV and V standards. The olefins contents of gasoline oil samples in Beijing and California were comparable, but the olefins contents in gasoline oil samples from other cities were much higher than from in California, USA. The olefins contents of gasoline oil samples in 8 cities in China all had strong brand differentiations. Small molecule olefins(C4-C7) were the main components of olefins in gasoline oil samples in China, which were account for about 86.2 % of sum olefins in gasoline oil samples. There was a great difference of different carbon numbers olefins contents between 8 cities. Single olefins were the main existence forms of olefins in gasoline oil samples from China, which were account for about 96.6 % of sum olefins in gasoline oil samples and were given priority to with normal olefins(4.8±1.8 vol%) and mono-branched-chain olefins(3.4±1.5 vol%), which were account for about 55.2 %, 39.1 % of sum olefins in gasoline oil samples from China, respectively. The two and three branched-chains olefins were the very few components in gasoline oil samples from China. All kinds of olefins contents in gasoline oil samples from China were much higher than from California USA. All kinds of olefins contents and distributions in gasoline oil samples had strong brand and fuel standards differentiations.3) The mean aromatics contents were 12.5±6.3、7.9±3.1 and 3.8±0.3 wt% in the China Ⅲ, Ⅳ and Ⅴ diesel oil samples, and the mean PAHs contents were 0.42±0.21、0.12±0.06 and 0.05±0.02 wt% in the China Ⅲ, Ⅳ and Ⅴ diesel oil samples, respectively. the aromatics and PAHs contents were lower in diesel oil samples from Beijing than from California, and the PAHs contents were also lower in diesel oil samples from Shanghai than from California, but the aromatics and PAHs contents were much higher in diesel oil samples from other cities than from California. In addition, the aromatics and PAHs contents in gasoline samples had strong brand differentiations in 8 cities of China. Phenanthrene(Phe), fluorene(Flu), naphthalene(Nap) and pyrene(Py) were the main components of PAHs in diesel oil samples from China, which were account for about 34.7 %, 20.8 %, 17.0 % and 16.6 % of sum PAHs in diesel oil samples in China. All kinds of PAHs were generally higher in diesel oil samples from Chongqing, Wuhan, Xi’an, Changchun and Urumqi were generally than from Beijing, Shanghai and Guangzhou. There were significant differences of PAHs contents and distributions in diesel oil samples between China and California, USA. The phenanthrene, fluorene, pyrene and fluoranthene contents were much higher in diesel oil samples from China than from California, USA, however, the naphthalene and Benzo(b)fluoranthene(Bb F) contents were lower in diesel samples from China than from California, USA. The average ratios of Ant/Ant+Phe and Flu/Flu+Py in diesel samples from China were 0.09±0.05 and 0.26±0.11, respectively, which were the same as the previous research results. But the PAHs ratios in diesel samples from 8 cities of China and California, USA had many differences.4)In recent years, the quality of commercial available gasoline and diesel has been greatly improved because of the upgrading of the fuel national standards, and the contents of main components in vehicle fuels all had a significant reduction, especially in megacities. However, when compared with the vehicle fuels in California in the corresponding period, there is still plenty of space to upgrade in China. |
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