What are the new approaches regarding blending components for the upcoming National VI A/B gasoline standards?

Compared with automotive gasoline (V), the main technical differences in automotive gasoline (VI) (including phases VIA and VIB) are as follows: the olefin content in automotive gasoline (VI) is reduced, with its volume fraction being revised from a maximum of 24% to a maximum of 18% (phase VIA) and 15% (phase VIB)； Reduce the aromatic content in automotive gasoline (VI) (including Phase VIA and Phase VIB); its volume fraction has been revised from not more than 40% to not more than 35% ； Reduce the benzene content in automotive gasoline (VI) (including Phase VIA and Phase VIB), with its volume fraction being revised from not more than 1.0% to not more than 0.8% ； The T50 limit for automotive gasoline (VI) (including Phase VIA and Phase VIB) has been revised from not more than 120°C to not more than 110°C℃ ； Gasoline is a mixture composed of alkanes, olefins, and aromatics within an appropriate boiling range. The olefins present in gasoline are components with good anti-knock properties; their octane rating is generally higher than that of straight-chain alkanes with the same molecular weight. They also constitute an important part of the components in catalytic cracking gasoline. However, due to the high volatility and strong photochemical activity of olefins, the low-molecular-weight olefins in gasoline are released into the atmosphere through evaporation. Under the action of sunlight, they can react with NOx, resulting in photochemical pollution. At the same time, olefins are thermodynamically unstable substances that produce gums during combustion, which accumulate in the engine’s intake system; therefore, the content of olefins should be appropriately controlled in vehicle gasoline standards. Aromatics in gasoline are a high-octane resource, but when their content is too high, it increases the tendency for deposits to form in the engine combustion chamber and raises emissions of CO and HC, especially benzene. Therefore, the EU imposes strict limits on the aromatic content in gasoline for use in vehicles. As emission regulations become stricter, the maximum volume fraction of aromatics allowed in gasoline has been reduced from 42% to 35%. Some studies abroad have also shown that the combustion of aromatics can result in the emission of carcinogenic benzene in exhaust gases, an increase in deposits in the combustion chamber, and increased emissions from the exhaust pipes. Reducing the aromatic content in gasoline can significantly lower the emission of toxic substances from vehicles. Due to the low production capacity for catalytic reforming in our country, gasoline domestically had a high content of olefins and a low content of aromatics at the beginning of the development of cleaner fuels. However, as the quality of gasoline has improved over the past few years, the olefin content has been strictly controlled. As a result, to maintain the octane rating of gasoline, the content of aromatics has been increasing steadily. Surveys of oil quality have shown that the aromatic compound content in some domestic automotive fuels is still relatively high, especially in 95-octane gasoline; in order to maintain the octane rating of this gasoline, its levels in some cases are even close to the limit values specified for Phase V standards. However, given the role of reducing aromatic content in minimizing particulate emissions from vehicles, especially direct-injection gasoline engines, refineries should reduce the aromatic content in gasoline further by installing new facilities for producing high-octane components and upgrading refining technologies, so as to meet the technical requirements of current EU standards. It is recommended that in Phase VI (including Phase VIA and Phase VIB), the volume fraction of aromatics in automotive gasoline should not exceed 35%.

Yes, National VI standards are very strict; olefins, aromatics, and benzene pose challenges. Quality must be achieved at the expense of production volume or efficiency

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