The relationship between olefins and octane number in gasoline hydrogenation
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In gasoline hydrogenation, the octane number of the resulting gasoline is primarily determined by the content of olefins; the higher the amount of olefins, the higher the octane number? Olefins basically come from the extracted light gasoline; in other words, the olefin content in light gasoline directly determines the octane rating of the final gasoline product. Can it be understood that way? Also, recently the olefin content under our factory’s control has been consistently above the limit, at over 33%. The measure taken has been to reduce the amount of light gasoline extracted. This approach is acceptable if the reduction in extraction volume is not significant, but I believe it has serious drawbacks: firstly, it can cause the desulfurization reactor downstream to overheat; secondly, it lowers the dry point of the light gasoline. In my opinion, it would be better to increase the intensity of the selective hydrogenation reaction, that is, to increase the amount of hydrogen used so that more olefins can be reacted away. I would appreciate some advice from those with more experience – is this approach feasible? ? ? There is another issue: the workshop wants to increase the octane rating, which means the olefin content needs to be raised. However, the olefin level cannot exceed 32%, and that makes it difficult to achieve this goal. The current octane rating of the crude oil is 92.1, while that of the finished gasoline is 89.6, resulting in a significant loss. I’m not sure how those with more experience handle this situation; I would appreciate some guidance! Additionally, is there a specific quantitative relationship between the olefin content and octane rating?
Hydrogenation leads to a loss of octane rating; hydrodesulfurization and hydrodenitrogenation also saturate some double bonds, and the octane rating can be adjusted later on
The impact of different components on gasoline octane number – you might find it useful to take a look!
The olefin content can only have a stabilizing effect on the overall octane rating, keeping it at around 89; it is the aromatic content that plays a key role in increasing the octane rating. In principle, hydrogenating and saturating some of the olefins has little impact on the overall octane rating
The octane rating is not guaranteed; even when the sulfur content in light gasoline is within acceptable limits, it still needs to be further purified. A hydrogenation temperature of 140–150 degrees is chosen, at which point saturation reactions of olefins begin to occur, with saturation reactions of diolefins being the main process. I don’t think it’s feasible to increase the temperature for selective hydrogenation in order to reduce the olefin content. Your product seems to be a mixture of light gasoline and stabilized gasoline; by raising the temperatures in the subsequent first and second stage hydrogenation reactors, it’s possible to reduce the olefin content. So why raise the temperature for selective hydrogenation?
Olefins don’t help much in improving octane rating!