Guys, I need help. Please help!~
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In the feed impurity specifications for the aromatic hydrocarbon extraction unit (SED technology from the Chinese Academy of Petroleum Sciences), the requirement for alkaline nitrogen is less than 0.5 mg/kg. Why is it necessary to control alkaline nitrogen? Will basic nitrogen react with sulfolane? Or does basic nitrogen have an impact on the downstream disproportionation unit? I would be extremely grateful if some experts could help explain this.
In the elemental composition of petroleum, the nitrogen content is generally in the range of several parts per ten thousand to several parts per thousand; the nitrogen content in crude oil in China is between 0.1% and 0.5%, which is relatively high. Nitrides in oil are primarily concentrated in high-boiling fractions and residue, and are difficult to remove. As the fraction becomes heavier, the content of basic nitrogen increases more slowly. Below 200°C, the total nitrogen content in light petroleum fractions is very low, and it is almost entirely in the form of basic nitrogen compounds. In the reprocessed oil, the content of basic nitrogen increases significantly due to the formation of pyrolysis products during the reprocessing process. Alkaline nitrogen can poison FCC catalysts, reducing the yields of gasoline and diesel while increasing the amount of coke. It also raises the iodine value of gasoline. In catalytic reforming reactions, alkaline nitrides in the feed oil generate ammonia under reforming conditions, which in turn leads to the formation of ammonium chloride; this weakens the acidic centers of the catalysts and causes them to become inactive. Many studies have shown that nitrides are one of the main causes of gum formation in oils; basic nitrides in oils can lead to a slight increase in the amount of soluble gums produced. Aniline, quinoline, and especially **quinoline have a significant impact on the color stability of gasoline and kerosene.