What causes gasoline to change color?

It is possible that there are oily unsaturated hydrocarbons, which react and turn into other substances when heated; it is also possible that the crude oil contains certain components containing oil

Heating accelerated the oxidation of olefins in the catalytically cracked gasoline, causing it to darken.

Poor oxidation stability; it has oxidized

Glucide oxidation is the root cause of gasoline discoloration.

Is it possible that the distiller was previously used to distill other oils, resulting in contamination remaining inside the condenser?

The storage stability of the gasoline is not up to standard, with a relatively high gel content; it is recommended to conduct an experiment to determine the actual gel content

If the gel content is high, what should be done? Furthermore, gasoline has a high volatility; what are the typical components responsible for this?

My view is that oil may contain unsaturated hydrocarbons, which react upon heating to form other substances. The speed at which it deteriorates depends on the hydrocarbon composition of the sample itself, as well as the amount of components that are prone to oxidation and deterioration, along with the presence of trace impurities. For example, regarding the olefin content, diesel and gasoline with a high level of diolefins are prone to condensation, resulting in the formation of color-causing substances that cause deterioration and discoloration ； The carbon nine aromatic hydrocarbon gasoline, a by-product of the ethylene process, contains high levels of dienes and has extremely poor storage stability. Furthermore, by adding antioxidants, the rate of oxidative deterioration can be slowed down, but it is difficult to change it fundamentally. At the same time, gasoline gums are one of the factors that affect color changes in gasoline; as chroma increases, the content of saturated hydrocarbons and olefins in gasoline decreases, while the content of aromatics increases. Non-hydrocarbon compounds also have an impact on color changes in gasoline, with nitrogen-containing compounds such as pyridine in combination with divalent copper ions, as well as sulfur-containing compounds such as n-octanethiol in combination with divalent copper ions, having a significant effect on gasoline chroma. N-octanethiol, a sulfur-containing compound, also exerts an influence on color changes in gasoline; when pyridine is present together with copper powder, or when n-octanethiol is present together with copper powder, chemical reactions occur in gasoline, resulting in the formation of dark green precipitates.

In this case, it should be new substances formed as a result of the accelerated oxidation reaction of unsaturated hydrocarbons when heated. To prevent gasoline products from discoloring, gasoline hydrogenation is a good option; the goal is to convert unsaturated hydrocarbons into saturated hydrocarbons through a hydrogenation reaction.

There are two possibilities: it might contain gums, which can easily cause oil to change color. You can use distilled gasoline and pass it through silica gel; if there are gums present, the silica gel will absorb them. Then observe whether the color changes – if it doesn’t change, it was caused by the gums. If the color still changes, it means that the high distillation temperature led to the thermal cracking of the residue oil, resulting in unsaturated hydrocarbons that change color upon oxidation