Lubricant base oil

According to the API (American Petroleum Institute) classification of lubricant base oils, mineral base oils of Group II III can be collectively referred to as hydrogenated oils, but there are still differences, which are embodied in the chemical process of hydrogenation the final base oil. On the indicators.

The preliminary hydrotreating is only to saturate the unsaturated hydrocarbons, aromatics, fused-ring aromatics in the base oil into corresponding alkanes cycloalkanes. The deeper hydrocracking isomerization will result in ring opening less conversion. Cyclic non-cyclic compounds are broken into smaller molecules at the same time, which in turn can deoxidize, denitrify, desulfurize. This is why the viscosity index of Group III base oil is higher than that of Group II oil. The so-called knowing it but knowing why.

We know that an ideal lubricant base oil component should have the following properties: 1. Appropriate viscosity good viscosity-temperature performance; 2. Low evaporation loss; 3. Excellent low temperature fluidity; 4. Good oxidation Stability; 5. Appropriate ability to dissolve oxidation products additives; 6. Good demulsibility air release value. Hydrogenation ring opening smaller molecules increase the viscosity index of the base oil lower the pour point; isomerization makes the pour point of the base oil lower. As mentioned last time, for the same viscosity, the evaporation loss of the hydrogenated oil is small, the molecular weight is similar, the viscosity of the hydrogenated oil is low. Based on this, we can understand that high-viscosity deep hydrorefined base oils are very rare; we can also understand that the deeper the degree of hydrorefining, the lower the tendency of the original unsaturated components to reverse reaction, so that the base oil The better the light stability oxidation resistance.

Of course, it is the "cleanness" of the hydrogenated base oil that makes the natural antioxidants contained in the hydrogenated oil close to no. The following phenomenon: Use the common rotating oxygen bomb method to test both 150SN 150N The oxidation induction period of base oil, pure base oil, the induction period of 150SN is greater than 150N. This is in contradiction with the oxidation resistance of hydrogenated oil as we said. On the contrary, if you add two kinds of base oils separately Re-testing the rotating oxygen bomb with an appropriate amount of antioxidants will give a very different result. The induction period of hydrogenated oil is much better than that of non-hydrogenated oil. In other words, hydrogenated oil is more susceptible to antioxidants. More sensitive to antioxidants! Just imagine, what kind of lubricating oil product does contain antioxidants? I'm afraid this is rarely the case.

In general, the performance of hydrorefined base oils is more in line with our expectations for high-quality lubricating oil products than non-hydrorefined base oils (solvent refined). Here, the solubility of oxidation products additives is an exception. The reasons for this are well-known will be repeated. Next time, we will talk about base oils.