Production of base oils from high-sulfur tatar crude oils

The following sequence of processing lube distillates from atmospheric-vacuum tubestill (AVT) units are most commonly used for production of base oils: selective treatment — dewaxing — hydrotreating. As a result of hydrotreating, sulfur and tars are removed from the intermediate product, the carbon residue decreases, and the color improves. This final stage frequently determines the quality of base oils. However, its role in obtaining the required quality is usually small, since the basic indexes are formed in the preceding stages.