In Iran, the production of groups II to IV base oils is not usual and manufacturers are concentrated to produce group I base oils which are classified as less than 90 percent saturates, greater than 0.03 percent sulfur and with a viscosity-index range of 80 to 120.

Depending on the characteristics of the lube cut as the feed of refineries, the sulfur content in group I base oils is ranging from 5000 to 15000 ppm. The presence of sulfur based heteroaromatic and unsaturated compounds in this type of base oils not only reduces their oxidation stability and corrosion inhabitation performance, but also affects the environment destructively.

Challenge: Desulphurization of Group I base oils from maximum 10000 ppm to less than 300 ppm

Limitations: Due to the proximity of Pars Oil Refinery to the metropolis of Tehran and subsequently safety considerations and air pollution issues, furthermore, limited useful space of the refinery the creation of desulfurization plant based on hydrogenation processes, construction of hydrogen generator units and towers to burn sulphurated hydrogen gases are not desirable.