ABSTRACT
The preferred molecules for lube oil manufacture are iso-paraffins having a high viscosity index (VI) and low pour point. The viscosity of base stocks is defined by the boiling range of hydrocarbons while their VI is defined by their chemistry. The typical VI of solvent refined paraffinic base stocks is in a range of 85-95 and many crude oils are not suitable for the production of lube oil base stocks. Both paraffinic and iso-paraffinic hydrocarbons are high VI components of petroleum while hydrocarbons containing ring structures, such as aromatic and some polynaphthenic hydrocarbons, are low VI components. The processes of hydrotreating, hydrocracking, and hydroisomerization were introduced to meet the ever increasing demand for higher quality mineral base stocks having a higher VI. Hydrogenation processes for the conversion of petroleum fractions can be classified as nondestructive and destructive. Nondestructive hydrogenation is generally used for the purpose of improving product quality without changing the boiling range. Destructive hydrogenation, such as hydrocracking, is characterized by the cleavage of carbon-carbon bonds (Speight, 2006).
