ABSTRACT
Conventional processing, based on solvent extraction and solvent dewaxing of lube oil distillates, is sufficient for many lubricant products and needed to produce wax. Traditional ways of lube oil finishing include adsorbent clay, which removes some undesirable molecules, such as residual solvents. In recent years, finishing of solventrefined base stocks has been replaced by a nonconventional catalytic process, such as hydrofinishing or hydrofining (HF). The commercial HF processes are based on heating the feedstock in a furnace and passing it with hydrogen through a reactor filled with catalyst. After passing through the reactor, the treated oil is cooled, separated from the excess hydrogen, and pumped to a stripper tower, where hydrogen sulfide is removed by steam, vacuum, or flue gas. The finished product leaves the bottom of the stripper tower and has improved color, odor, and lower sulfur content (Speight, 2006). The HF process is used to finish naphthas, gas oils, and lube oil base stocks. Under mild HF conditions, olefins are saturated and the aromatic contents of finished products are usually not affected. The nitrogen-, sulfur-, and oxygen-containing compounds undergo hydrogenolysis to split out ammonia, hydrogen sulfide, and water, respectively (Speight, 2006).
