Hydrofining

a process of selective hydrogenation of organic sulfur, nitrogen, and oxygen compounds found in motor fuels (gasoline, kerosene, and diesel fuel), oils, and other petroleum products (for example, in raw materials for catalytic reforming). When hydrogen is added, such compounds form hydrogen sulfide, ammonia, and water, which are removed from the product being refined.

Hydrofining occurs in the presence of a hydrogenating catalyst, such as cobalt alumomolybdate, at temperatures of 260°-430° C under a pressure of a hydrogen-containing gas of 1-10 meganewtons per sq m (MN/m²), or 10-100 kilograms-force per sq cm (kgf/cm²), and requires considerable quantities of hydrogen (to reduce the sulfur content by 1 percent, 9-18 cu m of hydrogen is needed for every cu m of raw material). Therefore, hydrofining installations are usually combined with catalytic reforming installations, which produce excess hydrogen. The hydrogen sulfide formed during hydrofining is collected and is used in producing sulfur and sulfuric acid. As a result of hydrofining, the quality of petroleum products is improved and equipment corrosion and air pollution are reduced. The hydrofining of lubricating oils, which is used instead of contact purification with clay, improves the color and smell of the oil and reduces its acidity and coking capacity. The hydrofining process has acquired special significance in connection with the processing of large quantities of sulfurous and high-sulfur petroleum (more than 1.9 percent sulfur).