Sulfur compounds in fuel are converted into SOx when combusted. Furthermore, SOx in automobile exhaust degrades the catalytic converter performance resulting in increased NOx emission which is another important air pollutant. In recent years, ultra-low-sulfur diesel (ULSD) was required in many countries by mandating stringent legislation to cut the S-content down to 10 ppm. At present, the traditional hydrodesulfurization (HDS), a conventional commercial technology, is wildly employed in the purification of fuels. Although HDS can remove various S-compounds such as thiols, sulfides and disulfides, when the deep desulfurization of diesel fuel is required, HDS is less effective due to the low hydrogenation activity to heterocyclic thiophenic compounds

The more stringent limitations on the content of sulfur in the petroleum raw materials stimulated in recent years new research dealing with catalytic desulfurization processes. The key trend in the purification of liquid hydrocarbon raw materials is hydrotreatment in which sulfur is removed as hydrogen sulfide, which is then subjected to the Claus process to be converted to elemental sulfur.

Ultra coarse tungsten powder can not only be used to prepare high-toughness and high-density alloys, such as petroleum perforating bullets, heavy armor-piercing bullets and radiation protection materials, but also raw materials for the production of ultra-coarse tungsten carbide, which is mainly used for ultra-coarse-grained cemented carbide, then used for drill bits for oil drilling, mining, tunneling, hard coating spraying, etc.