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.

Tungsten is a heavy metal exhibits the highest melting point among all the refractory metals. The pure tungsten has a yield strength of 750 MPa and excellent tensile strength of 900 MPa. Due to its amazing strength and hardness, tungsten was widely applied in various fields include defense industry, aerospace industry, and nuclear industry. The conventional alloying method by combining tungsten with other metals is a proven efficient route to enhance its properties to extend its applications.

The emergence of quaternary-compound tungsten electrode, which also called WX4, marks a new area of tungsten electrode material, as well as a revolutionary development of the relevant technology, making the reliability and stability of the electrodes further improved. In 2017, based on the Tri-mix composite rare earth technology, China’s researchers continued to break through the technical barriers and are the first one to add four kinds of different rare earths to tungsten, e.g. lanthanum, cerium, zirconium, and yttrium.