desulfuration

Desulfuration, also known as desulfurization, is the process of removing sulfur-containing compounds from a substance. It is important in fuels, natural gas, coal, and chemical synthesis because sulfur compounds can drive sulfur oxide emissions, cause corrosion, poison catalysts, and produce malodors.

In petroleum refining, hydrodesulfurization (HDS) is the principal method. It uses hydrogen gas and a metal catalyst (typically cobalt-molybdenum or nickel-molybdenum on an alumina support) at elevated temperatures and pressures. Sulfur compounds such as mercaptans, sulfides, thiophenes, and especially dibenzothiophenes are converted to hydrocarbons and hydrogen sulfide, which is subsequently treated or sold as sulfur. Other approaches include oxidative desulfurization (ODS), which oxidizes sulfur species to sulfones or sulfoxides for extraction, and extractive or adsorptive desulfurization using resins or solvents.

In natural gas and refinery gas streams, sulfur is removed to prevent corrosion and catalyst poisoning and to meet product specifications. Amine treating removes hydrogen sulfide and carbon dioxide; the resulting H2S can be processed in the Claus process to recover elemental sulfur.

Coal desulfurization can be achieved by physical cleaning, chemical leaching, or pyro-metallurgical methods to reduce both pyritic and organic sulfur before combustion.

In chemical synthesis and biology, desulfuration can refer to the removal of sulfur from organic substrates or to enzymatic steps that release sulfide groups. The practice is driven by environmental and economic concerns, notably to lower sulfur oxide emissions, and by the need to meet product standards.

Challenges include removing refractory sulfur compounds, managing energy consumption, and maintaining catalyst stability.