with an amine gas treating process. There are physical and chemical absorption processes to removing the toxic properties of these gases, both of which involve the syngas being washed with a lean solvent in an absorber to remove the H2S. Once the toxic gas leaves the bottom of the absorber it is sent to a regenerator where the solution is further stripped with steam under extremely lower pressures to remover the sulfur from the gas. The removed H2S is most often subsequently converted to by-product elemental sulfur in a Claus process or alternatively converted to valuable sulfuric acid in a WSA Process unit. Processes within oil refineries or natural-gas processing plants that remove mercaptans and/or hydrogen sulfide are commonly referred to as 'sweetening' processes because they result in products which no longer have the sour, foul odors of mercaptans and hydrogen sulfide. See also Oil refinery Rectisol Selexol References Natural gas Oil refining Industrial gases