 In other versions, the catalyst is impregnated onto charcoal granules.Processes within oil refineries or natural gas processing plants that remove mercaptans and/or hydrogen sulfide (H2S) are commonly referred to as "sweetening" processes because they results in products which no longer have the sour, foul odors of mercaptans and hydrogen sulfide.The liquid hydrocarbon disulfides may remain in the sweetened products, they may be used as part of the refinery or natural gas processing plant fuel, or they may be processed further.