Various natural gas sweetening processes were developed and grasped at home, and have met the gas field developing need on the whole at present.

“Sweetening” is the removal of CO2, hydrogen sulfide and other contaminants from contaminated gas, (often called sour gas due to the sulphur smell), and is a $12 billion-year-business in the US alone.

Thiophene is removed from a multicomponent gas mixture by using activated carbon as carrier. The sweetening agent of thiophene is recoverable and reusable.