What is Sulfolane?

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  • Written By: C. Martin
  • Edited By: C. Wilborn
  • Last Modified Date: 21 October 2019
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Sulfolane is a type of liquid chemical solvent. It is also called tetramethylene sulfone. It is a colorless, clear liquid that is soluble in water. Sulfolane solvent was first developed in the 1960s by the Shell Oil Company, who used it to purify natural gas.

One of the key properties of this chemical is its solubility in water. The reason for this chemical characteristic is that the molecule is strongly polar. A polar molecule is one that has a distinct positive charge at one side and negative charge at the other. This is similar to a battery, which has one positive end, or pole, and one negative pole.

The systemic name of the sulfolane molecule is 2,3,4,5-tetrahydrothiophene-1,1-dioxide, and it has a molecular structure of C4H8O2S. It belongs to a group of organosulfar molecules called sulfones. These types of molecules are characterized by possessing a sulfonyl group, which is a sulfur atom tightly bonded to two oxygen atoms. It is this sulfonyl group that makes the sulfolane molecule polar.

In its initial commercial usage by the Shell Oil Company, sulfolane was used to remove substances such as carbon dioxide (CO2) and other contaminants from acidic natural gas. The process used was called the sulfinol process. Since it was first discovered, further commercial uses for the chemical have been discovered.


Two of the main modern uses of the chemical are the sulfinol process, which is still used by Shell Oil, and the sulfolane extraction process. This extraction process is a method of producing aromatic hydrocarbons, substances that may be used in the development of some explosives, lubricants, preservatives, and plastics. Both the sulfinol process and the sulfolane extraction process are licensed processes that belong to the Shell Oil Company. The chemical is permitted to be used by other companies for alternate processes, and it is now widely utilized by many organizations in the petrochemical industry.

Sulfolane is generally a very stable chemical, and therefore can be reused multiple times in many of the various processes in which it is utilized. It is a poisonous substance to humans, and should not be ingested or inhaled. Due to its stable nature, it is generally considered safe if it is stored appropriately, and it is not explosive. It can, however, be hazardous if stored incorrectly. It can interact with various other chemicals to form hazardous products, and may also form explosive vapor mixtures with air.


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Post 2

@Charred - I think the article makes clear that sulfolane is safe and can easily be stored without exploding or anything like that.

As for alternatives, like you I don’t know much about the oil industry itself to make recommendations. Perhaps there are more bio friendly methods to purify gas, like bacterial cultures or something like that.

At any rate, as long as the chemical is safe, I don’t personally have a problem with it until we make a complete transition to a green economy.

Post 1

Sulfolane’s usage in ridding carbon dioxide from natural gas introduces a paradox, in my opinion.

In pushing companies to reduce their CO2 emissions, we may in fact be forcing them to use harmful chemicals in the process. In other words, we are fighting fire with fire, aren’t we?

I am not an expert in the oil industry so I don’t know if this is the only way to purify natural gas or if there are other, more environmentally friendly methods.

I just think that when we hand down regulations to reduce CO2 emissions, it should be done with the understanding that it’s done with safe processes.

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