The gas-to liquids process (GTL) takes hydrocarbons such as methane-rich natural gas and converts them into longer-chain hydrocarbons such as diesel fuel. There are two primary processes: Fischer-Tropsch and Mobile.
Fischer-Tropsch was developed by two German scientists in the 1920s, while Mobile was developed in the mid-1970s. Fischer begins the process with the partial oxidation of natural gas (methane) into carbon dioxide, carbon monoxide, hydrogen, and water. The ratio of hydrogen to carbon monoxide must be adjusted and later the excess carbon dioxide and excess water are removed. This leaves a synthetic gas (syngas) that is reacted to in an iron or cobalt catalyst. The result is liquid hydrocarbons and other byproducts.
Gas-to-Liquids process using the Fischer-Tropsch process
The Mobile process converts the natural gas to a syngas, and then it converts the syngas to methanol. It is then polymerized into alkanes over a zeolite catalyst.
While GTL can also produce other chemical feedstock, the primary commercial interest in this technology is the creation of transportation fuels. Entities with large amounts of low-cost natural gas reserves have explored using the technology as a way to create more markets for the natural gas. But it is only commercially viable if the cost of the natural gas resource, plus the cost of the conversion, is lower than the cost of traditional diesel or jet fuel refined from oil.