Sub-Product

The BTEX Complex is a Hydrocarbon mixture of Benzene, Toluene, Xylene and Ethylbenzene. These Compounds are refined from Low-Octane Petroleum Products into a High-Octane Gasoline Additive. While some volume of BTEX is native to Gasoline, it is also added to Finished Gasoline to boost its Octane Rating. The total volume of BTEX (Aromatics) in Finished Gasoline depends on the desired Octane Value and other desired Fuel Properties.

Source: Jessie Stolark, 30^th March 2016, Fact Sheet | A Brief History of Octane in Gasoline: From Lead to Ethanol, Environmental and Energy Study Institute.