The isomerization unit converts light naphtha into a higher-value gasoline blendstock by changing its molecular shape and raising its octane. The primary product of isomerization is called isomerate.

The value from isomerization is its ability to upgrade light naphtha into gasoline. While the resulting isomerate is not high octane (typically 82-87 RON) it is much better than light naphtha at around 70 RON.

How it works

Light naphtha containing C5s and C6s is mixed with a small amount of hydrogen, raised to 200-400 degrees F (93-204 degrees C), and injected into a reactor vessel containing a platinum catalyst. The catalyst and heat convert the C5 and C6 molecules into their isomers. Typically, unreacted C5s and C6s are recycled to increase yield.