Alkylate is the primary product of the alkylation unit, which converts light olefins (such as butylene) into a high-quality gasoline blendstock by reacting it with isobutane.
There are several types of alkylate, based on the different olefins used to produce it. The most common and desirable is C4 alkylate, which is produced from alkylating (joining) butylene with isobutane. However, alkylate can also be made from propylene and isobutane, or pentene and isobutane.
C4 alkylate is preferred because it has the most desirable properties for gasoline blending, high octane, and low vapor pressure. All alkylates also benefit from containing no aromatic components.
Alkylate is considered a premium gasoline blendstock because of its combination of properties:
- Low sulfur content - Alkylate has no sulfur
- Low aromatics content - Alkylate contains no aromatics
- Low vapor pressure - Alkylate has a low vapor pressure
- C4 alkylate has an RVP of 2.6 psi
- C3 alkyate has an RVP of 3.8 psi
- C5 alkylate has an RVP of 4.0 psi
- High octane - Alkylate has medium to high octane depending on the type
Author: Tim Fitzgibbon, Refining Industry Sr. Expert