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
    • C4 alkylate has a RON of 94-98 (MON of 92-94)
    • C3 alkylate has a RON of 89-92 (MON of 88-90)
    • C5 alkylate has a RON of 90-92 (MON of 88-93)

Author: Tim Fitzgibbon, Refining Industry Sr. Expert

McKinsey uses cookies to improve site functionality, provide you with a better browsing experience, and to enable our partners to advertise to you. Detailed information on the use of cookies on this Site, and how you can decline them, is provided in our cookie policy. By using this Site or clicking on "OK", you consent to the use of cookies.