Sub-Product

What is motor gasoline?

Gasoline is a fuel made from Crude Oil and other Petroleum liquids. Gasoline is mainly used as an engine fuel in vehicles. Petroleum refineries and blending facilities produce motor Gasoline for sale at retail Gasoline fueling stations.

Modern gasoline may be blended to meet simultaneously 10 to 15 different quality specifications, such as vapour pressure; initial, intermediate, and final boiling points; sulfur content; colour; stability; aromatics content; olefin content; octane measurements for several different portions of the blend; and other local governmental or market restrictions.^[1]

Gasoline blending is much more complicated than a simple mixing of components. First, a typical refinery may have as many as 8 to 15 different hydrocarbon streams to consider as blend stocks. These may range from butane, the most volatile component, to a heavy naphtha and include several gasoline naphthas from crude distillation, catalytic cracking, and thermal processing units in addition to alkylate, polymer, and reformate.^[1]

Common Gasoline Blends

Some examples of gasoline blends include:^[2]

• Gasoline blends based on their octane rating:
  • Regular gasoline: with an octane rating of 87, it is the most commonly used fuel for conventional gasoline-powered vehicles.
  • Mid-grade gasoline: typically with  an 89 octane rating, positioning it between regular and premium grades.
  • Premium gasoline: featuring higher octane ratings typically ranging from 91 to 94, it is specifically designed for high-performance engines and vehicles with turbochargers or superchargers.
• Ethanol Blends:
  • E10: the standard gasoline blend in most U.S. stations contains 10% ethanol mixed with conventional gasoline.
  • E15: This blend contains 10.5% to 15% ethanol mixed with gasoline and is available at over 3,000 stations across 31 U.S. states.
  • E85 (Flex Fuel): A high-ethanol blend containing 51-83% ethanol (percentage varies by season and geography) mixed with gasoline. This fuel is specifically designed for flex-fuel vehicles.
• Specialty Blends:
  • Reformulated Gasoline (RFG): A cleaner-burning gasoline containing specific additives and oxygenates to reduce harmful emissions.
  • Low RVP Gasoline: A special summer blend with lower volatility to minimize evaporation and reduce smog formation.
  • Ethanol-Free Gasoline (REC-90): A specialized 90-octane fuel without ethanol content, primarily marketed as recreational fuel for boats, small engines, and older vehicles.

Gasoline Specifications

For the refinery owners, the goal during blending is to meet the minimum specifications required, for the lowest costs. Exceeding the specification usually means too much of the expensive, high-end components have been used. On the other hand, not meeting the specification means a batch might have to be sold as a lower grade product, at less value.^[3]

The two properties of major importance are:^[3]

• the octane number (indicating how much compression the fuel can withstand before self-igniting)^[4]
• the Reid Vapour Pressure or RVP (indicating the volatility of the product). The RVP may vary between seasons, as the products will be less volatile in winter, when it is colder.^[5]

The relation between octane number and RVP for selected blending components used to formulate motor gasoline is presented in Fig. 1.^[6] 

Figure 1 - Typical Gasoline Blending Componet Properties.^[6]

Legend: The (R+M)/2 refers to the average of the research octane number (RON) and the motor octane number (MON) ratings.

The specification for selected gasoline types is presented in Table 1.^[6] 

Table 1 - Gasoline Specifications.^[6] 

Legend: a. RBOB stands for Reformulated Blendstock for Oxygenate Blending, a component that is used to create reformulated gasoline. Reformulated gasoline produces less smog than other gasoline blends. As a result, around 30% of the U.S. market requires gasoline to be reformulated.^[7] b. Tier 3 is a set of federal EPA standards that requires petroleum refiners to reduce the sulfur content of gasoline from an annual average of 30 parts per million (ppm) to 10 ppm.^[8] c. CARBOB, a special RBOB (Reformulated Blendstock for Oxygenate Blending) formula mandated by the state of California.^[9] d. Emissions from heavy-duty vehicles (Euro VI).^[10] e. China V gasoline.^[11]

Technical Review

For the reference, Chevron's Motor Gasoline Technical Review^[12] is made available. 

References

1. Gasoline blending, Britannica. (Accessed 14^th Nov 2024)
2. 18^th Nov 2024, Perplexity A.I. prompt: "What are commong types of gasoline blends, meaning types of retail gasoline based on their composition".
3. Gasoline blending in the oil & gas industry, KHRONE. (Accessed 14^th Nov 2024)
4. Gasoline explained, U.S. Energy Information Administration (E.I.A.). (Accessed 14^th Nov 2024)
5. Alan Apthorp, 29^th Mar 2023, What Is It - Reid Vapour Pressure (RVP), MANSFIELD.
6. Hye Kyung Timken et al., 6^th Mar 2020, A New Era for Alkylation: Ionic Liquid Alkylation – ISOALKY™ Process Technology white paper, Honeywell UOP.
7. RBOB Gasoline Futures Contract Specs, Chicago Mercantile Exchange Group.
8. tier 3, Chevron Global, Salt Lake City.
9. 20^th June 2017, The Gasoline BOBs – CBOB and RBOB (and CARBOB), We Are The Practitioners.
10. The EURO VI norms: what you should know, WollLubes.
11. Jan 214, CHINA V GASOLINE AND DIESEL FUEL QUALITY STANDARDS, The International Council on Policy Standards.
12. 5th Jun 2009, Motor Gasoline Technical Review, Chevron.