Fractional Distillation of Crude Oil and Its Final Products

In manufacturing petroleum products, the petrochemical plant must carry out a series of processes, one of which is fractional distillation of crude oil. The result of this process is called a fraction.

Then, what is the crude oil fraction? This article discusses fractions in the fractional distillation of crude oil and the fractional orders. So, read this article until the end!

An Overview of Crude Oil

Before we jump into crude oil fractions, you must know the main feedstock in fractional distillation, which is crude oil. Crude oil is a pitch-black oil naturally formed inside the Earth.

It contains organic hydrocarbons with complicated structures that come from millions of years of fossils. To extract crude oil, you must drill an oil well on land or sea.

According to Our World in Data, the United States sits at the top of crude oil production, with 9,620 TWh, followed by Saudi Arabia with 6,813 TWh. On the other hand, Statista mentioned that crude oil demand in 2024 reached 103.75 million barrels per day and is predicted to increase in 2025.

Crude oil that has been extracted from underground will be processed into petrochemical and other industrial products, such as plastic and rubber.

Fractional Distillation of Crude Oil Process

To be a fraction, crude oil must undergo one of the most important processes, which is fractional distillation, happening in a distillation tower or fractionation column.

Fractional distillation separates a mixture of substances in crude oil at a certain boiling point to produce distillate. The distillate is used as a final product or feedstock for commercial products.

The distillation process also separates hydrocarbon components in crude oil to make fractions. Fractions are hydrocarbon components having different boiling points. Moreover, here are the steps of fractional distillation of crude oil you should know:

Crude oil is heated to a high temperature (about 600 degrees Celsius).
The crude oil mixture will boil and form vapor (most of these substances turn into vapor).
The vapor that enters the fractional distillation column is introduced with the liquid in it. The temperature at each height of the column is different.
When the substance in the vapor reaches a temperature similar to its boiling point, it will condense into a liquid. The liquid is collected by the distillation column trays.

Crude Oil Fractions

The distilled crude oil components will form fractions. The lightest fractions are too volatile to condense, while the heaviest fractions are too compact to evaporate. Here is the order of crude oil fractions:

1. Natural Gas

Natural gas is the lightest distillate formed at the top of the distillation tower, which is the coolest area of the tower. Examples of natural gases are propane (C3H8) and butane (C4H10), which are used to make LPG.

Natural gas has approximately 1–4 carbon atoms per molecule with a boiling point below 20 degrees Celsius. Natural gas is used as a raw material for gas lighters, fuel for heaters, and to make other compounds, such as ethene, carbon disulfide, and carbon tetrachloride.

2. Ligroin and Petroleum Ether

Ligroin and petroleum ether have 5–7 carbon atoms per molecule with a boiling point between 20 and 120 degrees Celsius. Typically, these fractions are used to produce organic solvents.

3. Gasoline

Gasoline is a fraction having 5–12 carbon atoms per molecule and a boiling point of 40–205 degrees Celsius. Gasoline is commonly used for vehicle fuels, heaters, lighters, as well as paint and lubricant solvents. It also belongs to intermediate distillate and is classified as fuel. It is formed in the middle of the distillation tower.

4. Kerosene or Paraffin

Kerosene or paraffin is an intermediate distillate formed in the middle of the distillation tower. Kerosene has 12–18 carbon atoms per molecule with a boiling point of 175–325 degrees Celsius. Kerosene is used for heaters, lighters, jet fuels, and tractor fuels. It is also used as a solvent.

5. Gas Oil and Diesel

These two fractions are formed in the central area of the distillation tower. Gas oil and diesel have 12–25 carbon atoms per molecule and a boiling point of 275–400 degrees Celsius. Gas oil and diesel are often used for heaters, alternative fuels, diesel engine fuels, and feedstock in cracking processes.

6. Lubricant, Vaseline, and Wax

Lubricant, vaseline, and wax have more than 20 carbon atoms per molecule and a boiling point of over 400 degrees Celsius. These fractions are commonly used as solvents, medicines, raw materials for commercial wax, waterproof coatings, and ointments.

They belong to the low distillate formed at the bottom of the distillation tower. This product has a high density and boiling point. This fraction is also not used as a fuel but as a lubricant.

In addition to those three products, low distillates also include marine gas oil (MGO), heavy fuel oil (HFO), marine diesel oil (MDO), intermediate fuel oil (IFO), and marine fuel oil (MFO).

7. Asphalt, Bitumen, and Other Residues

Asphalt and bitumen are the residues produced at the bottom of the distillation tower. For your information, the higher up the distillation tower area, the colder the temperature, and vice versa.

This means that the residue is formed in the hottest areas of the tower and is too dense to evaporate to higher areas of the tower. Asphalt and bitumen have more than 40 carbon atoms and boiling points of over 400 degrees Celsius. Asphalt and bitumen are used for coating the road.

That concludes the information about fractional distillation of crude oil and the fractions. Crude oil gives many benefits, especially in becoming a feedstock for industrial chemical manufacture.

To provide high-quality industrial chemicals, Chandra Asri Group, as a leading chemical solution company in Southeast Asia, ensures that every manufacturing process is carried out in a standardized and proper manner.

As a result, Chandra Asri Group can supply chemicals, such as olefin, butadiene, and many more, for industrial purposes. Therefore, entrust your industrial chemicals to Chandra Asri Group!