In this blog post, we’ll explore just how important oil is to our daily lives and examine the process by which crude oil is refined and used as a raw material for various petrochemical products.

What would happen to the world if oil disappeared?

What would happen to our world if everything related to oil were to disappear right now? Let’s imagine you step outside for a moment and find that everything that relies on oil has vanished. The first thing you’d see would be deserted streets—though you couldn’t even call them streets. The paved sidewalks and roads would be gone, and the supermarket you frequented would be nowhere to be seen. To exaggerate a bit, a landscape resembling the vast grasslands seen in movies might unfold before you. It’s even highly likely that the clothes you’re wearing contain fibers made from petroleum. Panicked, you’d try to go back inside, but since your house is also made from various petrochemical products, it would be difficult for it to remain in its current form.
While this is a somewhat extreme scenario, it’s not entirely far-fetched. This is because it is extremely difficult to find a product that does not use petroleum at all. Of course, products aren’t made from petroleum alone. Various chemical raw materials obtained by refining and processing petroleum are used as the basic materials for countless industries.
Refining crude oil yields various petroleum products, including naphtha, gasoline, kerosene, diesel, liquefied petroleum gas (LPG), and heavy oil. Naphtha, in particular, is a key raw material for producing basic petrochemicals such as ethylene, propylene, and butadiene, which in turn serve as raw materials for synthetic resins, synthetic fibers, synthetic rubber, and various chemical products. Since the chemical products produced in this way are used as basic materials in various industries—including the automotive, electronics, construction, and textile sectors—the petrochemical industry has a profound impact on modern industry as a whole. Petroleum is not only the foundation of high-value-added industries but also an important resource that generates significant economic value in its own right.
Crude oil freshly extracted from the ground is a mixture of components such as gasoline, naphtha, kerosene, diesel, and heavy oil. Since the petrochemical industry uses naphtha as its primary feedstock, the process of separating the necessary components from crude oil is essential. Let’s now explore the methods used to separate naphtha and other petroleum fractions from crude oil.

What principles govern the separation of crude oil?

It is known that petroleum was formed when biological organic matter was deposited long ago and transformed over a long period under high pressure and temperature. While there are various theories regarding the formation process, the organic origin theory—which posits that marine microorganisms and plant-based organic matter were subjected to heat and pressure in sedimentary layers—is currently the most widely accepted. Crude oil consists mostly of hydrocarbons.
Since hydrocarbons are nonpolar molecules, intermolecular forces are primarily driven by dispersion forces. Generally, as molecular weight increases, dispersion forces become stronger, and as the number of carbon atoms increases, the boiling point rises. In contrast, polar molecules are subject to various intermolecular forces in addition to dispersion forces, such as dipole-dipole interactions and hydrogen bonding. The crude oil refining process takes advantage of these differences in the boiling points of hydrocarbons.
Crude oil is a liquid mixture of various fractions, such as gasoline, naphtha, kerosene, and diesel. Since each fraction contains a different number of carbon atoms, their boiling points also differ. When crude oil is placed in a flask and heated, the component with the lowest boiling point vaporizes first. If this vapor is cooled, it condenses back into a liquid and can be collected separately. This method of separating a liquid mixture by exploiting differences in boiling points is called fractional distillation.

How is crude oil refined in a distillation column?

In industrial settings, the principle of fractional distillation is applied in distillation columns. Distillation columns are generally tall, cylindrical structures. When crude oil is fed into the bottom of the column and the lower section is heated intensely, the components with lower boiling points vaporize first, one after another. Typically, the components are separated in the following order: liquefied petroleum gas (LPG), naphtha, kerosene, diesel, middle distillates, and residual oil.
Inside the distillation column, the temperature is higher at the bottom and gradually decreases toward the top. Therefore, components with lower boiling points rise to higher levels, while those with higher boiling points condense at the bottom. By installing outlets at the points where each fraction condenses, the desired components can be separated and obtained individually.
The typical number of carbon atoms and boiling point ranges for major fractions are as follows. Liquefied petroleum gas (LPG) has approximately 1 to 4 carbon atoms and a very low boiling point. Naphtha has approximately 5 to 10 carbon atoms, kerosene has approximately 11 to 15, diesel fuel has approximately 16 to 20, and fuel oil has approximately 21 to 25; components with a higher number of carbon atoms are classified as residual oil. Generally, as the number of carbon atoms increases, the boiling point also rises.
The crude oil refining process described here represents the most fundamental step in the petrochemical industry. In fact, the various products we use—such as plastics, synthetic fibers, automotive parts, materials for electronic devices, and raw materials for pharmaceuticals—are produced by subjecting refined petroleum fractions to a series of chemical processes. If reading this article has not satisfied your curiosity, I encourage you to explore petroleum and petrochemicals in greater depth. It will be of great help in understanding the processes through which the countless products around us are made.