How is Crude Oil Converted to Gasoline?

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  • Written By: Mary McMahon
  • Edited By: Niki Foster
  • Last Modified Date: 10 August 2018
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Crude oil is converted to gasoline through a relatively simple refining process. The transformation begins with the extraction of oil from the ground, after which it is usually loaded into large container ships that deliver it to refineries all over the world. As any viewer of news footage has seen, crude oil emerges as a thick black substance, which does not resemble the clear and free-flowing gas used in motor vehicles. This is because crude oil is actually a mixture of hydrocarbons.

As the prehistoric plants and animals that make up crude oil broke down, they formed hydrocarbons consisting of variously sized chains and structures. Each hydrocarbon has a unique application, which the refinery process aims to maximize. The use for each depends on the number of carbon atoms in its structure. Gasoline, for example, has eight carbons, while light gases like propane have only three. Hydrocarbons have a lot of energy, when they can be disentangled, and the refining process accomplishes this.

The most important part of the refining process is known as fractional distillation. Because the hydrocarbons all have different boiling points, they can be separated by heating. The crude oil is heated in a boiler to temperatures up to 1112°F (600°C), which coverts all the hydrocarbons into a vapor. As they cool below their boiling points, they precipitate out as liquids.


The vapor is routed through a distillation column. At the bottom, the hydrocarbons with the highest boiling points are caught first on a screen that pulls out the residual, or coke, which is often flashed or burned for energy. The vapor moves up the column, and as it cools, screens along the way catch the various hydrocarbons, such as diesel, kerosene, gasoline, naphtha, and the light gases.

All of these outputs must be treated for impurities before they can be shipped. A sulfuric acid column removes particles, unsaturated hydrocarbons, oxygen compounds, and nitrogen compounds. Then, the liquid is passed through an absorption column that removes water, and it is treated to remove sulfur. After this process, the various crude products can be shipped to their end destinations through a large network.

Gasoline comprises almost half the output of a barrel of crude oil, although the chains that make up this hydrocarbon do not make up half a barrel. This difference is resolved through chemical refining, which allows refineries to build up or break down hydrocarbon chains to get different products. Chemical refining outputs are changed depending upon the demand, which is frequently heaviest for gasoline.

When hydrocarbons are broken down into small components, it is called cracking. Cracking can be accomplished by introducing heat to the hydrocarbons or by using a chemical catalyst, like hydrogen gas. When hydrocarbons are combined to form longer chains, it is known as unification. Unification most commonly uses platinum as a catalyst to combine small carbon chains, producing hydrogen gas as a byproduct. The hydrogen gas can be used for cracking or sold. Hydrocarbons are also chemically altered in a a process called alkylation, which combines compounds of a low molecular weight with a catalyst and introduces the mixture to the hydrocarbons being altered.

The process whereby crude oil is turned into gasoline is carried on at high volume all over the world. Most refineries are extremely efficient, using every hydrocarbon chain separated during the distillation process and tweaking the output as needed to adjust for market demands. The supply of crude oil is known to be limited, however, raising questions about the longevity of the future of refining. In addition, most of the world is heavily dependent upon oil from one highly unstable source: the Middle East.


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Discuss this Article

Post 9

The process of refining the is simple, and you are killing the planet. Take the money out of gasoline and I know that there many self-sustaining fuel sources.

Post 8

Is there any other method to separate the various cuts of crude with out heating the crude?

Post 5

Are naphtha stoves safe for heating the house?

Post 4

Could someone tell me why you couldn't distill gas in your back yard?

Post 3

So one is led to believe that once the oil companies pay for a barrel of oil that only gasoline comes from it, and that's their only profit from that particular barrel.

Diesel, kerosene, naphtha, hydrogen and many more products are extracted from it. There fore fivefold profitable products are made. The beat goes on and on and on!

Post 2

@ Anon1976 - I live in the U.S., so our gasoline tax system is very different. Gas here is heavily subsidized through tax credits and direct subsidies to petroleum companies. There are also many variables in the final price of a gallon (or liter in your case) of gasoline. These variables can be the grade of the crude oil, current market price of crude, cost of ethanol (if gas is oxygenated), various tax rates, and distributor marketing and mark-ups. I'll try my best to break it down for you though.

I will use France as an example. Gas prices before taxes and duties in France are 0.54 €/liter. The average price of gas in France as of June 2010

is 1.37 €/liter (all of this information can be found at ). This makes Frances effective tax rate about 60.5% for gasoline (a little higher or lower depending on where you are in Europe).

I converted the average price per gallon in the U.S. to the average price per liter in Euros. I used the exchange rate, and average gasoline price for 14 June, 2010 so that the comparison could be as accurate as possible.

In the U.S., we pay the equivalent of 0.58 €/liter after taxes and fees. We also pay the same or nearly the same for gasoline before taxes and fees (0.54 €/liter). This means that our effective tax rate after subsidies, and taxes is somewhere around 9.3%. A big difference, but it has left us vulnerable to large swings in gas prices, and little money for the development of alternative energy technologies. These subsidies have made the United States much more dependent on crude oil than any other nation, so don’t feel too bad.

Post 1


pls. explain to me the following:

average price for gasoline is around 1,20 €.

about 80% is tax.

how can a material which costs around 25 cents

(not including tax), which is converted and has value added be made from a raw material which is sold at a much higher price?

where is my problem?

thanks for your reply

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