Back to: Jss2 Basic Science (BST)

Introduction

Crude oil is extracted deep in the earth. It can be burned as fuel, and the chemical industry uses it as a raw material. In this section, you’ll find out what crude oil and petrochemicals are, how crude oil is refined, and what crude oil and petrochemicals are used for.

Meaning of crude oil and petrochemicals

Crude oil is a thick, bituminous liquid that is also called petroleum. It is made up of different kinds of hydrocarbons (hydrocarbons are compounds that contain carbon and hydrogen only). When crude oil is refined, it can be used to make useful things like kerosene, gasoline, naphtha, diesel, and different kinds of petrochemicals.

BREAKING DOWN of Crude Oil

Crude oil is usually obtained by drilling for it. It is often found with other resources, like natural gas (which is lighter and sits on top of crude oil) and salt water (which is denser and sinks below). It is then cleaned up and turned into things like gasoline, kerosene, and asphalt, which are then sold to consumers.

Even though it is often called “black gold,” crude oil can be thick or thin and can be different shades of black or yellow, depending on the hydrocarbons it is made of. The first step in refining is distillation, which is when oil is heated and split into different parts.

Petrochemicals

The chemical products that come from oil are called petrochemicals. They include alkenes (e.g ethene and propene) and aromatic hydrocarbons (e g. benzene and toluene).  Catalytic cracking is the process by which these petrochemicals are made from petroleum fractions.

The most common types of petrochemicals are olefins, which include ethylene and propylene, and aromatics (including benzene, toluene, and xylene isomers). In oil refineries, olefins and aromatics are made by the fluid catalytic cracking of petroleum fractions. Natural gas liquids like ethane and propane are cracked with steam in chemical plants to make olefins. Naphtha is reformed with a catalyst to make aromatics. Olefins and aromatics are the building blocks for a wide range of materials, such as solvents, detergents, and glues. Polymers and oligomers, which are used to make plastics, resins, fibres, elastomers, lubricants, and gels, are made from olefins.

Based on their chemical structure, primary petrochemicals can be put into three groups:

Olefins

Ethylene, propylene, and butadiene are all types of olefins. Both ethylene and propylene are used to make a lot of important industrial chemicals and plastics. Man-made rubber is made with butadiene.

Aromatic 

Benzene, toluene, and xylenes are all types of aromatics. Benzene is used to make dyes and detergents made from chemicals. Benzene and toluene are used to make the isocyanates MDI and TDI, which are used to make polyurethanes. Plastics and synthetic fibres are both made with xylene.

Hydrocarbon

Carbon monoxide and hydrogen are mixed to make a synthesis gas. This gas is used to make ammonia and methanol. Urea, a type of fertilizer, is made from ammonia, and methanol is used as a solvent and as a step in the chemical process.

Refining of crude oil

1. Distillation

In modern distillation, oil is pumped through pipes in hot furnaces, and light hydrocarbon molecules are separated from heavy ones in tall, thin columns called distillation towers. These towers give refineries their distinctive skylines.

2. Cracking

Since the market decides what a product is worth, our competitive edge depends on how quickly we can turn middle distillate, gas oil, and residuum into the highest-value products. Using a series of plants that “crack” large, heavy molecules into smaller, lighter ones, refineries turn middle distillate, gas oil, and residuum into mostly gasoline, jet fuel, and diesel fuel. Three “cracking” methods use heat and catalysts to turn heavier oils into lighter products: fluid catalytic cracking (FCC), hydrocracking (Isomax), and coking (or thermal-cracking).

3. Treating (Removing Impurities)

Some natural impurities, such as sulphur and nitrogen, are found in the products from the Crude Units and the feeds to the other units. Hydrotreating, which is a milder version of hydrocracking, is used to get rid of these impurities so that our fuels don’t pollute the air as much when they are burned.

4. Reforming

The octane rating is a key way to figure out how well gasoline works in an engine. A lot of the gasoline that comes from the Crude Units or the Cracking Units doesn’t have enough octane to burn well in cars. In a refinery, gasoline process streams with a low octane rating are sent to a Reforming Unit, where their octane levels are raised. Because platinum and rhenium are used as catalysts in these reforming units, they are called “rheniformers.” In the process of reforming, molecules of hydrocarbon are “reformed” into parts of gasoline with a high octane rating. Toluene is made by changing methyl cyclohexane into it.

Blending

The last and most important step is mixing our products. For example, gasoline is made by mixing together parts that have been treated and made in different processing units. Operators in the Blending and Shipping Area mix these carefully so that the blend has the right octane level, vapour pressure rating, and other important specs. All of the products are mixed in the same way.

Quality Control

Chemists and technicians test the quality of all finished products in the refinery’s modern Laboratory. For example, they check the octane rating of gasoline. During the reforming process, hydrogen is taken out of low-octane gasoline. The hydrogen is used in different cracking (hydrocracking) and treating (hydrotreating) units all over the refinery.

Uses of crude oil

These things can be done with petroleum products:

1. Jet engines and cooking stoves use kerosene as fuel.
2. Petrol, which is also called gasoline, is used to power cars.
3. Naphtha is a raw material that is used to make plastics and petrochemicals.
4. Diesel is used in fueling diesel engines.
5. Lubricants like grease and motor oil are used to keep moving parts of engines from rubbing against each other.

Uses of petrochemicals

1. Some petrochemicals can be used in the following ways:
2. Ethene is used to make bin bags and film for cameras.
3. Polyester is used to make things out of plastic, like CDs and cassettes.
4. Candles are made out of wax.
5. Fertilizers are used to increase the amount of crops that can be grown on a farm.

Importance of crude oil to Nigeria

1. Crude oil is a source of income for the country.
2. It can be used to buy and sell foreign currency.
3. It’s a big source of energy.
4. It gives people in Nigeria a chance to get a job.