Petrochemicals, from Naphtha to Plastic
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Petrochemicals, from Naphtha to Plastic
Petroleum chemistry is the chemistry of oil derivations, principally naphthalene, and of natural gas. It has made great strides since the Second World War and, during recent decades, has demonstrated an exceptional growth.
The raw materials used by the petrochemical industry are mainly natural gas and naphtha from the oil refining operation. In petrochemical factories, which are inseparable from the refineries, naphtha is treated in a steam cracker where it's heated to a very high temperature of 800° Celsius in the presence of water vapor. It splits into light hydrocarbons, called the “major intermediaries”. They are olefins and aromatics.
Among the olefins there are chains of two carbons ( ), three carbons ( ), or four carbons (butane and butadiene). The aromatics consists of , and xylene.
Plastic materials do not exist in a natural state; they are obtained thanks to the magic of chemistry and polymerization. The latter is a chemical reaction that allows the creation of repeating chains of small molecules, thus forming long molecular chains called polymers.
When these polymers come out of a chemical factory, they still don't look like the plastics we see in everyday life. Most often they are in the form of granules or powders. Therefore, before being an everyday plastic object, they must follow a sequence of transformations. This sequence will give them a shape, a color and precise properties, according to the use one intends making of them.
They will be kneaded, heated, melted, supplemented with other chemical products, cooled, even molded. In the end, they come out in the form of tubes, plates, hollow or solid objects according to the transformation techniques used.
Petrochemicals are derived from petroleum — primarily naphtha and natural gas — and, increasingly, from .
Petrochemical plants use steam crackers to heat naphtha to 800°C, which breaks down (“cracks”) into lighter hydrocarbons known as intermediates. The olefins and aromatics obtained then undergo further processing to produce a wide array of products, such as plastics or solvents.
Plastics are obtained by , a chemical reaction that creates a repetitive chain of small molecules that form longer chains known as polymers. The polymers in pellet or powder form are then processed into all kinds of plastic materials. In addition to being sturdy and malleable, plastic has the added advantage of being lightweight. This makes it particularly attractive to many businesses looking to reduce their environmental impact.
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