| :: What are aromatics ? |
| In the beginning there was crude oil... |
| From aromatics to consumer products |
| The chemistry of aromatics |
In
the beginning was crude oil…It all begins with crude oil (petroleum) and natural gas. Crude oil and natural gas occur in the earth's crust; they were formed millions of years ago, as a result of slow and lengthy processes from decayed plants and animals, buried deep into the earth's crust under tremendous pressure.
Crude oil and natural gas are extracted from the ground, on land or under the oceans, by sinking an oil well. They are then transported to refineries, by ship and/or by pipeline, lines of pipe equipped with pumps, valves and various other control devices specially adapted for moving liquids and gases.
What
happens at the refinery
The job of the refinery
is to produce physical and chemical changes in crude oil and natural gas,
through an arrangement of extremely specialised manufacturing processes.
One of these processes is distillation, i.e. the separation of heavy crude
oil into lighter groups (called fractions) of hydrocarbons. Two of these
fractions are familiar to consumers. One, fuel oil, is used for heating
of for diesel fuel in automotive applications. Another one is naphtha,
used in gasoline and also as the primary source from which petrochemicals
are derived.
Petrochemistry
steps in
As far as the petrochemical product flow is concerned, refining is where
the job of the oil industry stops, and this is where petrochemistry takes
over. The petrochemical industry gets its raw material - known as feedstocks
- from the refinery: naphtha, components of natural gas such as butane,
and some of the by-products of oil refining processes, such as ethane
and propane.
These feedstocks are then processed through an operation that is known
as cracking.
Cracking is simply the process of breaking down heavy oil molecules into
lighter, more valuable fractions. In steam
cracking, high temperatures are used; when a catalyst is used it is
known as catalytic cracking. The plant were these operations are conducted
is called - logically enough - a cracker.
Once these operations are concluded, new products are obtained: the building
blocks of the petrochemical industry, olefins
(ethylene, propylene,
butadiene...)
and aromatics – benzene,
toluene, xylenes,
as we mentioned before.
From
mysterious to familiar products
These products are then processed in petrochemical plants into other,
more specialised products - and it sometimes takes much more than one
step for these products to be fit to be used by the so-called downstream
industries, the customer industries of petrochemistry. It takes more than
seven steps to go from benzene to the nylon
used in our clothes and sports equipment!
In the end, aromatics are contributing to manufacturing products that
we are all familiar with: healthcare products such as the aspirin, medical
equipment, plastics, soaps and detergents, synthetic fibres for clothes
and furniture, rubbers, paints, insulating materials...
This complex process is summed up in a flow
chart, detailing the main steps between aromatics and consumer products.
If you are curious about the impressive array of uses for aromatics, visit
the section: Aromatics
and everyday life.