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| Two elements |
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The checkered flag symbol was introduced
in 1956, capturing
Sasol’s winning spirit and courage |
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| Petrol, diesel, wax and many industrial chemicals are all made from the
two elements, carbon
and hydrogen. |
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| Many people find that difficult to believe because they think of
carbon as a solid, in the form of charcoal or coke, and of
hydrogen as a gas. How on earth can they be combined to form
a liquid, let alone plastics? |
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| The answer is that if you take, say, one atom of carbon and
form it into a molecule with four hydrogen atoms, you will have
a gas. Go through the same procedure, producing molecules
that each contain rather more atoms of carbon and hydrogen -
say 14 carbon atoms - and you will have a liquid. And how do
you go about forming such molecules? Why, you feed your
carbon and hydrogen atoms into a huge plant called a
reactor, along with a granular, metallic catalyst serving as
marriage broker, apply heat and pressure and wait for the
union to take place. It will do so in the form of a gas
comprised of molecules of all sorts of shapes and sizes. All
you have to do after that is sort them out, for most of them
have commercial value. The first step is to cool the gas so
that larger molecules will form liquids which can easily be
separated from those that form gases. |
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| It sounds easy, but it isn’t. Sasol’s achievement down the
decades has been to overcome major mechanical and
chemical engineering problems so thoroughly and cost-effectively
that, even when the price of crude oil sinks to low
levels, coal can still compete with it as a feedstock for motor
fuels and chemicals. |
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| The process begins, chemically, with the raw synthesis gas
produced by the gasifiers. It contains carbon and hydrogen
atoms, but also other chemical ingredients which Sasol wouldn’t
want in its reactors: sulphur, ammonia, carbon dioxide, phenol.
These are removed in successive stages by two processes: the one,
devised by Lurgi the gasifier manufacturer, is called Rectisol; the
other, known as Sulfolin, was jointly designed by Sasol and the
German company Linde, which also provided Sasol’s first oxygen-producing
plant in Sasolburg. Sasol was the first company in the
world to use both processes on a commercial scale. |
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| The purified synthesis gas, as it is known, is fed into a reactor.
Sasol began its operations using two types of reactor. The one,
initially known as the Kellogg reactor but subsequently
renamed Synthol, employs higher temperature than the other,
known as the Arge reactor. Both, however, employ catalyst
based on iron oxide. More about these remarkable things called
catalysts later; for the moment, let’s stay with the reactors. |
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| Rectisol gas-purification columns |
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