Oil and gas production handbook An introduction to oil ... - ABB Group

utane) to alkylates, mainly isooctane or isoheptane by adding an alkyl
group such as propene or butene over a strong acid catalyst, such as
sulfuric or hydrofluoric acid.
Dimerization is similar to alkylation, but uses a dimer group instead of an
alkyl group. For example, butenes can be dimerized into isooctene, which
may be hydrogenated to form isooctane.
Isomerization units convert linear molecules to higher-octane branched
molecules by rearranging the same atoms arranged in a different way. For
example, C 4 H 10 n-butane has the carbon atoms in a chain, while isobutane
has a central carbon with one hydrogen and three CH 3 groups attached. The
isobutane can then be fed to the alkylation unit.
Steam reforming produces hydrogen for the hydrotreaters or hydrocracker.
Typical is the steam methane reformer (SMR), where steam reacts with
Methane at 425 °C with a nickel catalyst to produce syngas, which is a
source for many different reactions:
CH 4 + H 2 O ↔ CO + 3 H 2
If more hydrogen is needed, followed by a gas shift reaction with CO:
CO + H 2 O ↔ CO 2 + H 2
Amine gas treater, Claus unit, and tail gas treatment converts hydrogen
sulfide from hydrodesulfurization into elemental sulfur, which is a valuable
traded product.
Figure 22. Claus process (Source: Wikipedia)
The Claus process is the most common with the overall reaction:
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