Naphtha Reforming


Naphtha is converted into a series of branched alkanes, cycloalkanes and aromatic hydrocarbons. Benzene is formed from hexane:

Similarly, methylbenzene and three dimethylbenzene isomers are formed from heptane and octane respectively:

The Reforming Process

During the reforming of naphtha, mainly straight chain alkanes, with 6 - 10 carbon atoms, are re-formed into molecules with the same number of carbon atoms but different structures.

The naphtha is first purified to remove sulphur, which would poison the catalyst, and then mixed with recycled hydrogen and heated to about 500°C, a process known as hydroforming.

This mixture passes into a series of reactors containing a catalyst, normally platinum/alumina. Older processes operate at 20 atmospheres pressure, but modern plants run at a lower pressure of 5 atmospheres and use continuous catalyst regeneration. This means the catalyst is withdrawn on a continuous basis and conveyed through a regeneration system before being returned to the reactor.


What advantages are there in working at lower pressures?


The aromatic compounds are separated from the non-aromatic compounds by solvent extraction, and are then fractionally distilled into benzene, methylbenzene and the dimethylbenzenes. Click for more details of separation methods used.





























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