Define aeromatisation reaction.

Aromatization is the conversion of a nonaromatic hydrocarbon to an aromatic hydrocarbon.

There are four common methods of aromatization.

1. Dehydrogenation of naphthenes

Naphthenes are a class of cyclic aliphatic hydrocarbons obtained from petroleum. They have the general formula <mathjax>C_nH_2n</mathjax>. The simplest naphthene is cyclohexane, C₆H₁₂. Catalytic dehydrogenation converts it to benzene.

C₆H₁₂ → C₆H₆ + 3H₂

2. Dehydroisomerization of naphthenes

Methylcyclopentane, C₆H₁₂, is catalytically isomerized and dehydrogenated to form benzene.

C₅H₉CH₃ → C₆H₆ + 3H₂

3. Dehydrocyclization of aliphatic hydrocarbons

Heptane is catalytically converted to toluene.

C₇H₁₆ → C₆H₅CH₃ + 4H₂

Small amounts of platinum on acidified alumina accomplish reactions (1), (2), and (3) readily.

4. Condensation of hydrocarbons

Propane is catalytically converted to benzene during the cracking of petroleum at 600-800 °C.

3C₃H₈ → C₆H₆ + 3CH₄ + 3H₂