Benzene

Benzene is the simplest and most fundamental aromatic hydrocarbon: a planar six-carbon ring with a fully delocalised π-electron system that gives it the distinctive stability and substitution (rather than addition) reactivity characteristic of aromatic compounds. That reactivity profile — readily substituted, resistant to addition or oxidation under mild conditions — is what makes it the universal starting point for the aromatic branch of the petrochemical industry.

At room temperature it is a colourless, highly mobile, volatile liquid with a characteristic sweet aromatic odour. It is only slightly soluble in water but miscible in all proportions with most organic solvents, and its high volatility and low flash point mean it is always handled as a flammable liquid under vapour-control precautions.

Where it fits in the value chain

Benzene sits at the head of three of the largest downstream chemical chains in the industry. Alkylation with ethylene gives ethylbenzene, dehydrogenated to styrene for polystyrene and styrenic polymers. Alkylation with propylene gives cumene, oxidised to phenol and acetone — phenol in turn feeding bisphenol-A and phenolic resins. Hydrogenation gives cyclohexane, oxidised and further processed to adipic acid and caprolactam, the monomers of nylon 66 and nylon 6. A fourth major route, nitration followed by hydrogenation, gives aniline, the feedstock behind the diphenylamine, 4,4'-methylenedianiline and MDI chemistry we also supply.

Grade we supply

Chelora Chemicals offers Benzene in nitration grade (99.9%+ purity), suited to the full range of downstream alkylation, nitration and hydrogenation chemistry described above. The grade is supplied with a batch-wise certificate of analysis.

Benzene is not typically synthesised from smaller building blocks on an industrial scale; instead it is recovered from streams that are already rich in six-carbon aromatics. The two dominant sources are catalytic reformate from petroleum refining, where naphtha is reformed over a platinum-based catalyst to boost its aromatic content, and pyrolysis gasoline (pygas), the aromatic-rich liquid by-product of steam-cracking naphtha or gas oil to make ethylene and propylene. In both cases benzene, toluene and xylenes (the BTX aromatics) are separated from the non-aromatic components by solvent extraction — commonly using sulfolane or a similar selective solvent — followed by fractional distillation to isolate benzene from toluene and the xylene isomers.

Where market demand calls for more benzene than reformate and pygas streams naturally provide, refiners also convert toluene to benzene by hydrodealkylation (reaction with hydrogen over a catalyst, stripping the methyl group as methane) or by toluene disproportionation to benzene and xylenes, giving the industry flexibility to shift the BTX pool toward whichever aromatic is in higher demand.