How benzene is made
Benzene was once a by-product of making coke for steel. Plastics outgrew that supply by the 1950s.
- stations
- 5
- things upstream
- 7
- raw sources
- 4
- steps from the ground
- 4
The short version
Benzene is a flammable liquid hydrocarbon that chemical plants turn into plastics, resins and dyes. Until World War II most came from coke ovens. Today refineries make it by catalytic reforming of naphtha, and some from steam crackers. Benzene is a carcinogen, so plants handle it in closed systems.
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Reform naphtha over a catalyst
A refinery blends a naphtha cut with recycled hydrogen and passes it over a catalyst. Straight-chain molecules curl into rings and shed hydrogen, so the unit makes more hydrogen than it takes in.
Goes in -
Crack naphtha for more
Steam crackers that make ethylene and propylene also yield a benzene-rich liquid, which joins the stream from the reformer.
Goes in -
Draw off the aromatics
The aromatic products are taken out of the reformate stream. They arrive as a mixture of benzene, toluene and xylenes.
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Convert toluene to benzene
Toluene from the mixture can be turned into more benzene by stripping a methyl group with hydrogen. This hydrogen-heavy step also leaves methane.
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Distill to pure product
Final distillation separates benzene from its neighbors in the mixture. The pure liquid is stored and shipped in closed tanks.
Worth repeating
- Charles Mansfield isolated benzene from coal tar in 1845 and began industrial-scale production four years later.
- In 1929 Kathleen Lonsdale used X-ray diffraction to confirm that the benzene ring is a flat hexagon.
- Benzene is partly responsible for the smell of gasoline.
Back to the ground
Follow every input upstream and benzene starts as these 4 raw sources.
Where it goes next
Benzene feeds 8 lines directly and reaches 283 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How benzene is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/benzene