How formaldehyde is made
Its discoverer was trying to make something else, and he got its formula wrong in his own paper.
- stations
- 5
- things upstream
- 4
- raw sources
- 3
- steps from the ground
- 2
The short version
Almost all of it starts as methanol vapor. Mixed with air and passed over a hot metal or metal oxide catalyst, the methanol loses hydrogen and becomes a pungent gas. The gas is dissolved in water straight away, since it would otherwise link up with itself, and tankers carry that solution to resin plants.
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Vaporize the methanol
Liquid methanol is boiled into vapor at the front of a closed plant. Oxidizing methane directly would be simpler on paper, but methanol reacts more readily, so methane stays out of the reactor.
Goes in -
Blend with air
The vapor is mixed with air, which supplies the oxygen. Everything stays inside closed pipework on the way to the reactor.
Goes in -
Pass over the catalyst
The gas stream flows over a catalyst of silver metal or of iron and molybdenum oxides. Methanol is oxidized on the surface and leaves as formaldehyde gas.
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Absorb into water
Hot gas goes up through water, which takes it in. A saturated solution is about 37% by mass and is sold as formalin. The dissolved molecule becomes mostly a hydrate.
Goes in -
Stabilize and ship
A little methanol stays in or is added to stop the solution from oxidizing and polymerizing. Tankers take it to plants making resins for particle board, coatings and plastics. It is a group 1 carcinogen, so handling is tightly controlled.
Worth repeating
- Aleksandr Butlerov discovered formaldehyde in 1859 while trying to make something else, and his paper gave it the wrong formula.
- Reactions in the upper atmosphere account for more than 80% of the formaldehyde in the environment.
- Global production was estimated at 26 million tons per year in 2024.
Back to the ground
Follow every input upstream and formaldehyde starts as these 3 raw sources.
Open the whole family tree
Where it goes next
Formaldehyde feeds 6 lines directly and reaches 179 things in total.
Further down the line
Keep walking
Sources
Cite this page: "How formaldehyde is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/formaldehyde