Production
Industrially, formaldehyde is produced by the catalytic oxidation of methanol. The most commonly used catalysts are silver metal or a mixture of an
iron oxide with molybdenum and vanadium. In the more commonly used iron oxide system (Formox process), methanol and oxygen react at 250°C to produce
formaldehyde according to the chemical equation
2 CH3OH + O2 → 2 H2CO + 2 H2O
The silver-based catalyst is usually operated at a higher temperature, about 650 °C. On it, two chemical reactions simultaneously produce
formaldehyde: the one shown above, and the dehydrogenation reaction
CH3OH → H2CO + H2
Further oxidation of the formaldehyde product during its production usually gives formic acid that is found in formaldehyde solution, found in ppm
values.
On a smaller scale, formalin can be produced using a whole range of other methods including conversion from ethanol instead of the normally-fed
methanol feedstock. Such methods however are of less commercial importance.
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