Propylene glycol turns into formaldehyde at around 200°C.
When the temperature exceeds the decomposition temperature of propylene glycol, propylene glycol will decompose and produce a series of decomposition products, such as acrolein, acrylic acid, formaldehyde, etc.
Propylene glycol decomposes at high temperatures to produce formaldehyde. Propylene glycol has the molecular formula C3H8O2, and its pyrolysis reaction can be written as: C3H8O2 → 3CH2O This reaction is a decomposition reaction that produces formaldehyde (CH2O) and other products. The conversion of propylene glycol to formaldehyde is a decomposition chemical reaction.