Formaldehyde is a naturally occurring, simple chemical compound composed of hydrogen, carbon and oxygen. At room temperature formaldehyde is a colourless gas. All organic life forms including bacteria, plants, fish, animals and humans, produce formaldehyde that is emitted at various low levels. Formaldehyde does not accumulate in the atmosphere because it is quickly broken down by sunlight, through a process called photo-oxidation. The human body is also able to quickly metabolise, or break down, formaldehyde so it does not accumulate in our bodies. Because formaldehyde has many useful chemical properties, it is also manufactured industrially and serves as a key building block in a wide range of applications. Commercially manufactured formaldehyde is usually sold in liquid form as formalin, a solution that is most commonly 37% formaldehyde.
Formaldehyde is generally produced commercially via the metal oxide process or the silver process. The diagram below illustrated the metal oxide process from Formox. A catalyst is used to create a reaction between methanol and oxygen at a high temperature which creates formaldehyde and water. The reaction between methanol and oxygen generates heat which is used to produce steam. CH3OH + ½ O2 → H2CO + H2O + heat. The gas mixture (air, formaldehyde and steam) is then cooled down and sent to an absorber where the formaldehyde is absorbed by water to produce an aqueous solution.
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