The chemical compound formaldehyde (also known by IUPAC nomenclature as methanol), is a gas with a strong pungent smell. It is the simplest aldehyde. Formaldehyde is a colorless gas at room temperature and pressure, with a density of 1.03. It is not commercially available as a gas and is normally used in a solution of 37% and 43% formaldehyde, as Formaldehyde gas is readily soluble in water. The water solution is colorless and has a very strong, pungent odor. This product is called by Trade names such as Formalin. Formaldehyde is also soluble in many of the common organic solvents, such as benzene and acetone. Its melting point is –118°C and its boiling point is –19°C in the gaseous form & 97°C in the form of 37% and 43% solution
Formaldehyde is also readily oxidized by atmospheric oxygen to form formic acid. Formaldehyde solutions must be kept tightly sealed to prevent this from happening in storage
Formaldehyde is a raw material for many types of industries as per details given below :-
Manufacture of moulding powders: 1. Various types of moulding powders are manufactured with formaldehyde 37% solution as raw material such as Urea formaldehyde, melamine formaldehyde and phenolic formaldehyde etc. 2. These moulding powders are further used for manufacture of buttons, electrical switches, melamine unbreakable crockery, backlite products, handles for various type of cooking appliances etc.
Resins: 1. Formaldehyde 37% is also used for manufacturing of various types of resins such as urea formaldehyde, melamine formaldehyde and phenolic formaldehyde. 2. These resins are either supplied in the liquid form, which has limited shelf life, or powder form, which has longer shelf life. These resins are used for manufacture of plywood, particleboard, MDF, lamination board, formica, sun mica etc.
Pharmaceutical Industries: 1. Formaldehyde 37% solution is used in pharmaceutical industries for various types of applications, including the manufacture of bulk drugs.
Explosives: 1. Formaldehyde 37% solution is used for manufacturing explosives in very large quantities.
Other uses: 1. Formaldehyde 37% solution is used for manufacturing Hexamine. It is further used for manufacture of Explosives,Moulding powders and Rubber Blowing Agents etc. 2. Formaldehyde kills most bacteria and so a solution of formaldehyde in water is commonly used as a disinfectant or to preserve biological specimens. It is also used as a preservative in vaccinations. In medicine, formaldehyde solutions are applied topically to dry the skin, such as in the treatment of warts. 3. Most formaldehyde, however, is used in the production of polymers and other chemicals. When combined with phenol, urea, or melamine, formaldehyde produces a hard thermoset resin. These resins are commonly used in permanent adhesives, such as those used in plywood or carpeting. They are also foamed to make insulation, or cast into molded products. Production of formaldehyde resins accounts for more than half of formaldehyde consumption. 4. Formaldehyde is also used to make numerous other chemicals. Many of these are polyfunctional alcohols such as pentaerythritol, which is used to make paints and explosives. Other formaldehyde derivatives include methylene diphenyl diisocyanate, an important component in polyurethane paints and foams and hexamethylene tetramine, which is used in phenol-formaldehyde resins and to make the explosive RDX. 5. It is used in artificial silk, cellulose esters and glass mirrors. 6. It is used in the manufacture of photographic materials, antiseptics and fumigants, in treatment of pulp and paper, in cosmetics, fertilizers and fuels, in treatment of fur and hair, mouth wash, germicidal soap, lavender water and cologne, sterilization of surgical instruments, as food preservatives, polishes for refining of hydrocarbons. It is used as anti-eaging agent in urea-fertiliser industry.
Formaldehyde is the oxidation/dehydrogenation product of methanol with oxygen in the presence of silver catalyst. A fixed quantity of methanol and water is introduced into a mixing vessel from where this mixture is taken into an evaporator. Air is also introduced into the evaporator. A temperature of 70°C is maintained which facilitates for the evaporation of methanol. The air and methanol vapor mixture is further heated to 100°C in the Super heater and then introduced into the Reactor where in presence of silver catalyst maintained at a temperature of 650 °C, the oxidation / dehydrogenation reaction takes place as per the following chemistry: