Stearic acid is a saturated fatty acid with higher hydrocarbons and it’s usually called as Octadeconic acid. Stearic acid is one of the most common saturated fatty acids found in nature and occurs in many animal and vegetable fat oils. It is a waxy white solid with chemical formula of CH3(CH2)16CO2H and molar mass of 284.48 g/mol. Stearic acid can be obtained from the hydrogenation of unsaturated vegetable oils. Stearic acid is actually a mix of stearic acid, palmitic acid and oleic acid. Stearic acid is available in different grades in the market, such as rubber grade, candle grade, double pressed grade and triple pressed grade. The many grades differ on the basis of iodine number, saponification value, acid number and the fatty acid composition.
Stearic acid is commercially produced from fatty acids by saponification with water at a high temperature and pressure, leading to the hydrolysis of triglycerides. The resulting product then distilled to remove the water. Stearic acid produced usually consist some palmitic acid as well, further purification can be done to get a high purity product.
There are different manufacturing process depending on the grade of stearic acid required and the type of raw material. Tallow and Grease are the most common raw material used for the production of stearic acid. There are two main steps for the production of stearic acids.
Firstly raw materials (fat or oil) are hydrolyzed to produce a mixture of fatty acids and glycerin followed by separation of two products.
Purification and separation of fatty acid mixtures.