This is a huge business (worldwide consumption of fats and oils was ~180 billion pounds in 2000) in which hydrogenation catalysts (first patented in 1902 in Germany) are used to control the shape, size and distribution of double bonds in fatty acids which allows one to modify the chemical stability and physical behavior of fatty acids or glycerides. Naturally occurring oils from soybeans, peanuts, coconut, cottonseed, sunflower seeds, corn, etc are used for many household products, such as margarine, cooking and salad oils, baking dough, etc. The partial hydrogenation of natural oils to shortenings, salad oils, toppings and various other edible products is among the largest application for hydrogenation catalysts, often Nickel based. Fatty acids, both natural and synthetic pervade many areas of industrial activity and are used in products such as detergents, cosmetics, candles and crayons. Vegetable oils derived from fatty acids and glycerol are build upon long chains of esters (glycerides) with varying levels of unsaturation (up to 3 double bonds per ester chain. Highly unsaturated chains are prone to oxidation (becoming rancid) in air, while partial hydrogenation improves their stability and consistency. Soy, cottonseed, and corn oil have different levels of C16 and C18 ester chains with varying levels of unsaturation. The function of the hydrogenation catalyst is to partially hydrogenate and isomerize double bonds in the ester chains, thus altering the chemical stability and plastic properties of the oils, while avoiding “over-hardening.”
Sources for more information:
- Fundamentals of Industrial Catalytic Processes, by R. Farrauto and C. Bartholomew, Blackie Academic, New York, 1997, pp 441-447.
- Hydrogenation of Fats and Oils: Theory and Practice, H. Patterson, AOCS Press, Champaign, IL, 1994
Contributed by John Armor
30 December, 2002