Hydrogenation of Fats and Oils

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:

  1. Fun­da­men­tals of Indus­trial Cat­alytic Processes, by R. Far­rauto and C. Bartholomew, Blackie Aca­d­e­mic, New York, 1997, pp 441–447.
  2. Hydro­gena­tion of Fats and Oils: The­ory and Prac­tice, H. Pat­ter­son, AOCS Press, Cham­paign, IL, 1994

 
Con­tributed by John Armor
30 Decem­ber, 2002