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