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Catalytic hydrogenation of linoleic acid over platinum‐group metals supported on alumina
Author(s) -
Kitayama Yoshie,
Muraoka Masahiro,
Takahashi Megumi,
Kodama Tatsuya,
Takahashi Eriko,
Okamura Mutsuo
Publication year - 1997
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-997-0175-0
Subject(s) - isomerization , catalysis , stearic acid , chemistry , linoleic acid , conjugated linoleic acid , cis–trans isomerism , double bond , platinum , selectivity , medicinal chemistry , organic chemistry , fatty acid
Catalytic activity and selectivity for hydrogenation of linoleic acid ( cis ‐9, cis ‐12 18:2) were studied on Pt, Pd, Ru, and Ir supported on Al 2 O 3 . Stearic acid (18:0) and 10 different octadecenoic isomers (18:1) in the products could be separated completely by using a new capillary column coated by isocyanopropyl trisilphenylene siloxane for gas‐liquid chromatography. The monoenoic acid isomers and dienoic acid isomers in the products on the various catalysts showed different distributions. The catalysts exhibited nearly equal selectivity for stearic acid formation. The 12‐position double bond in linoleic acid has higher reactivity than the 9‐position double bond in catalytic hydrogenation on platinum‐group metal catalysts. In addition to hydrogenation products of linoleic acid, geometrical and positional dienoic acid isomers ( trans ‐9, trans ‐12; trans ‐8, cis ‐12; cis ‐9, trans ‐13; trans ‐9, cis ‐13; cis ‐9, trans ‐12 18:2), due to isomerization of linoleic acid during hydrogenation, were contained in the reaction products. Ru/Al 2 O 3 exhibited the highest activity for isomerization of linoleic acid with the noble metal catalysts. Conjugated octadecadienoic acid isomers have been observed in products of the reaction on Pt/Al 2 O 3 , Ru/Al 2 O 3 , and Ir/Al 2 O 3 . Catalytic activities of noble metals for positional and geometric isomerization of linoleic acid during hydrogenation decreased in the sequence of Ru ≥ Pt > Ir » Pd.