Catalytic hydrogenation of linoleic acid over platinum-group metals supported on alumina

• Published in: Journal of the American Oil Chemists' Society Vol. 74; no. 5; pp. 525 - 529
• Main Authors: Kitayama, Yoshie, Muraoka, Masahiro, Takahashi, Megumi, Kodama, Tatsuya, Takahashi, Eriko, Okamura, Mutsuo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 1997; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Acids; Aluminum oxide; Catalysis; Catalysts; Catalytic activity; Catalytic hydrogenation; Catalytic reactions; Chemistry; cis/trans isomerization; double‐bond migration; Exact sciences and technology; General and physical chemistry; Heavy metals; Hydrogenation; Iridium; Isomerization; Isomers; isomers of dienoic and monoenoic acids; Linoleic acid; Liquid chromatography; Metals; Noble metals; Palladium; Platinum; Platinum metals; Reaction products; Ruthenium; Selectivity; selectivity for monoenoic acid; Siloxanes; Stearic acid; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Heterogeneous catalysis; Catalytic reaction; Isomerization; Transition metal; Dienic compound; Experimental study; Platinoid; Fatty acids; Alumina; Hydrogenation; Supported catalyst; Linoleic acid
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-997-0175-0

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 Al₂O₃. 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/Al₂O₃ 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/Al₂O₃, Ru/Al₂O₃, and Ir/Al₂O₃. Catalytic activities of noble metals for positional and geometric isomerization of linoleic acid during hydrogenation decreased in the sequence of Ru >= Pt > Ir » Pd.