Production of conjugated linoleic acid-rich cottonseed oil by supported Ru catalyzed isomerization

Supported metal (e.g. Ruthenium (Ru)) is capable to catalyze the isomerization of polyunsaturated fatty acids in plant oils into conjugated fatty acids. Conjugated linoleic acids (CLAs) produced from plant oils have not only been associated with diverse health and physiological effects, but also been interesting renewable compounds in producing industrial products such as paints, glues, and polymers, due to the presence of very reactive conjugated double bonds. To explore the industrial potential of heterogeneous supported metal catalyst in converting food-use limited cottonseed oil (CSO) into conjugated linoleic acid (CLA)-rich plant oil, Ru/C (J.M.), Ru/C (Sigma), Ru/Al2O3 and Ru black are examined for their catalytic efficiency/selectivity in decane and solvent-free systems. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) are employed for their surface chemical composition and morphology analyses. Deconvolution of Ru 3p and 3d spectra are executed by Gaussian and Lorentzian fitting; and a qualitative correlation between oxidation states of Ru and catalytic activity/selectivity of Ru catalysts are delineated. In 24 h in solvent-free system Ru black is capable to achieve 51.3% conversion of linoleic acid (LA) in CSO with excellent selectivity (83.7%) towards CLA formation (CLA-rich CSO can be easily obtained by simple filtration); conversion of LA doesnot show any Sn-2/Sn-1,3 region-preference; however, the reaction activity/selectivity is pronouncedly correlated to the content of Ru (IV) in catalysts. (C) 2016 Elsevier B.V. All rights reserved.