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Design of Ru–Zeolites for Hydrogen‐Free Production of Conjugated Linoleic Acids
Author(s) -
Philippaerts An,
Goossens Steven,
Vermandel Walter,
Tromp Moniek,
Turner Stuart,
Geboers Jan,
Van Tendeloo Gustaaf,
Jacobs Pierre A.,
Sels Bert F.
Publication year - 2011
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201100015
Subject(s) - isomerization , catalysis , chemistry , conjugated system , hydrogen , conjugated linoleic acid , solvent , heterogeneous catalysis , organic chemistry , polymer , linoleic acid , fatty acid
While conjugated vegetable oils are currently used as additives in the drying agents of oils and paints, they are also attractive molecules for making bio‐plastics. Moreover, conjugated oils will soon be accepted as nutritional additives for “functional food” products. While current manufacture of conjugated vegetable oils or conjugated linoleic acids (CLAs) uses a homogeneous base as isomerisation catalyst, a heterogeneous alternative is not available today. This contribution presents the direct production of CLAs over Ru supported on different zeolites, varying in topology (ZSM‐5, BETA, Y), Si/Al ratio and countercation (H + , Na + , Cs + ). Ru/Cs‐USY, with a Si/Al ratio of 40, was identified as the most active and selective catalyst for isomerisation of methyl linoleate ( cis ‐9, cis ‐12 (C18:2)) to CLA at 165 °C. Interestingly, no hydrogen pre‐treatment of the catalyst or addition of hydrogen donors is required to achieve industrially relevant isomerisation productivities, namely, 0.7 g of CLA per litre of solvent per minute. Moreover, the biologically most active CLA isomers, namely, cis ‐9, trans ‐11, trans ‐10, cis ‐12 and trans ‐9, trans ‐11, were the main products, especially at low catalyst concentrations. Ex situ physicochemical characterisation with CO chemisorption, extended X‐ray absorption fine structure measurements, transmission electron microscopy analysis, and temperature‐programmed oxidation reveals the presence of highly dispersed RuO 2 species in Ru/Cs‐USY(40).