title: Design of Ru-zeolites for hydrogen-free production of conjugated linoleic acids.
abstract: 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).
authors.affiliation: Department M2S, K.U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium.
authors.forename: An
authors.initials: A
authors.lastname: Philippaerts
authors.forename: Steven
authors.initials: S
authors.lastname: Goossens
authors.forename: Walter
authors.initials: W
authors.lastname: Vermandel
authors.forename: Moniek
authors.initials: M
authors.lastname: Tromp
authors.forename: Stuart
authors.initials: S
authors.lastname: Turner
authors.forename: Jan
authors.initials: J
authors.lastname: Geboers
authors.forename: Gustaaf
authors.initials: G
authors.lastname: Van Tendeloo
authors.forename: Pierre A
authors.initials: PA
authors.lastname: Jacobs
authors.forename: Bert F
authors.initials: BF
authors.lastname: Sels
mesh_terms: D002384:Catalysis; D005503:Food Additives / Q000138:chemical synthesis / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D058427:Hygroscopic Agents / Q000138:chemical synthesis / Q000737:chemistry; D007536:Isomerism; D044243:Linoleic Acids, Conjugated / Q000138:chemical synthesis* / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D017641:Zeolites / Q000737:chemistry*
chemical_list: D005503:Food Additives; D058427:Hygroscopic Agents; D044243:Linoleic Acids, Conjugated; D009942:Organometallic Compounds; D017641:Zeolites; D012428:Ruthenium; D006859:Hydrogen