Selektivhydrierung von Fettstoffen mit metallorganischen Mischkatalysatoren nach Ziegler‐Sloan‐Lapporte I: Selektive Hydrierung von Linolsäuremethylester und Modelldienen mit isolierten Doppelbindungen

Abstract

Linolsauremethylester 1XBt sich mit homogenen Ziegler-Slom-Lapporte-Katalysatoren auf Nickel-, Cobalt-oder Palladiumbasis unter sehr milden Bedingungen selektiv zum einfach ungesattigten Produkt hydrieren. Die Frage, ob dieses Verhalten durch die 1,bStellung der beiden Doppelbindungen im Linolsaureester verursacht wird, fihrte zu Hydriewersuchen an nichtkonjugierten a,w-Dienen unterschiedlicher Kettenlkge. Dabei zeigte sich, daB in dieser Homologenreihe eine signifkante Selektivitfit zur Monoolefihildung nur im Falle des 1,bPentadien gegeben ist. Bei den Dienen, deren Doppelbindungen weiter auseinanderliegen als in der Lmolsaure, macht sich eine Selektiviat fiir das Monohydrierungsprodukt nur noch in untergeordnetem MaBe oder nicht mehr bemerkbar. Zur Erklaung wird ein Modell mit unterschiedlich stabilen Katalysator-Substrat-Komplexen vorgeschlagen. Selective Hydrogenation of Fats and DerivativesUsing Ziegler-Type Organometallic Catalysts I: Selective Hydrogenation of Methyl-lino1ea.t and Other Dlenic Compounds with Isolated Double Bonds Homogeneous catalysts of Ziegler-Sloan-Lapporte-type, containing nickel, cobalt or palladium, were used to hydrogenate methyllinoleate under very mild conditions selectively to monounsaturated products. The question, wether this selectivity is caused by the 1,4-position of the olefmic double bonds, led to hydrogenation experiments with non-conjugated a,o-dienes of different chain length. A significant selectivity was only observed for the reduction of 1,Cpentadiene to pentene, dienes with greater distance between the double bonds than in lioleic acid were hydrogenated with less selectivity. To explain these facts, a kinetic model, including catalyst-substratecomplexes of different stabilities, is proposed. denen die Partialhydrierung von linolensaureesterhaltigen Substraten beschrieben wird23, 24. .A u f g a b e n s t e l l u n g Ein Ziel der Untersuchungen im Rahmen des BMFT-Forschungsverbundvorhabens ,,Neue Einsatzmoglichkeiten nativer Ole und Fette als Chemierohstoffe" ist die verbesserte Selektivhydrierung mehrfach ungesattigter Fettsaureester mit homogenen metallorganischen Mischkatalysatoren nach Ziegler. Durch gezielte Modifhtion der Katalysatorsysteme sol1 insbesondere die Partialhydrierung von Linol-und Linolensaureestern unter gleichzeitiger Riickdrihgung von Stellungs-und cisham-Isomerisierungen der verbleibenden Doppelbindungen erreicht werden. H3COOC----C18:3(9c,12c,15c) a-Linolensauremethylester CKat.1 +H2 H3COOC-L -C18:2 Octadecadiensaurernethylester-lsomerengernisch hier: C18:2(9c,12c) Linolsaurernethylester H,COOC C18:l Octadecensauremethylester-lsomerengemisch hier: C18:1(9c) ulsaurernethylester 'Kat-1i..2

Catalytic conversions in green aqueous media. Part 8: Partial and full hydrogenation of renewable methyl esters of vegetable oils

“…Shin et al [71] disclosed a one-pot process combining the transesterification and partial hydrogenation of soybean oil over copper catalysts in supercritical methanol to produce mainly monounsaturated fatty esters which is upgraded biodiesel fuel. Fell and Schäfer [125,126] homogeneously hydrogenated ML using Ziegler-Sloan-Lapporte catalysts based on Ni(acac) 2 or Pd(acac) 2 and Al(C 2 H 5 ) 3 with a high selectivity (>90%) to C18:1 products. However, a shortcoming of this reaction is the cumbersome separation of the catalyst from reaction products and its quantitative recovery in active form as well as the large quantities of triethyl aluminium required, i.e.…”

“…However, problems associated with the use of 1st generation biodiesel remain inter alia its low oxidative stability and low-temperature behaviour as well as its higher NO x emissions [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. Partial hydrogenation reactions of polyunsaturated FAME of vegetable oils to yield their monounsaturated (C18:1) counterparts [15,16,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][122][123][124][125][126][127][128][129][130][131] without increasing the content of the saturated part, i.e. methyl stearate (MS, Scheme 1) are useful reactions for upgrading 1st generation biodiesel [15,…”

“…Catalytic partial hydrogenation processes of polyunsaturated methyl esters of vegetable oils into their monounsaturated C18:1 counterparts (Scheme 1) [15,16,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][122][123][124][125][126][127][128][129][130][131] are of great interest in the fields of production of high quality 1st generation biodiesel fuel [15,16,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69]…”

Catalytic hydrogenation of CC and CO in unsaturated fatty acid methyl esters

“…Fell and Schäfer investigated the partial hydrogenation of methyl linoleate on Ziegler-type catalysts containing Ni, Co, or Pd metals and selectivities higher than 90% to C18:1 esters were measured. [36][37][38] In particular, Rh-based complexes exhibited high catalytic activity towards partial hydrogenation of polyunsaturated crude methyl esters of linseed and sunflower oils into monounsaturated counterparts. [39][40][41][42][43] Under optimized operating conditions, a selectivity of 79.8% towards C18:1 FAME could be achieved for the linseed, sunflower, and soybean oils.…”