Catalytic conversions in green aqueous media: Part 4. Selective hydrogenation of polyunsaturated methyl esters of vegetable oils for upgrading biodiesel

Reduction Reactions in Green Solvents: Water, Supercritical Carbon Dioxide, and Ionic Liquids

“…[9] Interestingly, the same catalyst system has shown excellent results for the selective hydrogenation of crude polyunsaturated methyl esters of linseed, sunflower, and soybean oils to achieve high selectivities, up to 79.8 mol %, of monounsaturated (C18:1) fatty acid methyl esters. [10] A different strategy to immobilize the catalyst in the water phase is the covalent attachment of the catalyst to supports such as silica, polymers, dendrimers, cyclodextrins, and others. For example, palladium nanoparticles with cyclodextrin receptors behave as an active catalyst for the hydrogenation of alkenes in water media.…”

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

“…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,…”

“…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 [15,16,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][...…”

“…We have studied the partial hydrogenation of polyunsaturated methyl esters of linseed (MELO), sunflower (MESO), cynara cardunculus (MECCO) and soybean (MESBO) oils to achieve high selectivities towards C18:1 FAME (Scheme 1) which is upgraded 1st generation biodiesel fuel in terms of increased oxidative stability, higher energy performance and elimination of the NO x -effect at a low pour point employing water-soluble rhodium, ruthenium and palladium TPPTS complexes in aqueous/organic two-phase systems [16,[53][54][55][56]. We have chosen MELO as a starting material because it mainly consists of ␣-MLN (56.8%, Table 1) and therefore constitutes a good model to investigate the whole spectrum of the catalytic hydrogenation reaction: C18:3 → C18:2 → C18:1 C18:0.…”

“…Under these conditions, however, the catalytic activity remained low (TOF = 160 h −1 ). The activity considerably increased to reach an exceptionally high TOF value of 117 000 h −1 in the partial Rh/TPPTS catalyzed hydrogenation of MESO at molar ratios of C C units/Rh = 15 000 and TPPTS/Rh = 3, at 120 • C, 50 bar H 2 and [Rh] = 34 ppm in water to obtain a total content of 68.3% in C18:1 regiomers within 5 min of reaction time without addition of any added surfactant or organic solvent in aqueous/organic twophase systems ( Table 1, entry 1/2) [54][55][56]. Cynara cardunculus (cardoon) [6,16,18,22,[26][27][28][29][30][31][32][33][34][35][36][37] is a perennial, low-input and robust plant known since ancient times which grows wild on marginal and abandoned from agricultural use land in the Mediterranean countries and other parts of the world and last years there is an increasing interest to use it as a low-cost multi-purpose energy crop because the seed oil with a fatty acid profile similar to its botanically related sunflower could be used for biodiesel production and the lignocellulosic biomass as a solid biofuel for heating applications or power generation by co-firing with coal.…”