Selective synthesis of monoglycerides from glycerol and oleic acid in the presence of solid catalysts
Laboratoire de Catalyse, URA CNRS 350, ESIP, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex, France Studies in surface science and catalysis
01/1997; 108:539-546. DOI: 10.1016/S0167-2991(97)80948-2
The selective synthesis of glycerol monooleate can be performed in the presence of solid catalysts less corrosive and more easily reusable than homogeneous mineral acids. The study of various acid solids (zeolite, clay, ion-exchange resin) for the esterification of glycerol (coproduct of methyl ester synthesis) with oleic acid has shown that cationic exchange resins were the best catalysts for the selective preparation of monooleyl glyceride in mild experimental conditions. Indeed, a selectivity of about 90% for an oleic acid conversion greater than 50% is obtained. It seems that the activity and the selectivity is influenced by the resin structure; depending on its crosslinking, the resin acts as a shape selective catalyst.
Available from: Zahra Gholami
- "As shown in Figure 2, it was reported that the role of coordinative unsaturated surface metal ions was to facilitate the hydroxyl leaving process in the glycerol etherification reaction (Ruppert et al., 2008). The electron-deficient metal cations exhibit acidic, electron-acceptor characteristics, whereas the electron-rich oxygen anions exhibit basic, electron-donor characteristics (Abro et al., 1997). "
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ABSTRACT: The activities of different heterogeneous alkaline-earth metal oxide catalysts and mixed-metal oxide catalysts were investigated. Glycerol etherification was carried out at 250°C in a three-necked glass reactor vessel at atmospheric pressure. In a typical experiment, 50 g of anhydrous glycerol was loaded into the reactor. Then, 2 wt.% of catalyst was added to the reactor. The reactor was then heated to the appropriate reaction temperature in nitrogen atmosphere under continuous stirring. The heterogeneous CaO catalyst showed the highest catalytic conversion (72%) compared with other alkaline-earth metal oxides, with a diglycerol yield of 19%. The highest glycerol conversion of 96% and diglycerol yield of 52% were observed for the mixed-metal oxide catalyst (Ca1.6Al0.4La0.6O3). Reusability and stability of this catalyst were tested. The ICP-AES analysis was performed to confirm the leaching of the metal species in the liquid phase of the reaction mixture.
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ABSTRACT: Glycerol was esterified with an equimolar amount of lauric acid to monolaurin using zeolites, sulfonic resins, and sulfonic mesoporous materials as catalysts. The latter were obtained by immobilization of 3-mercaptopropyl groups and oxidation with H2O2. In particular, fatty acid conversions, monoglyceride yields, and selectivities obtained with mesoporous (ordered, amorphous) sulfonic catalysts were compared with those of other heterogeneous or homogeneous catalysts. When using silica gel coated with propylsulfonic acids, high reaction rates are coupled to high monoglyceride yields, e.g., 53% mono yield for a 1 : 1 glycerol : lauric acid ratio. Minimizing the autocatalytic contribution of the fatty acid reactant is a critical issue. The influence of a number of reaction parameters is investigated. The mesoporous sulfonic catalysts are also employed in the esterification of propanediols andmeso-erythritol, and for reactions with other fatty acids.
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