UTN- FRC -Producción Académica de Investigación y Desarrollo

Permanent URI for this communityhttp://48.217.138.120/handle/20.500.12272/1932

Browse

Author: search.filters.author.Eimer, Griselda

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Relationship between mixed metal oxides properties and their role in glycerol valuation
    (5th Czech‐Italian‐Spanish Conference on Molecular Sieves and Catalysis, 2013) Bálsamo, Nancy; Agú, Ulises Ariel; Oliva, Marcos; Sapag, Manuel; Eimer, Griselda; Crivello, Mónica
    Biofuels are renewable solutions to replace the ever dwindling energy reserves and environmentally pollutant fossil liquid fuels. They are produced from low cost sustainable feedstocks. Biodiesel is mainly produced from vegetable oils or animal fats by the method of transesterification reaction using catalysts. Therefore, large surpluses of glycerol will be generated that require new commercial uses. Glycerol is used as an ingredient in cosmetics, paint, automotive industry, foods, pharmaceutical products, pulp and paper, leather and textiles, among many other applications (1). Homogeneous catalysts are conventionally used for glycerol valuation. Unfortunately, homogeneous catalysts are associated with problems which might increase the cost of production due to separation steps and emission of waste water. Inorganic heterogeneous catalysts are potentially low cost and can solve many of the problems encountered in homogeneous catalysts. In this paper, mixed metal oxides as transesterification catalysts are studied. Especially the relationship between physicochemical properties and catalytic activity was revised. Mixed metal oxides obtained by thermal decomposition of Layered Double Hydroxides have been studied in the transesterification of methyl stearate to monoglycerides production. In order to increase the basic property of the Mg-Al oxide from the hydrotalcite a third metal during the synthesis of the materials (Li, K or Cs) was incorporated. The preparative methods adopted in this study were direct co-precipitation and impregnation methods (2). All samples were examined by X-ray Diffraction, Surface Area determined by the BET method, pore size distributions, adsorption and Temperature-Programmed Desorption of CO2 and Inductive Coupled Plasma spectroscopy. The catalytic activity was performed by the transesterification reaction in a batch reactor at 220º C and the products were analyzed by Gas Chromatography. The catalytic results showed that conversion and selectivity to monoglyceride increased, specially, with the basic sites density. The oxide with Li incorporated by co-precipitation showed most metal proportion incorporated and most medium basic sites density. Also this material presented the highest catalytic performance
  • Thumbnail Image
    Item
    Activity and stability of mesoporous molecular sieves modified with vanadium in the oxyfunctionalization of alpha-pinene
    (5th Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis, 2013) Cánepa, Analía; Vaschetto, Eliana; Herrero, Eduardo; Eimer, Griselda; Casuscelli, Sandra
    Selective oxyfunctionalization of terpenes is an interesting route to utilize these inexpensive natural products for numerous industrial applications. Thus, the oxygenated derivates obtained from the α-pinene oxidation in liquid phase (campholenic aldehyde, verbenol, verbenone) are important as flavor chemicals and precursors of fine chemicals, including sandalwood fragrance, taxol and vitamins A and E [1]. Traditionally, the high aggregated value chemicals are frequently produced by classic organic chemistry, focusing only on the desired product instead of considering the synthesis route, which leads to generate significant amounts of contaminated effluents that cause a great environmental impact. Thus green chemistry appears as a practical approach to achieve clean technologies and sustainable developments, providing the catalysis as a fundamental tool to minimize the process steps and allow the use of mild reaction conditions. In addition, a catalytic process to be economically and environmentally viable, it is essential that the catalyst can be recovered and regenerated. However a particular problem associated with the use of solid catalysts in the liquid phase, as opposed to the gas phase, is the leaching of the metal ion into solution. Mesoporous molecular materials with V contents varying from 0.035 wt% to 1.21 %wt were prepared by hydrothermal synthesis [2] to be used as potential catalysts in the reaction of α-pinene oxidation with H2O2. The major products observed were: verbenone, verbenol and campholenic aldehyde which are used in the pharmaceutical, perfume and cosmetics industry. The material with lower V content (0.035% w/w) was selected for a further study due to its high activity, TON and selectivity to allylic oxidation products. In this way, the effect of the nature of protic solvent: ethanol (EtOH), isoamyl alcohol (iAOH), and nonprotic solvent: acetonitrile (AcN), methyl ethyl ketone (MEK), on the α-pinene activity and products distribution were studied. The best results were obtained with AcN. Finally, the stability of the catalyst to the leaching of the active species and the possibility of recycling were checked. The experiments confirm that the V active species are not leached during the reaction. Thus the heterogeneous catalyst can be recovered and reused many times without loss in catalytic activity and selectivity.