- Production of compounds to be used as fuel additive: Glycerol conversion using Nb-doped MgAl mixed oxide
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MgAl mixed oxide from hydrotalcite was modified with niobium and evaluated as a catalyst for a liquid-phase glycerol conversion in the presence of hydrogen peroxide. Niobium oxide exhibited high activity for glycerol conversion via heterogeneous catalysis at 250 C. Gas chromatography with mass spectrometry (GC-MS) analysis of the reaction showed that diglycerol, ethers and ketone were the main products. The results strongly suggest that the glycerol conversion involves acid groups and oxidizing species generated upon reacting with H 2O2 and niobium. Furthermore, catalytic tests monitored by electrospray mass spectrometry (ESI-MS) suggest that ethers, such as di, tri and tetra glycerols, are formed during the glycerol condensation (m/z = 167, 223, 241, and 315). Preliminary tests using the reaction products as additives for gasoline demonstrate that the octane is increased due to the presence of ether formed from glycerol conversion.
- Souza, Juber,Souza, Priscila M.T.G.,De Souza, Patterson P.,Sangiorge, Daniel L.,Pasa, Vanya M.D.,Oliveira, Luiz C.A.
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- Ionic-liquid-catalyzed decarboxylation of glycerol carbonate to glycidol
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Decarboxylation of glycerol carbonate (GLC) to produce 2,3-epoxy-1-propanol (glycidol) was conducted using various kinds of ionic liquids (ILs) as catalysts. ILs bearing an anion with medium hydrogen-bond basicity such as NO3- and I- exhibited the higher glycidol yields than those having an anion with low or strong hydrogen-bond. FT-IR spectroscopic analysis shows that both GLC and glycidol interact with anions of ILs through their hydroxyl groups. It was possible to improve the yield of glycidol when a zinc salt with a medium Lewis acidity was co-present along with an IL. The yield of glycidol was greatly increased up to 98% when the decarboxylation was conducted in the presence of a high-boiling aprotic solvent. Computational calculations on the mechanism using 1-butyl-3-methylimidazolium nitrate as a catalyst revealed that the first step is the NO3 - assisted ring-opening of GLC followed by the ring closure, resulting in the formation of a 3-membered ring intermediate species.
- Choi, Ji Sik,Simanjuntaka, Fidelis Stefanus Hubertson,Oh, Ji Young,Lee, Keun Im,Lee, Sang Deuk,Cheong, Minserk,Kim, Hoon Sik,Lee, Hyunjoo
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p. 248 - 255
(2013/02/23)
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- V- or Mo-modified niobium catalysts for glycerin conversion reactions in the presence of H2O2
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In the present work, amorphous niobium oxides with 5% (w/w) vanadium or molybdenum isomorphically substituted into the material structure were synthesized. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that vanadium and molybdenum were incorporated into the niobium oxide structure with concomitant changes in the morphologic and catalytic properties. Catalytic studies on the conversion of residual glycerin generated during biodiesel production in the presence of H2O2 showed enhanced efficiency of ether formation with the vanadium-containing material. The NbV/ethanol/glycerin/250 °C system was found to convert 80% of glycerin. Experiment-planning studies in conjunction with the analysis of the surface response via gas chromatography-mass spectrometry (GC-MS) aided in the determination of the optimal conditions. The catalytic tests monitored by GC-MS showed the formation a mixture of ethers obtained by the condensation of glycerol. Furthermore, it was observed that the modification of the catalyst directs the formation of larger molecules such as ketone mainly in the catalyst containing vanadium.
- Souza, Juber P.,Melo, Thaís,De Oliveira, Marcone A.L.,Paniago, Roberto M.,De Souza, Patterson P.,Oliveira, Luiz C.A.
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p. 153 - 160
(2012/11/13)
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- Original synthesis of linear, branched and cyclic oligoglycerol standards
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A variety of authentic standards of linear, branched and cyclic oligomers of glycerol, with well-defined structures and degrees of polymerisation from 2 to 5, have been efficiently synthesised. Linear oligomers were obtained by means of a convergent approach based on regioselective opening of bis(epoxides) with solketal; branched compounds were synthesised using oxidative cleavage of the corresponding anhydrohexitols as the key step. A 6-exo-trig halocyclisation reaction involving heteroatom-tethered unsaturated alcohols permitted an efficient synthesis of the precursors of selected cyclic dimers; larger cyclic oligomers were prepared by two one-pot Williamson reactions using a ditriflate derived from diglycerol. All these methodologies permitted further scaling up.
- Cassel, Stephanie,Debaig, Catherine,Benvegnu, Thierry,Chaimbault, Patrick,Lafosse, Michel,Plusquellec, Daniel,Rollin, Patrick
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p. 875 - 896
(2007/10/03)
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