Edmilson Miranda de Moura

Catalysts of Cu(II) and Co(II) ions adsorbed in chitosan used in transesterification of soy bean and babassu oils - a new route for biodiesel syntheses.

Catalysts of Cu(II) and Co(II) adsorbed in chitosan was used in transesterification of soy bean and babassu oils. The catalysts were characterized by infrared, atomic absorption and TG, and biodiesels was characterized by infrared, NMR, CG, TG, physic chemistry analysis. The maximum adsorption values found for copper and cobalt cations were 1.584 and 1.260mgg(-1), respectively, in 180min. However, conversion of oils in biodiesel was better when used Co(II) adsorbed in chitosan.

Synthesis of methyl acetate from methanol catalyzed by [(η5-C5H5)(phosphine)2RuX] and [(η5-C5H5)(phosphine)2Ru(SnX3)] (X=F, Cl, Br): ligand effect

Abstract Monometallic Ru and heterobimetallic complexes containing RuSn bonds, [(η5-C5H5) P2RuX] and [(η5-C5H5)P2Ru(SnX3)], where P=PPh3, PPh2Me, P2=1,2-bis(diphenilphosphine) ethane (dppe), and X=F, Cl, Br, were synthesized and characterized. These complexes were tested as catalysts in a single-step methanol conversion to acetic acid (methyl acetate) in the absence of CO. All complexes showed a high selectivity with their catalytic activity being strongly dependent on the nature of the ligands P and X. The effect of the ligand P showed the order of PPh3>PPh2Me≅dppe and the halogen effect: F>Cl≅Br and SnF3>SnCl3≅SnBr3. Heterobimetallic complexes showed ca. doubled activities compared to their monometallic analogues, indicating the importance of the RuSn bond in a catalytic active specie. The order of catalytic activities followed the increase in the positive charge on the ruthenium atom, which was confirmed by 31P and 119Sn NMR spectroscopy and X-ray diffraction techniques. The obtained data support the mechanistic view of acetic acid formation by dehydrogenation of methanol giving formaldehyde via the rate-determining β-hydrogen abstraction in the Ru(II)–OMe intermediate, followed by formaldehyde dimerization into acetic acid.

Synthesis, characterisation and molecular structure of Ru–Sn(II) containing derivatives

Abstract A series of new ruthenium-based derivatives were obtained by reactions of [Ru(η-C5H5)(PPh3)2Cl]. They are as follows: [Ru(η-C5H5)(PPh3)2SnF3] (1), [Ru(η-C5H5)(PPh3)2SnCl3] (2), [Ru(η-C5H5)(PPh3)2SnBr3] (3), [Ru(η-C5H5)(dppe)SnF3] (4), [Ru(η-C5H5)(dppe)SnCl3] (5), and [Ru(η-C5H5)(dppe)SnBr3] (6). Compounds 1–6 were studied by IR, NMR (1H, 13C, 31P and 119Sn) and 119Sn Mossbauer spectroscopies. In addition, 1, 2, 3 and 6 were structurally authenticated by X-ray crystallographic studies. Finally all the derivatives were tested as catalysts in the methanol to acetic acid conversion process, showing promising activities.

Syntheses, characterization and structure determination of {[CpRu(X)]2(η2,μ2-dppe)2} complexes (X=Cl, N3; dppe=Ph2PCH2CH2PPh2): Chelating vs. bridging behavior of a classical bidentate ligand

Abstract Phosphine substitution reactions between (η5-C5H5)Ru(PPh3)2Cl (1) and 1,2-bis(diphenylphosphino)ethane (Ph2P(CH2)2PPh2, dppe), in refluxing benzene or in toluene at 80°C afforded a mixture of complexes where dppe behaves both as a bridging and as a chelating ligand. CpRu(η2-dppe)Cl (2) and {[CpRu(Cl)]2(η2,μ2-dppe)2} (3) were separated by fractional precipitation from the reaction mother-liquor, and were characterized by 1H, 13C, 31P NMR, elemental analysis and IR spectroscopy. The (2):(3) ratio in the composition of the reaction product was found to be independent of the reaction time. In solution and at room temperature, (3) exists in both boat and chair conformers of a 10-membered ring, while at lower temperatures, and in the solid-state, only the chair conformer is observed. Compounds (2) and (3) undergo halide-displacement upon reacting with NaN3 in the presence of ethanol to yield CpRu(η2-dppe)(N3) (4) and {[CpRu(N3)]2(η2,μ2-dppe)2} (5), respectively. The crystal structures of (3) and (5) were determined.

Heterogeneous catalysis afford biodiesel of babassu, castor oil and blends

This work describes the preparation of babassu, castor oil biodiesel and mixtures in various proportions of these oils, using alkaline compounds of strontium (SrCO 3 + SrO + Sr (OH) 2 ) as heterogeneous catalysts. The mixture of oils of these oleaginous sources was used in the production of biodiesel with quality parameters that meet current legislation. The catalyst was characterized by X-ray diffractometry (XDR), physisorption of gas (BET method), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR). The viscometric technique was used to monitor the optimization. The transesterification reactions performed using strontium compounds reached conversion rates of 97.2% babassu biodiesel (BB), 96.4% castor oil biodiesel (COB) and 95.3% Babassu/Castor Oil Biodiesel 4:1 (BBCO41).

119Sn-Mössbauer spectroscopic studies on organoheterobimetallic half sandwich ruthenium–tin containing derivatives

A series of heterobimetallic complexes containing Ru–Sn bonds, of general formula [RuCp(L)2SnX2Y] [L = PPh3, 1/2 dppe = 1,2-bis(diphenylphosphino)ethane; X, Y = F, Cl and Br], was prepared and studied by elemental analysis, 119Sn-Mössbauer spectroscopy, i.r. and 1H-, 13C-, 19F-, 31P- and 119Sn-n.m.r. spectroscopy. 119Sn-Mössbauer studies allowed determination of the coordination number of the SnII center as well as the group electronegativity of the organometallic fragment [RuCp(L)2]+. These results, supported by multinuclear n.m.r. data suggested that the electronic charge distribution between the RuII and SnII centers are strongly dependant upon the nature of L and the electronegativity of X and Y.

Preparation of highly dispersed Ru-Sn bimetallic supported catalysts from the single source precursors Cp(PPh3)2Ru-SnX3 (X = Cl or Br)

In this work highly dispersed Ru-Sn bimetallic catalysts have been prepared from organobimetallic Cp(PPh3)2Ru-SnX3 (X = Cl or Br) complexes. These single source precursors can be easily impregnated in high surface area supports, such as activated carbon and sol-gel SiO2, and upon controlled thermal treatment the ligands are released as volatile products resulting in the formation of the bimetallic system Ru-Sn. Catalytic reactions, such as hydrodechlorination of CCl4 and chlorobenzene and TPR (Temperature Programmed Reduction) experiments carried out with these RuSn catalysts suggested a strong interaction between Ruthenium and Tin. Mossbauer measurements showed that these materials when exposed to air are immediately oxidized to form Sn (IV). It was shown that upon controlled reduction conditions with H2 it is possible to reduce selectively Sn to different oxidation states and different phases. The Sn oxidation state showed significant effect on the catalytic hydrogenation of 1,5-cyclooctadiene. The use of these single source precursors with a controlled decomposition/reduction procedure allows the preparation of unique catalysts with an intimate interaction between the components ruthenium and tin and the possibility of varying the Sn oxidation state around the Ru metal.

Strontium and Nickel Heterogeneous Catalysts for Biodiesel Production from Macaw Oil

It is presented herein heterogeneous catalysts comprised of strontium and nickel oxides synthesized using a coprecipitation method. They were applied for the preparation of biodiesel from macaw palm oil. The catalysts were characterized by X-ray diffraction (XRD), adsorption and desorption of nitrogen by Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential thermogravimetric analysis (TG-DTA). The conversion was determined by gas chromatography with flame detector (GC-FID). The best activity was obtained when the catalyst was calcined at 1100 °C for 3 hours. The highest conversion was reached (97%) when the following conditions were used: 5 hours, 2% of metal loading, 65 °C and oil/alcohol molar ratio of 1:9.

Cr/Al Oxide as Solid Acid Catalyst to Afford Babassu Biodisel

2g -1 ), pore size (7.0 µm), total acidity (182.28 µmol g -1 ), wherein Bronsted sites are the most active. Powder X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) show three phases of the catalyst (Cr2O3/Na2Cr2O3/Al2O3), 0.25:0.25:0.50, respectively. The reaction reached conversion about 98.6% under the conditions: alcohol/oil molar ratio (24:1), catalyst to oil mass ratio of 3.0%, 15 h and 70 oC. The turnover frequency (TOF) found was 24.5 × 10 -4 s -1 . Kinetic of the reaction was researched over a temperature range of 60-80 oC. A pseudo first-order model was proposed with the activation energy (Ea) of 49.18 kJ mol -1 . CRAL is active in the biodiesel production for just one cycle, because in the second one it loses its activity. The leaching of catalyst is about 13%, demonstrating that the catalyst is not totally heterogeneous.