Search results for "Methanol"
showing 10 items of 1026 documents
Direct synthesis of dimethyl carbonate with supercritical carbon dioxide: characterization of a key organotin oxide intermediate
2006
The direct synthesis of dimethyl carbonate (DMC) using carbon dioxide as solvent and reagent for its fixation to methanol was explored with din-butyldimethoxystannane in order to get insight into the reaction mechanism for activity improvement. Catalytic runs including recycling experiments allowed isolation and characterization by NMR, IR, and single-crystal X-ray diffraction of a new tin complex containing 10 tin atoms. This compound could be prepared independently and is considered as a resting species. The yield of DMC is highest under 20 MPa pressure that fits with a monophasic supercritical medium in agreement with fluid phase equilibria calculations. In line, preliminary kinetics and…
Double cross-linked polyetheretherketone proton exchange membrane for fuel cell
2012
Abstract The proton exchange membrane based on polyetheretherketone was prepared via two steps of cross-linking. The properties of the double cross-linked membrane (water uptake, proton conductivity, methanol permeability and thermal stability) have been investigated for fuel cell applications. The prepared membrane exhibited relatively high proton conductivity, 3.2 × 10 −2 S cm −1 at room temperature and 5.8 × 10 −2 S cm −1 at 80 °C. The second cross-linking significantly decreased the water uptake of the membrane. The performance of direct methanol fuel cell was slightly improved as compared to Nafion ® 117 due to its low methanol permeability. The results indicated that the double cros…
Methanol and proton transport through chitosan-phosphotungstic acid membranes for direct methanol fuel cell
2020
Composite chitosan-phosphotungstic acid membranes were synthesized by ionotropic gelation. Their liquid uptake is higher for thin membranes (23 ± 2 μm), while it is lower (~70%) for thicker membranes (50-70 μm). Polarization curves recorded using single module fuel cell at 70°C allowed to estimate a peak power density of 60 mW cm−2 by using 1 M as methanol and low Pt and Pt/Ru loadings (0.5 and 3 mg cm−2) at the cathode and at the anode, respectively. Electrochemical impedance spectroscopy was used to estimate the membrane conductivity and to model the electrochemical behavior of methanol electrooxidation inside the fuel cell revealing a two-step mechanism mainly responsible of overall kine…
Cross-linked PEEK-WC proton exchange membrane for fuel cell
2009
Abstract The low cost proton exchange membrane was prepared by cross-linking water soluble sulfonated-sulfinated poly(oxa- p -phenylene-3,3-phthalido- p -phenylene-oxa- p -phenylene-oxy-phenylene) (SsPEEK-WC). The prepared cross-linked membrane became insoluble in water, and exhibited high proton conductivity, 2.9 × 10 −2 S/cm at room temperature. The proton conductivity was comparable with that of Nafion ® 117 membrane (6.2 × 10 −2 S/cm). The methanol permeability of the cross-linked membrane was 1.6 × 10 −7 cm 2 /s, much lower than that of Nafion ® 117 membrane.
Covalent-ionically cross-linked polyetheretherketone proton exchange membrane for direct methanol fuel cell
2010
Abstract In this paper, the proton exchange membrane prepared by covalent-ionically cross-linking water soluble sulfonated–sulfinated poly(oxa- p -phenylene-3,3-phthalido- p -phenylene-oxa- p -phenylene-oxy-phenylene) (SsPEEK-WC) is reported. Compared with covalent cross-linked PEEK-WC membrane, this covalent-ionically cross-linked PEEK-WC membrane exhibits extremely reduced water uptake and methanol permeability, but just slightly sacrificed proton conductivity. The proton conductivity of the covalent-ionically cross-linked PEEK-WC membrane reaches to 2.1 × 10 −2 S cm −1 at room temperature and 4.1 × 10 −2 S cm −1 at 80 °C. The methanol permeability is 1.3 × 10 −7 cm 2 s −1 , 10 times …
CCDC 291811: Experimental Crystal Structure Determination
2006
Related Article: F.A.Cotton, C.A.Murillo, S.-E.Stiriba, Xiaoping Wang, Rongmin Yu|2005|Inorg.Chem.|44|8223|doi:10.1021/ic051282c
CCDC 291816: Experimental Crystal Structure Determination
2006
Related Article: F.A.Cotton, C.A.Murillo, S.-E.Stiriba, Xiaoping Wang, Rongmin Yu|2005|Inorg.Chem.|44|8223|doi:10.1021/ic051282c
Isolation of Four New CoII/CoIII and NiII Complexes with a Pentadentate Schiff Base Ligand: Syntheses, Structural Descriptions and Magnetic Studies
2011
In this paper we report the temperature and pH dependent syntheses and systematic characterization of four new Co(II)/Co(III) and Ni(II) complexes with a pentadentate Schiff base ligand H(3)L obtained by condensing 1,3,-diaminopropan-2-ol with 2-hydroxyacetophenone in 1:2 molar ratio. The room temperature syntheses involving Co(II) and Ni(II) nitrates and the ligand H(3)L lead to the isolation of the dinuclear species [Co(2)L(2)(H(2)O)] (1), and the mononuclear complex [Ni(LH)] (3), respectively, whereas refluxing at basic pH leads to the tetranuclear complexes, [Co(II)(2)Co(III)(2)L(2)(μ(3)-OMe)(2)(NO(3))(H(2)O)(2)]NO(3)·2(H(2)O) (2), and [Ni(4)L(2)(μ(3)-OMe)(2)(H(2)O)(2)]·2H(2)O (4). 1 is…
ESR, ENDOR and TRIPLE resonance studies on radical reactions of 1,4-benzoquinone and 1,4-hydroquinone in alkaline methanol and liquid ammonia
1990
The relative signs and absolute values of the hyperfine coupling constants of different methoxy-1,4-benzoquinones were measured by ESR, ENDOR and TRIPLE resonance spectroscopy. Reactions of 1,4-benzoquinone and 1,4-hydroquinone with methanol took place in alkaline methanol, giving rise to methoxy-substituted 1,4-benzoquinones. The same substitution reaction occurred in a mixture of ammonia and methanol. The reactions depended on temperature and the alkali concentration. Coupling constants were assigned by the modified additivity relationship method. An extremely small line width of 0.014 G was measured in the ESR spectrum of deuterated 2,5-dimethoxy-1,4-benzoquinone.
Boosting DMFC power output by adding sulfuric acid as a supporting electrolyte: Effect on cell performance equipped with platinum and platinum group …
2023
Direct methanol fuel cells (DMFCs) are promising electrochemical systems capable of producing electricity from the electrochemical oxidation of methanol and the reduction of oxygen. In this work, the effectiveness of the addition of sulfuric acid as a supporting electrolyte for methanol fuel composition was assessed. The results showed that the peak of power curve in DMFCs with Pt/C cathode electrocatalysts increased progressively from 70 mW cm−2 (0 mM of H2SO4) to 115 mW cm−2 with a concentration of 100 mM of H2SO4. These results underlined the positive effect of the addition of a supporting electrolyte in the methanol aqueous solution on the electrochemical output that was enhanced. Plati…