Showing papers on "Anhydrous published in 2009"

One-dimensional imidazole aggregate in aluminium porous coordination polymers with high proton conductivity.

Abstract: The development of anhydrous proton-conductive materials operating at temperatures above 80 degrees C is a challenge that needs to be met for practical applications. Herein, we propose the new idea of encapsulation of a proton-carrier molecule--imidazole in this work--in aluminium porous coordination polymers for the creation of a hybridized proton conductor under anhydrous conditions. Tuning of the host-guest interaction can generate a good proton-conducting path at temperatures above 100 degrees C. The dynamics of the adsorbed imidazole strongly affect the conductivity determined by (2)H solid-state NMR. Isotope measurements of conductivity using imidazole-d4 showed that the proton-hopping mechanism was dominant for the conducting path. This work suggests that the combination of guest molecules and a variety of microporous frameworks would afford highly mobile proton carriers in solids and gives an idea for designing a new type of proton conductor, particularly for high-temperature and anhydrous conditions.

Influence of water on the dissolution of cellulose in selected ionic liquids

Abstract: Cellulose (7% water) was thoroughly dispersed in various ionic liquids (IL) and the turbidity of the mixture was investigated to distinguish real dissolution from fine dispersion. The dissolving ability of 1-butyl-3-methylimidazolium chloride (BMIMCl know cellulose solvent) and 11 other commercial IL (not reported as cellulose solvents) was studied. From the latter, only 1,3-dimethylimidazolium dimethylphosphate (DMIMDMP) could dissolve cellulose. The influence of water content on the real dissolution of cellulose in these two IL was investigated. The maximum theoretical amount of dissolved anhydrous cellulose in the IL was determined by extrapolation methodology at different temperatures. For cellulose in BMIMCl, it was 8.75 g/100 g of IL at 95 °C. DMIMDMP could achieve real cellulose dissolution only in a practically anhydrous system (2.3 g/100 g of IL at 30 °C) but dissolution was physically limited by high viscosity.

Apparatus, system, and method for generating a gas from solid reactant pouches

Abstract: An apparatus, system, and method are disclosed for generating a gas. One or more liquid permeable pouches each define a cavity that contains a solid anhydrous reactant, such as a chemical hydride. A reaction chamber made of a heat, chemical and/or pressure resistant material receives the one or more pouches from a pouch feeder that transfers the one or more pouches into the reaction chamber successively at a feed rate. One or more liquid sources inject a liquid reactant into the reaction chamber so that the liquid reactant contacts a portion of the one or more pouches. The one or more liquid sources inject the liquid reactant at an injection rate that corresponds to the feed rate. A gas outlet releases a gas, such as hydrogen, oxygen, ammonia, borazine, nitrogen, or a hydrocarbon, that is produced by a reaction between the solid reactant and the liquid reactant.

Composite Polymer Electrolyte Containing Ionic Liquid and Functionalized Polyhedral Oligomeric Silsesquioxanes for Anhydrous PEM Applications

Abstract: A new type of supported liquid membrane was made by combining an ionic liquid (IL) with a Nafion membrane reinforced with multifunctional polyhedral oligomeric silsesquioxanes (POSSs) using a layer-by-layer strategy for anhydrous proton-exchange membrane (PEM) application. The POSS was functionalized by direct sulfonation, and the sulfonated POSS (S-POSS) was incorporated into Nafion 117 membranes by the infiltration method. The resultant hybrid membrane shows strong ionic interaction between the Nafion matrix and the multifunctional POSS, resulting in increased glass transition temperature and thermal stability at very low loadings of S-POSS (1%). The presence of S-POSS has also improved the proton conductivity especially at low humidities, where it shows a marked increase due to its confinement in the ionic domains and promotes water uptake by capillary condensation. In order to achieve anhydrous conductivity, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI) was incorporat...

Surface Enthalpy, Enthalpy of Water Adsorption, and Phase Stability in Nanocrystalline Monoclinic Zirconia

Abstract: A fundamental issue that remains to be solved when approaching the nanoscale is how the size induces transformation among different polymorphic structures. Understanding the size-induced transformation among the different polymorphic structures is essential for widespread use of nanostructured materials in technological applications. Herein, we report water adsorption and high-temperature solution calorimetry experiments on a set of samples of single-phase monoclinic zirconia with different surface areas. Essential to the success of the study has been the use of a new ternary water-in-oil/water liquid solvothermal method that allows the preparation of monoclinic zirconia nanoparticles with a broad range of (BET) Brunauer–Emmett–Teller surface area values. Thus, the surface enthalpy for anhydrous monoclinic zirconia is reported for the first time, while that for the hydrous surface is a significant improvement over the previously reported value. Combining these data with previously published surface enthalpy for nanocrystalline tetragonal zirconia, we have calculated the stability crossovers between monoclinic and tetragonal phases to take place at a particle size of 28 ± 6 nm for hydrous zirconia and 34 ± 5 nm for anhydrous zirconia. Below these particle sizes, tetragonal hydrous and anhydrous phases of zirconia become thermodynamically stable. These results are within the margin of the theoretical estimation and confirm the importance of the presence of water vapor on the transformation of nanostructured materials.

Cobalt Oxalate Nanoribbons as Negative-Electrode Material for Lithium-Ion Batteries

Abstract: Orthorhombic cobalt oxalate dihydrate has been prepared in the form of nanoribbons by a reverse micelles method. The crystallographic structure of the resulting solid differs from the monoclinic massive product. A careful dehydration of the nanocrystals leads to anhydrous cobalt oxalate in which the nanoribbon-shaped particles are preserved and Co2+ ions are located in a centrosymmetric environment. CoC2O4 is used for the first time as high-capacity lithium storage materials with improved rate performance. The anhydrous solids react with lithium, leading to metallic cobalt and lithium oxalate, as shown by XAS and FTIR measurements. The new electrode material displays reversible capacities close to 900 mA·h·g−1 between 0 and 2 V versus lithium by a novel reaction mechanism which involves cobalt reduction−reoxidation.

Volatile diffusion in silicate melts and its effects on melt inclusions

Abstract: A compendium of diffusion measurements and their Arrhenius equations for water, carbon dioxide, sulfur, flu- orine, and chlorine in silicate melts similar in composition to natural igneous rocks is presented. Water diffusion in silicic melts is well studied and understood, however little data exists for melts of intermediate to basic com- positions. The data demonstrate that both the water concentration and the anhydrous melt composition affect the diffusion coefficient of water. Carbon dioxide diffusion appears only weakly dependent, at most, on the volatile- free melt composition and no effect of carbon dioxide concentration has been observed, although few experi- ments have been performed. Based upon one study, the addition of water to rhyolitic melts increases carbon dioxide diffusion by orders of magnitude to values similar to that of 6 wt% water. Sulfur diffusion in intermedi- ate to silicic melts depends upon the anhydrous melt composition and the water concentration. In water-bearing silicic melts sulfur diffuses 2 to 3 orders of magnitude slower than water. Chlorine diffusion is affected by both water concentration and anhydrous melt composition; its values are typically between those of water and sulfur. Information on fluorine diffusion is rare, but the volatile-free melt composition exerts a strong control on its dif- fusion. At the present time the diffusion of water, carbon dioxide, sulfur and chlorine can be estimated in silicic melts at magmatic temperatures. The diffusion of water and carbon dioxide in basic to intermediate melts is on- ly known at a limited set of temperatures and compositions. The diffusion data for rhyolitic melts at 800°C to- gether with a standard model for the enrichment of incompatible elements in front of growing crystals demon- strate that rapid crystal growth, greater than 10 −10 ms −1 , can significantly increase the volatile concentrations at the crystal-melt interface and that any of that melt trapped by the formation of melt inclusions may not be rep- resentative of the bulk melt. However, basaltic melt inclusions trapped at 1300°C are more likely to contain bulk melt concentrations of water and carbon dioxide.

Potassium Phosphate Catalyzed a Rapid Three-Component Synthesis of Tetrahydrobenzo[b]pyran at Ambient Temperature

Abstract: An efficient, rapid, one-pot synthesis of tetrahydrobenzo[b]pyran is achieved via a three-component reaction of aldehydes, 1,3-diketone, malononitrile in 20% ethanol using anhydrous potassium phosphate as a catalyst at room temperature. The key advantages are the short reaction time, high yields, simple work-up, inexpensive catalyst and purification of products by non-chromatographic methods, i.e. by simple recrystallization from ethanol. An efficient, rapid, one-pot synthesis of tetrahydrobenzo[b]pyran is achieved via a three-component reaction of aldehydes, dimedone, malononitrile in 20% ethanol using anhydrous potassium phosphate as a catalyst at room temperature. The key advantages are the short reaction time, high yields, simple work-up, inexpensive catalyst and purification of products by non-chromatographic methods, i.e. by simple recrystallization from ethanol.

Crystal structures with a challenge: high-pressure crystallisation of ciprofloxacin sodium salts and their recovery to ambient pressure

Abstract: Two novel sodium salts of the antibiotic ciprofloxacin were crystallised at pressures of 0.25 and 0.6 GPa and subsequently recovered to ambient pressure. The structures are the first reported examples of ciprofloxacin chelating a Group IA monovalent cation. Ambient-pressure crystallisation of the same solution used for high-pressure experiments, yielded crystals of the known hexahydrate. In a parallel study, the previously unknown structure of anhydrous ciprofloxacin was determined from powder diffraction data. The structures are described and compared using the XPac method.

Reducing salt level in food: Part 1. Factors affecting the manufacture of model cheese systems and their structure-texture relationships

Abstract: A model lipoproteic matrix able to mimic hard-type cheese was produced with controlled structural and textural properties. Changes in the microstructural and rheological properties of these model cheeses made from different milk concentrate powder, anhydrous milk fat, salt contents and pH values at renneting were characterised. Rheological properties were measured by texture profile analysis, fat globule and protein aggregate size distributions by laser light scattering. Microstructural properties of the model matrices were studied by confocal laser scanning and scanning electron microscopy. Significant differences between the matrices were found for the structural, physico-chemical and rheological parameters measured. Cheeses with higher dry matter content were significantly harder and contained more insoluble proteins than cheeses with lower dry matter content. The salt concentration and the pH at renneting had significant influence on cheese hardness and adhesiveness of rheological parameters. The model lipoproteic matrix presented air bubbles and powder aggregates which could not be avoided during the manufacture of products. However, compared with classic cheese making with rennet or acid coagulation, the technology used here allows model cheeses to be produced rapidly with a good reproducibility of texture.

Drug-containing coordination and hydrogen bonding networks obtained mechanochemically

Abstract: In this communication we describe the solid-state preparation and structural characterization of the coordination and hydrogen bonding networks formed by the antibiotic 4-aminosalicylic acid and the nootropic drug piracetam with silver and nickel cations, respectively; the silver complex formed via solid-state reaction is anhydrous, while from solution its hydrated phase is obtained.

New energetic compounds based on the nitrogen-rich 5,5′-azotetrazolate anion ([C2N10]2−)

Abstract: The metathesis reaction between sodium 5,5′-azotetrazolate ([Na]+2ZT2−) pentahydrate and 1,3-dimethyl-5-aminotetrazolium iodide or semicarbazidium chloride in water leads to the formation of the corresponding ZT2− salts as the hydrated species (2 and 4). The anhydrous derivatives (1 and 3) were synthesized by reaction of silver 5,5′-azotetrazolate with a suitable halogenide salt in methanol. Alternatively, the crystal water in the hydrated salts 2 and 4 was quantitatively removed under vacuum leading to a safe up-scalable synthesis for compounds 1 and 3, which does not make use of highly sensitive silver salts. The formation of the salts was confirmed by analytical and spectroscopic methods and, in addition, the crystal structures of 2 and 4 were determined using low-temperature X-ray measurements (2: monoclinic P21/n, a = 9.3101(3), b = 6.5383(2), c = 19.5637(5) A; β = 90.48(1)°; V = 1190.84(6) A3 and 4: triclinic P, a = 4.563(5), b = 7.362(5), c = 11.334(5) A; α = 105.125(5), β = 90.48(1), γ = 102.871(5)°; V = 357.2(5) A3). Although the semicarbazidium salts 3 and 4 have relatively low thermal stabilities (<130 °C), the tetrazolium salts 1 and 2 decompose above 190 °C. All four compounds classify as insensitive, have high performances (1: P = 19.0 GPa and D = 7667 m s−1; 2: P = 25.1 GPa and D = 8585 m s−1; 3: P = 23.4 GPa and D = 8125 m s−1 and 4: P = 20.0 GPa and D = 7694 m s−1) and decompose giving (mainly) environmentally friendly gases. Lastly, the properties of salts 1–4 make them attractive for further studies as a new class of high performing, insensitive, environmentally more benign and, in the case of 1 and 2, also thermally stable energetic materials.

Supramolecular structures of six adenine- carboxylic acid complexes

Abstract: Studies concentrating on hydrogen bonding between the bases of DNA and small molecule proton acceptor/donators have led to an increased understanding of the role such complexes have in DNA binding. Here anhydrous and solvated multicomponent crystals of adenine have been prepared with benzoic acid, adipic acid, salicylic acid, 2,6-dihydroxybenzoic acid and 3,5-dihydroxybenzoic acid. The six crystalline forms reported are an anhydrous cocrystal, a methanolated cocrystal, an anhydrous proton-transfer complex, a hydrated proton-transfer complex, a methanolated proton-transfer complex and a doubly hydrated salt. All products were formed in solution and obtained by the slow evaporation technique. A comparison of hydrogen bonding motifs in the products is presented.

Method for purifying fermentation alcohol

Abstract: The present invention relates to a method for purifying an aqueous solution of fermentation alcohol to give anhydrous alcohol, wherein a mash column is controlled such a manner that an alcohol concentration of an alcohol/water mixed vapor distilled from a mash column is less than 50% by weight and a reflux amount of a condensate to a distillation column is controlled such a manner that an alcohol concentration of an alcohol/water mixed vapor that is distilled from the distillation column is 55 to 85% by weight. According to the present method, the purification for obtaining an anhydrous alcohol from an aqueous solution of a fermentation alcohol with the use of a mash column, a pressurized distillation column and a membrane separator can be more conveniently carried out with an extremely high energy efficiency as the whole process.

Method to improve water solubility of Rebaudioside D

Abstract: Thermally stable anhydrous Rebaudioside D can be provided by methods disclosed here and has been found to be more soluble in aqueous solutions than the previously known non-anhydrous Rebaudioside D. This physical property makes the anhydrous Reb D amenable to food and beverage manufacturing applications for which the non-anhydrous form is not suitable. Anhydrous Rebaudioside D is useful in sweeteners, and can be included in food and beverage products, which are also disclosed.

Extinguishment combination with hot gas sol

Abstract: The invention provides ''a hot aerosol fire-extinguishing composition'' and relates to an oxidative magnesium salt hot aerosol fire-extinguishing composition represented by anhydrous magnesium nitrate. The composition is characterized in that the composition can be magnesium nitrate, magnesium carbonate, or other magnesium salt, and can also be a compound of magnesium nitrate, or other magnesium salt with potassium nitrate, strontium nitrate, or other potassium salt or strontium salt; a reducer can be one of or the combination of a plurality of ammonium carbamidine, dicyandiamide, red prussiate of potash, formamine, triazole, and tetrazole; a capability improver can be magnesium carbonate, manganous carbonate, aluminium powder, powdered carbon, magnesium hydrate, metal oxide, etc.; and the bond adopts phenolic resin, etc. The preparation of the magnesium salt comprises the continuous steps: medium temperature and low pressure dehydration, spray under the protection of nitrogen-oxygen flow or ultrafine grinding of grinded colloid, and microencapsulated hydrophobic treatment, etc. Compared with the prior art, the fire-extinguishing composition has the advantages of low price, extensive source, fire-extinguishing capability of K-type composition, and low causticity and toxicity of the ultimate product of combustion.