Metallic membranes ethanol

Lopez, E., Divins, N.J. and Llorca, J. (2012) Hydrogen production from ethanol over Pd-Rh/Ce02 with a metallic membrane reactor. Catalysis Today, 193, 145-150. Montane, D., Bolshak, E. and Abello, S. (2011) Thermodynamic analysis of fuel processors based on catalytic-wall reactors and membrane systems for ethanol steam reforming. Chemical Engineering Journal, 175, 519-533. 

The need to develop alternative electrocatalysts with low or, even better, without noble metals (platinum), to decrease the costs due to Pt shortage. New nano-structured electrocatalysts (HYPERMEC by ACTA SpA for example, http // www.acta-nanotech.com) [51, 52] have been developed, which are based on non-noble metals, preferentially mixtures of Fe, Co, Ni at the anode, and Ni, Fe or Co alone at the cathode. With ethanol, power densities as high as 140 mW cm-2 at 0.5 V have been obtained at 25 °C with self-breathing cells containing commercial anion-exchange membranes. 

Ceynowa performed electron microscopic studies of 60—80 nm thick microtomed Nafion 125 membranes that were converted, for the purpose of affecting electron density contrast, to the Pb2+ form, and all of the excess cations and co-ions were removed. It is the heavy metal that provides electron density contrast between the phase in which it resides and the surrounding phase. These membranes were then exposed to ethanol and 1,2-epoxypropane, although these solvents would not have remained in the samples under the vacuum in the microscope column. The micrographs consisted of uniformly distributed points that were presumed to be ion clusters that were 3—6 nm in diameter. 

Selectivity sequences in solvents such as water, methanol and ethanol do not guarantee a similar behaviour in the lipid membrane. Experiments have been carried out in attempts to investigate the selective transfer of cations across model membranes, and these are exemplified here by reference to an investigation concerning the cryptands [2.2.2], [3.2.2], [3.3.3] and [2.2.C8]. Two aqueous phases (IN and OUT) were bridged by a chloroform layer into which the carrier can be dissolved. Alkali metal picrate was dissolved in two aqueous layers such that the IN layer was 1000 times more concentrated than the OUT layer. All layers were stirred and the transport monitored via increase in picrate in the OUT layer (UV) and increase in potassium in the OUT layer (atomic absorption). The membrane phase was also analyzed at the end of the experiment.497... 

Some dense inorganic membranes made of metals and metal oxides are oxygen specific. Notable ones include silver, zirconia stabilized by yttria or calcia, lead oxide, perovskite-type oxides and some mixed oxides such as yttria stabilized titania-zirconia. Their usage as a membrane reactor is profiled in Table 8.4 for a number of reactions decomposition of carbon dioxide to form carbon monoxide and oxygen, oxidation of ammonia to nitrogen and nitrous oxide, oxidation of methane to syngas and oxidative coupling of methane to form C2 hydrocarbons, and oxidation of other hydrocarbons such as ethylene, methanol, ethanol, propylene and butene. 

Arrays of concentric composite nanowires of Zr02 with Co cores were made in an alumina template by the sol-gel method from Zr02 sol [48]. The sol was made from Zr0Cl2 8H20, ethanol, HNO3 and acetylacetone. The alumina membrane was dipped in the sol for 0.5-1 h and after drying was aimealed at around 500 °C. The Zr02 template was then filled with Co metal by electrodeposition. This composite nanostructure had an enhanced coercivity compared to that of bulk Co. 

The existence of the blood-brain barrier does not preclude the passage of chemicals into the brain. As is the case with all other cellular membranes in the body, lipid-soluble nonionized chemicals enter the brain by passive diffusion. Anesthetics, ethanol, and CNS depressants, for instance, rapidly diffuse into the brain in a matter of a few seconds or minutes. They also exit the brain rapidly when the concentration gradient between blood and brain is reversed. Elemental mercury, methylmercury, and tetraethyl lead are examples of lipid-soluble forms of metals that easily enter the brain, while the ionized, much less lipid-soluble inorganic salts of mercury and lead penetrate only poorly. 

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