Freigelegt! Mit einer templatgestützten Elektroabscheidung gelang die Synthese stabiler Netzwerke aus Metall‐ oder Halbleiternanodrähten (siehe Schema). Dazu wurde a) mesoporöses Siliciumdioxid an einer Elektrode abgeschieden, b) die Kanäle mit dem Metall oder Halbleiter gefüllt und c) das Templat entfernt, um das Nanodrahtnetz zu erhalten.
Soybean oil has been partially hydrogenated in a proton exchange membrane (PEM) electrochemical reactor, with H2 gas as the anode feed and source of hydrogen. The reactor is similar
in design to that used in a H2/O2 fuel cell, with a membrane electrode assembly composed of a
Pd-black powder cathode and a Pt-black powder anode fixed to the opposite surfaces of a Nafion
117 cation-exchange membrane. The PEM reactor was operated at a moderate temperature (60−90 °C) and 1 atm of pressure using commercial-grade soybean oil as the cathode feed. The effects
of the current density, temperature, and oil flow rate on oil hydrogenation current efficiency
and product selectivity were investigated. The oil hydrogenation current efficiency (the efficiency
of electrogenerated H2 addition to fatty acid double bonds) increased with temperature, decreased
with current density, and ranged from 45 to 97%. Partially hydrogenated oil products were
characterized by a low percentage of trans-fatty acid isomers (which are known contributors to
coronary heart disease) and a moderately high concentration of saturated stearic acid (typical
of nonselective, precious metal hydrogenation catalysts). An improvement in fatty acid
hydrogenation selectivity was achieved by increasing the oil feed flow rate and inserting a
turbulence promoter into the oil feed channel of the PEM reactor. The use of a bimetallic cathode
(Pd/Co or Pd/Fe) increased the selectivity of the hydrogenation process, at the expense of a drop
in current efficiency and an increase in the trans isomer content of hydro-oil products.
Novel platinum nanowire network electrodes have been fabricated through electrodeposition using mesoporous silica thin films as templates. These electrodes were characterized by X-ray diffraction, transmission electron microscope, and scanning electron microscope. The electrochemical properties of the electrodes, such as electrochemical active area and methanol oxidation, have also been studied. Compared with conventional polycrystalline Pt electrodes, these novel nanowire network electrodes possess high electrochemical active areas and demonstrate higher current densities and a lower onset potential for methanol electro-oxidation. Enzymatic Pt nanowire-network-based sensors show higher sensitivity for glucose detection than that using conventional polycrystalline Pt electrode. Such macroscopic nanowire network electrodes provide ideal platforms for sensing and other device applications.
Partially hydrogenated soybean oils were prepared by electrochemical hydrogenation at a palladium/cobalt or palladium/iron cathode, moderate temperature (70-90°C) and atmospheric pressure. The trans fatty acid (TFA) contents of 90-110 IV products ranged from 6.4 to13.8% and the amounts of stearic acid ranged from 8.8 to 15.4% (the higher stearic acid contents indicated that some reaction selectivity had been lost). The solid fat values and melting point data indicated that electrochemical hydrogenation provides a route to lowtrans spreads and baking shortenings. Shortenings produced by conventional hydrogenation contain 12-25% trans fatty acids and up to 37% saturates, whereas shortening fats produced electrochemically had reduced TFA and saturate content. Electrochemical hydrogenation is also a promising route to low-trans spread and liquid margarine oils. Compared to commercial margarine/spread oils containing 8-12% TFA, the use of electrochemical hydrogenation results in about 4% TFA.
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