Halide ion-promoted desulfo-halogenation was applied successfully to synthesis of 4-chloro-2-azetidinone 1, a potent intermediate for carbapenem synthesis, and stereoselective N-glycosylation of 2,3-deoxyglycosides. Bromide ion/N-oxyl compounds (TEMPO) double mediatory systems enabled us to develop several aqueous electrolysis media free from organic solvents, e.g., silica gel or polymer particles/water disperse systems and water-soluble TEMPO-mediated oil-in-water emulsion systems, in which electrooxidation of alcohols was carried out successfully in a simple beaker-type undivided cell under a constant current condition. Notably, the work-up process was very simple and the solid particles (disperse phase) and the aqueous solutions (disperse media) were easily recovered and reused, offering a totally closed system. In Pd(OAc)2/TEMPO double mediatory systems, electrogeneration of active cationic palladium catalysts was integrated into electrooxidative Wacker-type reaction. In a similar manner, Wacker-type cyclization and homo-coupling of arylboronic acids were successfully achieved.
Electrochemical reduction of H2O2 in a neutral buffer solution was investigated with a binary oxide catalyst consisting of IrO2 and Ta2O5 prepared by thermal decomposition. Cyclic voltammograms obtained at 5 mV s−1 showed a diffusion-limited current for H2O2 reduction, and the reduction current was proportional to H2O2 concentration. The current/concentration ratio increased with decreasing thermal decomposition temperature, indicating the sensitivity to H2O2 reduction is enhanced. Cyclic voltammetry also revealed that H2O2 reduction on IrO2-Ta2O5 catalysts was independent of a presence of azide ions as an anti-oxidant.
Influences of space velocity and engine output power on the plasma particulate matter (PM) removal with a dielectric barrier discharge (DBD) reactor have been investigated. The PM removal ratio without plasma discharges is approximately in inverse proportion to space velocity. The PM removal ratio with plasma discharges has been found to be less susceptible to space velocity than that without plasma discharges. As a cause of this result, it is suspected that active oxygen species produced by the plasma discharges transfer with the floating PM within the DBD reactor and then react with the floating PM. The PM removal ratio decreases with the increase in the engine output power, and the more pronounced declination has been found to be observed with the higher discharge electric power. This result is not explained only by the increase in space velocity arising from increasing engine output power. The factors, PM size, PM concentration, and reaction temperature, increasing with engine output power are considered to reduce the effects of plasma discharges on the PM removal.
We studied the application of LaCoO3 system cathode to improve the performance of segmented-in-series tubular type solid oxide fuel cells (SOFCs) operating at high temperature (1173 K). (La1−xSrx)CoO3 (LSC, x=0.2 or more) was chosen to take advantage of two of its properties: high electric conductivity and favorable behavior of element diffusion to a cathode interlayer (CIL) of (Sm0.2Ce0.8)O2 (SDC20). The cell stack performances were compared using LSC and (La0.5Sr0.25Ca0.25)MnO3 (LSCM) to cathode current collection layer (CCCL). The modification of cell stack structure composed of effective generation part and interconnector part was also examined. The area specific resistance (ASR) of the overall cell stack resistance with LSC modifying a stack structure decreased 18% than that of the stack using LSCM with conventional structure at atmospheric pressure. In a pressurized test of the cell stack fabricated with LSC, an increase of pressure resulted in a decrease of the ASR. As a result of comparing the pressurized performances of LSCM CCCL/(LSCM-10YSZ) CIL, LSCM/SDC20 and LSC/SDC20, the effect of ASR decrease by pressurization fell as the cell stack performances improve. We also found, however, that the cell stack fabricated with LSC will require improvements in long-term durability and thermal cycle characteristics.