Hisanori Ando

Change of catalytic properties of FeZnO/zeolite composite catalyst in the hydrogenation of carbon dioxide

Abstract The hydrogenation of carbon dioxide was examined using the composite catalysts which were obtained by the physical mixing of Fe ZnO and HY zeolite. Fe ZnO was a typical F-T (Fischer-Tropsch) catalyst and Fe ZnO/HY is a composite catalyst which is able to induce a combined methanol synthesis and MTG (Methanol-to-Gasoline) reaction. To study these unique catalytic behaviors of Fe ZnO/HY, the adsorption and the dissociation of carbon monoxide on Fe ZnO as well as TPR measurements were carried out. Fe ZnO is able to produce hydrocarbons by F-T reaction and methanol. In the absence of zeolite, Fe ZnO exerts its ability for F-T reaction. However, HY diminishes the activity for F-T reaction and hydrocarbons were obtained via methanol formed over the modified Fe ZnO

Decisive Factors in the Photoisomerization Behavior of Crowned Spirobenzopyrans: Metal Ion Interaction with Crown Ether and Phenolate Anion Moieties

The influence of metal ion interaction with crowned spirobenzopyrans on the photoisomerization behavior was investigated through the use of various solvents, crowned spirobenzopyrans, and metal ions. Studies on the photoisomerization behavior of crowned spirobenzopyrans in various solvents revealed that solvation of the phenolate anion moiety in the merocyanine form induced photoisomerization back to the spiropyran form, giving rise to negative photochromism. Metal ion interaction with the phenolate anion moiety similarly caused photoisomerization back to the spiropyran form, while that with the crown ether moiety just produced a polar environment and its influence on photoisomerization behavior was dependent on the affinity of the metal ion captured by the crown ether moiety for the phenolate anion. Therefore, photochromic switching of crowned spirobenzopyrans between positive and negative to control the metal ion interaction with the phenolate anion moiety through the crown ether moiety is possible. This finding suggests a molecular design method for crowned spirobenzopyrans showing desired ion-responsive photochromism.

Hydrogenation of carbon dioxide over CuZn-chromate/zeolite composite catalyst: The effects of reaction behavior of alkenes on hydrocarbon synthesis

Abstract The hydrogenation of carbon dioxide was studied using composite catalysts comprised of CuZn-chromate and HY zeolite. These composite catalysts enabled the reaction combining methanol synthesis and methanol-to-gasoline reaction, and achieved the formation of ethylene and propene as the first example of the composite catalysts. The addition of alkaline metals, especially cesium, to CuZn-chromate enhanced the selectivities of those alkenes. The influences of the reaction pressure and the space velocity on the production of alkenes show that alkanes are obtained by the hydrogenation of the corresponding alkenes. The composite catalysts producing alkenes in high selectivity afforded heavier hydrocarbons preferentially. These results indicate that the hydrogenation of alkenes inhibits the carbon homologation of alkenes to result in the predominant formation of the corresponding lighter alkanes. From these observations, it was found that methanol synthesis catalysts used for the composite catalysts are required to be effective for methanol synthesis at high temperature (over 300°C) and to bear the low activity of the hydrogenation of alkenes.

Reduction behavior of Ru/CeO2 catalysts and their activity for wet oxidation

Three kinds of Ru/CeO2 catalysts were prepared. The mobility of the oxygen on Ru and their catalytic activity in the wet oxidation of acetic acid was investigated. Ru was present in the form of RuO2, and TPR experiment showed that the reaction, RuO2 + 2H2 → Ru + 2H2O, took place in different temperature ranges depending upon the kind of the catalysts. The catalyst with easily reducible oxygen on Ru had high activity in wet oxidation, and the importance of the release of oxygen from Ru to the reactant was suggested.

A comparative study on hydrogenation of carbon dioxide and carbon monoxide over iron catalyst

Abstract Hydrogenation of CO 2 to hydrocarbons over iron catalysts reduced with hydrogen at 350°C and 500°C has been compared with that of CO. The space time yield of hydrocarbons from CO 2 at 250°C is significantly lower than from CO and the selectivity to olefin compounds is also lower from CO 2 . During the reaction with CO, χ-Fe 2.2 C is formed, and the surface, which is oxidized even after the reduction at 500°C, is further reduced. On the other hand, formation of the carbide species is slight in hydrogenation of CO 2 while the surface is rather oxidized. The formation of the carbide species, which is probably the active site of hydrocarbon formation, is suppressed in the presence of CO 2 .

Catalytic hydrogenation of carbon dioxide to hydrocarbons

Abstract Hydrogenation of carbon dioxide was studied by using rare earth alloy catalysts, hybrid catalysts and Fe-Cu catalysts in order to convert carbon dioxide to fuel. Methanation of carbon dioxide was carried out by using rare earth metal alloys at 200∼400°C under 1–5MPa. Methane was obtained in high yield (93%). Hydrocarbons (C1 to C5) were obtained in 16% yield by using hybrid catalyst composed of Cu-Zn-Cr and zeolite HY at 400°C via methanol. Higher hydrocarbons (C1∼C9) were also obtained in 45% yield by using Fe-Cu catalyst at 400°C under 5MPa.

Molecular ion battery: a rechargeable system without using any elemental ions as a charge carrier

Is it possible to exceed the lithium redox potential in electrochemical systems? It seems impossible to exceed the lithium potential because the redox potential of the elemental lithium is the lowest among all the elements, which contributes to the high voltage characteristics of the widely used lithium ion battery. However, it should be possible when we use a molecule-based ion which is not reduced even at the lithium potential in principle. Here we propose a new model system using a molecular electrolyte salt with polymer-based active materials in order to verify whether a molecular ion species serves as a charge carrier. Although the potential of the negative-electrode is not yet lower than that of lithium at present, this study reveals that a molecular ion can work as a charge carrier in a battery and the system is certainly a molecular ion-based “rocking chair” type battery.

Hydrogenation of carbon dioxide over copper-pyrochlore/zeolite composite catalysts

Abstract The hydrogenation of CO2 was studied over composite catalysts obtained by mixing Cu-based methanol synthesis catalyst and HY zeolite. A mechanism associating methanol synthesis and MTG (methanol to gasoline) reaction allowed the formation of C1-C4 hydrocarbons. It was found that the catalytic behaviors of the composite catalysts were favorably influenced by the characteristics of the methanol synthesis catalysts. The Cu-La2Zr2O7 catalyst we recently developed associated with HY zeolite exhibited interesting performances in hydrocarbon synthesis. The addition of ZrO2 to CuLa2Zr2O7/HY enhanced the ability to produce hydrocarbons. Comparing composite catalyst systems prepared with different Cu-based methanol synthesis catalysts, the effect of Na contamination on methanol and hydrocarbon formation over composite catalysts were also discussed.

Chromened t-butylcalix[4]arenes: cooperation effect of chromene and calixarene moieties on photochromism and metal-ion binding ability

Abstract Novel t-butylcalix[4]arenes bearing several chromene molecules were synthesized, and their photochromism and metal-ion binding ability were examined with alkali and alkaline-earth metal ions. While the metal-ion binding ability of the t-butylcalix[4]arene moiety facilitated the photoisomerization of the chromene moiety to a great extent, the chromene moiety influenced the metal-ion binding ability of the t-butylcalix[4]arene moiety through lariat effect. Therefore, the metal-ion that induced the most facilitated photoisomerization of the chromene moiety was shifted drastically from Li+ to Ba2+ with the increase of the incorporated chromene number. Even without metal ions, the interaction among the chromene moieties derived from the cone-conformation of the t-butylcalix[4]arene moiety also facilitated the photoisomerization.

Reaction of pentaarylantimony with acid halide, aldehyde and ketone

Pentaarylantimony (pentaphenylantimony, penta-p-tolylantimony and penta-p-chlorophenylantimony) was found to be a mild arylation reagent. The arylation was chemoselective toward aromatic acid halides to give the corresponding aromatic ketones. No direct addition to ketone and acid anhydride occurred. Arylation reactions of aldehyde or ketone were promoted by the addition of Lewis acid. The nucleophilicities of aromatic antimony compounds depend on the number of antimony-aromatic carbon bonds.