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Methanol steam reforming was carried out over catalysts prepared from amorphous Cu-Zr alloys containing a small amount of noble metals. The reforming activity of the alloy with noble metal below 0.7at% decreased with repetition of oxidation, reduction and steam reforming sequences. The amorphous Cu-Zr alloys with small amounts of noble metals changed to fine copper particles supported on zirconium oxide by the heat treatment. Although the rate constant over the alloy with platinum was smaller than that over the alloy with rhodium, the carbon monoxide selectivity over the former was higher than that over the latter. These results suggest that the catalyst prepared from Cu-Zr alloy with lat% of platinum is suitable for the steam reforming.

Beckmann rearrangement of cyclohexanone over the regenerated TS-1 and SSZ-31 was carried out to clarify the effect of regeneration number and regeneration atmosphere on e-caprolactam selectivity and catalyst deactivation rate. The rearrangement rate constant for the both catalysts decreased with the number of regeneration, but the e-caprolactam selectivity and deactivation factor observed from TS-1 was almost constant. On the other hand, e-caprolactam from SSZ-31 regenerated in Ar atmosphere decreased with the number of regeneration. These behaviors indicated that the coke precursor deposited on the SSZ-21 surface changed to hard coke in the pore, whereas the coke precursor produced on the pore mouth for TS-1 was easily removed in Ar atmosphere.

The fluidization quality significantly decreased when the reaction involving a decrease in the gas volume was carried out in a fluidized catalyst bed. In the present study, we carried out the hydrogenation of CO2 and used relatively large particles as the catalysts. Since the emulsion phase of the fluidized bed with these particles does not expand, we expected that the bed was not affected by the gas-volume decrease. However, we found that the fluidization quality decreased and the defluidization occurred. We studied the effects of the reduction rate of the gas volume and the maximum gas contraction ratio on the fluidization behavior.

A pilot plant test of hydrodesulfurization (HDS) of an atmospheric residue (AR) was carried out to elucidate the effect of start-up conditions on catalytic performance and catalyst deactivation. When the AR containing a large amount of asphaltenes or related compounds was fed at start of run (SOR) to the HDS catalyst bed operated at low H2/HC ratio and low hydrogen pressure, the permanent strong adsorption of carbonaceous deposits (coke) on to the active sites of HDS catalyst caused severe catalyst deactivation. The activity of the deactivated catalyst did not recover even if the H2/HC ratio and hydrogen pressure changed to normal operating conditions. Since the HDS activity of the catalyst after a presulfiding is the highest during the operation time, a careful HDS operation including an adequate feed selection is required to obtain the good catalytic performance and catalyst life.

The effect of iron-oxidizing bacteria on the simultaneous leaching of zinc sulfide and manganese dioxide was studied. Some researchers have reported the enhancement of the leaching rate during the simultaneous leaching of metal oxides and metal sulfides. In the present study, we examined the effect of the presence of Thiobacillus ferrooxidans in the simultaneous leaching. We also examined the reaction rates during the simultaneous leaching in the presence of the bacteria in order to study the reaction kinetics. The rate equation was obtained for each reaction: the oxidation of zinc sulfide by ferric iron, the oxidation of zinc sulfide by ferric iron and by the bacteria, the reductive dissolution of manganese dioxide by ferrous iron, and the simultaneous dissolution of zinc sulfide and manganese dioxide. A kinetic model based on these equations was proposed and the extent of leaching during the simultaneous dissolution with T. ferrooxidans was determined.

The Beckmann rearrangement of cyclohexanone oxime has been carried out over high silica metallosilicate modified with noble metals to elucidate the effects of the noble metal modification and contact time (W/FAO) on the e-caprolactam selectivity and the catalyst deactivation rate. The deactivation factor decreases with contact time. The catalyst was deactivated in the following order; Pt

Publisher Summary This chapter describes catalyst deactivation of high silica metallosilicates in Beckmann rearrangement of cyclohexanone oxime. The vapor phase Beckmann rearrangemem was carried out over high silica ZSM-5 type metallosilicates to elucidate the effect of acid strength on caprolactam (CL) selectivity and catalyst deactivation rate. It was found that the indiosilicate, which had the lowest acid strength, was the best catalyst among the metallosilicates. When carbon dioxide and methanol were used as diluent gas and diluent solvent of cyclohexanone oxime, respectively, the deactivation rate decreased over indiosilicate. Furthermore, when the indiosilicate was modified with a precious metal, the catalyst deactivation significantly decreased. It was considered that the oxidation of coke on the surface was accelerated by the precious metal. In this chapter, the rearrangement has been carried out over a ZSM-5 type metallosilicates including iron, gallium or radium in the crystal lattice to elucidate the effect of acid strength on the catalyst deactivation rate. The chapter also examines the effects of diluent solvent and diluent gas of CHO on the deactivation rate and CL selectivity. Furthermore, the rearrangement was carried out over an indiosilicate modified with precious metals to decrease the catalyst deactivation.

The reaction of p-bromochlorobenzene(p-BCB) and p-dichlorobenzene(p-DCB) was carried out over HY, H-mordenite and HZSM-5 zeolites to elucidate the effects of micro pore size and acid strength distribution on catalytic activity, the product selectivity and catalyst deactivation rate. When p-DCB and p-CBB were supplied on HY zeolite, dehalogenation predominantly proceeded. Whereas, the isomerization of the reactant mainly proceeded over HZSM-5. The dechlorination and isomerization simultaneously proceeded over H-mordenite. The characterization of the used zeolites indicates that the acid sites effective for the dechlorination are different from for the isomerization.

The iron-oxidizing bacterium, Acidithiobacillus ferrooxidans, was cultivated on a medium without ferrous iron. Molecular hydrogen and air were supplied to the medium. It was found that A. ferrooxidans could grow with hydrogen in the pH range between 2.0 and 3.5. A trickle-bed contactor was used to increase the dissolution rate of hydrogen. The doubling time was increased and the cell concentration reached 4.0 x 10(9) cells ml(-1) after 6 days. When the cells taken from the hydrogen medium were transferred back into the medium containing ferrous iron, the growth rate and the iron-oxidizing ability were the same as the predictions assuming that the microorganism grown with hydrogen was A. ferrooxidans.

In a fluidized catalyst bed, the reactant gas transfers from the bubble phase to the emulsion phase and reactions proceed in the emulsion phase. The catalyst particles around the bubbles should contact the gases containing a high concentration of the reactants. Therefore, the effect of the catalysts around the bubbles is very important for estimating the conversion and selectivity in the reactor. In order to study the role of these catalysts, the hydrogenation of carbon dioxide was carried out in a fluidized catalyst bed. Based on the results, the amount of the catalyst that was effective for the reaction was calculated. In addition, the shape of the bubbles ascending in the fluidized catalyst bed was observed using a fast X-ray computer tomography (CT) scanner. The structure of the bubbles in the fluidized catalyst bed was very complicated and the surface area of the bubbles was much greater than the obtained when assuming spherical shaped bubble. By assuming that effective catalysts existed around the bubbles, the thickness of catalyst layer was obtained. Finally, the 3-dimensional images of the catalyst layers around the bubbles were reconstructed.

Since Yakushima Island is rich in rainfall, hydroelectric power produced on the island is sufficient to cover all the energy demands on this island. A hydrogen fueling station was constructed on this island and hydrogen was produced by water electrolysis. The hydrogen production rate is 1.25 N m 3 / h . The produced hydrogen was used for the driving tests of fuel cell vehicles, while the public acceptance of hydrogen energy was studied. This station is comprised of several systems, including hydrogen generation, hydrogen purification, compression and storage. During the operation of the station, the electricity consumption by each component and the production rate of hydrogen were measured. Since the facility is small, the energy efficiency is low. The total energy efficiency, which was calculated by dividing the potential energy of the compressed hydrogen by the total electrical energy input to the station, was 25% (LHV) and 30% (HHV).