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De-t-butylation of t-butylbenzenes was carried out over a pyridine poisoned solid acidic catalyst to determine the effect of acid strength distribution on the reaction rate and catalyst fouling rate. The acid sites on the solid acidic catalyst were divided into three groups by their acid strength. Moderate acid sites, which were effective for the de-t-butylation but ineffective for the coke formation, were exclusively left on the catalyst surface by the partial poisoning. It is found that the present modification of the catalyst is useful in preparing an acid catalyst without catalyst fouling by coke deposition. On a effectue la de-t-butylation de t-butylbenzenes sur un catalyseur solide acide empoisonne a la pyridine afin de determiner l'effet de la distribution de la force de l'acide sur la vitesse de reaction et la vitesse d'encrassement du catalyseur. Les sites acides sur le catalyseur solide acide ont ete repartis en trois groupes selon leur force acide. Les sites acides moderes qui se sont averes efficaces pour la de-t-butylation mais inefficaces pour la formation de coke, ont ete exclusivement laisses sur la surface du catalyseur par l'empoisonnement partiel. On a trouve que la modification actuelle du catalyseur est utile a la preparation d'un catalyseur acide qui ne presente pas d'encrassement du catalyseur par depot de coke.

Liquid-solid phase de-t-butylation of p-t-butylphenols was carried out over original and dealuminated zeolites to determine the effect of catalyst pore size and acidity on the reaction rate and catalyst fouling rate. The de-t-butylation rate over the original zeolites was mainly dependent upon their micro pore sizes. Although the dealumination by acid leaching decreased strong acid sites, the de-t-butylation rate over dealuminated HY zeolite was higher than that on the original zeolite. The present dealumination is a useful method to prepare an acid catalyst for de-t-butylation in a liquid-solid system. On a effectue la de-t-butylation en phase liquide-solide des p-t-butylphenols sur des zeolites originales et dealuminees afin de determiner l'effet de la taille des pores du catalyseur et de l'acidite sur la vitesse de reaction et la vitesse d'en-crassement du catalyseur. La vitesse de de-t-butylation sur les zeolites originales depend essentiellement de la taille de leurs micro pores. Bien que la dealumination par lixiviation a l'acide diminue les sites acides forts, la vitesse de de-t-butylation sur la zeolite HY dealuminee est plus elevee que sur la zeolite originale. Cette methode de dealumination est utile pour preparer un catalyseur acide pour la de-t-butylation dans un systeme liquide-solide.

Amorphous Pd-Zr alloys, produced by a rapid solidification technique, were studied to determine their catalytic activity for the hydrogenation of cyclohexene and benzene. The activity of the amorphous alloy without pretreatment by air was lower than that of the corresponding crystalline alloy, but it was gradually increased with the pretreatment. The surface area and the hydrogen adsorption activity of the alloys were simultaneously increased with the pretreatment. It is found from X-ray diffraction pattern and SEM observation that palladium, which is an active species for hydrogenation in the amorphous alloys, is highly dispersed on the granulated ZrO2 surface by the pretreatment. On a etudie des alliages Pd-Zr amorphes, produits par une technique de solidification rapide, dans le but de determiner leur activite catalytique pour l'hydrogenation du cyclohexene et du benzene. L'activite de l'alliage amorphe sans pretraitement a l'air est inferieure a celle de l'alliage cristallin correspondant, mais augmente progressivement avec le pretraitement. La surface et l'activite de l'adsorption d'hydrogene des alliages augmente simultanement avec le pretraitement. On a trouve par l'observation au microscope a balayage (SEM) et par diffraction des rayons X, que le palladium, qui est une espece active pour l'hydrogenation dans des alliages amorphes, est hautement disperse a la surface du ZrO2 granule, par le pretraitement.

The quality of fluidization of FCC particles (dp = 60μm) was studied by using six kinds of fluidizing gases in a 0.081 m diameter column. As several investigators have described, minimum fluidization velocity was inversely proportional to gas viscosity and was almost independent of gas density. The expansion ratio of the emulsion phase was, however, dependent on gas density and increased with viscosity and density. Both measured bubble frequency and deviation of pressure fluctuations were also influenced considerably by the gas properties. The voidage of the emulsion phase was considered to be dominated by the properties of the gas flowing through the emulsion phase. Thus the apparent viscosity of the emulsion, i.e. the quality of fluidization, is influenced by those properties of gases.

Mesure pour des lits de fines particules de : la vitesse minimale de fluidisation (Vmf), la vitesse de sedimentation (Vs) et la desaturation de la phase emulsion (E). La relation entre la vitesse et la desaturation est etablie experimentalement a partir de l'equation de Richardson et Zaki (pour Vmf et Vs). En ce qui concerne E, il est correle a un parametre adimensionnel qui prend en compte l'effet de la densite de gaz. Les resultats obtenus a l'aide des correlations sont en bon accord avec les resultats experimentaux

Dehydration of 1-phenylethanol has been carried out over a solid acidic catalyst in order to examine the effect of the concentration of effective acid sites on the reaction rate, styrene selectivity and catalyst fouling. The reaction rate increased with the concentration of effective acid sites, while styrene selectivity decreased. The catalyst deactivation depended upon the concentration of the effective acid sites and also the size of the micro pores in the catalyst. Taking into account the reaction rate and selectivity, ALO-4 alumina was the most suitable catalyst for the present reaction. An activation energy for the dehydration over ALO-4 alumina was 83.8 kJ mol−1. The dehydration reaction could be a useful tool for the characterization of the nature of the acid sites.

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.

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 carbon dioxide in a transparent column to observe the bed behavior. When the reaction rate was increased, the fluidity of the emulsion phase decreased and channeling occurred. When the fluidity of the emulsion phase decreased even further, the upper part of the bed was defluidized and this part was lifted up through the column. This phenomenon caused the entrainment of a large amount of catalyst particles from the reactor. We studied the effects of the reduction rate of the gas volume and the maximum gas contraction ratio on the fluidization behavior. The criterion for a stable operation, which could be successfully given by the gas-volume reduction rate, is useful for determining the operating conditions needed to establish good fluidization when the reactions involving a decrease in the gas volume are carried out in a fluidized catalyst bed.

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).

Description d'un modele mathematique base sur le modele des deux phases, pour predire le taux de conversion d'une reaction comportant un nombre decroissant de moles en lit fluidise. Application a l'analyse de la methanation de CO