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The oxidative coupling of toluene to bibenzyl and stilbene has been studied over lithium-modified lead oxide under anaerobic conditions. The selectivity for the coupled products can be improved by the addition of lithium metals to lead oxide. In order to understand the effect of the reaction conditions on the selectivity, kinetic studies have also been carried out.

重質油の水素化処理触媒の活性劣化に及ぼすコークおよびメタルの同時たい積の影響を検討する目的で, 1年間商業反応装置で使用した触媒からコークおよびメタルたい積量の異なる5種類を採取し, たい積したコークのキャラクタリゼーションと残余活性測定を行った。また, これと合わせて上記と同一新触媒による重質油の反応を行い, 触媒上にコークをたい積させ, そのキャラクタリゼーションを行った。使用済触媒の物性 (表面積, 細孔容積, 平均細孔径) および残余活性は, コークとメタルの比容積を用いて計算したたい積物容量に対して良好な相関があった。また, コークたい積量とC/H比は比例関係にあることから, コークは反応経過時間によらず同質のコーク前駆体から形成され, これが反応器内で徐々に縮重合するメカニズムで進行することが推察された。さらに, たい積したコーク量はメタルたい積量の増加とともに減少する傾向にあり, これとともに脂肪族性炭素が芳香族性炭素より大きく減少した。商業装置から得られた使用済触媒の残余活性は, コークとメタルたい積物容積の和の増加とともに直線的に減少した。以上の結果から, 反応初期の急激な活性低下の後, 緩やかな劣化が進行するのは, メタルのたい積が既に蓄積したコークを排除していることが一つの要因と考えられ, コークとメタルのたい積は, 独立に進行する現象でなく, 互いに関連していることが分かった。

Methanol steam reforming was carried out over catalysts prepared from amorphous Cu50Zr50, (Cu50Zr50)100−xAux and (Cu50Zr50)100−xPdx alloys in a fixed bed reactor operated at atmospheric pressure. The selectivity for carbon dioxide, which is a measure of steam reforming, was dependent on the composition of the amorphous alloy. When the reaction was performed over Cu50Zr50 amorphous alloy, the selectivity for carbon dioxide was essentially unity, whereas methanol conversion was very low. On the other hand, methanol conversion increased with the palladium content over the Cu–Zr–Pd amorphous alloy, but the selectivity for carbon dioxide was lower than that over Cu–Zr alloy. When the reaction was carried out over catalysts prepared from amorphous Cu–Zr–Au alloy, the methanol conversion increased with the gold content, whereas the carbon dioxide selectivity was almost unity over the range of gold content. The surface area measurement revealed that the dispersion of copper, which was effective for the steam reforming reaction, increased with the content of gold in the amorphous alloy. On the other hand, the dispersion of palladium, which was effective for dehydrogenation of methanol, increased with the palladium content. These results indicate that gold in the Cu–Zr alloy plays an important role in increasing the dispersion of copper.

The vapor phase Beckmann rearrangement of cyclohexanone oxime (CHO) over solid acid catalysts including zeolites was carried out to elucidate the effects of the acid strength and the micropore size of the catalysts on the selectivity of e-caprolactam (CL) and the catalyst deactivation rate. It was found that the catalyst deactivation rate was strongly dependent on the acid strength of the acid catalysts. The improvement of catalyst life was achieved by using MFI-type metallosilicates having weak acid sites. The CL selectivity decreased over the acid catalysts with micropores larger than those of the MFI zeolites. Furthermore, using methanol and carbon dioxide as the diluent solvent and diluent gas improved CL selectivity and catalyst life, respectively.

The hydrogenation of benzene in a fixed-bed type reactor operated at atmospheric pressure over amorphous Pt-Zr alloys with different platinum composition (Pt 20 Zr 80 , Pt 28 Zr 72 , Pt 32 Zr 65 ) produced by a rapid solidification technique was investigated. Although the catalytic activity of the alloys was very low at virgin state, it gradually increased with increasing number of regeneration (oxidation and reduction)-reaction cycles. The activity approached a constant value after 5 or 6 regenerations. The hydrogenation activity of Pt-Zr alloy is higher than those of Pd-Zr and Ni-Zr alloys with the same composition. Furthermore, the turnover frequency of Pt-Zr defined as the reacting molecule per active site per second is also higher than those of Pd-Zr and Ni-Zr alloys. The hydrogenation order of the turnover frequency in the present study is almost the same as the order of the hydrogenation of olefins over the corresponding catalysts prepared from impregnation method. The characterization of the platinum catalyst prepared from the amorphous alloy revealed that the dispersion of platinum is higher than the impregnated catalysts, even though the platinum content of the former catalyst is much higher than that of latter. It is considered that this is a remarkable feature of the amorphous alloy catalyst.

それぞれを流動化すると良好な流動化状態を示すアルミナ触媒とFCC触媒を混合すると流動性が大きく低下した．乾燥した状態で流動化すると多量の粒子が塔内壁へ付着し，チャンネリングが観察された．この原因は粒子の化学組成の違いによって，二種の粒子が別方向の電荷を帯び，粒子の凝集性が高まったためと考えられる．粒子細孔内に4wt%の水を含ませた場合や温度を523K以上に上げた場合，帯電の影響は緩和された．

重質油の残さを無触媒で部分燃焼的にガス化するプロセスは, 残さの有効利用法として魅力ある方法の一つである。この系は還元雰囲気下で行われるため, 鉄, バナジウムおよびニッケルを含む炭素 (すすと言う) が生成する。このすすに含まれるニッケルおよびバナジウムを有効に回収することを目的として, 硝酸, 硫酸あるいは硫酸/硫酸アンモニウム水溶液による抽出実験を行い, 金属抽出率に及ぼす操作条件の影響について検討した。ガス化装置から生成したすすをそのまま用いると, バナジウムは80%以上回収できるが, ニッケルの回収率は20%程度と低かった。この原因は, ニッケルが硫化物として存在するため, 硫酸への溶解性が小さいためと考えられた。すなわち, ニッケルの溶解性を向上させるには, ニッケル硫化物を酸化物にする必要があった。そこで, すすを部分酸化した試料を用いて抽出実験を行ったところ, 酸化率が90%以上のすすを用いると80%のニッケルが回収された。さらに, ニッケルおよびバナジウムの抽出率に及ぼす溶液の組成と溶液量等について検討した。これらの結果から, 金属を効率よく回収するための条件を設定し, この回収法を工業的に行うための概念的なフローシートを提案した。

流通式反応器を使用して, 微量の有機硫黄化合物あるいは金属塩を添加した常圧残さ油の熱分解反応を480°Cで行い, 軽質化およびコーク生成に及ぼす添加物の影響について検討した。ここで有機硫黄化合物としては, 末端に4個のチオール基を有する3-pentaerithritol tetrakis-3-mercaptopropionate (PTMP) を用いた。また, 金属塩としては鉄, ニッケル, バナジウムのナフテン酸塩を使用した。PTMPを添加すると, わずかに軽質化が促進されたが, その濃度を変化させても軽質化の程度には差が見られなかった。一方, 鉄を添加すると, 軽質化は促進されたが, 同時にコーク生成が著しく促進され, 反応管の閉そくが起こった。そこで, PTMP (1000ppm) とナフテン酸鉄 (100ppm) を同時に添加すると, コークによる反応管の閉そくなしに大幅な軽質化が観察された。これは, 熱分解で生成した炭化水素ラジカルをチオール基が捕そくして, 再結合を妨げていることによると考えられる。このように, PTMPとナフテン酸鉄の同時添加は, 現在の精製装置に変更を加えることなく, 常圧残さ油の軽質化を促進するすぐれた方法である。

A fast-scanning X-ray CT system, designed for measuring dynamic events in multiphase fluids, was used to obtain the transient 2-dimensional cross sectional gas-phase distribution in a fluidized bed. The captured data was sent to a PC for image reconstruction, and the density distributions across the column cross section were visualized. Using image processing techniques, a pseudo 3-dimensional image of bubbles was obtained. The spatial and time resolutions of the system were sufficient for the measurement of ascending bubble behavior in a fluidized bed with fine particles. Bubble shape, interfacial area, and bubble holdup over the cross section can be measured by this system.

The hydrogenation of benzene and carbon dioxide was carried out over Zr-based catalysts prepared from amorphous alloys containing palladium, platinum, rhodium or nickel as the second metal. Although the hydrogenation activity of the alloys was very low in the virgin state, the activity gradually increased after oxidation and reduction in a hydrogen atmosphere. Characterization of the alloys revealed that the increase in surface area caused by oxidation of zirconium was responsible for the increase in hydrogenation activity. When the amorphous alloys were oxidized in an oxygen atmosphere, both the active metals for the hydrogenation and zirconium in the alloys were simultaneously oxidized. When the oxidized alloys were reduced in a hydrogen atmosphere, the oxides of the active metals were reduced to the respective metals, whereas zirconium remained in the oxide state. As a result, palladium, platinum, rhodium or nickel were highly dispersed on the produced zirconium oxide crystals. The principal advantage of a catalyst prepared from an amorphous alloy is the very high dispersion of active metal on the surface, despite the high metal content. It is considered that amorphous alloys containing zirconium as the second metal are attractive catalyst precursors for hydrogenation.

In this research, biodiesel is produced by in situ transesterification (direct transesterification) method from the rubber seeds using KOH as a catalyst. The influence of methanol to seeds mass ratio, duration of reaction, and catalyst loading was investigated. The result shows that, the best ratio of seeds to methanol is 1:6 (10 g seeds with 60 g methanol), 120 minutes reaction time and catalyst loading of 3.0 g. The maximum FAME yield obtain was 70 %. This findings support FAME production from the seeds of rubber tree using direct transesterifcation method from the seeds of rubber tree as an alternative to diesel fuel. Also, significant properties of biodiesel such as cloud point, density, pour point, specific gravity, and viscosity were investigated.

The pore radius of the silica glass prepared from a borosilicate glass could be controlled by the content of alumina in the starting glass in the range from 1.9 run (0 wt% alumina) to 1.9 nm (4.5 wt%). The hydrogenation of three kinds of 1-hexenes and 1-octenes, respectively, was carried out over nickel catalysts supported on a series of the porous glasses different in pore size to elucidate the effects of pore size on the rates of hydrogenation. The rates over the catalyst with the largest pore radius (1.9 nm) were almost the same among the 1-hexenes and 1-octenes, respectively. As the pore radius decreased, however, there was observed an increasing tendency that the rates of branch-ed (or more spherical) olefins such as 3,3-dimethyl-l-butene and 2,4,4-trimethyl-l-pentene far exceeded than those of the corresponding linear olefins, i.e. 1-hexene and 1-octene, respectively. This shape selective behavior is quite different from that of the zeolite-supported catalyst. These results confirm that a catalyst support with unique shape selectivity can be synthesized from the borosilicate glass with a small amount of alumina.

When a fluidizing gas is switched from a low-density gas to a high-density gas, particles in the emulsion phase agglomerate and bubbles disappear. At the same time, channeling occurs and a decrease in the pressure drop over the bed is observed. The disturbance of fluidization is temporary, and normal fluidization is restored after several minutes. The study of mechanisms of the transient phenomena shows that the difference in diffusion rates of the two gases in the emulsion phase caused the agglomeration of particles. Because the mobility of particles was reduced, channels were formed and the fluidizing gas bypassed through them. Effects of the properties of the fluidizing gases and particles on the intensity of the transient phenomena were also studied. The intensity increased with increasing difference in the densities of the two gases. The transient phenomena were considerable for small- and light-particle systems.

The surface area and micropore distribution of the porous glass prepared from borosilicate glass were controlled by the addition of metal oxides. When alumina or zirconia was added to the borosilicate glass, the micropore size distribution was very sharp and the maximum of the distribution was located at 1–2 nm. The addition of manganese oxide or antimonial oxide did not produce a sharp micropore distribution in the porous glass. When the hydrogenation of benzenes, substituted with a different number of methyl groups, was carried out over nickel catalysts supported on the porous glass prepared from the borosilicate glass with zirconia, the hydrogenation rate decreased according to the number of methyl groups and the position of the groups. These results indicate that a shape-selective nickel catalyst can be prepared from the porous glass synthesized from the borosilicate glass with a small amount of metal oxide.

Thiobacillus ferrooxidans, isolated from mine water, utilized not only ferrous iron but also glucose to grow. By using ferrous-iron medium containing glucose, a 7-fold population increase was obtained after 96 h of incubation. The ability to oxidize ferrous iron was maintained during cultivation on the iron-glucose medium.

The overall mass transfer coefficient between the bubble phase and the emulsion phase was measured at ambient temperature in a fine particle fluidized bed. The measurements were carried out using the absorption of carbon dioxide in air by porous alumina particles impregnated with an aqueous solution of NaOH. The pressure fluctuations and the ascending velocity of bubbles were also measured. The overall reaction rate was influenced by the mass transfer between the two phases and the fraction of particles in the freeboard at high gas velocity. The flow pattern of bubbles was discussed in relation to the surface area of bubbles calculated from the mass transfer coefficient and the bubble signals detected by optical probes.

The Ni2+ resistance of Thiobacillus ferrooxidans was enhanced by repeated culturing in medium containing Ni2+ and gradually increasing the Ni2+ concentration. The extraction of nickel sulfide was enhanced by the adapted strain following the direct leaching mechanism of the microorganism.

The Beckmann rearrangement of cyclohexanone oxime was carried out over high-silica HZSM-5 zeolites and boron-modified HZSM-5 to elucidate the effects of silica alumina ratio and boron modification on the catalyst deactivation rate. The relationship between cyclohexanone oxime conversion and time on stream could be represented by the equation x ( t ) = x (0)·exp(− b · t ) where x ( t ) and x (0) are conversions at a time on stream t and at the initial stage t = 0, respectively, and b is the deactivation coefficient. The deactivation coefficient increased with increasing concentration of strong acid sites. When the deactivated zeolites were evacuated under a pressure of 1 Torr at 573 K for 5 h, the catalytic activity was recovered up to 50% of the initial activity. The deactivation of the ZSM-5-type zeolite was mainly due to the adsorption of volatile material on the acid sites.

ベンゼン及び二酸化炭素の水素化反応をジルコニウムを含むアモルファス合金から調製された触媒を使用して行った.アモルファス合金は, 作製した状態ではほとんど活性を示さないが, 同一合金を繰り返し使用して, 酸化・還元・水素化反応を行うと徐々に活性が向上した.使用済み合金の表面積は, 繰り返し操作とともに大きくなり, これにはジルコニウムの酸化がこれに大きく寄与することが合金のキャラクタリゼーションから明らかになった.アモルファス合金が結晶化温度以下で酸化されると, 結晶化合金よりも大きな速度でジルコニウム及び水素化反応に活性を持つ金属 (Pd, Pt, Rh またはNi) の双方が同時に酸化されるが, 水素処理によって, 後者が金属状態に還元されるのに対して, 酸化ジルコニウムはそのまま残された.この結果, アモルファス合金は徐々に酸化ジルコニウムを担体とする触媒へと変化して行くことが結論された.この触媒の最大の特長は, 水素化活性種となる金属含量が高いにもかかわらず, その分散度が高いために, 反応器体積を小さくできる点にある.ジルコニウムを含むアモルファス合金は, 水素化触媒を調製するためのすぐれた前駆体になることを示した.

The hydrogenation of benzene over amorphous Ni-Zr alloys with different Ni compositions (Ni33Zr67, Ni40Zr60, Ni50Zr50, Ni70Zr30, Ni90Zr10) produced by means of a rapid solidification technique was investigated. Although the catalytic activities of the alloys were very low in the virgin state, they gradually increased with increasing number of regeneration (oxidation and reduction) reaction cycles, and the activity approached a constant value after six regenerations. The benzene hydrogenation activity increased with nickel content up to 50%, but then decreased with Ni content. It was shown that the surface area measured by the nitrogen adsorption method had almost the same dependence on Ni content. These results suggest that the Ni50Zr50 alloy is easily relaxed by the regeneration, and Ni atoms effective for the hydrogenation are highly dispersed on the micro ZrO2 crystals produced from the alloy by the oxidation.

The rearrangement of cyclopentanone oxime was carried out over HZSM-5 and boron-modified HZSM-5 zeolites to elucidate the effect of acid strength distribution on the δ-valerolactam selectivity and catalyst deactivation rate. The results were compared with those of the reaction of cyclohexanone oxime. Although the rearrangement of cyclopentanone oxime was faster than that of cyclohexanone oxime, the catalyst deactivation rate for cyclopentanone oxime was slower than that for cyclohexanone oxime. These results indicated that since the molecular size of cyclopentanone oxime was smaller than that of cyclohexanone oxime, cyclopenatanone oxime could diffuse into the micropores of HZSM-5. The difference in the amount of effective acid sites between the reactions of cyclopentanone oxime and those of cyclohexanone oxime affected the rates of reaction and catalyst deactivation.

A significant defluidization occurs when carrying out reactions involving a decrease in gas volume in a fluidized catalyst bed. The cause of this phenomenon is a decrease in the gas velocity in the emulsion phase below the minimum fluidization velocity. Fluidization quality is improved by a staged gas feed when hydrogenation of CO2 is carried out. To evaluate the experimental results, two parameters are introduced; gas-volume reduction rate and gas-volume ratio. Fluidization quality and defluidization zone are indicated as a map using these parameters. The vertical distributions of these parameters are calculated using a reactor model to obtain operating lines. The calculation shows that fluidization quality can be improved by operating the reactor by avoiding the operating lines of the defluidization zone in the map. For this purpose, it is required to control the gas-volume ratio at a level near unity and maintain the gas-volume reduction rate below 0.01/s. © 2010 American Institute of Chemical Engineers AIChE J, 2010

The surface area and micropore distribution of porous glass prepared from borosilicate glass were controlled by the addition of alumina up to 8 wt%. The surface area increased with increased alumina content in the range from 0 to 3 wt%, but it suddenly decreased when the percent alumina exceeded 4 wt%. The mean pore diameter and micropore volume also decreased with increased alumina content. When nickel ion was supported into the porous glass, the surface area decreased to about one-half that of the original glass. Since the amount of nickel supported on the porous glass increased directly with surface area, the silanol group was considered to be uniformly distributed on the glass. La surface specifique et la distribution de micropores de verre poreux prepare avec du verre de borosilicate. ont ete contro'lees par l'ajout d'alumine jusqu'a 8% en poids. La surface specifique augmente avec la teneur en alumine dans la gamme de 0 a 3% en poids, mais diminue soudainement lorsque ce taux excede 4% en poids. Le diametre moyen des pores et le volume de micropores diminuent egalement lorsque la teneur en alumine augmente. Lorsque du nickel ionique est depose sur du verre poreux, la surface specifique diminue environ de moitie par rapport a la surface originale. Etant donne que la quantite de nickel depose sur du verre poreux augmente directement avec la surface specifique, on considere que le groupe des silanols est distribue uniformement sur le verre.

The hydrogenation of benzene has been carried out over a catalyst prepared from an amorphous Pd-Zr alloy held in an alumina matrix. The catalytic activity was compared with that over the alloy cut into 1 mm fragments. It was found that the fixed alloy in the alumina had not only higher catalytic activity, but also a smaller catalyst fouling rate than the fragments of the alloy. The effect of palladium content in the amorphous alloy on the hydrogenation activity was examined. It was found that the initial activity increased with the fraction of palladium. However, the activity of the catalyst which had the highest palladium content decreased with repeated regeneration and reaction, whereas the activity of the other catalysts reached a stable value. On a effectue l'hydrogenation du benzene a l'aide d'un catalyseur prepare a partir d'un alliage amorphe de Ph-Zr depose sur une matrice d'alumine. L'activite catalytique a ete comparee a celle de l'alliage decoupe en fragments de 1 mm. On a trouve que l'alliage fixe dans l'alumine a non seulement une activite catalytique plus elevee, mais egale-ment une vitesse d'encrassement du catalyseur plus petite que dans le cas des fragments d'aliiage. On a examine l'effet de la teneur en palladium dans l'alliage amorphe sur l'activite d'hydrogenation. On a trouve que l'activite initiale augmente avec la fraction de palladium. Cependant, l'activite du catalyseur qui a la plus haute teneur en palladium diminue a la suite d'une regeneration et d'une reaction repetees, alors que l'activite des autres catalyseurs atteint une valeur stable.

The hydrogenation of CO2 was investigated over a rhodium catalyst supported on niobium oxide at atmospheric pressure. Niobium oxide was prepared by the hydrolysis of niobium chloride and its crystallitic structure was controlled by calcination temperature. It was found that the activity was lower but the selectivity of C2+ hydrocarbons was higher for the γ and γ′ forms than for the β and α forms of the niobium oxide.

The vapor phase Beckmann rearrangement of cyclohexanone oxime has been carried out over zeolites and boria modified HZSM-5 zeolites to elucidate the effects of acidity and acid strength distribution on the conversion and e-caprolactam selectivity. Although e-caprolactam selectivity was increased with the SiO2Al2O3 ratio in a HZSM-5 zeolite, the highest selectivity in the study was accomplished over a boria modified HZSM-5. The selectivity was dependent on the ratio of weak acid sites to strong acid sites. The boria played an important role in controlling the acid strength distribution of the zeolites. It was found that the production of a polymer over strong acid sites caused a decrease in e-caprolactam selectivity during the reaction. On a effectue la transposition de Beckmann en phase vapeur d'une oxime de cyclohexanone sous l'action de zeolites et de zeolites HZSM-5 modifiees par le bore afin d'elucider les effets de l'acidite et de la distribution de force de l'acide sur la Conversion et la selectivite du e-caprolactam. Bien que la selectivite e-caprolactam soit amelioree avec le rapport SiO2/Al2O3 dans une zeolite HZSM-5, la meilleure selectiavite dans l'etude a ete obtenue avec la HZSM-5 modifiee par le bore. La selectivite depend du rapport des sites acides faibles sur les sites acides forts. Le bore joue un role important dans le controle de la distribution de force de l'acide des zeolites. On a trouve que la production d'un polymere sous l'action de sites acides forts entraǐnait une diminution de la selectivite du e-caprolactam lors de la reaction.

The apparent viscosity was measured in a fluidized bed with fine particles. The measurement was performed in the bed expanded uniformly at gas velocities between minimum fluidizing velocity and minimum bubbling velocity by means of the falling-sphere method. As the apparent viscosity obtained decreased with the diameter of the falling spheres, the viscosity value was determined by extrapolation. The apparent viscosity obtained was correlated with particle diameter, density and bed voidage. An equation for predicting the apparent viscosity in the emulsion phase in a bubbling fluidized bed was introduced by combination with the correlation of the voidage of the emulsion phase. Comparison of the values predicted from this equation with the data in the literature shows good agreement. To investigate the influence of the apparent viscosity on the fluidization quality, deviations of pressure fluctuations and bubble diameter were correlated with the apparent viscosity. It was shown that the proposed correlation for the apparent viscosity was useful for predicting the fluidization quality.

The preparation of ultrafine particles of titania was carried out by the thermal decomposition of titanium tetra-isopropoxide in gas phase. The effects of preparation conditions on the surface area, micropore distribution and acid concentration of the titania were examined to elucidate the applicability of the particles to a catalyst support.It was found that the particles had about 100m2·g-1 of surface area, but they had no pore volume. The acid concentration in the titania was dependent upon the preparation temperature of the particles. Nickel catalyst prepared by an impregnation method on the titania had high activity for benzene hydrogenation.

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.

The thiourea leaching of gold and silver from the gold-bearing silicate ore of the Hishikari mine (Kagoshima, Japan) was studied. The apparent activation energy of the extraction of gold and silver was smaller than that of the reaction rate of thiourea consumption by ferric iron. We carried out the leaching after the leaching solution was preserved for several hours. The gold recovery at 288 K was greater than that at 308 K when the pretreatment period was over 3 h. This is because the concentration of thiourea was decreased by the oxidation at 308 K, while the thiourea was not consumed by ferric ion at 288 K. It is considered that the lower temperature operation is preferable when the leaching solution is recycled.

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.

Surface tensions for the liquid mixture nitrogen + oxygen + argon have been measured using the capillary rise method. The measurements were made for various compositions at temperatures from 90 to 115 K and at vapor pressures up to 900 kPa. The experimental data were correlated with those calculated from a simple equation using the pure component results.

The differential capillary rise method has been used to measure the surface tension for a nitrogen+oxygen binary system and for a nitrogen+oxygen+argon ternary system at low temperatures. Several correlations have been tested against the mixture data

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.

A fast-scanning X-ray CT system was used to obtain the transient 2-dimensional cross sectional gas-phase distribution in a fluidized catalyst bed with fine particles. The captured data was sent to a PC for image reconstruction, and the density distributions across the horizontal cross-section were visualized. Using image-processing techniques, pseudo 3-dimensional images of bubbles and the density distribution across the vertical cross-section were obtained. The bubble structure was studied based on these images and the results obtained previously in a 2-dimensional fluidized bed. It was found that bubble shape was not spherical, but that the bubble ascending in a fluidized catalyst bed consisted of some smaller bubbles.

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 hydrogenation of benzene and methyl-benzenes was performed over a nickel catalyst supported on the porous glass prepared from borosilicate glass with an alumina content ranging from 3% to 5%. The micropore size of the porous glass decreased with increasing alumina content. Although the overall reaction rates of benzene and toluene did not significantly change with the alumina content in the borosilicate glass, the rate of 1,3,5-trimethylbenzene, which is the bulkiest molecule among the hydrocarbons tested, decreased as the content of the alumina in the support increased. This result indicates that a catalyst support with molecular shape selectivity can be prepared from borosilicate glass containing alumina. On a effectue l'hydrogenation du benzene et de methyle-benzenes sur un catalyseur au nickel depose sur du verre poreux prepare a partir de verre au borosilicate ayant une teneur en alumine comprise entre 3 et 5%. La dimension des micropores du verre poreux diminue quand la teneur en alumine augmente. Bien que les vitesses de reaction globales du benzene et du toluene ne change pas de maniere significative avec la teneur en alumine dans le verre au borosilicate, la vitesse du 1,3,5-trimethylebenzene, la molecule la plus volumineuse parmi les hydrocarbures testes, diminue a mesure que la teneur en alumine du support augmente. Ce resultat montre qu'un support de catalyseur possedant une selectivite de forme moleculaire peut ětre prepare a partir de verre au borosilicate contenant de l'alumine.

The decomposition reaction of p–t-butylcumene and t-butylbromobenzene have been carried out over pyridine poisoned silica-alumina and HY zeolite in order to examine the effect of acid strength on selectivity. Since the catalyst deactivation rate for isomerization over the poisoned silica-alumina was greater than that of de-t-butylation in the reaction of p–t-butylcumene, the selectivity of de-t-butylation gradually improved with process time. In the reaction of t-butylbromobenzene over poisoned HY zeolite, the de-bromination rate was suppressed by the poisoning because the nature of active sites was different between silica-alumina and HY zeolite. The poisoned HY zeolite was found to be favorable for the de-t-butylation of halogenated-t-butylbenzenes. On a realise une reaction de decomposition du p–t-butylcumene et du t-butylbromobenzene sur des catalyseurs a base de silice-alumine et de zeolithe HY empoisonnes par de la pyridine dans le but d'etudier l'effet de la force acide sur la selectivite. La vitesse de desactivation du catalyseur au cours de la reaction du p–t-butylcumene s'etant averee plus grande dans le cas de l'isomeration sur le catalyseur de silice-alumine empoisonne, que dans celui de la de-t-butylation, la selectivite de la de-t-butylation s'est progressivement amelioree avec la duree du procede. Dans la reaction du t-butylbromobenzene sur un catalyseur zeolithique HY empoisonne, la vitesse de de-bromuration a ete diminuee par l'empoisonnement, la nature des sites actifs etant differente entre la silice-alumine et la zeolithe HY. La zeolithe HY empoisonnee s'est averee meilleure pour la de-t-butylation des t-butylbenzenes halogenes.

The kinetics of the methanation of carbon dioxide was investigated using an alumina supported Ni-La2O2 catalyst in a differential and integral reactor. In the differential reactor the molar ratio of H2 to CO2 was varied from 0.6 to 30. In the integral reactor the rates were measured with up to 90% conversion. Both reactor tests were carried out at temperatures between 513 and 593 K. The experimental results were described by a Langmuir-Hinshelwood type equation. The kinetics can be explained by assuming equilibrium of dissociative carbon dioxide and hydrogen adsorption, and assuming hydrogenation of surface carbon as the rate determining step.

It was found that bubbles grew in a fluidized bed of alumina particles, categorized as typical Group A powders of Geldart, when the bed was fluidized by hydrogen. These particles, however, showed good fluidity, and small and constant bubbles were observed in a bed fluidized by air. The fluidization quality in the hydrogen flow was thus different and rather similar to that of larger and denser particles in the air flow. Such changes in bubble behavior caused by varying the fluidizing gases were explained successfully in terms of the concept of the apparent viscosity of the emulsion phase.

Pressure fluctuations and bubble frequency in fluidized beds were measured at several stages of temperature ranging from 280 K to 640 K. Four types of powders belonging to group A of Geldart''s classification were used. The quality of fluidization at various temperatures was evaluated by a uniformity index based on pressure fluctuations and by bubble size obtained from bubble frequency. The reduction both in the deviation of amplitude of pressure fluctuations and in bubble size showed that the quality of fluidization improved with increasing temperature. However, at room temperature, beds of dry particles were affected by electrostatic phenomena and thus the fluidity was decreased. The influence of the electrification decreased at elevated temperature, or at room temperature when the particles held water in the pores.

A large decrease of fluidization quality was observed when methanation of carbon dioxide was carried out in a fluid-bed reactor even if the catalyst particles had the optimal properties for good fluidization. The cause of this phenomenon was explored by measuring pressure fluctuations, bubble frequency and extent of CO2 conversions. The results indicated that the decrease of the fluidity was caused by a reduction in volume of reactant gases due to the reaction. The voidage in the emulsion phase is considered to be an important factor affecting the fluidity. The fluidization quality and contacting efficiency could be improved by such devices as baffle internals or two-stage spargers.

A model was proposed to describe the expansion behavior of a gas fluidized bed of fine particles by using the elastic wave velocity. The difference between the maximum bed voidage in homogeneous fluidized beds, emb, and the emulsion-phase voidage in bubbling beds, ee could be explained by the proposed model. These voidages were calculated by comparing the voidage propagation velocity with the elestic wave velocity, the latter being represented as a function of the volume elasticity and the rigidity for uniformly expanded beds. In the emulsion phase of bubbling fluidized beds, however, the rigidity was neglected. This difference reflected the fact that emb was larger than ee in any gas–solid system of fine particles. Since it was difficult to formulate quantitatively the value of the elastic wave velocity based on the theoretical approach, it was modified by experimental data in the literature.

Methanation of CO in a fluid bed, carried out by Ni catalyst at 573K and atmospheric pressure, was studied experimentally and theoretically. Reaction rates of methanation and the water-gas shift reaction were measured in a fixed bed reactor. A fluid bed model considering a decrease in number of moles caused by reactions is proposed to analyze the data obtained with a fluid bed reactor of 8.1cm i.d. An effective bubble diameter is introduced as an adjustable parameter in the model. The experimental results are well explained by the model when the bubble diameter is assumed to be 3.6cm. It is found that the influence of the decrease in number of moles on conversion cannot be ignored in analyzing the fluid-bed reaction data.