A straight-through microchannel (MC) is an array of through-holes microfabricated on a silicon plate. An earlier study reported that a straight-through MC with an oblong section is suitable for preparing monodisperse emulsions by forcing the to-be-dispersed phase into the continuous phase through the MC. This study investigated the effects of the slot aspect ratio and the to-be-dispersed phase flux on the droplet formation from straight-through MCs with equivalent diameters of approximately 20 µm and a depth of 200 µm. Straight-through MCs below a threshold slot aspect ratio of approximately three resulted in the formation of polydisperse droplets, driven by the continuous phase flow. In contrast, straight-through MCs exceeding a threshold slot aspect ratio of approximately three stably yielded monodisperse droplets with average diameters of about 40 µm and coefficients of variation below 3%. The to-be-dispersed phase that grew from these slots was transformed spontaneously into mono-sized droplets. Below the critical to-be-dispersed phase flux, the size and size distribution of the formed monodisperse droplets were almost independent of the to-be-dispersed phase flux. Above the critical to-be-dispersed phase flux, formation of polydisperse large droplets and a drastic increase in the resultant droplet size were observed with an increase in the to-be-dispersed phase flux. A large silicon straight-through MC plate, which measures 40 mm×40 mm×0.4 mm, was developed to scale the emulsification device up. This plate achieved the stable preparation of monodisperse emulsions with maximum droplet productivity of 35 mL/h.

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Less expensive acrylic microchannel (MC) plates compared with conventional silicon MC plates were manufactured by molding injection method. The acrylic MC showed strong anti-alkalinity and hydrophobicity. We prepared emulsions using the acrylic MC plates and found that monodispersed water-in-oil (W/O) emulsions were produced successfully. In the pressure ranges for stable droplet formation, the average droplet diameters increased gradually with pressure. In water/trolein (containing 3 wt% of surfactant tetraglycerin condensed ricinoleic acid ester, CR310) system, the average droplet diameters of emulsion produced by acrylic MC plates with channel depths of 5, 10 and 20µm were 27-43, 42-60, 62-98µm, respectively. Each coefficient of variation (CV) was less than 10%, and the monodispersity was comparable with silicon MC emulsification system. When we used the continuous phases with different viscosities, it was found that the average diameters and CV values increased, the pressure ranges for stable droplet formation and droplet formation rate decreased as the viscosity of the continuous phase increased.

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The ultimate objective of this work was to form microemulsions with motor oil at low salinity for detergency application. Three surfactants of alkyl diphenyl oxide disulfonate (ADPODS, Dowfax 8390), bis (2-ethylhexyl) sulfosuccinic acid sodium salt (AOT) and sorbitan monooleate (Span 80) were used to obtain a proper balance between hydrophobicity and hydrophilicity in order to form microemulsions with motor oil. The mixed surfactant system of 1.5 wt% Dowfax 8390, 5 wt% AOT and 5wt% Span 80 was found to exhibit a Winsor Type III microemulsion (middle phase) at a very low salinity of 2.83%. With this selected formulation, detergency performance increased with increasing active surfactant concentration and the maximum oily soil removal was found at around 0.1% active surfactant on all three types of fabrics (pure cotton, polyester/cotton (65/35) blend and pure polyester). Moreover, for any given active surfactant concentration, % detergency and % oil removal on pure cotton was slightly higher than those on the other two types of fabrics and the lowest % detergency was found on the pure polyester. Interestingly, increasing amount of rinsing water was found to affect insignificantly the oil removal efficiency. In addition, the detergency performance was optimized with twice rinse steps.

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In recent years, recovery and separation of metal using solvent impregnated resins and microcapsules have been as an alternative technique to solvent extraction. It is easy to make them have great selectivity between metals because selection of extractant is possible.
In this work, a study on the sorption behavior of gallium and indium into a microcapsule containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester is investigated. The sorption rates are measured under various experimental conditions. The effects of pH and metal concentration on the sorption rate are examined to estimate the sorption mechanism. The initial sorption rates are compared with the initial extraction rates measured for the corresponding solvent extraction system. It is clarified that the initial sorption rate varies with pH and the metal concentration following the same manner as that for the solvent extraction system.
The sorption of the metals into a microcapsule is considered to proceed as follows. The metal ions firstly diffuse through the liquid film around the microcapsule. The metal ions diffusing through the liquid film react with the extractant on the surface of the microcapsule. The metal-extractant complexes formed diffuse through the pore in the microcapsule.
The rate-determining step is evaluated from the activation energy estimated experimentally. As the results, it is found that both the complexation reaction and the intraparticle diffusion control the overall sorption rates.

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Reverse micelles, which are nanoscopic pools of water in bulk organic solvent stabilized by a surrounding layer of surfactant molecules, have been widely studied because of their resemblance to biological membranes and their ability to solubilize enzymes and catalyze biochemical reactions. Most of studies have been carried out on sodium bis(2-ethylhexyl)sulfosuccinate, known as Aerosol OT. We also employed a new synthesized surfactant, dioleyl phosphoric acid (abbreviated as DOLPA), to form reverse micelles, and DOLPA reverse micelles exhibit superior potential for protein. However, very little is known about the relationship between the molecular structure and the function of reverse micelles. Therefore, the goal of this study is to gain an atomic-level picture of the structure and dynamics of reverse micelles and some insight into the possible mechanism of fulfilling its function by molecular dynamics simulations. After substantial conformational rearrangement during the simulations, the final configurations appear to have roughly spherical shapes in the aggregate. Surfactant molecules almost cover the whole core waters. The core of the DOLPA micelle changed from a spherical to an oval shape, while the core remained spherical in an AOT reverse micelle. From the coordination number among micelle components, the difference comes from the interaction between potassium ions and the hydrophilic groups of surfactant, i.e. the phosphoric acid groups of DOLPA and the sulfuric acid groups of AOT.

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Highly crystallized GeO₂ nanosheets were synthesized by hydrolysis and condensation reactions of germanium alkoxide using 2-dimensional flat thin water phase of lamellar structure composed of surfactant molecules and water at the liquid-liquid interface as a confined reaction space. Lamellar phase was made by contacting water with mixed solution of surfactant (laurylamine (LA)) and germanium alkoxide (Ge(OEt)₄). In situ small angle X-ray scattering (SAXS) measurements were carried out every second for several minutes using strong X-rays by synchrotron radiation in the SPring 8, and the formation processes of GeO₂ nanosheet was examined. SAXS results showed that layered structure composed of GeO₂ nanosheets and LA bilayer was formed at 2.5 sec after contact and increased with time when the mole ratio of Ge(OEt)₄ to LA was 0.2. The produced GeO₂ nanosheets were characterized by transmission electron microscope (TEM) images, X-ray diffraction (XRD), selected area electron diffraction (SAED) and SAXS. The square shape of GeO₂ nanosheets was observed by TEM, and XRD and SAED results showed that GeO₂ nanosheets had highly crystallized structure. The periodical distance of a layered structure was almost constant regardless of time, being 3.7 nm corresponding to the total thickness of LA bilayer and nanosheet. The analysis of the peak shape of the lamellar phase obtained by SAXS revealed that 84 % Gauss distribution at 2.5 sec changed to 100 % Lorentz distribution after 25 sec from contact of two liquids at [Ge(OEt)₄]/[LA]=0.2, indicating increase in crystallinity with time. These findings clearly showed the formation of highly crystalized GeO₂ nanosheets at extremely low temperature. This formation method of nanosheets is easily applicable for the formation of other ceramic nanosheets.

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Dielectric dispersion analysis (DDA) method was selected to the evaluation for variation of membrane properties of liposome and proteoliposomes (liposomes in the bilayer of which membrane protein is incorporated) under stress condition. For DDA, we measured dielectric spectra and performed fitting analysis with two-type function of Debye's equation against the spectra, and we obtained a characteristic frequency observed around 50 MHz (f_c2), which is one of the fitting parameters and corresponds to an extent of the rotational motions of lipid molecules. The change of membrane properties of the liposome was first investigated in the liposome suspension with hydroperoxide in order to investigate the effect of oxidative stress. 1-Stearoyl-2-arachidonyl-sn-glycero-3-phosphocholine (SAPC) was herewith used as an easily-oxidizing phospholipid. In the case of SAPC liposome, the decrease of the f_c2 value was observed, suggesting the restriction of molecular motion of the surface of SAPC liposome by the oxidation of the SAPC in the presence of hydroperoxide. The stress response of proteoliposome incorporated (Na⁺, K⁺)-ATPase as a membrane protein was secondly analyzed in the SAPC liposome solution. Compared with the f_c2 value of liposome without the membrane protein, the f_c2 value of proteoliposome was found to be small, probably, due to the restriction of lipid molecules by the incorporation of and interaction with the membrane protein. A significant decrease of the f_c2 value was also observed under the heat and oxidative stress, together with the hydrolysis activity of ATPase. Based on the above results, the molecular motion of lipid on the liposome surface was found to be analyzed under stress conditions, even in the presence of membrane protein.

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The reactivity of the immobilized glucose oxidase-containing liposome (IGOL) prepared in our previous work is improved by incorporating the channel protein OmpF into the membrane as well as by entrapping catalase (CA) together with glucose oxidase (GO) inside the liposome. CA is for decomposing hydrogen peroxide since it is more rapidly produced in the presence of OmpF enhancing the glucose permeation. Firstly, the GO plus CA-containing liposome (GOCAL) is prepared and characterized. The remarkable protection effect of the membrane on CA inside liposome at 40°C is verified from the fact that the CA activity efficiency, defined as the observed CA activity relative to the intrinsic activity of the GOCAL, is much more stable compared to the activity of free CA. Secondly, the OmpF is incorporated into the GOCAL membranes. The highest value of the GO activity efficiency, defined in the same way as above, of the system (GOCAL-OmpF) is obtained when 5 OmpF molecules are charged in one liposome, giving the 17 times greater GO activity efficiency than that for the GOCAL and leaking neither GO nor CA at 40°C. Finally, the GOCAL-OmpF is covalently immobilized to the chitosan gel beads. The performances of this novel biocatalyst (IGOCAL-OmpF) are examined by following the change in the glucose conversion as well as the remaining GO activity with the successive 15 h-air oxidations for the repeated use at 40°C in an airlift bioreactor. The IGOCAL-OmpF shows higher reactivity and reusability than the IGOL as well as the OmpF-incorporating IGOL (IGOL-OmpF). Due to the absence of CA, the IGOL-OmpF is least stable and results in drastically inhibited GO.

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Reactivity of phospholipaseA₂ on hydrolysis of phosphatidylcholine in W/O microemulsion was kinetically investigated. The desired solvent combinations were prepared by mixing isooctane (C₈*) as the main solvent and 1-butanol (C₄), 1-pentanol (C₅), 1-hexanol (C₆), and 1-octanol (C₈) as co-solvents. Mixed organic solvents were designed by the molar ratio of isooctane to co-solvents. We used the hydrophobicity based on logP as an indicator of the mixed organic phase. Its experimental range was from 3.816 to 4.090. The alcohol-free isooctane/PC system had very slight increase of production. When 1-butanol was directly injected into the running isooctane/PC system, the initial reaction rate was dramatically promoted about 150-fold. Hydrolysis was successfully performed by injecting 1-butanol, and the reaction rate was promoted. Initial reaction rate was remarkably promoted in the molar ratio of isooctane:1-butanol=11:0.05 to 0.2. More than the molar ratio of 1-butanol=0.2, the increasing of initial reaction rate was achieved maximum level. These findings strongly suggested that alcohol is a necessary co-solvent for quick initiation, even if it was small addition amounts. As a typical reaction characterization in this investigation, a slight delay of fatty acid production was recognized as the lag phase at the beginning of hydrolysis. It was measured as 45 minutes in alcohol-free isooctane/PC system (logP=4.090). When the hydrophobicity decreased, the lag phase was reduced, i.e. from 45 minutes (logP=4.090, C₈*alone) to 1.5 minutes (logP=3.816, C₈*:C4=11:1). These results suggested that alcohol functioned not only as a good solvent of PC but also as a promoter of hydrolysis.

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Crystalline sugars are significant commodities in the world market, however the crystallization behaviour of many sugars is still not well known. Recently it has been shown that the mutarotation reaction of reducing sugars plays a significant role in determining the crystallization rate of these sugars, and thus it is beneficial to be able to model and predict mutarotation rates for common sugars. The mutarotation rate and equilibrium of simple carbohydrates; D-glucose, D-galactose, D-cellobiose, D-maltose, and D-turanose, in aqueous solutions were measured between 7 and 35°C, using ¹³C-NMR. The effects of sugar concentration and temperature on the rate of mutarotation and mutarotation equilibrium were observed. It has been found that the rate of mutarotation slightly decreases as the sugar concentration increases. The rate constant of the studied sugars follows an Arrhenius relationship with respect to temperature, and activation energies for the reactions were found from an Arrhenius plot. There are no clear correlations between the equilibrium constant and the sugar concentration or the temperature. Finally, it is quite clear that the mutarotation rate of ketose sugars is higher than the mutarotation rate of aldose sugars, and the number of rings in the structure (i.e. monosaccharide and disaccharide) does not have a significant effect on the rate of mutarotation.

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Motion of condensed water or water-ethanol mixture drop on a cold copper surface with gradient of contact angle was studied for the purpose of applicability of surface tension gradient driven capture/removal of the small liquid droplets on the substrate. In this work, a new method of generating a gradient surface has been developed that painting self-assembled monolayers (SAMs) of hydrophobic perfluoroalkylthiols and hydrophilic mercaptoalcohols on the electrochemically reduced oxide-free varying roughness copper surface. The wettability gradient of the surface could be manipulated in a wide range with a Wenzel-relation. Ethanol-water mixture vapor condensation test on the hydrophilic, hydrophobic and wettability gradient copper surfaces was carried out. The results of the vapor condensation on the gradient copper surfaces were shown that numerous liquid droplets nucleate and grow by coalescence with surrounding drops, then the droplet rapidly moved from the perfluoroalkylthiol SAMs covered hydrophobic side to the mercaptoalcohols SAMs covered hydrophilic ones. This phenomenon could be useful for passively enhancing heat transfer including two-phase flow.

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An additive salt, LiNO3, was used as a shield in the preparation of single crystalline ZnO particles via an ultrasonic spray pyrolysis route in order to prevent particle-agglomeration and enhance the crystallinity of the product. LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. Agglomerate-free particles having a mean particle size of 26 nm were successfully obtained after washing the product. Powder X-ray diffractometry, field-emission scanning electron micrograph and transmission electron micrograph data indicate that the size and morphology of ZnO were strongly influenced by the operating temperature used and the residence time of the particle in the reactor.
Also using the same apparatus, i.e. ultrasonic spray pyrolysis method, europium doped ZnO (ZnO:Eu) phosphor particle was directly synthesized. The crystal structure of product was designated by europium ions concentration and the synthesis temperature. We identified the coexistence of Eu²⁺ and Eu³⁺ in the as prepared ZnO, which was strongly influenced by the doping concentration and the synthesis temperature. With the addition of 0.5 mol % concentration of europium ion, only Eu²⁺ ion existed in the particles, while both Eu²⁺ and Eu³⁺ ions existed in the particles when using 1 mol % or higher concentration of europium ions. We also found that by changing the wavelength of excitation source, both of blue luminescence and red luminescence can be obtained.

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Nickel and nickel oxide nanoparticles, as model materials, prepared from different types of precursors (aqueous Ni (NO₃)₂.6H₂O, NiCl₂, and Ni (HCO₂)₂.2H₂O) by using a low pressure spray pyrolysis (LPSP) is reported in this paper. Effects of type of precursor, temperature, pressure, carrier gas flow rate, concentration of precursor and type of reducing agents on the production of nickel and nickel oxide nanoparticles were investigated. It is found that different types of precursors and temperatures from 400 to 900 °C have great influences on controlling the size and morphology of final particles in low pressure environment. Higher solubility of precursor and higher temperature are in favor of the formation of nanoparticles.
The results also showed that pressure and carrier gas flow rate play crucial roles in the reduction of NiO to nickel in LPSP process. Relative higher solution concentration is suitable for the generation of nanoparticles. Cosolvents such as formic acid and ethanol as well as H₂ were treated as the reductives in the synthesis of nickel (nanoparticles) from nickel metal salts. Weak NiO peaks together with strong nickel peaks in powder XRD patterns indicated that nickel nanoparticles are easier to be oxidated compared with the submicron sized one investigated in the conventional spray pyrolysis due to their higher surface potential. Another possible reason may come from the incomplete reduction in very short residence time because of the decrease of H₂ amount in some cases. Possible mechanism of nickel and NiO nanoparticles formation in LPSP is suggested as well.

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Crystalline Fe-Si alloy particles ranging from 22 to 155 nm in diameter were produced by thermal decomposition of a mixture of Fe(CO)₅ and SiH₄ in a furnace aerosol reactor. The reactor was made of alumina, 2.4 cm in diameter and 100 cm in length. The operating variables were reactor temperature (800 to 1400°C), the Fe(CO)₅ concentration (2.5×10^-5 to 1.5×10^-4 mol/L), the molar ratio of Fe(CO)₅ to SiH₄ (100:0 to 50:50), and the residence time (1.7 to 5 s). The primary particle size increased with reactor temperature increase and decreased with increasing the Si content of the precursor. The sintering of the particles within the agglomerates was an important factor in determining the primary particle size, and the sintering was inhibited by the silicon. By high-resolution transmission-electron-microscopy study, a particle 20 nm in diameter was nearly a single crystal with an external oxide layer 2 nm in thickness. The coercive force ranged from 58 to 493 Oe, increasing with decreasing the particle size, and the saturation magnetization was in the range of 50 to 100 emu/g, lower than that of bulk iron, due to the presence of non-magnetic silicon and of the oxide layer.

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Transient charging on particle was estimated by solving orbital motion limit model equation, where ion and electron fluxes were calculated by considering the particle surface electric field. Using equilibrium charge on particle, particle trajectory in capacitive glow discharge was estimated by solving motion equation, which considered external forces as fluid drag force, gravitational force, electrostatic force and ion drag force. Glow discharge was calculated by continuous model, which considers continuity and flux equations for electron and ion. Calculation results showed quantitative effect of plasma structure induced from various plasma input condition, such as power input, pressure and gas properties on the characteristic motion of particle in glow discharge plasma space. We attempted to synthesize Fe and Pt containing alloy nanoparticles using the above phenomena. The plasma was modulated with a square-wave on/off cycle of varying period to study the growth kinetics. The synthesized particles were directly collected onto TEM sample grid placed in the plasma electrode. TEM pictures showed two kinds of particles, one of which is nanometer size and isolated and the other appeared a coagulate of nanometer size particles. The size of particle coagulates was controlled in the 10-100 nm range by adjusting the plasma-on time. The size distribution of the particle coagulates collected through the skimmer was as small as 5%. The alloy particles magnetization was measured by VSM(Vibrating Sample Magnetometer). As-synthesized particles showed no magnetization, though the composition was precisely adjusted to Fe50Pt50. Heat treatment in hydrogen atmosphere results in the magnetization. FePt annealed over 650 °C showed large magnetization.

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Adhesion characteristics of Cu/C:H films on the polyethylene terepht halate(PET) were investigated with special attention to pretreatment methods. The Cu/C:H film was prepared by ECR-MOCVD at room temperature. PET substrates were subjected to industrially feasible pretreatments such as Ar ion implantation, O₂ plasma, chromo-sulfuric acid, and sandblasting. Surface topography and roughness before and after deposition of pretreated samples were investigated by atomic force microscopy (AFM). The measurements of the adhesive force between the film and substrate were carried out with a pull-off test by using an Instron® and the surface energy was calculated by the contact angle measurement. Our experimental results showed that adhesion of deposited films mostly depended on the surface roughness of PET substrate before the deposition. Therefore, we can construe that chemical and mechanical pretreatment are efficient ways for the deposition of Cu/C:H film on PET substrate. In the case of chromo-sulfuric acid pretreatment, the surface roughness increased initially and then decreased after passing a maximum, with the increase of the acid soaking time. Cu/C:H film with good adhesion characteristics could be obtained at maximum value of surface roughness and surface energy.

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Vapor deposition methods have been used to form continuous films on substrates, however, formation of nanoislands at the initial deposition stage is recently gathering interests from the viewpoint of nanotechnology. Especially for non-epitaxial growth, various nanostructural changes appear. But non-epitaxy is not understood well compared with epitaxy due to its complicated phenomena. To see the whole picture of non-epitaxial growth, we have introduced a simple concept; thermodynamics controls the unit-structure within the surface diffusion length of deposits whereas kinetics controls the ensemble-structure of larger scale. Based on this concept, various phenomena occurring at the initial stage of non-epitaxial growth are systematized by referring to the results of our continuing research as examples. As is well known, the balance among the surface and interfacial energies of deposits and substrates thermodynamically determines the shape of islands. The balance among bulk, surface, and interfacial energies thermodynamically determines the crystallographic structure of islands, and sometimes amorphous-to-crystalline transition occurs for deposits on amorphous substrates. Both adatom surface diffusion and island migration kinetically affect the structure of island ensembles, and interspacing among islands roughly corresponds to the characteristic length of diffusion and migration. Incubation for deposition appears more frequently in chemical vapor deposition than in physical vapor deposition, which is caused by the changes either in the sticking probability of precursors or in the desorption rate of adsorbates. These insights will help us to understand and control nanostructural evolution during non-epitaxial growth.

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The mechanism and kinetics on the synthesis of silver nanoparticles using anhydrous dextrose as the reducing agent are discussed here. The keys to the success of this process rely on the quantity of alkaline for silver conversion and PVP for keeping silver colloids in the nanometer range. Complete conversion can be achieved when sufficient NaOH (molar ratio to AgNO₃ of 1.5) is added for this synthesis reaction: 2 Ag⁺ + C₆H₁₂O₆ + 3OH- --> 2 Ag + C₆H₁₂O₇- + 2 H₂O. The rate-determining step is speculated to be the attack of alkaline ion to dextrose (reducing agent) to liberate two electrons to convert silver ion to silver. Our kinetic data fitted well according to this mechanism and its activation energy is determined to be around 34.6 Kcal/mole. Other characteristics of silver colloids, such as morphology, particle size and crystal structure will also be reported as functions of synthesis parameters.

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Many attempts has been made to make nucleation kinetics clear so far, but many issues remain to be unknown. Here, focusing on the relationship between incubation period which can be seen before the formation and growth kinetics of particles, we investigate formation kinetics of gold nanoparticles. Based on the in-situ observation of laser-photo reduction of gold complex, AuCl₄-, using UV-Vis spectroscopy and transmission electron microscopy (TEM), we propose simple model for reduction, formation and growth kinetics of gold particles, and discuss how metal nanoparticles form in aqueous solution. Gold nanoparticles, which consist of zero-valence gold atoms, are mainly produced after incubation period. During incubation period, reduction of gold complex to zero-valence gold atoms is dominant, particle formation is not dominant due to the lack of the source materials, zero-valence gold atoms. On the other hand, at the end of the incubation period, the concentration of zero-valence gold atoms in solution is high enough to cause the particle formation of gold. After that, reduction of gold complex, formation and growth of gold nanoparticles occur at the same time. Thus, the whole reduction process can be practically divided into two periods, 1) from the beginning of the irradiation of laser pulses to the end of incubation period, 2) after incubation period. Reduction process of gold complex is discussed in 1st period, and nucleation and particle growth processes are treated in 2nd period. Irradiated laser fluence is important factors in both periods.

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The Catalytic Reaction Engineering toward Green Chemical Processes project was undertaken between 2001 and 2003, funded under the Scientific Research in Priority Areas program of the Ministry of Education, Culture, Sports, Science and Technology of Japan. The representative of the project is Prof. T. Hattori of Nagoya University. This research project was aimed at establishing the hybrid field of catalytic reaction engineering, which bridges a large gap between nano-scale catalytic chemistry and macroscopic chemical reaction engineering as an essential discipline for the realization of a sustainable society. Research was divided into three areas; the development of reaction fields using structured catalysts, the control of catalytic functions using reaction fields, and the design of catalytic reaction fields for achieving "green" chemical processes. The research is currently being prepared for publication.

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This paper reports promotion effect of HC-SCR activity of Ag/Al₂O₃ catalyst by the control of reaction atmospheres, i.e., (1) the use of higher hydrocarbons as reductants, (2) co-feeding of water vapour, and (3) co-feeding of small amount of hydrogen. Although Ag/Al₂O₃ was not active for propane-SCR below 623 K, the conversions of NO to N₂ were above 65 % when n-octane was used. Co-feeding of water vapour resulted in nearly 100 % NO conversion in the SCR by n-octane, which may be because of the suppression of the poisoning by carbonaceous deposits. In the case of SCR by lower alkanes at lower temperatures, it was clarified that the co-feeding of small amount of hydrogen is effective. The promotion effect of hydrogen is caused by the modification of Ag species on alumina, i.e., Ag⁺ species was reduced and agglomerated by hydrogen into Ag cluster, which is active for the SCR reaction. These effects of reaction atmospheres are discussed from a point of view of surface reaction pathway and dynamics of active species measured by in-situ FT/IR and in-situ UV-Vis spectra.

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The deactivation and modeling of nitrided and sulfided 12.5 wt% MoO3/Al2O3 catalysts were studied during the hydrodesulfurization of dibenzothiophene at 573 K and a total pressure of 10.1 MPa. The deactivation behavior was expressed by an equation on the basis of two types of active sites one of which was quickly deactivated and the other deactivated with difficulty: Φ = 1 - k1ln(t + α1) + k2exp(-α2t), where α1 and α2 are the first order rate constant for easily deactivated sites and sites deactivated with difficulty, respectively. The former sites were based on the Elovich kinetics which represented the initial deactivation caused by sulfur accumulation and nitrogen release. The latter sites were based on first order deactivation kinetics in the intermediate stage of the reaction. The catalyst lifetime of the 973K-nitrided catalyst was 2.3, 24.8 and 44.5 times longer than those of the 773 K- and 1173 K-nitrided and 623 K-sulfided catalysts, respectively, at a conversion of 10%. The behavior of nitrogen release, carbon deposition, and sulfidation was determined by XPS and related to the deactivation parameters.

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Recently, computational chemistry made great impacts on the catalysts research and development. On the other hand, the construction of new research field "Catalysis Reaction Engineering" by the merge of "Catalysis Chemistry" and "Catalysis Engineering" is strongly demanded. Static first-principles calculation has been employed to clarify the catalytic reaction, while molecular dynamics method has been employed to elucidate transport phenomena. However, the above methods cannot simulate both the catalytic reaction and transport phenomena at the same time, since the first-principles calculation cannot deal with the transport phenomena and molecular dynamics method cannot deal with the catalytic reaction. However, in order to establish new research field "Catalytic Reaction Engineering", both the catalytic reaction and transport phenomena should be simulated at the same time. Hence, recently we have succeeded in the development of new simulation program, which realizes the simulations of both the catalytic reaction and transport phenomena for the first time. This new simulation program is based on our original tight-binding quantum chemical molecular dynamics method. This program enables us to establish new research field "Theoretical Catalytic Reaction Engineering". The objective of this review is the introduction of the concept of "Theoretical Catalytic Reaction Engineering" and the characteristics of our new simulation program. Moreover, various successful applications of our new simulation program to the wide range of catalyst systems are also summarized.

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Effect of presence of oxygen upon steam reforming of methanol (CH₃OH + H₂O --6gt; 3H₂ + CO₂) is investigated with ZnO supported various group 8-10 metal catalysts. In the absence of oxygen, Pd/ZnO and Pt/ZnO catalysts exhibit high activity and selectivity for the steam reforming, while the other group 8-10 metal catalysts such as Fe, Co, Ni, Ru and Ir give poor selectivity and the decomposition of methanol (CH₃OH --> 2H₂ + CO) occurs in preference to the steam reforming. Effects of the presence of oxygen over Pd/ZnO and Pt/ZnO catalysts are markedly different from those over the other group 8-10 metal catalysts. Over Pd/ZnO and Pt/ZnO catalysts, partial oxidation of methanol (CH₃OH + 1/2O₂ --> 2H₂ + CO₂) rapidly occurs with high selectivity and conversion of methanol and rate of hydrogen production are drastically enhanced in the presence of oxygen. By contrast, over the other group 8-10 metal catalysts, oxidation of methanol (CH₃OH + 3/2O₂ --> 2H₂O + CO₂) occurs predominantly and the rate of hydrogen production is not so increased, although the conversion of methanol is increased. Characterization studies by means of temperature-programmed reduction and X-ray diffraction reveal that PdZn and PtZn alloys are formed by reduction of Pd/ZnO and Pt/ZnO catalysts at high temperature, whereas for the other group 8-10 metal catalysts, no alloys are formed. The steam reforming and partial oxidation of methanol selectively proceed on such Pd and Pt alloys.

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Highly reactive zinc metal was prepared by electrolysis of a DMF solution containing naphthalene and a supporting electrolyte in a one-compartment cell fitted with a platinum cathode and a zinc anode. This reactive zinc (EGZn/Naph) was used for transformation of bromoalkanes into the corresponding organozinc bromides, which can not be achieved by the use of usual zinc metals. Reaction of the organozinc compounds thus prepared with various aryl bromides in the presence of 5 mol% of palladium catalyst gave the corresponding cross-coupling products in high yields. Arylzinc iodides were also prepared by the use of EGZn/Naph, and they were reacted with other aryl halides to give the corresponding cross-coupled biaryl in good yields.

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Preparation procedure of Sn-incorporated in meso pores of MCM-41 has been studied for reduction of acetophenone to 1-phenylethanol. Tin was incorporated into the meso pores of MCM-41 by a template ion exchange (TIE in the following) method. Almost 20 wt% of Sn was loaded in the meso pores and ca. 70 % of template was still remained together. Calcination treatment to remove the residual template ions brought about significant collapse of the periodical hexagonal structure of MCM-41 and decrease of surface area because of heat of combustion of the template in the pores accompanying with sintering of incorporated tin. We have investigated the procedure to remove the template from the MCM-41 by rinsing with HCl before or after the tin incorporation to avoid vigorous exothermic combustion during the calcination. Almost 70-80 % of template was liberated by the rinse with HCl. The hexagonal structure and surface area were maintained after Sn incorporation. The rinse with HCl aqueous solution before the tin incorporation brought about an enhancement of specific activity, formation rate of 1-phenylethanol from acetophenone per incorporated amount of Sn. The rinse of HCl before the incorporation increased the specific activity by a factor of 2-3.

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A catalyst support with both small pores and large pores, as well as a distinct bimodal pore structure, has excellent advantages in industrial solid-catalysis reaction because the large pores provide pathways for rapid molecular transportation and the small pores serve a large area of active surface. A simple preparation method of bimodal supports was developed by introducing SiO₂ or ZrO₂ sol into large pores of SiO₂ gel pellet directly. The pores of the obtained bimodal supports distributed distinctly as two kinds of main pores. The obtained bimodal support loaded with cobalt was applied in slurry-phase Fischer-Tropsch synthesis (FTS). The bimodal catalyst presented the best reaction performance in slurry-phase FTS as higher reaction rate and lower methane selectivities, because the spatial promotional effect of bimodal structure and chemical effect of the porous zirconia were available inside the large pores of original silica gel.

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SO₂ storage by copper containing mixed oxides, such as CuTa₂O₆, CuNb₂O₆ and so on, was investigated. SO₂ sorption occurred under the presence of oxygen and it was desorbed under the presence of H₂. The sorption/desorption process can be regarded as not only the low concentration-SO₂ removal from, e.g. flue gas but also the concentration process of SO₂ to be a chemical feedstock. The crystals of CuTa₂O₆ and CuNb₂O₆ have perovskite- or columbite-type structure. These catalysts showed very high SO₂ storage capacity by several cycles of oxidative sorption and reductive desorption. The amounts of the SO₂ uptake per Cu atom were much more than those based on the assumption of surface adsorption and the specific surface area and also the amounts of SO₂ uptake by CuO, Ta₂O₅ and Nb₂O₅. Hence, the storage occurs not only on the surface but also inside the bulk of the catalysts in probably in sulfates ion form and the storage is enhanced by the presence of Ta or Nb. In this study, this remarkably high sorption ability was named Synergetic Oxidative Sorption (SOS)of SO₂. From XRD measurement, the crystal structures of the catalysts were gradually destroyed by the cycles and the XRD patterns showed that the catalysts finally became amorphous when SOS appeared. Another interesting finding was that just mechanical mixtures of CuO and Ta₂O₅ or Nb₂O₅ also showed the high SOS activity. Effect of partial replacement of Ta by Nb was also investigated.

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Vapor phase Beckmann rearrangement over new type zeolite (SSZ-31) with medium pore size and weak acid sites were carried out to elucidate the effects of acid strength and micro pore size on the selectivity to ε-caprolactam (CL) and the catalyst deactivation. Furthermore, the titanosilicate with ZSM-5 type structure (TS-1) was used for the rearrangement to clarify the effect of Si/Ti ratio on the CL selectivity and catalyst deactivation rate. The results obtained from the new catalysts were compared with the results over HZSM-5.The selectivity to the CL over the catalyst with strong acid sites was lower than that over high silica HZSM-5 with weak acid strength. The CL selectivity over the catalyst with large micro pore was lower than that over the catalyst with MFI structure. These results indicate that the CL produced in medium pore (about 1.0 nm) changes to oligomers and the deposited oligomer in the pore gradually changes to coke or its precursor. The oligomerization should be accelerated by the strong acid sites. The SSZ-31 with medium pore is not suitable to the Beckmann rearrangement, whereas TS-1 with small pore was good catalyst for the rearrangement.

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Methane is attracting a great deal of attention as a next-generation carbon resource. It is a chemically unstable molecule, and it is difficult to convert it to low-grade or long-chain hydrocarbons. For example, the direct conversion of methane to ethane and hydrogen is usually accompanied by thermodynamic disturbances(ΔG(298 K) = 68.6 kJ/mol). On the other hand, highly-efficient reforming of methane may become possible if a separation reaction technique and a light irradiation field can be introduced by using a combination of a plasma zone, an electrical reaction zone, a membrane, plate catalysts, etc.
This paper describes the latest research and development results, with the emphasis on two keyword subjects: "high-efficiency methane reforming" and "special reaction zones."

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Zeolites have micro pores within their crystals, diameters of which are almost equal to molecular diameters of lighter hydrocarbons. Therefore, zeolite membranes without any pinholes are expected to show high performance for shape selective separation of hydrocarbons. Moreover, by applying the zeolite membrane with catalysis to reaction in series, there is the possibility for producing intermediate species at higher yields than in those using conventional reactors. In this study, catalytic ZSM-5 zeolite membranes were employed to a reaction of methanol to olefins (MTO reaction). The ZSM-5 zeolite catalyst membrane without pinholes was successfully prepared by synthesizing a ZSM-5 zeolite layer on an outer surface of a cylindrical alumina ceramic filter. The membrane was used as the catalytic membrane reactor to recover olefins from methanol. Though olefins were successfully produced at a high selectivity from methanol, the paraffin production was observed at the feed side of the zeolite membrane. In order to inhibit the production of paraffin and aromatics, the acid site distribution of the ZSM-5 zeolite membrane was controlled by CCS method (Catalytic Cracking of Silane method developed in our laboratory). Deactivation of acid sites at the outer surface of the zeolite membrane (feed side of reactant) by the CCS method enable to increase the selectivity of olefins and decrease in the selectivities of paraffin and aromatics.

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A wall reactor system, in which a metallic wall is directly catalyzed, is a reaction system that enables an efficient transfer of thermal energy, a rapid response to fluctuating loads. Application of the system in a reactor involving reformers and water gas shift converters for power generator system by fuel cells is expected. In order to develop a high-performance plate-type catalyst for wall-type methanol reformer and CO shift converter, a structured copper-based catalysts were prepared by electroless plating, consisting of a displacement plating of zinc, an intermediate chemical plating of various metals, and a chemical plating of copper. The reforming and shift performances and the physicochemical properties of the plated catalysts were investigated. Results showed that the prepared catalysts had different performance depending on the metal species used in the intermediate plating. Among them, a plate-type Cu-Fe/Zn catalyst on an intermediate iron plating exhibited high reforming and shift performances. The performances of the Cu-Fe/Zn catalyst made much progress by pre-oxidizing in air stream before reaction, which were nearly the same and/or higher with that of a commercial granular catalyst. Characterization including an X-ray diffraction (XRD) suggested that the oxidation treatment produced a copper-zinc alloy on the plated surface where zinc atoms existed in proximity of copper atoms. The existence of copper and zinc atoms in proximity might have formed an active site that accelerated the formation and decomposition of an intermediate species in both reactions, which led to the increased catalytic activity. It was also demonstrated that the declined activity of the Cu-Fe/Zn catalyst was repeatedly recovered by oxidizing, which is practically convenient in using the Cu-Fe/Zn catalyst as a plate-type catalyst for a wall-type methanol reformer and shift converter.

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To supply H₂ for a small proton exchange membrane fuel cell (PEMFC) as a power source for portable electronic devices, a multi-layered microreactor system with methanol reformer was developed. The microreactor consists of four units (a methanol reformer with catalytic combustor, a CO remover, and two vaporizers) and was designed using thermal simulations to establish an appropriate temperature distribution for each reaction. The microreactor was constructed from thirteen microchanneled glass plates stacked with anodic bonding and placed in a vacuum package for thermal isolation. An appropriate catalyst for each reaction was deposited on the microchannel of each reactor. When the microreactor was heated by applying voltage to a thin-film heater attached to one side of the reformer, the temperature distribution observed for each unit approximated the simulated results. Finally, methanol reforming was achieved in the microreactor using heat supplied from the internal catalytic combustor. The reforming temperature of the microreactor could be maintained at 280°C without a supply of electrical power. A hydrogen production rate sufficient to generate 2.5 W of electrical power was obtained.

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The performance of Pd/SiO₂ catalysts modified with La and Nb oxides in the selective hydrogenation of acetylene was investigated. The amounts of H₂ chemisorbed on the catalysts were significantly reduced when the catalysts were reduced at high temperatures, e. g., 500°C. This is because the Pd surface is covered with small patches of partially reduced La and Nb oxides after the high temperature reduction, which is the characteristic of a well-known strong metal support interaction (SMSI) phenomenon. X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) results indicated that the Pd surface was also modified electronically, such that the adsorption of ethylene to the Pd surface was weakened. Such behaviors of metal oxides affected the ethylene selectivity and lifetime of the catalysts. The ethylene selectivity of Pd-La/SiO₂ and Pd-Nb/SiO₂ was improved due to the geometric and electronic modifications of Pd by the oxides. Pd-La/SiO₂ showed more significant improvement in the ethylene selectivity than Pd-Nb/SiO₂. The activity of Pd-Nb/SiO₂ was comparable to that of Pd/SiO₂, even though the Pd surface was partially covered with Nb oxide, because the oxide had an additional hydrogenation activity. The catalyst deactivation was also retarded when the Pd surface was modified with La and Nb oxides. Thermogravimetric analysis (TGA) and temperature-programmed oxidation (TPO) results showed that Pd-La/SiO₂ and Pd-Nb/SiO₂ produced less amounts of coke and the coke species were more volatile than in the case of Pd/SiO₂.

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Gamma-alumina supported bimetallic Pt-Ru catalyst (Pt-Ru/γ-Al₂O₃) was prepared by impregnation of Pt₃Ru₆(CO)₂₁(μ₃-H)(μ-H)₃ cluster in CH₂C_l2 solution on γ-Al₂O₃ and decarbonylated in helium at 300°C. Changes of the cluster before and after decarbonylation, monitored by infrared (IR) spectroscopy indicated that Pt₃Ru₆(CO)₂₁(μ₃-H)(μ-H)₃ adsorbed strongly to surface of γ-Al₂O₃ and could not be extracted from support by CH₂C_l2 solvent. In addition, Pt-Ru/γ-Al₂O₃ was characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy which confirmed that Pt and Ru were still intact after decarbonylation. Some changes in the cluster bonding were likely caused by cluster-support interaction. The catalyst was active for ethylene hydrogenation and n-butane hydrogenolysis. The temperature dependence of both reactions gave apparent activation energy of 8.4 ± 0.1 and 30.9 ± 0.1 kcal/mol, respectively.

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With the growing demand for high quality diesel fuels more and more severe environmental regulations are imposed to the refineries. In order to meet the new stringent specifications, the development of new efficient catalysts is required while making efforts to elucidate the reaction mechanism. Previous research showed that for the second row the highest HDS activity was obtained over ruthenium sulfides for unsupported catalysts, and rhodium sulfides for transition metal (TM) sulfides supported on carbon. Such TMs exhibit high intrinsic HDS activity that can be enhanced by using appropriate carriers, preparation and pre-activation methods. On the other hand, in order to achieve deep hydrodesulfurization it is important to examine the reactivity of refractory sulfur compounds, such as 4,6-dimethyl- dibenzothiophene (4,6-DMDBT). Therefore, in the present study, we investigated the HDS of dibenzothiophene (DBT) over various metals (Co, Mo, Ni, Cr, W, Pd, Pt, Ru, Rh, Re, Ir) supported on alumina. For the TM catalysts showing the highest HDS activity, the effects of carrier, metal loading and preactivation methods on DBT and 4,6-DMDBT HDS activity and product selectivity were examined. The results showed that the alumina-supported rhodium catalyst exhibited the highest HDS activity of the 2nd row. Especially, Rh/Al₂O₃ catalysts exhibited a superior HDS performance compared with a conventional CoMo alumina catalyst (based on the specific activity per metal atom). In addition, the HDS activities of such catalysts could be further increased for instance by changing the support or the preactivation method. The behavior of sulfur on the working catalyst using ³⁵S tracer was also introduced.

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In this research, oxidation of n-butane to maleic anhydride (MA) over vanadium-phosphorus oxide(VPO)catalyst ,prepared in an organic medium, was investigated in a fixed bed reactor.A comparative study has been conducted between promoted(promoted with molybdenum) and unpromoted VPO catalysts. It was observed that the molybdenum(MO) increases the selectivity toward MA. Experiments showed that a catalyst having P/V atomic ratio equal to 1.1,Mo/V weight ratio of 0.08 ,give the maximum selectivity 98% at a temperature of 450–425°C and contact time1.28s (GHSV=2800 hr^-1 ) and an inlet n-butane concentration of 1% of air and n-butane mixture.

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The transesterification experiments of triolein with ethanol using various ion-exchange resins were conducted to produce the ethyl oleate which is available as a biodiesel fuel. The anion-exchange resins, Diaion PA308, PA306s and HPA25, showed much more catalytic activities than the cation-exchange resin, Diaion PK208. Among the anion-exchange resins, PA306s with the lowest crosslinking degree was most active. For PA306s of 4 g, the conversion of triolein to ethyl oleate reached about 90 % at 1.5 hours, which was reasonably comparable to the results using the conventional homogeneous catalysts, NaOH and KOH. The continuous transesterification experiments were carried out using an expanded-bed reactor packed with PA306s. The bed expansion was linearly related with the flow rate and the bed voidage and the residence time through the expanded-bed was calculated by this relation. The concentration of ethyl oleate in the effluent solution increased with the residence time and then hardly changed over 20 min. The transesterification was considered to be in the equilibrium state at this residence time. The equilibrium conversion of triolein to ethyl oleate was about 60 %.

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Chlorinated polyethylene (CPE) is usually produced in either solution or suspension phase. In order to study the behavior of photochlorination reaction and structural configuration of the obtained products, the radical chlorination reaction of polyethylene has been carried out in perchloroethylene as solvent, at atmospheric pressure and a temperature around 100°C. The photochlorination reaction was carried out via sparging of chlorine gas into the PE solution and exposing to the UV light. This PE solution consists of HDPE or LDPE dissolved in perchloroethylene solvent. Instrumental analyzing has been accomplished on the samples which have been taken in equal periods of time during the reaction. The recorded FTIR spectra of CPE's samples in comparison with the initial PE spectra indicate the gradual changes, which have been occurred at the polymer chains. The multiplications of methylene (CH₂) groups of peaks and chloromethylene (CHCL) groups of peaks that appeared in the H-NMR spectra were characterized. The sequences of methylene units between two subsequent chloromethylene units in the polymeric chain have been determined from the H-NMR spectra and their results have bee verified with the data of some model compounds. The relative fractions of these methylene sequences have been plotted versus the concentration of chlorine. The procedure of variations of methylene sequences resulted from this curve also have been discussed. The chlorine percentage of each sample has been calculated from their H-NMR spectra base on the relative integrated value of methylene and chloromethylene group of peaks. The results of this quantitative analyzing have been confirmed with an elemental analyzing technique such as flask combustion method in a plot versus the reaction time. Finally the procedure of variations observed at reaction rate has been described.

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Photo-activated electrons reduce reactants and photo-generated positive holes oxidize reactants in photocatalysis. The electrons and holes, however, mostly or partly recombine before used for the reactions because photocatalyst particles are basically symmetry, and thereby can not generate effective electric field to separate electrons and holes. Both the reduction and the oxidation proceed in the same space simultaneously in conventional photocatalysis reactors using suspended or supported catalyst particles, and thereby reduced products tend to be oxidized and oxidized products to be reduced. These reverse reactions and the infertile recombination of electrons and holes lower photon-efficiency of photocatalysis. In an effort for preventing the reverse reactions and the recombination to raise photon- efficiency, the authors fabricated a reactor equipped with a hetero-sided photocatalyst plate supporting an oxidation photocatalyst at one surface of a conductive metal plate and reduction catalyst at the other surface of the metal plate. The hetero-sided photocatalyst plate can generate the effective electric field to drive electrons and holes opposite directions due to its asymmetrical structure and the Schottky potential generated at the interface between the reactant solution and the photocatalyst. The plate divides the reactor volume into two spaces, oxidation and reduction spaces. The divided reactor equipped with the hetero-sided photocatalyst plate achieved a high photon-efficiency, five times as large as the undivided reactor, when hydrogen was generated at 20% photon-efficiency (the external quantum yield) from acidic water in the reduction space while formic acid was oxidized in the oxidation space.

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A Taylor vortex photocatalytic reactor was developed that creates unsteady Taylor-Couette flow in between the two co-axial cylinders by re-circulating fluids form bulk to the inner cylinder wall, which was coated with TiO₂. Systematic investigation for flow development as well as photocatalytic degradation of three different organic compounds was carried out. The effect of Reynolds number and catalyst loading on photocatalytic degradation were compared for both slurry and fixed catalyst system. The experimental results demonstrate that Taylor vortex photocatalytic reactor is promising for water purification even when catalyst is fixed, as there is no significant difference in overall degradation rate between slurry and immobilized systems.

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Chlorinated volatile organic compounds (CVOCs) such as chloroform (CF), carbontetrachloride (CTC), tri- and tetrachloroethylene (TCE and PCE) are pollutants commonly found in ground water and soil. Their oxidation in a novel, bubble column photochemical reactor combining the mass transfer of pollutant from the gas phase followed by a free-OH radical reaction in a liquid phase (UV/H₂O₂ system) is described mathematically and in terms of economic feasibility. It was shown that the reaction rates in liquid phase followed the pseudo-first order kinetics and the process could be therefore examined for electrical energy efficiency by the figure of merit Electrical Energy per Order (EE/O). The EE/O values were shown to depend on the initial concentration of pollutant and hydrogen peroxide, as well as the reactor radius. In all cases, the value of EE/O is decreasing with increasing reactor radius, as does the apparent rate constants of pollutant degradation. It was shown that the levels of PCE and TCE in the order of 20 mg/L could be treated economically. However, the treatment of compounds with low affinity to OH radicals was shown to be economically unfavorable even for ppb level concentrations.

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An overview is presented on how surface-active solutes, e.g., aliphatic alcohols, surfactants, and polymers, affect acoustic cavitation bubbles in a multibubble system. The discussion explains how trace amounts of alcohols quench sonoluminescence (SL) in aqueous solutions, whereas charged surfactants enhance SL under certain concentration conditions. Polymers, such as polyethylene oxide, affect the SL intensity from aqueous solutions by influencing the formation of the spatial structures of multibubble cavitation "clouds". The influence of surface-active solutes on the ultrasound production of nanoparticles, such as, Au, is described. Finally, it is shown how pyrolysis products from the thermal decomposition of alcohols in sonicated aqueous solutions can be used to calculate a mean cavitation bubble temperature.

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The sonochemical efficiency in the continuous flow sonochemical reactor with the maximum volume of 3.9 dm³ was investigated as a function of flow rate. The sonochemical efficiency was estimated by the oxidation in aqueous solution of 0.1 mol·dm^-3 potassium iodide (KI). We estimated the apparent rate constant of production of I₃^- on the basis of the traditional modeling equation of the pipe flow reactor. The reaction rate increased with increasing flow rate but saturate at the flow rate larger than 10 dm³·h^-1.

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Metal colloids have been widely studied in recent years, because their physical and chemical properties are often quite different from those of the bulk materials. Various methods to prepare nanoparticles from metal ions in an aqueous solution have been proposed, and a sonochemical preparation is one of the unique methods, as the organic additives such as alcohols and surfactants can be used as the reducing agents. The formation rates of gold, silver and platinum nanoparticles were studied by using an ultrasonic cleaning bath of 20, 200 or 600 kHz frequencies, and it was found that the formation rate was controllable by selecting the type of the additives as well as the hydrogen ion concentration in the solution. When lower alcohols such as methanol or ethanol were used, the formation rate of gold or platinum nanoparticles in the neutral region of pH was rapid comparing with that in acid region or alkaline region. The formation rate of gold or platinum nanoparticles using higher alcohol such as pentanol or hexanol was higher than that using lower alcohol at low pH conditions. However, the formation rate became very slow at higher pH than 9.5, when butanol, pentanol or hexanol was used as an additive. On the other hand, for the preparation of silver nanoparticles, the formation rate at higher pH than 9 adjusted by ammonium was extremely high due to the silver-ammonium ion complex.

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A countercurrent continuous washing apparatus for tar removal under ultrasonic irradiation has been developed. Tar was dissolved in DMF and sand was soaked into the resulting tar solution to prepare samples of tar-contaminated sand. Tar contents in DMF were determined from absorbance at 336.5 nm by UV-spectrophotometer. The removal rate of tar content from this tar-contaminated sand was measured in two different conditions, one under the condition of mechanical stirring and the other with ultrasonically induced agitation. The removal rate can be described in terms of first order reaction equation, which enables us to calculate the residue fraction in continuous washing at steady state. Comparison of tar-removal with mechanical stirring and ultrasonically induced agitation has demonstrated that the ultrasound is more effective than the simple mechanical stirring. The basic mechanism of tar removal is, for both removal procedures, peeling of tar-covered layer on sand surface and the particles produced under ultrasonic field are much finer than for the case of mechanical agitation.

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The removal performance of chlorinated organic compounds from porous materials under ultrasound irradiation was experimentally investigated. o-dichlorobenzene and hexane were used as the model PCB and the solvent. Wood chips were impregnated with o-dichlorobenzene at 200 Pa for 24 hours and they were used as the sample. The apparatus consisted of a water bath, a glass vessel and an ultrasonic oscillator. The o-dichlorobenzene concentration in solvent was measured by using a UV spectrometer and the removal ratio of o-dichlorobenzene was calculated. The ultrasonic intensity at the center of vessel bottom was measured by using a hydrophone. The sample size, solvent temperature, ultrasonic intensity and frequency were varied, and the removal ratio of o-dichlorobenzene from sample was measured. For a comparison, the shaking cleaning was also conducted.In the case of shaking, the removal ratio increased with time for the different-size samples. For the ultrasonic irradiation, the removal ratio rapidly increased and became almost unity after 100 minutes when the sample lengths were 5 and 10 mm. At the same length of sample, the removal rate for ultrasonic irradiation was much higher than that for shaking. The difference of removal ratio between the ultrasonic irradiation and the shaking became larger as the sample was longer. The removal ratio increased with increasing ultrasonic intensity and became constant beyond a certain ultrasonic intensity. The removal ratio depended hardly on the frequency and temperature, but was strongly controlled by the ultrasonic intensity. Under ultrasonic irradiation, o-dichlorobenzene was removed from the sample mainly by the longitudinal vibration.

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Effect of ultrasonic irradiation on solute permeation across a cellulose membrane was studied under various operating conditions. Sodium salts of carboxylic acids having different alkyl chain length were dissolved in deionized water and the solution used as feed. The membrane was set to face its dense layer to feed side and the supporting layer to receiving side. Ultrasound irradiation of from receiving side enhanced the solute permeation rate rather than that from the feed side. The degree of enhancement was around a few tens percent increase and an extraordinary effect cannot be expected. Interestingly, a "jump" of concentration in receiving side was observed when ultrasound is on. When the ultrasound was off, the concentration went back to the original curve which was extended from the time before ultrasound irradiation. Such a stepwise increase and a regression of the concentration can be interpreted as desorption from the membrane by ultrasonic irradiation. Since the membrane has a porous structure, the membrane retains the solute on its surface. Propagation of ultrasound can help to release adsorbed solute. Flow visualization showed that the existence of standing wave for slower flow when the permeation was enhanced ultrasonically. While for faster flow, the flow disturbed the standing wave and no enhancement was observed. This implies the standing wave adjacent to membrane surface contributes to the enhancement of solute permeation.

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The properties and behavior of dust particles generated in the plasma reactor and their effects on film contamination are studied. The motion and spatial distribution of dust particles suspended in a PECVD reactor during fabrication of a SiO₂ thin film using tetraethylorthosilicate/oxygen/nitrogen plasma are visualized by using a laser light scattering technique. It is found that the particles are in many cases trapped at a certain region of plasma. The size of the dust particles and the structure of the particle clouds trapped are strongly dependent on the plasma operating conditions, and these also in turn influence the level of particulate contamination of the substrate. It was concluded that proper process conditions must be sought carefully to achieve films of good quality and sufficiently high growth rate with minimum particulate contamination.

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Deposition of single crystalline gallium nitride (GaN) was done using atomic layer epitaxy (ALE) technique with trimethylgallium (TMG) and ammonia (NH₃) as the reactants, at temperatures, T, ranging from 753 to 963 K. The process variables to obtain self-limiting growth mode were investigated. For T = 853 K, ALE growth of GaN was accomplished by alternative pulsing 0.072 mol% of TMG for 4 seconds and 98.3 mol% of NH₃ for 6 seconds. Kinetic analysis of the growth rates per ALE cycle as a function of exposure time for each reactant was performed. The results showed that activation energy for each half reaction increased with increasing surface coverage. An averaged activation energy of 26.3 kcal/mol was obtained for the reaction of NH₃ on Ga-terminated surfaces, 27.7 kcal/mol for TMG on N-terminated surfaces. The large concentration supply ratio of [NH₃]/[TMG] (about 1400) that makes NH₃ adsorb as much as TMG may be responsible for the comparable activation energies.

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