Editor-in-Chief
Takao Tsukada (Tohoku University)

Associate (Editor-in-Cheifs)
Manabu Shimada (Hiroshima University)
Masahiro Shishido (Yamagata University)

Editors
Ryuichi Egashira (Tokyo Institute of Technology)
Jun Fukai (Kyushu University)
Choji Fukuhara (Shizuoka University)
Toshitaka Funazukuri (Chuo University)
Takayuki Hirai (Osaka University)
Jun-ichi Horiuchi (Kitami Institute of Technology)
Eiji Iritani (Nagoya University)
Yoshinori Itaya (Gifu University)
Noriho Kamiya (Kyushu University)
In-Beum Lee (Pohang University of Science and Technology (POSTEC))
Kouji Maeda (University of Hyogo)
Hideyuki Matsumoto (Tokyo Institute of Technology)
Nobuyoshi Nakagawa (Gunma University)
Masaru Noda (Fukuoka University)
Hiroyasu Ogino (Osaka Prefecture University)
Mitsuhiro Ohta (The University of Tokushima)
Eika (W. Qian Tokyo University of Agriculture and Technology)
Yuji Sakai (Kogakuin University)
Noriaki Sano (Kyoto University)
Naomi Shibasaki-Kitakawa (Tohoku University)
Ken-Ichiro Sotowa (The University of Tokushima)
Hiroshi Suzuki (Kobe University)
Nobuhide Takahashi (Shinshu University)
Shigeki Takishima (Hiroshima University)
Yoshifumi Tsuge (Kyushu University)
Tomoya Tsuji (Nihon University)
Da-Ming Wang (National Taiwan University)
Takuji Yamamoto (University of Hyogo)
Yoshiyuki Yamashita (Tokyo University of Agriculture and Technology)
Miki Yoshimune (National Institute of Advanced Industrial Science and Technology (AIST))

Editorial office:
The Society of Chemical Engineers, Japan
Kyoritsu Building, 4-6-19, Kohinata, Bunkyo-ku
Tokyo 112-0006, Japan
journal@scej.org

AIMS AND SCOPE:

Journal of Chemical Engineering of Japan, an official publication of the Society of Chemical Engineers, Japan, is dedicated to providing timely original research results in the broad field of chemical engineering ranging from fundamental principles to practical applications. Subject areas of this journal are listed below. Research works presented in the journal are considered to have significant and lasting value in chemical engineering.

Physical Properties and Physical Chemistry
Transport Phenomena and Fluid Engineering
Particle Engineering
Separation Engineering
Thermal Engineering
Chemical Reaction Engineering
Process Systems Engineering and Safety
Biochemical Food and Medical Engineering
Micro and Nano Systems
Materials Engineering and Interfacial Phenomena
Energy
Environment
Engineering Education

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The parallel competing iodide–iodate reaction scheme was used to investigate micromixing efficiencies in an aerated stirred tank with diameter T=0.3 m. Half-elliptical blade-disc turbines (HEDT) with diameters (D) 76, 100, and 150 mm, corresponding to D/T of 0.25, 0.33, and 0.50, respectively, were used. The appropriate injection time and feed-pipe diameter were first determined to eliminate the effects of macromixing and backmixing on micromixing performance. The influences of impeller diameters D, power inputs P_m, superficial gas velocities V_s, and feed positions on the micromixing efficiency in the impeller discharging area were investigated. The results showed that HEDT with D/T 0.25 could be excluded from industrial applications because of the extremely high agitation speed N_cd for complete gas dispersion and poor micromixing performance in the presence of the gas. Given the same P_m, HEDT with smaller D/T showed better micromixing performance than that with bigger D/T, because the former leads to a higher pressure head H. As for the feed positions in the discharging area, the closer the feed position to the impeller, the better the micromixing performance. Generally, the introduced gas did not have a significant influence on micromixing in the discharging area of HEDT, except for a negative effect of aeration on micromixing when the tank was fed at the furthest feed position (0.3D away from the impeller tip along the radial direction).

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We use a front-tracking method to simulate solidification with volume change of a droplet on a fixed cooling plate. The problem includes temporal evolution of three interfaces, i.e., solid–liquid, solid–air, and liquid–air, that are explicitly tracked under the assumption of axisymmetry. The solid–liquid interface is propagated with a normal velocity that is calculated from the normal temperature gradient across the front and the latent heat. The liquid–air front is advected by the velocity interpolated from nearest bulk fluid flow velocities. Accordingly, the evolution of the solid–air front is simply the temporal imprint of the triple point at which simple and straightforward conditions are imposed. The governing Navier–Stokes equations are solved for the whole domain, setting the velocities in the solid phase to zero and with the non-slip condition on the solid–liquid interface. Computational results are compared with exact solutions for two-dimensional Stefan problems and with corresponding experimental results, and show good agreement.

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Process feasibility experiments were carried out to form 1,3-propanediol precursor, acrolein, at 400°C and 35 MPa using supercritical water with sulfuric acid and a large concentration of glycerol. In the experiments, optimization methods for reaction time and sulfuric acid concentration deduced from a reaction model were examined as functions of initial glycerol concentration. The optimum reaction time at which the yield peaked was inversely proportional to the initial glycerol concentration. Optimum sulfuric acid concentration was estimated by maintaining a constant ratio of the squared proton concentration to the initial glycerol concentration when the acid concentration was optimized at a certain initial glycerol concentration. A yield larger than 70% was obtained at 15 wt% of the initial glycerol concentration by using the conditions predicted by the optimization methods.

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Co-doped (Fe³⁺–N,S) TiO₂/SiO₂-multiwalled carbon nanotubes (MWCNTs) photocatalyst thin films have been prepared via the peroxo titanic acid (PTA) solution as the TiO₂ source via sol–gel method. The samples were analyzed by Fourier-transform infrared spectroscopy and UV-Vis spectroscopy. The photocurrents of prepared photocatalysts were measured using an automated potentiostat. The photoactivities of photocatalyst thin films with various MWCNT content were tested in the degradation of methylene blue (MB) under UV and visible light irradiation. The optimal concentration of MWCNTs was 0.05 wt%. The results showed that the co-doped samples with MWCNTs exhibited higher photocatalytic activity than no-doped TiO₂/SiO₂. The outstanding photocatalytic activity could be attributed to the synergistic effect of co-dopants and MWCNTs which may act as a narrowing energy band gap state in the TiO₂ lattice and reducing the recombination rate of electron/hole, resulting in enhancing the photocatalytic activity of co-doped TiO₂/SiO₂–MWCNTs.

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An experimental and theoretical study on nitric oxide (NO) was carried out in a dielectric barrier discharge (DBD) reactor with various electrode configurations. Two different configurations, a dentate electrode and columnar electrode, were employed as a ground electrode. The electric field near the inner electrode was stronger with the dentate electrode, enhancing the disassociation and excitation rate of N₂. When the energy density was 375 J/L, the NO removal in the dentate electrode reactor was 2.6 times higher than that in the columnar electrode reactor. The maximum energy efficiency for NO removal was 6.9×10⁻⁶ g/J in the dentate electrode reactor, as the NO removal efficiency was 31%, which was higher than 6.1×10⁻⁶ g/J for the columnar electrode reactor. The equivalent capacitance and field distribution also changed under various electrode configurations, and the discharge power was higher in the dentate electrode reactor under the same applied voltage.

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We have fabricated the catalytic tubular reactor whose inner wall is coated with thin palladium oxide (PdO) layer (ca. 3 µm). Continuous decomposition of aqueous formic acid (HCO₂H) was examined by the flow reaction system installed with the catalytic tubular reactor. Reactor with PdO inner surface showed superior catalytic performance than that obtained by the reactor having metallic Pd surface. Higher temperature and longer residence time increased the reaction conversion but the effect of pressure was small. Steady generation of hydrogen (H₂) was achieved keeping >99% conversion of formic acid at 300°C (10 MPa) within 4.3 s residence time. H₂ and carbon dioxide (CO₂) were major products with ca. 1 : 1 molar ratio and the generation of carbon monoxide (CO) was minor. Generation of CO was considerably suppressed by increase of sodium formate ratio i.e., formate/(formate+formic acid) ratio. Long term test revealed that steady productivity of H₂ was maintained more than 600 h reaction. The XPS spectrum of catalytic surface after long time use evidenced the presence of PdO in large excess along with small amount of metallic Pd indicating that reduction of PdO surface proceeded quite slowly.

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A new optimization framework for the design of natural gas liquid (NGL) recovery processes was developed to effectively investigate design complexities associated with complex column arrangements and heat and power recoveries. Design interactions were evaluated in a holistic manner, and optimal operating conditions were determined for the recovery process, leading to efficient energy use and recovery. Rigorous modeling of the NGL recovery process was performed using a process simulator combined with an optimization solver to obtain optimal solutions. The candidates for the optimal conditions of the decision variables were generated by the solver, and were updated until optimal solutions were obtained, while an objective function was evaluated with the aid of the process simulator. Process integration methodology was applied to assess the true potential of heat recovery and improve energy recovery for the entire process within the proposed optimization procedure. A case study was presented that demonstrated how heat and power recovery issues could be collectively and systematically considered with the design of separation and recovery arrangements, which clearly showed the usefulness and applicability of the design and optimization method developed in this work.

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We have evaluated the mixing performance of a microreactor with inline ultraviolet (UV) and Fourier transform-infrared (FT-IR) measurement. We performed the well-known Villermaux–Dushman reaction with inline and offline UV measurements. Absorbance was continuously reproduced at each flow rate with inline measurement. The difference between the inline and offline measurement results was within ±5% at faster flow rates than 2 mL/min. However, the difference between the inline and offline measurement results at 1 mL/min occurred because the sample changed until the start of offline measurement. It is shown that “real-time” monitoring and more accurate analyses were performed with this inline measurement system. We have also performed the methanol–ethanol mixing process with inline FT-IR measurement. The absolute slope of absorbance peak height with changing from methanol to a mixing solution became larger as the flow rate increased, while it hardly changed at faster flow rates than 10 mL/min (1.0×10⁻⁵ m³/min).This suggests that the mixing performance improved as the flow rate increased, while the mixing performance was saturated at faster flow rates. The tendency in the mixing performance was in good agreement with that obtained from the Villermaux–Dushman reaction. Therefore, it has been confirmed that the mixing performance of microreactors could be appropriately evaluated with inline UV or FT-IR measurement.

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We have successfully prepared monodisperse poly[methacryloxypropyl Tris(trimethylsiloxy)silane] (poly-TRIS) microspheres by employing the Shirasu porous glass (SPG) membrane emulsification technique. The preparation was carried out by preparing TRIS monomer-contained oil-in-water (O/W) emulsions first and exposing to UV-irradiation subsequently to polymerize the emulsions, and poly-TRIS microspheres were formed eventually. The optimized surfactant used in this study was sodium dodecyl sulfate (SDS), an anionic surfactant which facilitates the formation of uniform monodisperse TRIS emulsions. The diameter and size distribution of the TRIS emulsions and poly-TRIS microspheres could be strictly controlled due to the narrow pores size distribution feature of SPG membrane. By varying the SPG membrane pore sizes from 0.5 to 5 µm, the average diameter of the resulting poly-TRIS microspheres ranged from 1.42 to 12.31 µm with coefficient of variation (CV) less than 12%.

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The purity of crystal beds was investigated in the suspension melt crystallization of an organic acid. Methacrylic acid was used as the target material, and a certain amount of methanol was used as the solvent. Phenol was added as the representative of impurities. Under the various initial methanol ratios that mean mole fraction ratios of methanol to methacrylic acid, the effect of a small amount of the maleic acid byproduct formed during the methacrylic acid synthesis was focused on in batch crystallizations. In the presence of maleic acid, the impurity phenol concentrations of obtained crystal beds were higher than in the absence of maleic acid, and the difference became large with decrease of initial methanol ratio. Similarly, in the presence of maleic acid, the adherence ratios of mother liquor on the crystal beds were higher. However, although the adherence ratios descended with decrease of initial methanol ratio at first, since then they demonstrated an increasing trend. In the high range of initial methanol ratio, it was presumed that the reduction of the adherence ratios was attributed to decrease of specific surface area of crystal beds. Meanwhile, it was presumed that the degradation of adherence ratios in the low range of initial methanol ratio was derived from the influence of crystal bed height. Therefore, the relationship between impurity concentration and slurry density that was associated with crystal bed height was examined. As the result, although impurity concentrations were almost constant in the low slurry density range, they demonstrated increasing trends with ascent of the slurry density at high slurry density range. Moreover, in the presence of maleic acid, the impurity concentration demonstrated higher tendency when they were compared under the similar slurry density condition. These results indicates that the impurity phenol concentrations of obtained crystal beds immediately after the solid–liquid separation from slurry was affected by the crystal bed height especially in the higher slurry density range, further, the dependency of those was higher in the presence of maleic acid.

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In cooling melt suspension crystallization, scale formation becomes a problem which seriously reduces the heat transfer coefficient of cooling surfaces, and the scale formation results in low productivity and low energy effectiveness. Scale formation still remains an issue to be discussed in cooling melt suspension crystallization, although some previous studies have been reported. The mechanisms of scale formation have been investigated based on surface interaction between crystal and cooling surface. However, studies on the operation method to prevent the scale formation have been insufficient. In the present study, the effect of the morphology of suspended crystals on scale formation dynamics (especially the transition speed of scale formation process) during start-up operation is investigated experimentally in melt crystallization for organic compounds. Scale formation dynamics are investigated using two kinds of seed crystals of different morphologies. As a result, the scale formation dynamics at the initial stage changed with morphology of seed crystals. Therefore, it is clear that crystal morphology is an important factor to consider scale formation dynamics. Moreover, this result suggests that modification of morphology in suspended crystals can be applied to prevent scale formation.

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Ionic liquid-in-oil (IL/o) microemulsion (ME) techniques have been employed to increase the solubility of sparingly soluble drugs and enhance the extent of their topical and transdermal delivery. Methotrexate (MTX) has been used as a model drug in the current study. The size and size distributions of the ME droplets in the presence and in the absence of MTX were determined by dynamic light scattering analysis. The mean droplet diameter of the ME droplets containing 4 mg/mL of MTX was less than 20 nm, and smaller than the corresponding value observed in the absence of MTX. MTX was incorporated into IL droplets as well as other formulations and its permeation across Yucatan micropig (YMP) porcine skin evaluated. The use of IL/o ME has been shown to dramatically increase MTX administration. The results obtained in this study reveal the versatility of IL/o MEs as efficient drug delivery systems for sparingly soluble drugs.

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