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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It has been widely recognized that microchannels can be used to enhance mass transfer rate between two immiscible fluids. This feature has attracted interests of many researchers in the field of chemical engineering. To exploit such feature of microchannels, the flow characteristics and mass transfer behavior must be fully understood. In addition, to construct an industrial scale process consisting of microchannels, an efficient numbering-up technique is required. In this review, an overview of the recent literature on the fluid flow and mass transfer behavior in multiphase flow in microchannels will be given. An attention is also paid to the numbering-up technique and extension to multiphase system involving three fluids.

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The reaction mechanism of the breakpoint chlorination process has been investigated by the computational chemistry based on density functional theory (DFT) calculations. Although ammonia had been known to be converted to chloroamines (finally to NCl₃ via NH₂Cl and NHCl₂) by successive chlorination in the presence of HOCl, our previous experimental study observed only NHCl₂ species with no trace of NH₂Cl and NCl₃ before the breakpoint. While the calculated energetics support the formation of NHCl₂ from ammonia via NH₂Cl by successive chlorination as mentioned, a more favorable decomposition pathway of NHCl₂ to N₂ and HCl has been identified rather than the further chlorination of NHCl₂ to NCl₃. The computational approach employed in this study has shown its general usefulness in explaining experimental results by tracking down the most probable reaction pathways.

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An interface-capturing method for simulating two-phase flows in complex geometries is proposed. A structured orthogonal grid is used, and the presence of stationary solid boundaries is taken into account by using the volume fraction of the solid phase in a computational cell. The transport equation of the fluid volume fraction in the presence of solid boundaries is derived. The fluid phases are transported by using the THAINC (tangent of hyperbola with adaptive slope for interface capturing) method. An immersed boundary method is implemented to accurately calculate the volume flux of each fluid phase through a computational cell face, a part of which is blocked by the solid phase. Transportation of a fluid square in the presence of solid boundaries is carried out, to confirm that the errors in shape and volume conservation are low. The applicability of the proposed method to two-phase flows in complex geometries is examined through simulations of a flow about cylindrical tubes in a staggered arrangement and a dam break problem with an obstacle. In the former the pressure drop in the single-phase condition agrees well with the available correlation and the gas–liquid behavior in the tube geometry is qualitatively well predicted. The predicted liquid flow in the dam break problem also agrees well with available experimental data.

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In a fluidized bed, particle agglomeration and channeling have been observed when the fluidizing gas is switched from lower to higher density. This defluidization is a transient phenomenon, and fluidization is restored after several minutes. In this paper, we assume this behavior can be explained by non-equimolar diffusion, which causes pressure gradients in the bed and subsequently leads to viscous flow. To verify this assumption, pressure changes were measured for several binary diffusion systems in a packed bed. After the packed bed was filled with a gas, another gas was supplied to the bed’s outer surface to replace the first gas. These gases were exchanged by diffusion, and the pressure at the closed end of the column either increased or decreased due to differences in the gases’ molecular weights. The pressure changes were compared with pressure changes calculated from a model based on both an unsteady-state diffusion equation and the Kozeny-Carman equation. The measured pressure changes in the packed beds could be correlated with the calculated values without any adjustable parameters. In a fluidized bed, after the gas switched from lower to higher density, differences in diffusion rates due to the gases’ various molecular weights caused a net molecular flow from the emulsion phase to the bubble phase. This flow caused a decrease in gas velocity in the emulsion phase and a contraction of the emulsion phase; channeling and defluidization were then observed.

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CaCO₃–Al(OH)₃ mixtures were calcined at 1,273 K by varying the mixing ratio and the removal behavior of PO₄³⁻ from solution was examined. The calcination products of CaCO₃ mixed with a small amount of Al(OH)₃ (Ca/(Ca+Al)=0.85–0.91), whose major crystalline component was lime (CaO), showed higher PO₄³⁻ removal than the calcination products of other CaCO₃–Al(OH)₃ mixtures and of CaCO₃: The maximum amount of PO₄ removal and the lowest concentration of the remaining PO₄³⁻ in solution were 10 mmol·g⁻¹ and 0.002 mmol·dm⁻³, respectively. PO₄³⁻ ions were removed by the precipitation of hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) and the related compound, Ca₈(HPO₄)₆(OH)₄·H₂O.

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This study investigates the liquid–liquid equilibrium measured between coal tar absorption oil and aqueous solution of methanol, ethylene glycol, diethylene glycol, triethylene glycol or 1,3-butandiol, which was expected to increase the distribution coefficients of the nitrogen heterocyclic compounds in the coal tar absorption oil. The distribution coefficients of the nitrogen heterocyclic and homocyclic compounds are found to be larger with the aqueous solution of each selected compound than those with water. The distribution coefficients of the nitrogen heterocyclic compounds are found to be higher than those of the homocyclic compounds. For the emulsion liquid membrane permeation, the aqueous solutions of the organic compounds are used as the membrane solutions. The nitrogen heterocyclic compounds selectively permeated with any membrane solution, and the permeation rates of the components in the absorption oil are found to be enhanced relative to those without additive in the membrane solution. The overall volumetric permeation coefficients increased as the distribution coefficients and the effects of the organic compounds in the membrane solution used in the present study.

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AlCl₃/γ-Al₂O₃ and AlCl₃/silica gel catalysts were respectively prepared by closely pressurized and atmospheric loading methods, and then used as the catalysts for the alkylation reaction between thiophene and 1-hexene in benzene. The influences of the preparation conditions of AlCl₃ supported catalysts on the catalytic activity in the alkylation reaction were investigated. The results show that the catalysts prepared by the closely pressurized loading method present a higher catalytic activity than those by the atmospheric loading method. The ion chromatography, nitrogen adsorption, scanning electron microscope and X-ray diffraction techniques were used to characterize the composition and structure properties of catalysts. Compared with the atmospheric loading method, the closely pressurized loading method could effectively promote the active component amounts and its combined forms on the catalyst surface, and improve the pore structure of the support during the preparing processes. Among all catalysts, Si2H prepared with 2 g of AlCl₃ loaded on 10 g of silica gel by the closely pressurized loading method has the best catalytic activity, which should be attributed to the appropriate loading amount and combined forms of AlCl₃ in this catalyst, as well as the more suitable pore structure. The thiophene conversion rate of the Si2H catalyst can reach up to about 80% in the model coking benzene system and remains stable in five cycle experiments, where the thiophene concentration is 700 mg/L and the molar ratio of 1-hexene to thiophene is 6 : 1.

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In the light of the existing control problems in coke oven gas collector pressure systems, a model predictive control (MPC) method based on subspace identification of the gas collector pressure control system is presented. Through the analysis of a number of measurable variables, the main decision variables which affect gas collector pressure including the controllable input variables and the measurable disturbance can be obtained. The proposed method employs a subspace technique for the identification of the coke oven gas collector pressure control system, and simulates the disturbance of coal charging by a pulse signal with a certain width. A two-layer structure optimal control system of coke oven gas collector pressure is established and thus steady-state optimization and dynamic control can be realized, respectively. With consideration of the influence of measurable disturbance, we calculate the steady-state target through the degrees of freedom of the system, and then constrained MPC dynamic optimization is carried out. The algorithm has been successfully applied in the JN-8-type coke oven gas collector pressure control system of an iron and steel group, and has achieved good results.

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It is known that running biochemical processes under optimal temperature control is more profitable than using isothermal conditions. To quantify this phenomenon, a biotransformation process with native enzyme deactivation independent of the substrate concentration occurring in a perfect batch reactor was analyzed. A general analytical expression was derived that can answer the question of how much enzyme can be saved by applying optimal temperature control instead of the commonly used isothermal conditions. The presence of both lower and upper temperature limitations were taken into account. From these equations, it is possible to obtain an all-dependences expression describing the amount of saved enzyme that may be present in biotransformations with the analyzed enzyme deactivation. The effect of the activation energy quotient on the magnitude of such benefits was also considered. It was proven that, lower catalyst activity, for relatively high values of the activation energy quotient causes significant enzyme savings by two times or even more when applying optimal temperature control rather than the isothermal process. Based on examples of sucrose hydrolysis by invertase and xylan hydrolysis by xylanase, the obtained results were verified.

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We have applied our microreactors providing better mixing performance at lower flow rates to the Sandmeyer reaction of aniline via an unstable diazonium ion. The mixing performance of our microreactor was evaluated using the well-known Villermaux–Dushman reaction. Our microreactor provided better mixing performance than the IMM (Institute für Mikrotechnik Mainz GmbH) single mixer even at low flow rates of less than 8 mL/min (8×10⁻⁶ m³/min). With using our microreactor, the mixing time became shorter and the reaction time for each stage in multistage reactions could be put into a more proper perspective. In the Sandmeyer reaction, the maximum yield of the objective product, chlorobenzene was 80% when the times for the 1st and 2nd steps were 23.6 and 179.9 s, respectively. We also performed reaction rate analyses to understand the reaction mechanism. The calculated results for aniline, chlorobenzene, and the byproduct from chlorobenzene were in good agreement with the experimentally measured ones. It was suggested that reaction rate analyses for experimental data using microreactors are effective for understanding reaction conditions in multistage reactions. The yield in this study was 29% higher than the value reported for the batch method and 9% higher than that for the chip-based method. In this study, with using our two microreactors providing fast mixing in series, an appropriate reaction time and reaction temperature were set for both the 1st and 2nd steps, while there were micro channels for both steps on a plate in the chip-based method.

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Multi-wall carbon nanotube (MWNT), highly textured pyrolytic graphite, necklace-like carbon, and spherical carbon particle were prepared by arc discharge method under atmospheric pressure. These carbon nanomaterials were characterized by field emission scanning electron microscope (FE-SEM), transition electron microscopy (TEM), and Raman spectroscopy. Two-color pyrometry was conducted to measure the temperature of anode surface by high-speed camera. The deposition temperature of MWNT is in the range of 2,400–2,700 K, which indicates that a suitable quenching effect is a necessary condition for the formation of MWNT on the anode surface. The growth mechanism of carbon nanomaterials on the anode surface was estimated, quenching effect playing an important role in the formation of these carbon nanomaterials.

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