Associate Editor-in-Chiefs Masahiro Shishido (Yamagata University) Ken-Ichiro Sotowa (The University of Tokushima)
Editors Choji Fukuhara (Shizuoka University) Toshitaka Funazukuri (Chuo University) Yoshihiro Hashimoto (Nagoya Institute of Technology) Shunji Homma (Saitama University) Jun-ichi Horiuchi (Kyoto Institute of Technology) Yoshinori Itaya (Gifu University) Masashi Iwata (Osaka Prefecture University) Noriho Kamiya (Kyushu University) In-Beum Lee (Pohang University of Science and Technology (POSTEC)) Kouji Maeda (University of Hyogo) Hideyuki Matsumoto (National Institute of Advanced Industrial Science and Technology (AIST)) Michiaki Matsumoto (Doshisha University) Nobuyoshi Nakagawa (Gunma University) Tsuguhiko Nakagawa (Okayama Prefectural University) Yasuya Nakayama (Kyushu University) Masaru Noda (Fukuoka University) Mikihiro Nomura (Shibaura Institute of Technology) Eika W. Qian (Tokyo University of Agriculture and Technology) Yuji Sakai (Kogakuin University) Noriaki Sano (Kyoto University) Naomi Shibasaki-Kitakawa (Tohoku University) Hiroshi Suzuki (Kobe University) Nobuhide Takahashi (Shinshu University) Kazuhiro Takeda (Shizuoka University) Shigeki Takishima (Hiroshima University) Yoshifumi Tsuge (Kyushu University) Tomoya Tsuji (Nihon University) Shigeyuki Uemiya (Gifu University) Da-Ming Wang (National Taiwan University) Takayuki Watanabe (Kyushu University) Takuji Yamamoto (University of Hyogo) Tetsuya Yamamoto (Nagoya University) Masahiro Yoshida (Kagoshima University) Yasuo Yoshimi (Shibaura Institute of 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 email@example.com
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
A computational fluid dynamic (CFD) model and a deposition model are coupled to predict the molten slag deposition behavior in radiant syngas cooler (RSC) for entrained flow coal gasification. The slag particle deposition model is developed by identifying the excess rebound energy as a criterion to determine if the particle is deposited or rebounded from the wall while slag solidification in the impact process is also considered. The simulation results show that molten slag particles stick on the membrane wall between the height of 12.2–22.0 m for Reference Case with the maximum deposition rate 1.5×10−5 kg/(m2·s) at the position of height about 16.8 m. The deposition rate increases with increasing inlet temperature and operating load. Small inlet diameter leads to high deposition rate due to high transport rate and high deposit propensity, while small inner cylinder diameter leads to higher deposition rate due to higher deposit propensity.
The Petlyuk process is known as a prospective energy-saving distillation process, which consists of a prefractionator and a main column with a side stream, connected by two vapor/liquid streams. Some of the modified structures by adding a reboiler or a condenser to the prefractionator have been proved to provide good operability and controllability. In this paper, we propose necessary conditions for flow rates of the interconnecting vapor and liquid streams which give better separation performance for a modified Petlyuk process equipped with a reboiler at the bottom of the prefractionator. The separation characteristics compared with a conventional two-column process and the original Petlyuk process are also presented by numerical examples. The simulation results demonstrate that the proposed necessary conditions give useful information to reduce the amount of optimization calculation and that the energy saving performance of the modified Petlyuk process is close to that of the Petlyuk process when the feed composition of the middle component becomes larger.
The azeotropic point of the binary system of acetone–methanol varies sensitively depending on the pressure change. This principle can be applied in order to obtain substantially pure acetone and methanol by using two distillation columns operated in sequence at two different pressures. The process of separation through this mechanism is known as pressure-swing distillation (PSD). This study mainly focused on the modeling and optimization of the PSD process as an effective method of separating an azeotropic mixture of acetone–methanol. The proper thermodynamic model to be used in the simulation was selected based on the prediction of the liquid activity model which gives the best fit for the experimental vapor–liquid equilibrium data of the involved binary system. For the simulation works, PRO/II with PROVISION v9.2 was utilized to create a model of PSD using two column configurations, a low–high pressure (LP+HP) column configuration and a high–low pressure (HP+LP) column configuration. The optimum theoretical number of stages, reflux ratios and feed stage locations were determined for the low-pressure (LP) column and high-pressure (HP) column to minimize the heat duty. Since PSD operates at different pressures, the hot and cold utility consumption is quite large. Therefore, heat integration was applied to the system to eliminate the high– and low– temperature utility consumption of the reboiler and condenser.
The counter-diffusion method is an attractive approach for the preparation of zeolitic imidazolate framework-8 (ZIF-8) membranes for propylene/propane separation. In the present study, the effects of the preparation-solution concentration on the structure and the single-component and binary gas permeation properties of ZIF-8 membranes prepared on a porous α-alumina hollow capillary substrate were evaluated in order to explore the mechanism of membrane formation. ZIF-8 membranes were prepared using various concentrations of methanolic 2-methylimidazole and zinc nitrate solutions with a fixed molar ratio of 2-methylimidazole to zinc nitrate of 4. Increasing the solution concentration led to increased coverage of the ZIF-8 layer within the substrate, and ZIF-8 layers were eventually generated even on the inner surface of the substrate. A higher solution concentration facilitated inter-diffusion of the solutes in the counter-diffusion method. Binary permeation measurements using an equimolar mixture of propylene and propane subjected to a total pressure difference of 0.1 MPa at 298 K gave rise to a propylene permeance of 7.0×10−9 mol·m−2·s−1·Pa−1 with a maximum achieved propylene/propane selectivity of 42.
The present study investigates the extraction of lithium ion from the high concentration ratio of magnesium and lithium salt lake brine in a series of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs), in which the alkyl chain lengths were n-butyl (C4), n-pentyl (C5), n-hexyl (C6), n-heptyl (C7), n-octyl (C8) or n-nonyl (C9), in the presence of triisobutyl phosphate (TIBP)+kerosene systems. The results showed that with shorter alkyl chain length of imidazolium-based ILs there was higher extraction efficiency of lithium ion. The optimal novel FeCl3-free extraction system of [C4mim][PF6]+TIBP+kerosene was established, and the single-pass extraction and back extraction efficiencies for lithium ion were 74.14% and 86.37% under the optimal conditions of [C4mim][PF6] : TIBP : kerosene=1 : 8 : 1 (v/v), pH=5.0, R(O/A)=2.0 in the extraction step, as well as 1 mol/L HCl eluent, R(O/A)=3 in the back extraction step. A comparison of extraction behaviors in a multilevel cross-flow and multistage counter-current extraction process for lithium ion was also carried out. On the basis of infrared spectroscopy and slope analysis methods, a cation-exchange extraction mechanism in the system of [C4mim][PF6]+TIBP+kerosene for lithium ion extraction was demonstrated.
Processes for potassium extraction from abundant K-feldspar have recently attracted interest to ensure potash self-sufficiency for developing countries. Concurrently, distiller waste and soda residue formed in the ammonia–soda process (Solvay method) have resulted in serious pollution. A method of potassium extraction from K-feldspar with distiller waste and soda residue as additives is proposed. The effects of roasting temperature, particle size of K-feldspar and the amount of additive on potassium extraction for the K-feldspar–CaCl2–CaCO3 system were studied. The reaction kinetics of the system with mass ratios of K-feldspar (106–160 µm) : CaCl2 : CaCO3=1 : 2 : 2 at 750–850°C were modeled by the diffusion-based Ginstling–Brounshtein equation. The apparent activation energy was approximately 111 kJ·mol−1. On the basis of the XRD and SEM–EDS analysis, two different reaction mechanisms were proposed below and above the melting point of CaCl2 (772°C). A pilot test was carried out at a roasting temperature of 850°C and the recovery of potassium was approximately 82%. The encouraging results obtained in the laboratory were replicated at the pilot scale.
Three kinds of ZSM-5 (MFI structure) zeolites [SiO2/Al2O3=23.8 (Na form), 39.0 (NH4 form) and 193(NH4 form)] were alkali-treated, and the changes in structural and water adsorptive properties were investigated. With the alkali treatment, the MFI structure was preserved; a siliceous species was selectively dissolved from the framework of a zeolite, and mesopores were created in the zeolites. At the same time, NH4-form ZSM-5 zeolites (SiO2/Al2O3=39.0 and 193) were ion-exchanged to form Na in an aqueous solution of NaOH. In particular, for ZSM-5 (SiO2/Al2O3=23.8), the water adsorption changed with the alkali treatment. The difference in the amount of adsorbed water on the zeolite between 30°C (adsorption temperature) and 100°C (desorption temperature) increased by the treatment. The desorption temperature of water adsorbed at the stronger site decreased from 106 to 72°C with the alkali treatment. These results indicate that the introduction of mesopores in ZSM-5 contributed to the enhanced water adsorption.
Lipid extraction from microalgae using a chloroform-methanol mixture was performed to obtain optimum conditions for the isolation of total lipids. The effects of extraction parameters including proportions of methanol to chloroform and the ratios of total solvent volume to dry biomass on extraction yields were evaluated. In addition, the effect of water on extraction performance was investigated for the purpose of applications to extract lipids from wet microalgae. The optimum conditions maximizing lipid yields were as follows: the proportion of methanol to chloroform of 1 : 1 and the ratio of total solvent volume to dry biomass of 30 mL/g. Water positively affected lipid extraction efficiency when chloroform, methanol, and water formed a monophasic solution. Finally, the newly-developed method was compared with existing extraction methods.
The process intensification of photocatalytic p-anisaldehyde (p-MB) synthesis was examined by relying on a mini glass reactor and UV-LED lamp. TiO2 photocatalyst was highly loaded in ethyl acetate solvent and dispersed by a magnetic stirrer and oxygen bubbling in a glass cell reactor. The reactor was irradiated by the UV-LED lamp in the UV intensity range less than 224 mW/cm2 at the reactor surface. The generation rate of p-MB (GR) from p-methoxytoluene (p-MT) was evaluated by GCMS. The GRs per lamp power attained in this study were found to be much higher than those in the previous studies on the photocatalytic p-MB synthesis from p-MT or even from p-methoxy alcohol. The attained high reaction efficiency can be attributed to the high efficiency of the UV-LED and small size of the reactor that enabled better penetration of UV light through the entire volume of the reactor in spite of high catalyst loading.
MCM-41 (#41 Mobil Composition of Matter) is a favorable material for heterogeneous reactions because of its unique porous structure. However, the catalytic activity of MCM-41 for the oxidative dehydrogenation (ODH) of isobutane to isobutene is known to be quite low. In the present study, a metal-doping method was employed to improve this catalytic activity. Doping of Cr, Co, Ni, or Mo into MCM-41 resulted in a great improvement in the catalytic activity. Since chromium-doped MCM-41 (Cr-MCM-41) showed the greatest catalytic activity among these catalysts, its redox property was further analyzed via XPS, XAFS and H2-TPR techniques. The XPS spectrum of Cr-MCM-41 suggested that it has Cr3+ and Cr6+ species on its surface. Also, a pre-edge peak due to Cr6+ species was confirmed in the XANES spectrum of Cr-MCM-41. In H2-TPR measurement, Cr-MCM-41 was more reducible than crystalline Cr2O3, which showed low catalytic activity for the ODH of isobutane. The reducible Cr6+ species on Cr-MCM-41 contributed to an improvement in the catalytic activity of MCM-41.
Electrochemical synthesis of hydroxyapatite particles was performed galvanostatically from a homogeneous solution of Na2H2EDTA·2H2O, KH2PO4 and CaCl2. The electrogeneration of OH− ions by water reduction at the cathode plays an important role in the formation of hydroxyapatite by an electrochemical method. The OH− ions induce the liberation of Ca2+ ions and the dissociation of phosphoric acid, which serve as the reactants for the formation of hydroxyapatite. We found that the final product obtained, i.e. brushite or hydroxyapatite (HA), corresponds to the pH of the solution. Brushite is formed when the pH is <7, and HA is formed when the pH >7. Aging the suspension for 72 h at 40°C transforms brushite to HA even at pH <7. The presence of Ca2+ during aging accelerates brushite conversion. EDTA serves as a chemical agent to mediate particle nucleation and growth. The reaction mechanism and its kinetic model proposed for the HA formation could predict the experimental results well.
Mesoporous silicas have shown promise as materials for solid catalysts or catalyst supports due to their unique characteristics. Metal-doped mesoporous silicas are known to be catalytically active in the oxidative dehydrogenation (ODH) of isobutane. However, heavy-metal-free mesoporous silicas have not been studied closely for their use as catalysts. In the present study, MCM-41 (#41 Mobil composition of matter) was acid-treated to enhance its catalytic activity, although pure MCM-41 was confirmed as catalytically inactive for the ODH of isobutane (isobutene yield=0.9%). The pH of a slurry of as-synthesized MCM-41 was changed during acid treatment. A pH adjustment to 6.5 resulted in great improvement in catalytic activity (isobutene yield=6.1%), but a pH adjustment to 4.5 resulted in insufficient improvement (isobutene yield=4.5%). It was confirmed via XRD and N2 adsorption-desorption measurement that the pH adjustment to 4.5 degraded the ordered structure of MCM-41. This degradation would be a crucial factor that would render acid treatment less effective. In addition to the acid treatment, Al doping to MCM-41 was conducted. Al doping also greatly enhanced the acidity and catalytic activity of MCM-41.
Mesoporous Ni–CeO2 catalyst was prepared by a polymer (P123)-assisted co-precipitation method and used for reverse water–gas shift reaction. Compared with the catalysts prepared by traditional co-precipitation methods, the mesoporous Ni–CeO2 catalyst shows higher stability for the reverse water–gas shift reaction at 600°C but with no formation of the side product CH4. Moreover the mesoporous Ni–CeO2 catalyst is also highly active for reverse water–gas shift reaction. TPR and XRD results suggest that, in the mesoporous Ni–CeO2 catalyst, Ni2+ ions are incorporated into the CeO2 lattice to form a NixCeyO2 solid solution, which produces a large number of oxygen vacancies and enhances the reducibility of the surface CeO2. The excellent performance of the mesoporous catalyst is related to the lack of exposed NiO particle on the surface, and the large amount of oxygen vacancies in the uniform mesoporous structure.
In view of the deficiencies in recent internal model control (IMC)-based scheme for set-point tracking and the load disturbance rejection for integrating and double integrating processes with time delay, a novel scheme based on IMC structure is proposed to deal with the step load disturbance for integrating and double integrating time-delay processes control. A two-degree-of-freedom (TDF) control scheme is introduced to separate the optimization of the load disturbance rejection from set-point tracking. The set-point tracking controller and load disturbance rejection controller are designed based on the process model without time delay. There is only a single adjustable parameter in each of the proposed controllers to make a satisfied trade-off between system response performance and closed loop system robust stability in essence. Straightforward parameter tuning guidelines are provided for the control performance. At the same time, the robust tuning constraints are provided to accommodate process uncertainties in practice. In the end, illustrative examples from the recent literatures are considered to show the effectiveness and flexibility of the proposed method for different types of integrating process control.
Empirical models tend to suffer from unreliable extrapolation behavior, and this presents an issue when they are applied in model-based controller strategies such as nonlinear model predictive control (NMPC). This paper presents the development and implementation of the parallel OBF-NN model in the NMPC framework. The aim is to evaluate the applicability and the potential extrapolation benefits of the model in a closed-loop environment. For this purpose, closed-loop performance comparison is analyzed between the parallel OBF-NN and the conventional neural networks (NN) models. Results on two nonlinear case studies show that the NMPC based on the parallel OBF-NN model notably improved the closed-loop performance in the extrapolated regions of operation when compared to NMPC based on the conventional NN model without the need for re-training or any adaptive scheme.
Gold nanoparticles were precipitated on the surface of silica gel without mechanical mixing. Polyethylenimine (PEI) which was coated on the surface of silica gel reduced raw materials of hydrogen tetrachloroaurate (III) tetrahydrate (HAuCl4·4H2O). Formation of gold nanoparticles on silica gel was confirmed by using Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray Fluorescence Spectrometer (EDX). In this study, particles size distribution and coverage ratio of gold on silica gel were investigated.
ZnO particles were synthesized by a parallel flow precipitation hydrothermal process with Zn(NO3)2·6H2O and NH3·H2O as raw materials. The morphology and structure of as-synthesized ZnO particles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The results revealed that all of the obtained ZnO samples had a hexagonal wurtzite structure, with the precipitation reaction pH being a key factor in the formation of the hexagonal prism structure. The photocatalytic activity of ZnO was evaluated via Rhodamine B (RhB) dye degradation. The ZnO-3 sample synthesized at a precipitation pH=6.8 possessed excellent photocatalytic degradation efficiency after three photocatalytic experiments. No significant change of photocatalytic activity could be detected when NO3− was added, however, the presence of SO42− and Cl− reduced the photocatalytic activity, with SO42− most severely reducing activity.
Morphological control can be used to improve the catalytic activity of cerium oxide (ceria, CeO2). In this study, ceria with a high specific surface area was synthesized via the hydrothermal reaction of ceric nitrate and was tested for the catalytic conversion of ethanol to ethylene. As a reference, ceria was also synthesized via a precipitation reaction of cerous nitrate using aqueous ammonia. The Japan reference catalyst JRC-CEO-1 also served as a reference. The specific surface area of the hydrothermally synthesized ceria was as high as that of JRC-CEO-1, but was much higher than that of either reference after calcination at 873 K. Thermogravimetric analysis and IR spectroscopy revealed that the cerias made by hydrothermal and precipitation reactions consisted of high-purity CeO2, whereas JRC-CEO-1 contained 1.5% decomposable functional groups (OH−, CO32−). For both ethanol conversion and ethylene selectivity in a catalytic dehydration reaction of ethanol, the activity of the hydrothermally developed ceria was higher than that for either reference. The reaction pathway for the dehydration reaction of ethanol over ceria showed that the specific surface area and the basicity of the Lewis basic sites of the ceria were influential properties. The high catalytic activity of the hydrothermally synthesized ceria was derived from its high specific surface area and high-purity CeO2.
As one of the principal anticipated goals in 2015, government and scientists have been paying increasing attention to energy saving. Energy-saving potentials play an important role in economical and sustainable development in the gold industry. Through analyzing the factors that significantly influence energy consumption in the grinding and flotation processes in a gold treatment plant, three models for energy consumption prediction are established based on large amounts of actual production data. The multiple linear regression model demonstrates low prediction accuracy. In consideration of the advantages of artificial neural networks (ANNs), a back-propagation (BP) neural network model is built to provide higher prediction accuracy. Moreover, a hybrid GA-BP neural network model is established combining the typical characteristics of a genetic algorithm (GA) and a BP neural network. Subsequently, validation and comparison of the relative prediction errors, as well as the RMSE of the three models illustrate that the hybrid GA-BP neural network model presents the highest prediction accuracy. The total shift percentage of the hybrid GA-BP neural network model is 98% and 80%, when the relative prediction errors of the model are within ±5% and ±3%, respectively, and its prediction results show a minimum RMSE of 1.29. In contrast, of the three models, the hybrid GA-BP neural network model can provide the highest prediction accuracy of energy consumption, and consequently, can offer a positive reference for real production.
Combustion optimization is an effective and economical approach for reducing nitrogen oxide (NOX) emissions from coal-fired utility boilers. To implement an online reduction in NOX, a precise and rapid NOX emissions model is required. This study establishes an efficient NOX emission model based on the principle component analysis (PCA) and support vector regression (SVR). Modeling performance comparisons were also conducted using a traditional artificial neural network (ANN) and SVR. A considerable amount of worthwhile real data was acquired from a 1000-MW coal-fired power plant to train and validate the PCA-SVR model, as well as the traditional ANN and SVR models. The predictive accuracy of the PCA-SVR model is considerably greater than that of the ANN and SVR models. The time consumed in the establishment of the PCA-SVR model is also shorter compared with that of the other two models. The proposed PCA-SVR model may be a better choice for the online or real-time modeling of NOX emissions in achieving a reduction of NOX emissions from coal-fired power plants.
With the goal of utilizing Jatropha crude oil (JCO) as a fuel in diesel engines, we have developed a technique for the selective extraction of triglycerides from Jatropha seeds, containing glycerides, free fatty acids, phosphorus, and water, using supercritical CO2 extraction. To evaluate the feasibility of using the extracted JCO as a substitute for diesel fuel in diesel engines, the performance and emission characteristics of a diesel engine fueled by JCO/diesel blends were investigated. We found that it was not possible to completely remove the free fatty acid and moisture content from the JCO using the supercritical extraction method. In addition, no remarkable differences in thermal efficiency and specific fuel consumption were observed between JCO and diesel fuel. On the other hand, the amount of CO emissions from JCO was lower than that from the diesel fuel, owing to the complete combustion of CO at high engine loads. Based on the results of the previous study, JCO appears to be a viable substitute for diesel in diesel engines, although the long-term performance of the engine fueled by JCO needs to be further evaluated.
To recover phosphorus from composted chicken manure, a batch method with aqueous HNO3, HCl and H2SO4 was used to examine the elution behavior of the aqueous calcium and phosphate contained in the manure. Since the main components in manure are Ca2+ and K+ along with PO43− and those ions can be dissolved using an acidic eluate, it was expected that most of the aqueous Ca2+, K+ and PO43− could be obtained via the elution. Therefore, it seemed plausible that the removal of the aqueous K+ obtained by the elution of composted chicken manure would result in the formation of calcium phosphates. If calcium phosphates are formed, they can be used for phosphate rock, which also consists of various calcium phosphates. When using 0.1 mol/L HNO3, HCl or H2SO4, the elution behavior of the PO43− was not dependent on the acids. However, 0.1 mol/L H2SO4 was not sufficient for the elution of Ca2+, probably due to the precipitation of the calcium sulfate. The eluted amount of K+ using 0.1 mol/L HNO3 was lower than that using 0.1 mol/L of either HCl or H2SO4. Since the poor elution of K+ should enrich the concentrations of Ca2+ and PO43− in the acidic aqueous solution after the elution, it was suggested that aqueous HNO3 would be suitable as an eluate in the present system. After the elution of the composted chicken manure, when 0.1 mol/L HNO3 was used to adjust the solution pH of the acidic aqueous solution to greater than 6, Ca2+ and PO43− were precipitated, but K+ was not. The precipitate was calcium hydroxyapatite, one of the typical components of phosphate rock, which showed that composted chicken manure could be replaced phosphate rock as a new source of phosphorus.
Measuring the size distribution of fine particles (<5 µm) in a few hours is difficult when using the sedimentation method due to a decrease in sedimentation rate. Herein, we discussed the validity of using a combination of the buoyancy weighing–bar method and the Rosin–Rammler equation to estimate the particle size distribution. When the cumulative mass oversize exceeds about 0.15, the Rosin–Rammler equation can be used to estimate the particle size distributions of suspended solids.