JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Print ISSN : 0021-9592
Volume 35 , Issue 12
Showing 1-14 articles out of 14 articles from the selected issue
Thermodynamics, Physical Properties and Molecular Simulation
  • Hiromitsu Takaba, Eriya Matsuda, Balagopal N. Nair, Shin-Ichi Nakao
    Type: Research Papers
    Subject area: Thermodynamics, Physical Properties and Molecular Simulation
    2002 Volume 35 Issue 12 Pages 1312-1321
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    Molecular simulation of permeation by various single gases (H2, He, Ne, Ar, O2, N2, CO2, CH4) through different density amorphous silica membrane models at several temperatures has been carried out using the grand canonical ensemble molecular dynamics technique. The purpose of this study is to investigate the gas permeation mechanism through amorphous silica membranes from a microscopic point of view with regard to the microscopic structure of the membrane. The calculated gas permeability in two membrane models, with density values of 1.25 g/cm3 and 1.50 g/cm3, is found to decrease with increase in molecular weight of the permeating species, except for He permeation in a 1.50 g/cm3 density model that showed higher permeability than that of H2. This means that molecular sieving occurs in this system, which agrees with experimental data in chemical vapor deposition (CVD) silica membranes. Molecular trajectory analysis also supports the presence of molecular sieving that clearly reveals He has many permeation paths in the membrane in addition to the path of H2. The permeability for all gases decreases as the temperature increases, which is inconsistent with the experiments. This inconsistency would be due to the relatively broad pore size distribution of the model used in simulations and we concluded that activated permeation against temperature needs the pore size less than 0.5 nm with sharp distribution.
    Download PDF (3186K)
Transport Phenomena, Fluid Mechanics and Mixing
  • Rachid Chebbi, Sami A. Abd Elrahman, Hassan K. Ahmed
    Type: Short Communications
    Subject area: Transport Phenomena, Fluid Mechanics and Mixing
    2002 Volume 35 Issue 12 Pages 1330-1334
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    The kinetics of unidirectional viscous-gravity spread of oil is addressed for the case where oil is discharged at a constant rate on a calm water surface. A new experimental setup is used along with the order-of-magnitude approach to study the dynamics of spreading. Experimental results are consistent with the order-of-magnitude-analysis based spreading-law expression and, in addition, yield the prefactor needed in this expression. Results also provide the accuracy of the constant-volume-based approximation for the spreading rate.
    Download PDF (72K)
Catalysis, Kinetics and Reactor Design
  • Yasuhisa Hasegawa, Ken-Ichiro Sotowa, Katsuki Kusakabe, Shigeharu Moro ...
    Type: Research Papers
    Subject area: Catalysis, Kinetics and Reactor Design
    2002 Volume 35 Issue 12 Pages 1244-1251
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    When CO is removed from H2 by selective oxidation using a catalytically active membrane, the CO is oxidized during its permeation through the catalytic layer to the permeate side. Since the oxidation rate of CO is proportional to the inverse of its concentration, the rejection of CO using an H2-selective microporous layer which is overlaid on the zeolite layer is also effective. In this study, Y-type zeolite membranes with different thicknesses were prepared on the outer surface of porous α-Al2O3 tubes by hydrothermal synthesis. The membranes were modified to different extents by ion-exchange with Pt ions. Gas permeation properties of the membranes were then determined using single-component H2 and CO, as well as mixtures of H2, CO, O2 and Ar. Thus, the effects of the membrane thickness, the amount of Pt loading and the size of micropores on CO oxidation could be evaluated. For the Pt/NaY membrane prepared by hydrothermal synthesis for 12 h and ion-exchanged using a 2.0-mmol L–1 solution of [Pt(NH3)4]Cl2, the H2 permeance and the H2/CO separation factor were 1.1 × 10–6 mol m–2 Pa–1 s–1 and 1.9 at 473 K. The thickness of the zeolite layer had no detectable effect on CO oxidation. When the membrane was ion-exchanged with a 10.0-mmol L–1 solution of [Pt(NH3)4]Cl2, the CO/H2 mole fraction ratio on the permeate side was minimized to 0.007 at 493 K for a feed of H2:CO:O2:Ar = 4:2:1:93 on a molar basis. The membranes were further modified with SiO2 using dip-coating and chemical vapor deposition techniques. The latter technique led to a membrane, the outer surface of which was coated with an H2-selective microporous SiO2 layer. This resulted in a decrease in CO concentration in the zeolite layer. Thus the CO oxidation proceeded effectively in the catalytically active zeolite layer, and the CO/H2 mole fraction ratio on the permeate side was 0.01 at 523 K for a feed of H2:CO:O2:Ar = 4:2:1:93 on a molar basis.
    Download PDF (2390K)
  • Geun-Hee Lee, Teppei Nunoura, Yukihiko Matsumura, Kazuo Yamamoto
    Type: Research Papers
    Subject area: Catalysis, Kinetics and Reactor Design
    2002 Volume 35 Issue 12 Pages 1252-1256
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    Global power-law rate expressions were determined for the decomposition of 2-chlorophenol (2CP) when NaOH was added to supercritical water (SCW). The experiments were conducted in a plug-flow reactor at temperatures between 673 K and 733 K and pressures from 20 to 30 MPa. Reactor residence time ranged from 0.05 to 0.42 s. The initial 2CP concentrations were between 1.95 × 10–3 and 1.56 × 10–2 mol/L and the initial NaOH concentrations ranged from 1.56 × 10–2 to 7.78 × 10–2 mol/L. The global kinetics for 2CP decomposition was described by a rate law which was obtained by nonlinear regression analysis. The global power-law rate expression is rate = 109.7±1.1exp(–15600 ± 3000/RT)[2CP]1.41±0.12[NaOH]0.30±0.07[H2O]–2.71±0.21, where the activation energy is in calories per mole and all concentrations are in moles per liter. This global kinetics is very fast when it is compared to that of 2CP oxidation in SCW.
    Download PDF (150K)
  • Choji Fukuhara, Akira Igarashi
    Type: Research Papers
    Subject area: Catalysis, Kinetics and Reactor Design
    2002 Volume 35 Issue 12 Pages 1322-1329
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    A plate-type nickel catalyst on an aluminum plate prepared by electroless plating, which consisted of displacement of aluminum with zinc and the deposition of nickel by chemical reduction, has high activity and high selectivity to form hydrogen and carbon monoxide for methanol decomposition. This nickel catalyst, then would be suitable for a plate-type catalyst for the construction of a wall reactor system, which has an effective exchange of heat energy, a quick load response due to a low pressure loss and a downsized dimension of the reactor. In this study, in order to accumulate any kinetic information and derive the reaction rate equation for constructing the wall reactor system, a kinetic study for methanol decomposition on the plate-type nickel catalyst prepared by electroless plating was conducted at 533–623 K and atmospheric pressure.
    The reaction rate equation revealed that a methanol molecule is strongly adsorbed on the plate-type catalyst surface, forming a methoxy species (CH3O-), and the rate-determining step involves the abstraction of hydrogen from the adsorbed methoxy species. Furthermore, the reaction rate was depressed by the introduction of carbon monoxide in the reaction feed, but was not affected by that of hydrogen. By assuming the Langmuir–Hinshelwood mechanism, the integrated rate equation is derived from the obtained kinetic data in fitting parameters, such as the constant of the reaction rate and adsorption equilibrium for methanol, hydrogen, and carbon monoxide, by means of the Simplex method. The derived rate equation is well expressed with each experimental result.
    Download PDF (329K)
Materials and Devices
  • Tadahiro Murakata (Aita), Yuhki Higashi, Norio Yasui, Takeshi Higuchi, ...
    Type: Research Papers
    Subject area: Materials and Devices
    2002 Volume 35 Issue 12 Pages 1270-1276
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    Nanoparticles of Au, Ag, Pt and Cu (unimetal nanoparticles) and mixtures of two of them (bimetal nanoparticles) are prepared through photocatalytic reduction of the corresponding metal ions in H2O-EtOH solution in the presence of ultrafine TiO2 particles which are made so as to disperse stably in various organic solvents. The resultant nanoparticle solutions show intense colors owing to surface plasmon absorption of the nanoparticles and have high colloidal stability. Au unimetal nanoparticles isolated from the solution redisperse stably in organic solvents and their dispersibility increases when they are treated with THF. Ag-Au and Pt-Au bimetal nanoparticles are prepared through successive photoreduction that Au ion first and then Ag or Pt ion is photoreduced. The bimetal nanoparticles are found to be not alloyed but to be mixtures of unimetal nanoparticles. The mechanism for the formation and the colloidal stabilization of the nanoparticles in the presence of the ultrafine TiO2 particles are suggested to be different from that for reaction systems using bulk TiO2.
    Download PDF (252K)
Separations
  • Wen-Churng Lin
    Type: Research Papers
    Subject area: Separations
    2002 Volume 35 Issue 12 Pages 1257-1262
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    For environmental protection, it is necessary to reduce the aromatic contents in hydrocarbon products. Solvent extraction of aromatics from C9+ oil (medium petroleum fraction that contains hydrocarbons with carbon number larger than nine and boils in the range of 440–540 K) was studied in the present work. In this study, n-decane, n-dodecane, n-tetradecane, n-butylbenzene, 1, 4-diisopropylbenzene, and n-octylbenzene were chosen as C9+ model compounds oil and sulfolane was used as the aromatic extractant. The binary interaction parameters of UNIQUAC for the multicomponent system at 348.15 K were obtained and applied to batch and continuous multistage extraction simulations. Furthermore the relationship between the ideal stage number and the solvent-to-feed ratio was derived. The concentration of aromatics in C9+ oil could be reduced within 2 mol% by using sulfolane as a solvent under the appropriate extraction conditions.
    Download PDF (153K)
  • Chia-Chang Lin, Tsung-Jen Ho, Wen-Tzong Liu
    Type: Research Papers
    Subject area: Separations
    2002 Volume 35 Issue 12 Pages 1298-1304
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    This work presents a novel rotating packed bed owing to its applicability in distillation. Distillation experiments were conducted using the methanol-ethanol system at atmospheric pressure and total reflux conditions with two packings. Rotor speeds ranged from 600 to 1600 rpm, which provided 42–298 equivalent gravitational force. Experimental results indicated that 1–3 theoretical plates were achieved with a packing thickness of 8.6 cm. Consequently, the height equivalent of a theoretical plate (HETP) of about 3–9 cm can be obtained in a rotating packed bed, i.e., much lower than that in a conventional packed bed. An empirical correlation was also proposed, implying that the HETP value varied with centrifugal force to the 0.23–0.26 power.
    Download PDF (353K)
  • Yasuhiro Shiraishi, Takayuki Hirai, Isao Komasawa
    Type: Research Papers
    Subject area: Separations
    2002 Volume 35 Issue 12 Pages 1305-1311
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    A desulfurization process for light oil has been investigated based on chemical oxidation of sulfur-containing compounds over Ti-containing molecular sieve catalysts. Sulfur compounds, when dissolved in n-tetradecane (model light oil), were oxidized to the corresponding sulfoxides and sulfones in the presence of the catalysts and H2O2, and were removed successfully from the oil. However, by use of this basic process, the sulfur concentration of actual light oil failed to be reduced to the required deep desulfurization level (0.05 wt%). This is because alkyl-substituted sulfoxides and sulfones, produced during the process, are adsorbed on the surface of the catalyst, thus decreasing the catalytic activity. When desulfurization was carried out in the presence of polar acetonitrile solvent, the adsorption of these compounds onto the catalyst was suppressed significantly and the deep desulfurization was achieved successfully. In this process, the denitrogenation of light oil also proceeded effectively. The catalyst recovered showed no decrease in the catalytic activity and could be reused for further desulfurization and denitrogenation of light oil.
    Download PDF (155K)
Particle Technology and Fluidization
  • Fukuji Ebihara, Satoru Watano
    Type: Research Papers
    Subject area: Particle Technology and Fluidization
    2002 Volume 35 Issue 12 Pages 1263-1269
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    This paper discusses an optimal process for making a novel granular detergent by using an aqueous inorganic solution. This process contains a step of coating with inorganic solutions (sodium carbonate or sodium sulfate solution) onto granular detergent by spraying, which provides an improved solubility of the granular detergent as well as providing better physical properties (e.g., higher bulk density, flowability, etc.). The inorganic solutions used for the coating can also act to prevent sticking of the product. In this study, the feasibility to make better performance of granular detergent by using aqueous inorganic solutions as binder was discussed and the optimum process centerline was determined. It was also found that the Froude number could be used for the scale up/down of the coating process.
    Download PDF (1697K)
Process Systems Engineering
  • Qing-Guo Wang, C. C. Hang, Xue-Ping Yang
    Type: Research Papers
    Subject area: Process Systems Engineering
    2002 Volume 35 Issue 12 Pages 1231-1243
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    In this paper, a design method for multivariable controllers in a unit output feedback configuration is presented. With the internal model control (IMC) principles, the objective closed-loop transfer functions are characterized in terms of process unavoidable non-minimum phase elements. A multivariable controller for best achievable performance is obtained with block diagram analysis and model reduction. The proposed design provides users with an option to choose between PID and high-order controllers to suit applications better. Stability and robustness are analyzed and simulation is provided to substantiate the superior performance of the proposed method.
    Download PDF (245K)
  • Takashi Hamaguchi, Yoshihiro Hashimoto, Toshiaki Itoh, Akihiko Yoneya, ...
    Type: Research Papers
    Subject area: Process Systems Engineering
    2002 Volume 35 Issue 12 Pages 1282-1289
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    It is desirable to support operator activity in abnormal correction of chemical plants. Although fault diagnosis systems have very fertile grounds for theoretical and industrial development, there are few papers discussing countermeasure planning. In this paper, a method to select operating modes, in order to settle the abnormal situations down, is proposed. The operating modes are categorized into “maintained”, “compromised” and “shutdown”. In the maintained mode, all controlled variables can be maintained by using alternative actuators or sensors in abnormal situations. The compromised mode and shutdown mode are distinguished by the controlled variables to be abandoned in abnormal situations. Three fault trees, which are “safety”, “quality” and “quantity”, are prepared to classify the controlled variables. If the controlled variables, which are included in a safety tree, cannot be maintained, the shutdown mode is selected. In order to judge the capability to maintain the controlled variables, a controller configuration design method based on CE-matrices is applied. If all controlled variables for safety can be maintained, and if controlled variables for quantity or quality cannot be maintained, the plant can be operated in the compromised mode. In this paper, a countermeasure planning algorithm based on fault trees and CE-matrices is proposed. Even though this algorithm cannot propose the quantitative actions, it can suggest the situation, to which the abnormal plant will be settled down, to the operators. And it is also suggested to maintain a safe operation, which actuators should be manipulated and which sensors should be observed. This selection method of operating modes in abnormal situations is as useful as the first stage of countermeasure planning.
    Download PDF (4878K)
Biochemical, Food and Medical Engineering
  • Tomoyo Kurokawa, Chunyeon Lee, Naofumi Shiomi, Atsushi Nakano, Shigeo ...
    Type: Research Papers
    Subject area: Biochemical, Food and Medical Engineering
    2002 Volume 35 Issue 12 Pages 1277-1281
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    The C-terminal region of α-amylase (Amy1A/3D) secreted from recombinant Saccharomyces cerevisiae and Pichia pastoris was characterized by use of an anti-peptide antibody against this region of Amy1A/3D. In flask-culture of S. cerevisiae cells, the activity of α-amylase increased processing of the C-terminal region, a serine- and cysteine-protease inhibitor leupeptin was added to culture broth time to time. When leupeptin was adequately added, the activity of α-amylase with the intact C-terminus was 7 times the activity obtained without addition of leupeptin. Although in flask-culture of P. pastoris cells, the activity of α-amylase and cell density were much higher than those of S. cerevisiae, the protease activity was also much higher than that in S. cerevisiae, and thus the percentage of α-amylase with the intact C-terminus became about 60% in secreted α-amylase after 72 h induction. On the other hand, in cultivation of P. pastoris cells with a jar fermentor under controlled DO and the methanol concentration, the percentage of α-amylase with the intact C-terminus remained about 90%. Therefore, it is important to optimize fermentation conditions for depressing secretion of protease in production of recombinant proteins by secretion.
    Download PDF (1625K)
Safety, Environment and Energy
  • Koichi Yamada, Nobuhide Takahashi, Ching-Ju Wen
    Type: Research Papers
    Subject area: Safety, Environment and Energy
    2002 Volume 35 Issue 12 Pages 1290-1297
    Published: 2002
    Released: January 25, 2003
    JOURNALS RESTRICTED ACCESS
    Solid oxide fuel cells (SOFCs) with high reaction activity to use the hydrocarbon fuels are promising for solving environmental pollution problems. We designed and evaluated an SOFC system operated at 800°C, which uses cells and heat exchangers of micro-tubes with the outer-diameter of 2.4 mm. We found that a compact SOFC system (55.8 kg, 0.064 m3) can supply a maximum power of 64 kW for driving and that the system efficiency is 3–4 times higher than an internal combustion engine (ICE) system with a power output less than 20 kW.
    Download PDF (357K)
feedback
Top