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Volume 38, Issue 10
Displaying 1-14 of 14 articles from this issue
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Akira IgarashiArticle type: Review
2005 Volume 38 Issue 10 Pages 779-784
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL FREE ACCESSThe 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. Hattori of Nagoya University. This research project was aimed at establishing the hybrid field of catalytic reaction engineering to bridge the 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. Each of these research fields was further divided into three subgroups. Importantly, each division worked together toward achieving the overall result of catalytic reaction engineering. This project produced many useful and progressive results, as presented at the 10th Asian Pacific Confederation of Chemical Engineering (APCChE 2004).View full abstractDownload PDF (799K) -
Masatoshi Nagai, Hiroyuki Tominaga, Takeshi Arahata, Atsushi IrisawaArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 785-790
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSThe deactivation and modeling of the 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 of the nitrided catalysts was expressed by an equation based on two types of active species, 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 constants for the easily deactivated species and the species deactivated with difficulty, respectively. The former species were based on the Elovich kinetics which represented the initial deactivation caused by sulfidation. The latter species were based on the first order deactivation kinetics during the intermediate stage of the reaction and deactivated by nitrogen release. The behavior of the nitrogen release, sulfidation, and carbon deposition was determined by XPS and related to the deactivation parameters of the equation. The catalyst lifetime of the 973-K-nitrided catalyst was estimated to be 2.3 and 24.8 times longer than those of the 773-K- and 1173-K-nitrided catalysts, respectively, at a conversion of 10%. For the sulfided catalyst, the initial deactivation of the sulfided Mo/Al2O3 catalyst was caused by sulfur poisoning during the dibenzothiophene HDS and by sulfur release in the intermediate stage.View full abstractDownload PDF (442K) -
Jong Rack Sohn, Jun Seob LimArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 791-800
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSA series of catalysts, NiSO4/Al2O3-ZrO2, for acid catalysis were prepared by the impregnation method, where support, Al2O3-ZrO2 was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and aluminum nitrate solution followed by adding an aqueous ammonia solution. Characterization of prepared catalysts was performed by using Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry and by measuring surface area. No diffraction line of nickel sulfate was observed up to 20 wt%, indicating good dispersion of nickel sulfate on the surface of Al2O3-ZrO2. The addition of nickel sulfate (or Al2O3) to ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperature because of the interaction between nickel sulfate (or Al2O3) and ZrO2. 10-NiSO4/Al2O3-ZrO2 containing 10 wt% NiSO4 and 5 mol% Al2O3 was calcined at 973 K and exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The addition of Al2O3 up to 5 mol% gradually enhanced the acidity, thermal property, and catalytic activities of NiSO4/Al2O3-ZrO2 due to the interaction between Al2O3 and ZrO2.View full abstractDownload PDF (762K) -
Keiji Takagi, Hideaki Izumida, Yuichi Ichihashi, Satoru Nishiyama, Shi ...Article type: Research Paper
2005 Volume 38 Issue 10 Pages 801-806
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSPreparation procedure of tin-incorporated in mesopores of MCM-41 has been studied for reduction of acetophenone to 1-phenylethanol. Tin was incorporated into the mesopores of MCM-41 by a template ion exchange (TIE in the following) method. Almost 20 wt% of tin was loaded in the mesopores and about 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 tin 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 tin. The rinse of HCl before the incorporation increased the specific activity by a factor of 2–3.View full abstractDownload PDF (4009K) -
Masatoshi Nagai, Tatsuhiko KurakamiArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 807-812
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSThe reverse water gas shift reaction on molybdenum carbides was studied at 573 K and atmospheric pressure. Molybdenum carbides with various C/Mo atomic ratios were synthesized on γ-Al2O3 using a vertical tube hot-wall chemical vapor deposition (CVD) reactor in a stream of MoCl5, benzene, and hydrogen at 1000 K and total pressure of 0.13 kPa. The activities of the molybdenum carbide catalysts prepared by the CVD method were compared with those by the temperature-programmed reaction (TPR). The ratio of the C 1s peak of carbidic carbon to the Mo 3d peak of the alumina-supported molybdenum carbide, prepared by changing the benzene/MoCl5 ratio, was determined by XPS spectroscopy. The activities of the CVD and TPR catalysts with the C/Mo ratio of molybdenum carbides for CO2 hydrogenation were discussed. The turnover frequencies of the CVD catalysts were 0.347–0.498 s–1 and higher than those of the TPR catalysts.View full abstractDownload PDF (486K) -
Leo Chau-Kuang Liau, Hsuan Chang, Thomas Chun-Kuang Yang, Chien-Lung H ...Article type: Research Paper
2005 Volume 38 Issue 10 Pages 813-817
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSFilms of TiO2 photocatalyst were fabricated using a sol-gel method and processed with low temperature treatments. The TiO2 sample films were prepared using the sol-gel solution coated on glass substrates. After drying, the coated films were carried out by different thermal treatments. These treatments, including hot water, water-vapor exposure, and sintering, were applied on fabricating the films to evaluate their effects on the photocatalytic activity of the prepared TiO2 films. The photocatalytic activity of these sample films were demonstrated by a dye degradation test with lighting of UV wavelength at 385 nm. A first order kinetic equation was utilized to estimate the effects of these thermal treatments on the photocatalytic activity of the treated films. Results show that the photocatalytic activity and surface geometry can be observed quite differently by these thermal treatments. The water-vapor exposure method can greatly improve the photocatalytic abilities of the TiO2 films, although the adhesion was in ill-condition. However, hot water and sintering treatments can improve the adhesion of the films on the glass substrate. In addition, the surface images of the films were obtained by SEM photos to illuminate the influences of these thermal treatments on the surface geometry.View full abstractDownload PDF (4516K) -
Eiji Suzuki, Shusuke Yoshida, Hisanao Usami, Akihiko Nakasa, Hitoshi F ...Article type: Research Paper
2005 Volume 38 Issue 10 Pages 818-823
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSPhoto-activated electrons reduce reactants and photo-generated positive holes oxidize them in photocatalysis. The electrons and the holes, however, mostly or partly recombine yielding thermal energy before being used for the reactions because photocatalyst particles are basically symmetry, and thereby cannot generate any effective electric field to separate the electrons and the 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 proposed and fabricated a reactor equipped with a hetero-sided photocatalyst plate, that is, a conductive metal plate coated with photocatalyst at its front surface and with a reduction catalyst such as Pt at its back surface. The hetero-sided photocatalyst plate can generate the effective electric field to drive the electrons and the 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 reactor equipped with the hetero-sided photocatalyst plate achieved a high photon-efficiency (the external quantum yield) 20%, five times as large as the undivided reactor, when hydrogen was generated from acidic water in the reduction space while formic acid was oxidized in the oxidation space.View full abstractDownload PDF (529K) -
Eiji Suzuki, Yukari Hayashi, Yoko Shimomura, Shusuke Yoshida, Hisanao ...Article type: Short Communication
2005 Volume 38 Issue 10 Pages 824-827
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSOnly few reaction engineering studies on photocatalysis have been reported, although such studies are necessary for its successful application. The authors studied reaction engineering matters such as the effects of temperature, reactant concentration, catalyst amount, and irradiation intensity on the photocatalytic reaction rate of hydrogen generation from H2S, a waste generated in the fuel oil desulphurization process. CdS/ZnS photocatalyst, which can be activated by solar light, was spread over the bottom of a beaker containing an H2S water solution and irradiated by a Xenon lamp. The photocatalytic hydrogen generation rate was independent of the catalyst amount as far as the photocatalyst particles cover the bottom surface. The reaction rate increased with but less than in proportion to the irradiation intensity, suggesting that a rate limiting step other than photo-activation exists. The activation energy of the reaction, 38 kJ mol–1, suggested that an elevated reaction temperature would be advantageous. The reaction rate is the first order of the reactant concentration, suggesting that the adsorption of the reactant could be a rate limiting step. The external quantum yield was 19%, comparable to solar cells.View full abstractDownload PDF (2461K) -
Seong-Ick Kim, Yoshihide Watabe, Takashi Aida, Hiroo NiiyamaArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 828-834
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSAddition of cobalt oxide (Co3O4) as a heating promoter, absorbing microwave energy with high efficiency, was suggested in order to accelerate microwave heating of zeolite adsorbent or catalyst. The effect of the addition of Co3O4 on the microwave heating of Co-modified mordenites prepared by the impregnation method and physical mixing was investigated. Catalytic oxidation of ethylene on Co-modified mordenites was also examined under microwave irradiation. Co3O4 promoted microwave heating of the mordenite bed when Co3O4 and mordenite were mixed physically. The physical mixture with Co3O4 of 50 wt% was heated up to 518 K by microwave irradiation. The desorption peak of water for pellet type Co-modified mordenite was very sharp in microwave heating after pre-adsorption of water vapor and most of adsorbed water desorbed in the initial stage of the microwave heating. The sharp desorption peak of water indicates that the pelletized sample was heated to higher temperatures than powder one. In the case of the pelletized Co-modified mordenite with Co3O4 of 75 wt%, adsorbed water on mordenite was almost desorbed during microwave irradiation. Co3O4 had both functions of the heating promoter and catalyst, and ethylene was removed with high conversion (93%) when the pelletized mixture of Co3O4 (75 wt%) and mordenite was irradiated by microwave under steady feed of ethylene, water vapor, and oxygen.View full abstractDownload PDF (501K) -
Savas Koparal, Susumu Nii, Fumio Kawaizumi, Katsuroku TakahashiArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 835-840
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSA countercurrent continuous washing apparatus for tar removal under ultrasonic irradiation has been developed. Tar was dissolved in dimethylformamide, DMF and sand was soaked into the resulting tar solution to prepare samples of tar-contaminated sand. Tar contents in DMF were determined by a UV-spectrophotometer from absorbance at 336.5 nm. 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 was described in terms of a first order reaction equation, which enables us to calculate the residue fraction in continuous washing at a 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 a tar-covered layer on the sand surface and the particles produced under the ultrasonic field are much finer than for the case of mechanical agitation.View full abstractDownload PDF (495K) -
Worapon Kiatkittipong, Shigeo Goto, Tomohiko Tagawa, Suttichai Assabum ...Article type: Research Paper
2005 Volume 38 Issue 10 Pages 841-848
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSThe production of C2 hydrocarbons and electricity through oxidative coupling of methane in an SOFC reactor operated at maximum power at load was simulated. La0.85Sr0.15MnO3/8 mol%Y2O3-ZrO2/La1.8Al0.2O3 (abbreviated as LSM/YSZ/LaAlO) were used as a cathode, electrolyte and an anode, respectively. A plug flow reactor model (PFRM) was developed using kinetic parameters of the oxidative coupling of methane and the oxygen permeability through LSM/YSZ/LaAlO from our previous works. Good agreements of power generation between experimental and simulation results were obtained. The effect of operating conditions; i.e., operating temperature, methane feed flow rate and concentration on the anode, oxygen concentrations on the cathode, and operating pressure were investigated. Methane conversion and C2 selectivity increase with increasing operating temperature. In our system, most of C2 production is ethylene, which is more favored than ethane. Methane conversion decreases with increasing methane feed flow rate while C2 selectivity slightly increases. No effort on air purification is required in the SOFC system. Higher methane feed concentrations on the anode give higher power. The reactor performance increases at higher pressures. The results suggest that our SOFC system is an excellent reactor for C2 production where electric power is generated simultaneously.View full abstractDownload PDF (562K) -
Tomoaki Mizuno, Hiroshi Yamada, Tomohiko Tagawa, Shigeo GotoArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 849-853
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSThe liquid-phase oxidation of benzene to phenol in a benzene–water bi-phase system was studied. The catalyst was dissolved in water that was saturated with benzene. Therefore benzene was oxidized to phenol in water. The produced phenol was extracted to the benzene phase. By extracting the produced phenol into the organic phase, products were easily separated from the catalyst. Therefore consecutive oxidation of phenol was prevented. The experiment was carried out in a stirred tank batch reactor.
Two kinds of catalyst systems were used. One was an Fe–H2O2 system and the other was a V–O2 system. The effect of the reaction conditions such as hydrochloric acid concentration, oxidant concentration and catalyst concentration on the yield of phenol and selectivity to phenol in the Fe–H2O2 system was discussed. The yield became large at low hydrochloric acid concentrations, high oxidant concentrations and high catalyst concentrations. The selectivity was independent of the oxidant concentration and the catalyst concentration. But the hydrochloric acid concentration affected the selectivity. The effect of the catalyst concentration on the yield of phenol and the selectivity to phenol in the V–O2 system was discussed. The yield was increased with an increase of catalyst concentration. Selectivity slightly decreased when the yield increased. An extractor that had aqueous alkaline, was used to separate phenol from the reactor. Selectivity was improved when phenol was taken out from the reactor by the extractor in both catalyst system cases.View full abstractDownload PDF (2837K) -
Yoshihiro Kawamura, Naotsugu Ogura, Takashi Yahata, Kazuto Yamamoto, T ...Article type: Research Paper
2005 Volume 38 Issue 10 Pages 854-858
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSTo 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 a methanol reformer was developed. The microreactor consists of four units (a methanol reformer with a 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.View full abstractDownload PDF (537K) -
Toshiro Tsuji, Satoshi Okajima, Akira Sasaki, Takao MasudaArticle type: Research Paper
2005 Volume 38 Issue 10 Pages 859-864
Published: 2005
Released on J-STAGE: October 20, 2005
JOURNAL RESTRICTED ACCESSSteam reforming of oils derived from plastics has been investigated to produce gas from waste plastics. Two types of oils, from polyethylene and from polystyrene, were produced by thermal decomposition at relatively low temperatures (350–450°C). Steam reforming of these oils was conducted at temperatures from 650 to 850°C under a pressure of 1 atm using three types of Ni-Al2O3 catalysts. Gas yield, gas composition, carbon conversion, and the coking ratio for these catalysts were measured. Although the plastic-derived oils contain heavy hydrocarbons or aromatics, they are gasified well with a low coking rate at temperatures above 800°C and a steam carbon ratio = 3.5 and LHSV = 1 h–1. Among the three catalysts, C11NK, which is a commercial steam reforming catalyst for naphtha, possessed moderate activity, but had the lowest rate of coking. Gas compositions agreed well with values calculated from chemical equilibria. Product gas contained approximately 72 vol% hydrogen for polyethylene-derived oil and 68 vol% for polystyrene-derived oil.View full abstractDownload PDF (2872K)
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