Updated on 2021/11/30

写真a

 
FUJIKI Junpei
 
Organization
Graduate School of Engineering Materials Process Engineering 1 Designated lecturer
Graduate School
Graduate School of Engineering
Graduate School of Engineering
Title
Designated lecturer
Contact information
メールアドレス

Degree 1

  1. 博士(工学) ( 2011.3   明治大学 ) 

Research Interests 7

  1. Adsorption, Porous Materials

  2. DFT calculation

  3. process optimisation

  4. adsorption

  5. porous materials

  6. numerical calculation

  7. mass transfer and diffusion

Research Areas 2

  1. Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Transport phenomena and unit operations

  2. Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Thermal engineering

Current Research Project and SDGs 1

  1. Highly efficient CO2 capture

Professional Memberships 5

  1. 化学工学会

  2. 日本冷凍空調学会

  3. 日本吸着学会

  4. 分離技術会

  5. International Adsorption Society

 

Papers 28

  1. Enhancement mechanisms of water vapor adsorption rate onto silica-gel in acoustic field Reviewed

    Fujiki, Junpei, Nakayama, Masayuki, Ueda, Yuki, Akisawa, Atsushi

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER   Vol. 148   page: 119088   2020.2

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:PERGAMON-ELSEVIER SCIENCE LTD  

    This study was focused on the evaluation of the adsorption kinetics of water vapor onto silica-gel with and without an acoustic field, in an objective to reveal the enhancement mechanisms of water vapor adsorption by an acoustic wave. Adsorption uptake curves of water vapor from humidified air onto the silica-gel with and without acoustic field were measured at room temperature under various conditions, after which the adsorption kinetic parameters (fluid film mass transfer coefficient and intraparticle diffusivity) were determined from the uptake curves with the aid of numerical calculations. The results demonstrated that the acoustic field exhibited no effect on the intraparticle diffusion, because the fluid film mass transfer was the rate-limiting step under the condition of this study. In contrast, the fluid film mass transfer was enhanced by the velocity amplitude of the acoustic field. However, the diminished mass transfer was also observed in some cases. For the enhancement and diminution of adsorption rate by the acoustic wave, it was suggested that the ratio of the oscillation flow (U) to the steady flow (u), U' = U/u, was an important factor. Moreover, the enhanced adsorption kinetics was observed under the conditions of U' > 2, whereas the adsorption rate was diminished or invariant under the condition of U' < 2. This would be understood from the viewpoint of the thinning and thickening of fluid film by the oscillation flow caused by the acoustic wave. Even when the direction of the oscillation flow is countercurrent to the steady flow, the thinning of fluid film by the oscillation flow is still possible under U' = U/u > 2. (C) 2019 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijheatmasstransfer.2019.119088

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  2. Effect of Counter Cations on the Hydrothermal Conversion of FAU-Type Zeolites into ABW or ANA and Their Potential Applicability for CO2/N-2 Separation Reviewed

    Fujiki, Junpei, Yogo, Katsunori

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   Vol. 53 ( 1 ) page: 17 - 23   2020.1

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:SOC CHEMICAL ENG JAPAN  

    In this study, the hydrothermal conversion of FAU-type zeolites using an aqueous ammonia solution was investigated to understand the solid-phase transformation mechanism of the selective synthesis of target zeolites. In addition, the CO2/N-2 separation ability of prepared materials was estimated from single-component adsorption isotherms by the ideal adsorbed solution theory. ABW and ANA-type zeolites were successfully synthesized from the FAU-type zeolites such as Li-LSX and Na-X, respectively, by a hydrothermal treatment using an aqueous ammonia solution. Li-LSX was completely converted into ABW by treating at a temperature above 150 degrees C for 24h, and ANA was mainly produced from Na-X at 250 degrees C after treating for over 72 h. The pellet shape of the raw zeolites was maintained even after the hydrothermal treatment. Considering the transformation mechanisms, the results suggest that the transformation of the zeolite topology was caused by the ion exchange between the counter cation of the zeolite and ammonium ion in the solvent and the cation structure-directing effect under hydrothermal conditions. It can be concluded that the counter cations of the raw zeolites played an important role in the structural transformation. The simple synthesis method presented in this study enables the conversion of FAU-type zeolites, particularly X-type zeolite, into other types of zeolites without using strong bases, such as alkali hydroxides. In terms of the CO2/N-2 separation ability, CO2/N-2 selectivity for post-combustion CO2 capture conditions drastically increased upon the hydrothermal treatment. In particular, the ABW-type zeolite exhibited extremely high CO2/N-2 selectivity over 10000.

    DOI: 10.1252/jcej.19we149

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  3. Water adsorption on nitrogen-doped carbons for adsorption heat pump/desiccant cooling: Experimental and density functional theory calculation studies Reviewed

    Fujiki, Junpei, Yogo, Katsunori

    APPLIED SURFACE SCIENCE   Vol. 492   page: 776 - 784   2019.10

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER  

    Nitrogen-doped porous carbons were prepared via chemical activation of chitosan using alkali-metal carbonates (Na2CO3, K2CO3, Rb2CO3, and Cs2CO3), and the water adsorption isotherms of prepared carbons were measured to estimate the performance of the carbons in adsorption heat pump/desiccant cooling. Pre-doping of an alkali carbonate activator into the chitosan precursor resulted in a highly developed micropore structure and the introduction of macropores. The macropore structure clearly depended on the alkali carbonate activator. Na2CO3 resulted in two-dimensional macropores because of the hard-template effect, whereas the other alkali carbonate activators resulted in three-dimensional macropores with different cell sizes. A density functional theory calculation study based on X-ray photoelectron spectroscopy analyses of nitrogen-doped activated carbons indicated that pyridinic (pyridine, pyridone, and pyridine N-oxide), amide, and quaternary N groups might be effective for low-pressure water adsorption. Although the water adsorption capacities of the prepared carbons at P/P-0 > 0.5 increased with increasing micropore volume, those at the low-pressure region (P/P-0 < 0.1) were dependent on the surface density of nitrogen or oxygen functional groups. In addition, the shape of water isotherms preferable for adsorption heat pump/desiccant cooling was observed for the carbons with an appropriate surface density of nitrogen functional groups.

    DOI: 10.1016/j.apsusc.2019.06.267

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  4. Study on the Adsorption Enhancement by Acoustic Wave with Respect to the Effect of Frequency

    秋澤淳, 大久保賢一, 上田祐樹, 藤木淳平

    日本冷凍空調学会論文集   Vol. 36 ( 3 ) page: 149‐156   2019.9

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    Language:Japanese   Publisher:公益社団法人 日本冷凍空調学会  

    &lt;p&gt;The objective of this study is to investigate the effect of frequency of acoustic wave on the adsorption enhancement. Experimental measurements were conducted, which results were analyzed to derive the condition of acoustic wave in which the adsorption rate is increased. 3 cases with different frequency which corresponding to the resonance mode indicated that the enhancement rate would depend on the frequency. It was also found that the critical velocity amplitude of the acoustic wave above which the enhancement effect was observed would increase as the frequency is higher. The authors proposed a model that the enhancement effect occurs when the effective displacement amplitude of the oscillation flow is larger than the certain value. Mathematical analysis of the model suggested the critical velocity amplitude would be expressed in a linear function with the frequency, which was verified based on the observation of the experimental results. It revealed that the mechanism of the enhancement effect would be explained by the model.&lt;/p&gt;

    CiNii Article

    J-GLOBAL

  5. Enhancement Mechanism of the CO2 Adsorption-Desorption Efficiency of Silica-Supported Tetraethylenepentamine by Chemical Modification of Amino Groups Reviewed

    Yamada, Hidetaka, Chowdhury, Firoz A., Fujiki, Junpei, Yogo, Katsunori

    ACS SUSTAINABLE CHEMISTRY & ENGINEERING   Vol. 7 ( 10 ) page: 9574 - 9581   2019.5

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Tetraethylenepentamine (TEPA) and its derivatives were used to functionalize mesocellular silica foam (MSU-F) supports by wet impregnation for utilization as solid sorbents for CO2 capture. TEPA derivatives were synthesized by introducing various substituents into the amino groups of TEPA. The CO2 adsorption and desorption properties of the solid sorbents were evaluated to assess the effects of substituent introduction. TEPA derivatives with bulky alkyl groups such as 3-pentyl (Pe) substituents drastically enhanced the adsorption and regeneration performance of the solid sorbents, while the introduction of hydroxyalkyl substituents had a negative effect on the CO2 adsorption capacity. The mechanisms governing these effects are discussed in terms of CO2 affinity and diffusivity, depending on the introduced functionality. For a simulant flue gas of 14% CO2, 5% O-2, 4% H2O, and balance N-2 at 40 degrees C, MSU-F-supported Pe-TEPA showed a working capacity higher than 4 mmol CO2/g by inert-gas sweeping regeneration at 60 degrees C with excellent cyclic stability. The results demonstrate that the regeneration performance is greatly improved by chemical modification of the amino functional groups of amine-impregnated solid sorbents. This approach is promising for developing low-energy and low-temperature CO2 capture technologies.

    DOI: 10.1021/acssuschemeng.9b01064

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  6. Role of silanol groups on silica gel on adsorption of benzothiophene and naphthalene Reviewed

    Fujiki, Junpei, Yogo, Katsunori, Furuya, Eiji

    FUEL   Vol. 215   page: 463 - 467   2018.3

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCI LTD  

    The adsorptive removal of sulfur-containing compounds such as thiophene derivatives from transportation fuels has received extensive attention because of its economic and environmental advantages compared to the hydrodesulfurization process. In our previous study, we suggested that the adsorption sites for benzothiophene and naphthalene on the silica surface consist of different types of silanol groups, and the removal of vicinal silanols from the silica surface should enable silica materials to adsorb benzothiophene selectively. In this study, an attempt is made to prove this hypothesis for the development of novel desulfurization sorbents. Heat treatment of silica gel was performed at different temperatures to remove vicinal silanol groups, and the adsorption capacities of benzothiophene and naphthalene were evaluated. The amount of naphthalene adsorbed on heat-treated silica gel decreased with increasing heat-treatment temperature, whereas the amount of benzothiophene adsorbed on silica gel treated at 873 and 1073 K showed only a slight decrease. Considering the heat treatment might lead to the removal of vicinal silanols due to dehydration of surface silanols, the results indicate that vicinal silanol groups were selective adsorption sites for naphthalene. Moreover, for binary-component systems, the adsorption capacities of benzothiophene and naphthalene were almost identical because of multilayer adsorption of naphthalene on adsorbed benzothiophene, and the adsorption capacities of benzothiophene for single-and binary-component systems were also identical. This suggests that the heat treatment of silica enables the selective removal of benzothiophene.

    DOI: 10.1016/j.fuel.2017.11.070

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  7. Effect of isopropyl-substituent introduction into tetraethylenepentamine-based solid sorbents for CO2 capture Reviewed

    Yamada, Hidetaka, Fujiki, Junpei, Chowdhury, Firoz A., Yogo, Katsunori

    FUEL   Vol. 214   page: 14 - 19   2018.2

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCI LTD  

    Chemical modification of the amino functional groups of amine-impregnated solid sorbents is an effective strategy for drastically improving the regeneration performance for CO2 capture. In this study, isopropyl groups were introduced into tetraethylenepentamine (TEPA) to obtain N-(isopropyl)-TEPA (IP-TEPA), which was impregnated in mesocellular silica foam (MSU-F). The obtained solid sorbent enabled low-temperature regeneration with a low regeneration energy. To clarify the role of the IP groups, experimental and computational methods were used to compare the IP-TEPA/MSU-F sorbent with TEPA/MSU-F in terms of CO2 working capacity, reaction product stability, self-diffusion coefficient, C-13 spin-lattice relaxation time, and CO2 capture performance in steam-aided vacuum swing adsorption.

    DOI: 10.1016/j.fuel.2017.10.108

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  8. A Simple Method for the Determination of Adsorption Kinetic Parameters Using Recycle Fixed-Bed Adsorber Reviewed

    Fujiki, Junpei, Kawakita, Takashi, Teshima, Kazuki, Furuya, Eiji

    TRANSPORT IN POROUS MEDIA   Vol. 120 ( 2 ) page: 359 - 372   2017.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    This study focuses on the development of a novel analysis technique for determining the intraparticle diffusivity and fluid film mass transfer coefficient from a concentration history curve of a recycle fixed-bed reactor without using the linear driving force approximation and empirical equations for the estimation of . The recycle fixed-bed method requires lesser amounts of working fluid for experiment purposes, which is an advantage over the usual fixed-bed method. Based on the characterization results of the concentration history curves, simulated by rigorous numerical calculations, a novel analysis technique was established. The value can be determined from the experimentally obtained time at which the concentration of the curve is minimal . The value can be determined from the value and Biot number (Bi), which can be estimated from the experimental ratio of the maximum concentration to the minimum concentration . The and values of phenol adsorption on an activated carbon material were determined experimentally using the proposed analysis method. This method enables the determination of reliable adsorption kinetic parameters through a simple and economical experiment. However, appropriate experimental data must be acquired under regulated experimental conditions, especially in the case of fluctuation of the concentration history curve.

    DOI: 10.1007/s11242-017-0925-x

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  9. Highly efficient post-combustion CO2 capture by low-temperature steam-aided vacuum swing adsorption using a novel polyamine-based solid sorbent Reviewed

    Fujiki, Junpei, Chowdhury, Firoz A., Yamada, Hidetaka, Yogo, Katsunori

    CHEMICAL ENGINEERING JOURNAL   Vol. 307   page: 273 - 282   2017.1

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    A novel amine-based solid sorbent was prepared for CO2 capture, and the CO2 adsorption characteristics were evaluated for simulated flue gas. Furthermore, CO2 capture tests using a lab-scale three-column fixed-bed system were performed. A novel amine compound was synthesized by attaching hindered functional groups to the terminal primary amino groups of a polyamine, followed by impregnation into pelletized mesoporous MSU-F silica. This novel amine-impregnated solid sorbent overcame the problem of limited CO2 diffusion and exhibited extremely high regenerability even at low temperatures. Lab-scale CO2 capture tests suggested that operation conditions such as temperature, cycle time, rinsing time, flow rate, and regeneration method directly affected CO2 capture performance. In particular, direct low-temperature steam stripping desorption drastically enhanced CO2 capture performance. Steam-aided vacuum swing adsorption (SA-VSA) process was feasible for our amine-based solid sorbent and enabled the recovery of CO2 with high purity (>98%) and recovery rate (>93%). The regeneration heat calculated from the amount of recovered CO2 and the amount of supplied steam was considerably lower (1.47 GJ/t-CO2) than that of liquid amine solvents and other amine-based solid sorbents. (C) 2016 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cej.2016.08.071

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  10. Development of post-combustion CO2 capture system using amine-impregnated solid sorbent Reviewed

    Numaguchi, Ryohei, Fujiki, Junpei, Yamada, Hidetaka, Chowdhury, Firoz A., Kida, Koji, Goto, Kazuya, Okumura, Takeshi, Yoshizawa, Katsuhiro, Yogo, Katsunori

    13TH INTERNATIONAL CONFERENCE ON GREENHOUSE GAS CONTROL TECHNOLOGIES, GHGT-13   Vol. 114   page: 2304 - 2312   2017

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    Language:Japanese   Publishing type:Research paper (international conference proceedings)   Publisher:ELSEVIER SCIENCE BV  

    A new synthetic polyamine was found as a suitable compound for amine-impregnated solid sorbent through screening of amine compounds with the aid of density functional theory calculations. CO2 capture performance of the sorbent was evaluated on a lab-scale CO2 capture system. The solid sorbent was excellently regenerable even at low temperature condition. Then, Bench-scale demonstration will be started on current project, using the sorbent developed by Research Institute of Innovative Technology for the Earth (RITE) and moving bed system of Kawasaki Heavy Industries, Ltd (KHI). (C) 2017 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2017.03.1371

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  11. Applicability of the K(F)a(v) model in the prediction of fixed bed breakthrough curve Reviewed

    Kawakita, Takashi, Seida, Yoshimi, Murota, Akihiko, Fujiki, Junpei, Furuya, Eiji

    ADSORPTION SCIENCE & TECHNOLOGY   Vol. 35 ( 1-2 ) page: 178 - 193   2017

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:SAGE PUBLICATIONS INC  

    Applicability of the K(F)a(v) model in the prediction/simulation of the breakthrough curve of a fixed bed adsorber was studied through quantitative evaluation of the estimation error of the breakthrough curves calculated by the K(F)a(v) model with those calculated by the phenomenological rigorous adsorption process model. The evaluation was carried out on the basis of dimensionless equations of each model as a function of the Biot number and the parameters of adsorption isotherms used in the phenomenological rigorous adsorption process models. Influence of the non-linearity of the adsorption isotherm and the Biot number to the estimation error of breakthrough curves obtained by the K(F)a(v) model was clarified quantitatively. The application quality and/or degree of reliability of the K(F)a(v) model were clarified systematically.

    DOI: 10.1177/0263617416674013

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  12. A simplified technique to determine intraparticle diffusivity of macro-reticular resins Reviewed

    Kawakita, Takashi, Fan, Huan-Jung, Seida, Yoshimi, Fujiki, Junpei, Furuya, Eiji

    SUSTAINABLE ENVIRONMENT RESEARCH   Vol. 26 ( 6 ) page: 249 - 254   2016.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE BV  

    Both resins and activated carbons are commonly used as adsorbents in water and wastewater treatment. In general, intraparticle diffusion mechanisms within macro reticular resin particles (such as XAD-2000) are different from those in activated carbon particles. Currently, completely mixed batch reactor (CMBR) technique can be used to determine the intraparticle diffusivity for phenolic compounds adsorbed onto activated carbon systems. However, the technology cannot determine the intraparticle diffusivity accurately if the fluid-film resistance is significant, such as synthetic macro-reticular resins. Therefore, this study develops a technique to determine the intraparticle diffusivities of XAD-2000 resin. This paper characterized the concentration decay curves of para-nitrophenol in CMBR to determine effective pore diffusivity (D-P) of the resin. The obtained mean and standard deviation of DP are about 1.1 x 10(-5) and 3.2 x 10(-6) (cm(2) s(-1)), respectively. The technology developed in this study has the advantages of significant chemical saving and easy operation. (C) 2016 Chinese Institute of Environmental Engineering, Taiwan.

    DOI: 10.1016/j.serj.2016.09.001

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  13. Density functional theory study of adsorption of benzothiophene and naphthalene on silica gel Reviewed

    Fujiki, Junpei, Furuya, Eiji

    FUEL   Vol. 164   page: 180 - 185   2016.1

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCI LTD  

    The adsorptive removal of sulfur-containing compounds such as thiophene and dibenzothiophene derivatives from transportation fuels has received extensive attention because of the economical and environmental advantages of adsorptive removal compared to the hydrodesulfurization process. Metal-ion-exchanged zeolites have been known to exhibit high desulfurization performance. However, zeolites induce side reactions because of their strong acidity. Accordingly, silica-based adsorbents showing lower acidity have potential for the desulfurization adsorbent. In this study, to facilitate the development of efficient desulfurization adsorbents, the mechanisms of benzothiophene and naphthalene adsorption onto silica surface were investigated using density functional theory (DFT) in conjunction with experimental approaches. Both the computational and the experimental results suggested that the sites at which benzothiophene and naphthalene adsorb onto silica gel are different types of silanol groups. The adsorption sites of benzothiophene at the initial stage were vicinal-type and/or geminal-type silanols and the final adsorption sites were isolated-type silanols. In addition, the results of DFT calculations suggest that multilayer adsorption might occur. In contrast, the adsorption sites of naphthalene at the initial stage were vicinal-type silanols. Afterward, multilayer adsorption through a T-shape interaction might occur successively on the silica surface. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.fuel.2015.10.013

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  14. The increased CO2 adsorption performance of chitosan-derived activated carbons with nitrogen-doping Reviewed

    Fujiki, J., Yogo, K.

    CHEMICAL COMMUNICATIONS   Vol. 52 ( 1 ) page: 186 - 189   2016

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Highly porous nitrogen-doped activated carbons (NACs) were prepared by the chemical activation of chitosan using alkali carbonates. The NACs exhibited extremely high CO2 capacities of 1.6 mmol g(-1) (15 kPa) and 4.9 mmol g(-1) (100 kPa) at 25 degrees C. Nitrogen atoms doped into carbon frameworks clearly enhanced CO2 adsorption at low partial pressures.

    DOI: 10.1039/c5cc06934c

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  15. Mesoporous Silica Sorbents Impregnated with Blends of Tetraethylenepentamine and Alkanolamine for CO2 Separation Reviewed

    Yamada, Hidetaka, Duc Sy Dao, Fujiki, Junpei, Yogo, Katsunori

    SEPARATION SCIENCE AND TECHNOLOGY   Vol. 50 ( 18 ) page: 2948 - 2953   2015.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS INC  

    Mesocellular silica foam (MSU-F) supports were functionalized via wet impregnation with various amine and alcohol compounds for use as high-capacity adsorbents for CO2 separation. The effect of the amino, hydroxyl, and ether functional groups in the impregnating mixture on the CO2 adsorption capacity was investigated. Chemical adsorption was controlled by the composition of the compounds, and the blending effect on the adsorption performance was dependent on the temperature. MSU-F (30 wt.%) impregnated with a mixture of tetraethylenepentamine (40 wt.%) and aminoethylethanolamine (30 wt.%) showed a high adsorption capacity of 5.4 mmol/g at 333 K for 15 kPa CO2.

    DOI: 10.1080/01496395.2015.1085416

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  16. Enhanced adsorption of carbon dioxide on surface-modified mesoporous silica-supported tetraethylenepentamine: Role of surface chemical structure Reviewed

    Fujiki, Junpei, Yamada, Hidetaka, Yogo, Katsunori

    MICROPOROUS AND MESOPOROUS MATERIALS   Vol. 215   page: 76 - 83   2015.10

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE BV  

    Amine-impregnated mesoporous silica materials were prepared using surface-modified silica supports for CO2 capture, and the effects of the surface chemical structure of the support on the CO2 adsorption performance of surface-modified silica-supported amines were investigated systematically. The thermal stability and CO2 adsorption characteristics of amine-impregnated materials were determined experimentally. The surface modification of mesoporous silicas by particular functional groups leads to increases in thermal stability of loaded amine and CO2 adsorption capacity. In particular, the CO2 adsorption performance in the presence of water vapor was remarkably enhanced by surface modification of the silica support. Computational analyses indicated that increases in the thermal stability of loaded amine and CO2 adsorption capacity were due to the hydrophilicity and electron donativity (nucleophilicity) of introduced functional groups. Compared to non-modified support, CO2 adsorption capacities for surface-modified silica supported amines were increased up to 118% in the absence of water vapor and 182% in the presence of water vapor. It is suggested that the surface structure of supports for amine-impregnated mesoporous silica materials plays an important role in CO2 adsorption performance. (C) 2015 Elsevier Inc. All rights reserved.

    DOI: 10.1016/j.micromeso.2015.05.037

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  17. Carbon Dioxide Adsorption onto Polyethylenimine-Functionalized Porous Chitosan Beads Reviewed

    Fujiki, Junpei, Yogo, Katsunori

    ENERGY & FUELS   Vol. 28 ( 10 ) page: 6467 - 6474   2014.10

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Polyethylenimine-functionalized porous chitosan (PEICS) beads were prepared and their CO2 adsorption performance was evaluated. The CO2 adsorption capacity of PEICS was dependent upon both the amine content and surface area of the functionalized beads. PEICS showed a CO2 adsorption capacity of 2.3 mmol/g at 313 K and 15 kPa of CO2 in the absence of water vapor that considerably increased to 3.6 mmol/g in the presence of water vapor. To rationalize this phenomenon, the CO2 adsorption mechanisms in the absence and presence of water vapor were investigated by diffuse reflectance infrared Fourier transform spectroscopy. The results indicated that the mechanism of CO2 adsorption onto PEICS, in both the absence and presence of water vapor, involved the formation of carbamate. Therefore, the higher CO2 adsorption capacity in the presence of water vapor was attributed to the increased accessibility to amino groups of PEICS, owing to swelling of the polyethylenimine chain and/or chitosan framework upon adsorption of water. The herein reported chitosan-based material displays high CO2 adsorption capacity as well as excellent regenerability and, thereby, shows potential as an adsorbent for CO2 capture.

    DOI: 10.1021/ef500975g

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  18. Simplified Determination Method of Intraparticle Diffusivity Within a Resin Adsorbent from Binary-Component Liquid Adsorption Uptake Curves Reviewed

    Fujiki, Junpei, Noll, Kenneth E., Kawakita, Takashi, Nakane, Yuki, Furuya, Eiji

    TRANSPORT IN POROUS MEDIA   Vol. 102 ( 3 ) page: 349 - 364   2014.4

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:SPRINGER  

    To design and use adsorbers, adsorption kinetic properties must be determined. Several experimental methods and many analysis techniques for determining intraparticle diffusivity have been proposed for single- and multi-component adsorption systems. However, determining values from experimental data of multi-component adsorption systems requires trial and error curve-fitting of experimental with theoretical curves. Furthermore, adsorption calculations of multi-component systems are complicated. For example, displacement adsorption, which causes concentration overshoot phenomena, is troublesome when analyzing experimental data. This report focuses on a simple alternative analysis technique for determining the values of each component from binary-component adsorption uptake curves. This new analysis method was established for binary-component and pore diffusion-controlling adsorption systems, and enables to analyze binary-component uptake curves by use of single-component uptake curves. Treatment of the equilibrium relation is significant when calculating single-component adsorption uptake curves. This method is useful to analyze experimental results, even if the results show concentration overshoot.

    DOI: 10.1007/s11242-014-0278-7

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  19. Development of amine-impregnated solid sorbents for CO2 capture Reviewed

    Yamada, Hidetaka, Dao, Duc Sy, Chowdhury, Firoz A., Fujiki, Junpei, Goto, Kazuya, Yogo, Katsunori

    12TH INTERNATIONAL CONFERENCE ON GREENHOUSE GAS CONTROL TECHNOLOGIES, GHGT-12   Vol. 63   page: 2346 - 2350   2014

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    Language:Japanese   Publishing type:Research paper (international conference proceedings)   Publisher:ELSEVIER SCIENCE BV  

    Based on insight into the amine-CO, chemistry from quantum chemical calculations, we designed and developed energy efficient amine solid sorbents for CO2 capture. Novel amine absorbent were synthesized and used for the wet impregnation into mesoporous materials. The blending effect on the CO2 capture was also investigated for various amine absorbents. The developed amine solid sorbents showed high performance in terms of adsorption capacity, desorption efficiency, and regeneration energy. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-ind/3.0/).

    DOI: 10.1016/j.egypro.2014.11.255

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  20. Polyethyleneimine-functionalized Biomass-derived Adsorbent Beads for Carbon Dioxide Capture under Ambient Conditions Reviewed

    Fujiki, Junpei, Yogo, Katsunori

    CHEMISTRY LETTERS   Vol. 42 ( 12 ) page: 1484 - 1486   2013.12

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:CHEMICAL SOC JAPAN  

    A chitosan-based adsorbent functionalized by polyethyleneimine has been prepared using a freeze-drying method. The adsorbent showed a CO2 adsorption capacity of 2.38 mmol g(-1) at 333 K and 15 kPa of CO2. Furthermore, the adsorption capacity increased up to 3.61 mmol g(-1) in the presence of water vapor. This biomass-derived material is, therefore, a potential low-cost and efficient adsorbent for CO2.

    DOI: 10.1246/cl.130675

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  21. A Simple Determination Method of Adsorption Kinetics from a Liquid Phase Fixed-Bed Breakthrough Curve Reviewed

    Kawakita, Takashi, Fujiki, Junpei, Tsubomatsu, Kenta, Furuya, Eiji

    CHEMICAL ENGINEERING & TECHNOLOGY   Vol. 36 ( 2 ) page: 259 - 267   2013.2

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    The mass transfer zone (MTZ) method using the linear driving force (LDF) approximation is the most common and frequently used technique for the analysis of adsorption kinetics from a fixed-bed breakthrough curve and for adsorptive process design. However, the adsorption kinetics obtained by the MTZ method includes approximations and estimation errors. This report describes a new analytical method for determining the intraparticle diffusivity (D-S) and the fluid-film mass transfer coefficient (k(F)) from an experimental breakthrough curve without using the LDF approximation and empirical correlations for estimating k(F). The proposed method has the advantage of less trial and error on the curve-fitting process and helps better determine DS and k(F). The estimation procedure of the Biot number that represents the ratio of DS to kF is the key of this method. The values of DS and k(F) for the adsorption of phenols onto activated carbon were determined from experimental breakthrough curves using the new analytical method. The results indicate that the method presented in this study yields reliable values.

    DOI: 10.1002/ceat.201200319

    Web of Science

  22. A Simple Determination Method of Adsorption Kinetics from a Liquid Phase Fixed-Bed Breakthrough Curve Reviewed

    Takashi Kawakita, Junpei Fujiki, Kenta Tsubomatsu, Eiji Furuya

    Chemical Engineering Journal   Vol. 36 ( 2 ) page: 259 - 267   2013.2

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    Language:English   Publishing type:Research paper (scientific journal)  

    The mass transfer zone (MTZ) method using the linear driving force (LDF)<br />
    approximation is the most common and frequently used technique for the analysis of adsorption kinetics from a fIxed-bed breakthrough curve and for adsorptive process design. However, the adsorption kinetics obtained by the MTZ method includes approximations and estimation errors. This report describes a new analytical method for determining the intraparticle diffusivity (Ds) and the fluid-fIlm mass transfer coeffIcient (kF) from an experimental breakthrough curve without using the LDF approximation and empirical correlations for estimating kF.The proposed method has the advantage of less trial and error on the curve-fItting process and helps better determine Ds and kF. The estimation procedure of the Biot number that represents the ratio of Ds to kp is the key of this method. The values of Ds and kp for the adsorption of phenols onto activated carbon were determined from experimental breakthrough curves using the new analytical method. The results indicate that the method presented in this study yields reliable values.

    DOI: 10.1 002/ceat.20120031

  23. Experimental determination of fluid-film mass transfer coefficient from adsorption uptake curve Reviewed

    Fujiki, Junpei, Shinomiya, Tatsuru, Kawakita, Takashi, Ishibashi, Seiji, Furuya, Eiji

    CHEMICAL ENGINEERING JOURNAL   Vol. 173 ( 1 ) page: 49 - 54   2011.9

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    To design fixed-bed adsorbers, kinetic parameters such as the fluid-film mass transfer coefficient and intraparticle diffusivity are required. The fluid-film mass transfer coefficient is usually estimated by theoretical and/or empirical equations. Most of the equations were derived from experimental data obtained through techniques other than adsorption. Thus, values estimated from empirical equations are unreliable to use for adsorption systems. The fluid-film mass transfer coefficients (k(F)) were determined experimentally from adsorption uptake curves measured under conditions of low Reynolds numbers. The experimental k(F) values were compared with several empirical equations, such as Carberry equation. The experimental values were found to be always 4/3 of the Carberry and Yoshida et al. equation. The experimental k(F) values were converted into modified k(F) values (=k(F)Delta a(v) = k(F)epsilon(p)/phi(s)). and compared with these equations. The particle void (epsilon(p)) and shape factor (phi(s)) were introduced into the particle surface area (a(V)) for experimental values to modify the area where mass transfer at the fluid-film boundary surrounding adsorbent particles affects. Those k(F) values were nearly identical, suggesting that only mass transfer around particle pores contributes to the k(F) value for adsorbent particles. To represent the mass transfer at fluid film appropriately, k(F)a(V) should be employed, since the error of a(V) is included in k(F) value. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cej.2011.07.035

    Web of Science

  24. Determination of Bed Void Fraction from Fixed Bed Breakthrough Curve

    Junpei Fujiki, Toshiaki Kusaba, Shinji Miyamoto, Eiji Furuya

    J. Chem. Eng.   Vol. 5   page: 202-206   2011.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    Accurate physical and chemical properties of adsorbents are required for the efficient design of fixed bed adsorbers. The bed<br />
    void and particle void are significant physical properties. One of the experimentally determination technique for the bed void is a<br />
    breakthrough curve method. In the present paper, experimental conditions for determining the bed void from breakthrough curve were<br />
    investigated because complex conditions are required. The values of bed void were determined from theoretical elution curve at the<br />
    point of c/c0 = 0.5 under the condition of negligible amount adsorbed. The bed void value determined from elution curve was clearly<br />
    affected by particle void and fluid velocity, and regarded as “apparent” bed void values. For large porosity particles, it was difficult to<br />
    determine the true bed void value due to the effect of penetration into macro pores. Then, the bed void fraction can be determined safely<br />
    from breakthrough curve when particles possessing small particle void are used.

  25. Computational Study on Optimization of a Single Fixed-Bed Adsorber for Separation of a Multi-Component Mixture

    Fujiki Junpei, Furuya Eiji

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   Vol. 44 ( 3 ) page: 164 - 170   2011

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    Language:Japanese  

    Web of Science

  26. Computational Study on Optimization of a Single Fixed-Bed Adsorber for Separation of a Multi-Component Mixture Reviewed

    Fujiki, Junpei, Furuya, Eiji

    JOURNAL OF CHEMICAL ENGINEERING OF JAPAN   Vol. 44 ( 3 ) page: 164 - 170   2011

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:SOC CHEMICAL ENG JAPAN  

    In general, adsorptive separation includes an adsorption and a desorption process in which the separation is affected by the operating conditions of each stage. In this study, the optimum operational conditions for the recovery using a fixed-bed adsorber are investigated numerically. Adsorption/desorption curves for a ternary component mixture are simulated under various operation conditions. The amount and percentage of each component recovered from the mixture are evaluated from the curves. These values are then used in the theoretical determination of the optimal operating conditions. The elution behavior of each component is controlled by adjusting the desorption starting time, whereby efficient recovery of a target component can be achieved by controlling the elution behavior using this technique. The results suggest that sufficient recovery of each component can be performed by use of a single fixed-bed adsorber. The recovery of each component is clearly related to the formation of adsorption zones, and the minimum bed length required for the establishment of constant pattern adsorption zones is an adequate bed length for efficient recovery.

    DOI: 10.1252/jcej.10we295

    Web of Science

  27. Experimental determination of intraparticle diffusivity and fluid film mass transfer coefficient using batch contactors Reviewed

    Fujiki, Junpei, Sonetaka, Noriyoshi, Ko, Kian-Ping, Furuya, Eiji

    CHEMICAL ENGINEERING JOURNAL   Vol. 160 ( 2 ) page: 683 - 690   2010.6

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    The mass transfer properties of adsorbates are generally critical factors for design of a fixed bed adsorber. For single-component systems, the completely mixed batch reactor (CMBR) method is a convenient and frequently used experimental technique for determining mass transfer properties. However, the effect of fluid film mass transfer resistance is neglected in the conventional analytical technique of CMBR method when estimating the intraparticle diffusivity (D(S)). This effect should be considered to determine the diffusivities more accurately. In this study, a new analytical technique was proposed for determination of D(S) and fluid film mass transfer coefficient(k(F)) from one concentration decay curve and it was applied in practical experiments. This technique will be useful to estimate diffusivities when the fluid film mass transfer resistance cannot be regarded as being negligible. Under the experimental conditions of this study, the fluid film mass transfer resistance could be neglected at high stirring speeds (i.e., >200 rpm). Therefore, values of D(S) can be estimated by the conventional technique from kinetic experiments performed at relatively high stirring speeds. On the other hand, values of k(F) obtained by the proposed technique showed a similar tendency to values estimated from Hixson's empirical equation. (c) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cej.2010.04.012

    Web of Science

  28. Computer-aided design of surface modified adsorbent for adsorption of 5-hydroxy-methyl-furfural Reviewed

    Fujiki, Junpei, Fan, Huan-Jung, Hattori, Hideo, Taijma, Kiyohiko, Tsai, Yung-Sen, Furuya, Eiji

    SEPARATION AND PURIFICATION TECHNOLOGY   Vol. 60 ( 3 ) page: 223 - 229   2008.5

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE BV  

    The saccharide containing in high-starch crops could be converted into various products such as 5-hydroxy-methyl-furfural (HMF) which could be used to manufacture plastics. Currently, most of plastics are produced from petroleum feedstock that is one of the main sources of greenhouse gases. Therefore, the use of HMF produced from high-starch crops might reduce the generation of greenhouse gases since the high-starch crops is renewable. For example, D-fructose derived from high-starch crops could be decomposed into HMF in concentrated hydrochloric acid solution. The HMF could be effectively recovered by phenyl groups surface modified silica gel (PMSG) adsorbent during the decomposition process. However, the optimum loading of phenyl groups on the silica gel surface of PMSG would rely on time-consuming experimental works. Therefore, this research focuses on using Molecular Mechanics Simulator based on frontier orbital theory to obtain the optimum loading of phenyl groups on the silica gel in order to reach the maximum adsorption capacity of HMF. The simulated optimum loading of phenyl groups on the silica surface was about 0.5 mequiv./g. This dosage was in consistent with the value obtained from the experimental tests. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.seppur.2007.08.019

    Web of Science

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MISC 12

  1. Measurement of adsorption enhancement by acoustic wave under low pressure

    KOBAYASHI Yoshiaki, NAKAYAMA Masayuki, HUJIKI Junpei, UEDA Yuki, AKISAWA Atsushi

    The Proceedings of Conference of Kanto Branch   Vol. 2019 ( 0 ) page: .   2019

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    Language:Japanese   Publisher:The Japan Society of Mechanical Engineers  

    &lt;p&gt;The authors found that acoustic wave enhanced the adsorption speed of Silica gel under atmospheric pressure. It is interesting to know whether the adsorption enhancement occurs in low pressure conditions because adsorption chillers work at very low pressure of refrigerant. The objective of this study is to investigate the effect of acoustic wave in lower pressure than atmospheric one. The experiments were conducted to measure the adsorption performance with acoustic wave at the pressure of 50kPa and 10kPa. The results showed that the enhancement effect was observed in both cases while the effect at 10kPa was smaller than that at 50kPa. It is estimated that the effect decreases when the pressure becomes lower.&lt;/p&gt;

    CiNii Article

  2. Analysis of Adsorption of Silica Gel Particles in an Oscillating Flow Field Using CFD

    SATO Syu, AKISAWA Atsushi, UEDA Yuki, FUJIKI Junpei

    The Proceedings of the Symposium on Environmental Engineering   Vol. 2019 ( 0 ) page: .   2019

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    Language:Japanese  

    This study focuses on the phenomenon that the adsorption speed is improved by acoustic wave. An experimental study reported the velocity amplitude of acoustic wave is closely related to the adsorption acceleration. The purpose of this study is to elucidate the adsorption acceleration phenomenon by CFD analysis. A model representing a packed bed was created and analyzed. A result showed that the adsorption of a silica gel particle is faster on the upstream side than on the downstream side in uniform flow, which indicates good agreement with the calculation of Mcbain equation. In addition, adsorption analysis with some oscillatory flows reproduced the adsorption enhancement similar to the experimental results. It suggests that the calculation by CFD can estimate the behavior of adsorption in an oscillating flow.

    CiNii Article

  3. Study on the Adsorption Enhancement by Acoustic Wave with Respect to the Effect of Frequency Reviewed

      Vol. 36 ( 3 ) page: 149-156   2019

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    Language:Japanese  

    CiNii Article

  4. CFDを用いた振動流場におけるシリカゲル粒子の吸着挙動解析

    佐藤秀, 秋澤淳, 上道茜, 上田祐樹, 藤木淳平

    日本冷凍空調学会年次大会講演論文集(CD-ROM)   Vol. 2019   2019

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  5. カーボン表面の含窒素官能基への水蒸気吸着モデルの密度汎関数計算

    藤木淳平

    日本吸着学会研究発表会講演要旨集   Vol. 32nd   page: 56   2018.11

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    Language:Japanese  

    J-GLOBAL

  6. 定常流と振動流の共存場における水蒸気吸着速度

    藤木淳平, 中山政行, 上田祐樹, 秋澤淳

    日本吸着学会研究発表会講演要旨集   Vol. 32nd   page: 16   2018.11

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    Language:Japanese  

    J-GLOBAL

  7. Sound Wave Assisted Enhancement of Water Adsorption Kinetics

        page: C333-1-5   2018

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    Language:Japanese  

    CiNii Article

  8. 音波による水蒸気吸着促進機構の解明

    藤木淳平, 中山政行, 上田祐樹, 秋澤淳

    日本冷凍空調学会年次大会講演論文集(CD-ROM)   Vol. 2018   page: ROMBUNNO.C333   2018

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    J-GLOBAL

  9. CO₂回収技術の現状・課題と求められる分離材料

    藤木 淳平, 余語 克則

    Material stage   Vol. 15 ( 1 ) page: 1 - 7   2015.4

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    Language:Japanese   Publisher:技術情報協会  

    CiNii Article

  10. 7-1-2 Energy Balance of Post-Combustion CO_2 Capture using a Novel Solid Sorbent

    GOTO Kazuya, FUJIKI Junpei, YAMADA Hidetaka, NUMAGUCHI Ryohei, KIDA Koji, YOGO Katsunori

    Proceedings of the Annual Conference of The Japan Institute of Energy   Vol. 24 ( 0 ) page: 226 - 227   2015

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    Language:Japanese   Publisher:The Japan Institute of Energy  

    Energy analysis was conducted to precisely evaluate performance of CO_2 capture with a RITE-developed solid sorbent from a coal-fired power plant. The solid sorbent had an advantage of low regeneration energy consumption and the energy efficiency of a power plant with CO_2 capture was estimated to improve by about 2% when the solid sorbent was used in place of a latest liquid amine solvent. The solid sorbent also had a high regeneration performance in low temperature of 60 ℃. That is, there is a high possibility that a low-temperature waste heat was easily used for regeneration of the solid sorbent.

    CiNii Article

  11. Numerical Conditions to Estimate Breakthrough Curves by Use of Overall Mass Transfer Model for Surface diffusion Controlling Systems

      ( 48 ) page: 9-14   2013.3

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    CiNii Article

  12. ステップ応答を用いた充填層空隙率の決定

    草場 敏彰, 宮本 真二, 藤木 淳平, 古谷 英二

    化学工学会 研究発表講演要旨集   Vol. 2010 ( 0 ) page: 67 - 67   2010

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    Language:Japanese   Publisher:公益社団法人 化学工学会  

    CiNii Article

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Presentations 4

  1. Measurement of adsorption enhancement by acoustic wave under low pressure

    KOBAYASHI Yoshiaki, NAKAYAMA Masayuki, HUJIKI Junpei, UEDA Yuki, AKISAWA Atsushi

    The Japan Society of Mechanical Engineers 

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    Event date: 2019

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

    <p>The authors found that acoustic wave enhanced the adsorption speed of Silica gel under atmospheric pressure. It is interesting to know whether the adsorption enhancement occurs in low pressure conditions because adsorption chillers work at very low pressure of refrigerant. The objective of this study is to investigate the effect of acoustic wave in lower pressure than atmospheric one. The experiments were conducted to measure the adsorption performance with acoustic wave at the pressure of 50kPa and 10kPa. The results showed that the enhancement effect was observed in both cases while the effect at 10kPa was smaller than that at 50kPa. It is estimated that the effect decreases when the pressure becomes lower.</p>

    CiNii Article

  2. Analysis of Adsorption of Silica Gel Particles in an Oscillating Flow Field Using CFD

    SATO Syu, AKISAWA Atsushi, UEDA Yuki, FUJIKI Junpei

    The Japan Society of Mechanical Engineers 

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    Event date: 2019

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

    This study focuses on the phenomenon that the adsorption speed is improved by acoustic wave. An experimental study reported the velocity amplitude of acoustic wave is closely related to the adsorption acceleration. The purpose of this study is to elucidate the adsorption acceleration phenomenon by CFD analysis. A model representing a packed bed was created and analyzed. A result showed that the adsorption of a silica gel particle is faster on the upstream side than on the downstream side in uniform flow, which indicates good agreement with the calculation of Mcbain equation. In addition, adsorption analysis with some oscillatory flows reproduced the adsorption enhancement similar to the experimental results. It suggests that the calculation by CFD can estimate the behavior of adsorption in an oscillating flow.

    CiNii Article

  3. Sound Wave Assisted Enhancement of Water Adsorption Kinetics

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    Event date: 2018

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

    CiNii Article

  4. ステップ応答を用いた充填層空隙率の決定

    草場 敏彰, 宮本 真二, 藤木 淳平, 古谷 英二

    公益社団法人 化学工学会 

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    Event date: 2010

    Language:Japanese   Presentation type:Oral presentation (general)  

    Country:Japan  

    CiNii Article

KAKENHI (Grants-in-Aid for Scientific Research) 2

  1. 音場における熱物質移動の物質分離場としての利用

    Grant number:20K04303  2020.4 - 2023.3

    科学研究費助成事業  基盤研究(C)

    藤木 淳平

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    Authorship:Principal investigator 

    Grant amount:\4290000 ( Direct Cost: \3300000 、 Indirect Cost:\990000 )

    本研究課題では、効率的な物質分離場としての音場の利用を目的として、音場内における熱物質移動が吸着現象に与える効果を調査し、音波による吸着促進機構を明らかにすることで、音を利用した物質分離という革新的分離プロセスの開発に繋がる知見を得る。まず、音場内における熱物質移動の効果について実験的に評価を実施した後、音場が吸着現象に与える効果に関して、実験ならびに理論解析により明らかにすることで、音場の物質分離場としての有効性を示す。

  2. Development of carbon-based high performance water adsorbent for adsorption heat pump/desiccant cooling

    Grant number:16K18357  2016.4 - 2020.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Young Scientists (B)

    Fujiki Junpei

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    Authorship:Principal investigator 

    Grant amount:\4290000 ( Direct Cost: \3300000 、 Indirect Cost:\990000 )

    In this study, the adsorption mechanisms of water vapor onto nitrogen-doped carbon was investigated for further development of carbonaceous adsorbent for adsorption heat pump/desiccant cooling (AHP/DC) systems. A density functional theory calculation study based on X-ray photoelectron spectroscopy analyses of nitrogen-doped carbons indicated that pyridinic, amide, and quaternary N groups might be effective for low-pressure water adsorption. The water adsorption capacities of the prepared carbons at the low-pressure region (P/P0 < 0.1) were dependent on the surface density of nitrogen or oxygen functional groups. In addition, the shape of water isotherms preferable for AHP/DC was observed for the carbons with an appropriate surface density of nitrogen functional groups. According to the results of the reconsideration for synthesis procedure, microwave-assisted activation of chitosan gel using appropriate alkali carbonate gave nitrogen-doped carbon with high water adsorption capacity.