Faculty Profiles - KAWAJIRI Yoshiaki

Papers - KAWAJIRI Yoshiaki

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A concurrent approach for determining binary isotherm and optimizing moving bed adsorber for solid amine adsorbent in the coexistence of CO2 and H2O Reviewed International journal

Okumura T., Yamaguchi T., Kawajiri Y.

Separation and Purification Technology Vol. 359 2025.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Separation and Purification Technology

A concurrent approach, which allows for determining multi-component equilibrium isotherms and designing a multi-component adsorption process within a realistic amount of time and effort, is demonstrated for the first time in a moving bed process using an amine-impregnated solid adsorbent in the presence of CO2 and H2O. The proposed approach extracts measurement points for the binary isotherms from the temperature and partial pressure regions that exist in the optimized process from all potential combinations of CO2 partial pressure, H2O partial pressure, and temperature. At the extracted points, the equilibrium adsorption amounts were measured experimentally to obtain multi-component adsorption amount data, with which the binary isotherm parameters were determined by the Tikhonov regularization. The accuracy of the equilibrium isotherm was further improved iteratively by repeating the steps described above. The proposed approach enables us to determine the binary interactions parameters in the isotherm model reducing the multi-component measurement points only to 12, while obtaining the optimized process operation at the same time.

DOI： 10.1016/j.seppur.2024.130567

Scopus

Process Robustness Evaluation for Various Operating Configurations of Multi-column Chromatography Processes with Nonlinear Isotherm Reviewed International journal

Kensuke Suzuki, Tomoyuki Yajima, Yoshiaki Kawajiri

Chemical Engineering Science Vol. (in press) 2025.2

Estimation and Uncertainty Quantification of Solvent Strength Parameters in Gradient Elution of Chromatography Using Sequential Monte Carlo Method Reviewed International journal

Yuan Ziting, Kensuke Suzuki, Yota Yamamoto, Tomoyuki Yajima, Yoshiaki Kawajiri

Processes Vol. 13 ( 1 ) page： 114 2025.1

Modeling and uncertainty quantification of CO<inf>2</inf> absorption process using phase separation solvent Reviewed International journal

Sota Yuyama, Hiroshi Machida, Tomoyuki Yajima, Yoshiaki Kawajiri

Chemical Engineering Science Vol. 298 page： 120348 2024.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Absorption using an amine solvent is one of the primary means for capturing CO2 from many combustion sources such as fossil fuel power plants. CO2 capture systems by absorption need a large amount of thermal energy to strip CO2 from the amine solvent. In recent years, absorption using a phase separation solvent, which forms two phases when CO2 is absorbed, has been demonstrated as a promising technique to reduce the energy consumption. In this study, we examine several process models for the CO2 absorption process using a phase separation solvent, and quantify the uncertainty of the model parameters. We estimated model parameters, including equilibrium and mass transfer parameters, from two sources of experimental data: solubility tests, as well as lab-scale absorber tests. Model parameters were estimated by Bayesian inference using the Markov chain Monte Carlo method. The proposed approach successfully quantified the uncertainties of the model parameters.

DOI： 10.1016/j.ces.2024.120348

Scopus

Surrogate model optimization of vacuum pressure swing adsorption using a flexible metal organic framework with hysteretic sigmoidal isotherms Reviewed International coauthorship International journal

Yuya Takakura, Suryateja Ravutla, Jinsu Kim, Keisuke Ikeda, Hiroshi Kajiro, Tomoyuki Yajima, Junpei Fujiki, Fani Boukouvala, Matthew Realff, Yoshiaki Kawajiri

International Journal of Greenhouse Gas Control Vol. 138 page： 104260 2024.10

A parameter estimation method for chromatographic separation process based on physics-informed neural network Reviewed International journal

Tao Zou, Tomoyuki Yajima, Yoshiaki Kawajiri

Journal of Chromatography A Vol. 1730 page： 465077 2024.8

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Chromatographic separation processes are most often modeled in the form of partial differential equations (PDEs) to describe the complex adsorption equilibria and kinetics. However, identifying parameters in such a model requires substantial computational effort. In this work, a novel parameter estimation approach using a Physics-informed Neural Network (PINN) model is developed and tested for a binary component system. Numerical accuracy of our PINN model is confirmed by validating its simulations against those of the finite element method (FEM). Furthermore, model parameters in the kinetic model are estimated by the PINN model with sufficient accuracy from the observed data at the column outlet, where parameter fitting error can be reduced by up to 35.0 % from the conventional method. In a comparison with the conventional numerical method, our approach can reduce the computational time by up to 95 %. The robustness of the PINN model has also been demonstrated by estimating model parameters from noisy artificial experimental data.

DOI： 10.1016/j.chroma.2024.465077

Scopus

PubMed

A comprehensive analysis of ammonia synthesis over a commercial iron-based catalyst using differential and integral reactor models Reviewed International journal

El-Shafie M., Harada H., Yajima T., Tsuda S., Inazu K., Kawajiri Y.

International Journal of Hydrogen Energy Vol. 58 page： 1009 - 1019 2024.3

Language：English Publishing type：Research paper (scientific journal) Publisher：International Journal of Hydrogen Energy

The current study describes a novel approach for analyzing the ammonia production rate over a commercial catalyst, AmoMax®10RS. Differential and integral reactor models were developed based on the power rate law expression. The integral reactor model equations were solved using the gPROMS package to predict the ammonia synthesis rate, gas temperature, and velocity profiles. The significant impacts of the inlet gas temperature, heater temperature, H2/N2 ratio, and catalyst bed loading on the ammonia synthesis were revealed by simulations and compared with experimental data. The simulation results showed that higher inlet gas temperatures enhanced the ammonia synthesis rate. Furthermore, the H2/N2 ratio affected the rate of ammonia synthesis and catalyst activity, and the optimum ammonia synthesis rate was achieved at an H2/N2 ratio of 2. The simulation model not only predicted the rate of ammonia synthesis, but the integral model fitted the experimental measurements well.

DOI： 10.1016/j.ijhydene.2024.01.173

Scopus

Parameter estimation for reactive chromatography model by Bayesian inference and parallel sequential Monte Carlo Reviewed International journal

Sugiyama H., Yamamoto Y., Suzuki K., Yajima T., Kawajiri Y.

Chemical Engineering Research and Design Vol. 203 page： 378 - 390 2024.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Chemical Engineering Research and Design

Reactive chromatography overcomes many disadvantages of conventional separation processes by improving yields and reduces costs by combining reaction and separation in a single operation. Model-based optimization is essential to realize industrial applications of this process. Parameters in the model must be estimated accurately, and evaluating the uncertainty of the model parameters is crucial. However, uncertainty quantification of model parameters has not been performed for reactive chromatography processes. In this study, we propose an approach to estimate the parameter uncertainty of reactive chromatography processes using Bayesian inference and parallel sequential Monte Carlo. As an example, the esterification synthesis of acetic acid and methanol catalyzed by a cation exchange resin was considered. Parameter estimation was performed using a reactive chromatography experiment and a non-reactive experiment in which only the products were injected. The results of the analysis showed that using both the reactive and non-reactive chromatography experimental data simultaneously improved the accuracy of the estimation. In addition, correlations between some parameters were revealed.

DOI： 10.1016/j.cherd.2024.01.056

Scopus

Model-based techno–economic analysis of an integrated synthetic natural gas production system with direct air capture and water electrolysis Reviewed International coauthorship International journal

Harada H., Sinha A., Yajima T., Kawajiri Y.

Carbon Capture Science and Technology Vol. 10 2024.3

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon Capture Science and Technology

In this study, a techno-economic analysis is performed for an integrated system of carbon capture and utilization (CCU). The proposed system utilizes CO2 captured by a direct air capture (DAC) process using a metal–organic framework adsorbent. The captured CO2 is converted into a methane product, or synthetic natural gas (SNG), using hydrogen produced by water electrolysis. Rigorous mathematical models are used for the mass and energy balances in the major components of the proposed integrated system, allowing us to estimate the capital and operating costs and energy consumption. A sensitivity analysis is also performed to identify model parameters that significantly affect the SNG cost. Our analysis indicates that the thermal and electrical energies required to produce SNG are 0.409 MJ/Nm3-SNG and 19.6 kWh/Nm3-SNG, respectively, and the cost of SNG is within the range of 1.43–2.60 $/Nm3-SNG.

DOI： 10.1016/j.ccst.2023.100181

Scopus

Modeling of moving bed CO2 capture process using amine solid adsorbent and its validation using pilot plant test data Reviewed

Takehi Okumura, Takahiro Yamaguchi, Shohei Nishibe, Ryohei Numaguchi, Yoshiaki Kawajiri

International Journal of Greenhouse Gas Control Vol. 133 page： 104094 2024.3

Model-based techno-economic analysis for integrated synthetic natural gas production system using atmospheric CO<inf>2</inf> captured by metal organic framework adsorbent Reviewed International coauthorship International journal

Hideki Harada, Anshuman Sinha, Tomoyuki Yajima, Yoshiaki Kawajiri

Computer Aided Chemical Engineering Vol. 53 page： 2023 - 2028 2024.1

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings)

This study proposes an integrated system of carbon capture and utilization (CCU) to produce synthetic natural gas (SNG), and performs a techno-economic analysis. The proposed system employs a direct air capture (DAC) process using a metal organic framework adsorbent and converts the captured CO2 into CH4 product using H2 produced by water electrolysis. Mass and energy balances in the main components of the system are described by rigorous mathematical models, enabling us to evaluate the capital and operating costs and energy consumption. In addition, a sensitivity analysis is carried out to find model parameters that influences the SNG cost.

DOI： 10.1016/B978-0-443-28824-1.50338-0

Scopus

Parameter Estimation for Reactive Chromatography Model by Bayesian Inference and Parallel Sequential Monte Carlo Reviewed International journal

Hikari Sugiyama, Yota Yamamoto, Kensuke Suzuki, Tomoyuki Yajima, Yoshiaki Kawajiri

Chemical Engineering Research and Design 2024.1

A Comprehensive Analysis of Ammonia Synthesis over a Commercial Iron-Based Catalyst using Differential and Integral Reactor Models Reviewed International journal

Mostafa El-Shafie, Hideki Harada, Tomoyuki Yajima, Shoichi Tsuda, Koji Inazu, Yoshiaki Kawajiri

International Journal of Hydrogen Energy 2024.1

Mapping adsorbent properties to optimal process performance of two-bed temperature swing adsorption by superstructure optimization Reviewed International journal

Yuchi Sugiura, Tomoyuki Yajima, Yoshiaki Kawajiri

Chemical Engineering and Processing - Process Intensification Vol. 191 2023.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Temperature swing adsorption (TSA) is one of the promising separation techniques for large-scale CO2 capture, and many adsorbents are being developed today. However, it is difficult to identify the optimal operating configurations of multi-bed TSA process to fully utilize the potential of a given adsorbent. This is because optimal operating conditions and cycle configurations are highly dependent on the adsorbent properties. In this work, we propose a comprehensive approach that maps adsorption isotherms to the optimal multi-bed TSA operation identified from various alternatives. A case study for separation of CO2 and N2 is presented where isotherm properties of the adsorbent are parameterized to analyze the influence on the optimal TSA operating cycle configurations and process performance. Our analysis shows that the optimal throughput increases by 68% when the CO2 selectivity is doubled, and 96% when the CO2 selectivity and capacity are both doubled. Furthermore, the frequency of the reflux operations and the cycle time in the optimal operating cycle are found to be dependent on the CO2 capacity.

DOI： 10.1016/j.cep.2023.109438

Scopus

Modeling, parameter estimation, and uncertainty quantification for CO2 adsorption process using flexible metal–organic frameworks by Bayesian Monte Carlo methods Reviewed International journal

Saeki Sugimoto, Yuya Takakura, Hiroshi Kajiro, Junpei Fujiki, Hossein Dashti, Tomoyuki Yajima, Yoshiaki Kawajiri

Journal of Advanced Manufacturing and Processing 2023.7

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

Abstract

Flexible metal–organic frameworks (flexible MOFs) are considered promising adsorbents for CO<sub>2</sub> capture, some of which have sigmoidal isotherm shapes that allow adsorption and desorption operations within a narrow partial pressure range. Nevertheless, modeling of adsorption processes employing flexible MOFs remains a challenge due to the unique isotherm shapes and kinetics. In this work, a Bayesian estimation framework is applied sequentially to handle two experimental data sets: isotherm and breakthrough measurements. The computational challenge for estimating the isotherm and kinetic parameters from the isotherm measurements and breakthrough experiments is resolved by Markov chain and sequential Monte Carlo methods. The uncertainties of the model parameters are obtained as probability distributions.

DOI： 10.1002/amp2.10165

Subambient temperature swing adsorption utilizing cold energy from liquefied natural gas Reviewed International journal

Yukino Kuwabara, Takaya Tokunaga, Tatsuya Moriyama, Masahisa Koizumi, Shiho Mizuno, Takuro Hagino, Shinpei Kusaka, Ryotaro Matsuda, Tomoyuki Yajima, Yoshiaki Kawajiri

International Journal of Greenhouse Gas Control Vol. 126 2023.6

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

This study proposes a CO2 capture process by temperature swing adsorption (TSA) using latent heat of evaporation for liquefied natural gas (LNG) as a cold energy source, which is currently unused and discarded into seawater. The proposed subambient process has several advantages: (1) the total energy cost can be saved by the LNG cold energy; (2) the equilibrium capacity of CO2 at subambient temperature can be increased substantially; and (3) water in the flue gas which would lead to deterioration of the adsorbent can be removed by a pretreatment step utilizing LNG cold energy. For the adsorbent in the TSA system, zeolite 13X, MIL-101, UiO-66, and CPL-1, which are considered effective for CO2 adsorption in the subambient, were considered and adsorption isotherm data were obtained at subambient conditions. Comparisons of these adsorbents were carried out using a rigorous dynamic model of the TSA process. It was found that CPL-1 gives a high recovery rate of 70% and purity of 95%. It was also found that the proposed system has the potential to capture up to 6% of the CO2 emitted from Japan.

DOI： 10.1016/j.ijggc.2023.103910

Scopus

Breakthrough analysis for parameter estimation of CO2 adsorption on pelletized flexible metal–organic framework Reviewed International journal

Junpei Fujiki, Hiroshi Kajiro, Yuya Takakura, Tomoyuki Yajima, Yoshiaki Kawajiri

Chemical Engineering Journal Vol. 460 2023.3

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Pellets of elastic layer-structured metal–organic framework-11 (ELM-11), one of the flexible metal–organic frameworks (MOFs), were prepared by mixing ELM-11 powder with a cellulose binder, and the CO2 adsorption behavior of ELM-11 pellets in a fixed-bed adsorber was analyzed to estimate equilibrium and kinetic parameters. Adsorption breakthrough tests were performed under various conditions for the simulated flue gas (20 % CO2–80 % N2) of a blast furnace gas in addition to CO2 isotherm measurements. Experimental CO2 adsorption isotherms on ELM-11 followed a weighted dual-site Langmuir equilibrium model well. The breakthrough analysis results by numerical calculation using the equilibrium model suggested that the gate-opening pressure of ELM-11 shifted to a lower pressure through repeated breakthrough tests. The CO2 adsorption kinetics on ELM-11 pellets agreed well with the linear-driving-force model. Furthermore, CO2 adsorption behavior under various conditions was described well by a mathematical model using a constant value of the mass transfer coefficient under the condition of this study, which was validated against additional experimental data. In addition, it was found that the mass transfer becomes slow under certain conditions that the driving force of the phase transition of ELM-11 is smaller than a threshold, where the amount of CO2 adsorbed on the breakthrough tests did not reach the equilibrium capacity of CO2, which may because the rate-limiting step may be dependent on the CO2 partial pressure and temperature.

DOI： 10.1016/j.cej.2023.141781

Scopus

Modeling of Nucleation, Growth, and Dissolution of Paracetamol in Ethanol Solution for Unseeded Batch Cooling Crystallization with Temperature-Cycling Strategy Reviewed International coauthorship International journal

Youngjo Kim, Yoshiaki Kawajiri, Ronald W. Rousseau, Martha A. Grover

Industrial & Engineering Chemistry Research Vol. 62 ( 6 ) page： 2866 - 2881 2023.2

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

Controlling crystal size distributions is critical to ensure the quality of products and operational efficiency for downstream processing. In batch cooling crystallization, temperature cycling strategies are often employed to control the crystal size distribution and minimize fines. Optimizing the complex operation of this strategy, where crystallization and dissolution occur in a single batch run, remains a challenge. For this problem, we develop a model of the process by a population balance considering nucleation, growth, and dissolution of crystals. In a case study of paracetamol in ethanol, the parameters in the population balance model were estimated from multiple experimental runs. The developed model was validated against additional experimental data sets, where the concentration and crystal size distributions of the final crystal products were predicted successfully. R2 values are greater than 0.96 in all cases.

DOI： 10.1021/acs.iecr.2c03465

Scopus

Estimation and statistical analysis of model parameters using sequential Monte Carlo for phenol and p-cresol separation Reviewed International journal

Ziting Yuan, Yota Yamamoto, Tomoyuki Yajima, Yoshiaki Kawajiri

Journal of Chromatography A Vol. 1688 2023.1

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Model-based design and optimization methods facilitate industrial applications of chromatographic separations. The uncertainty of the model parameters must be quantified to ensure robust design and control. In this study, we propose an approach using the sequential Monte Carlo (SMC) method based on the Bayesian principle to estimate the uncertainty of the parameters. The linear driving force model for separation of phenol and p-cresol was considered as an example. By comparing different injection tests, we confirmed the necessity of pulse injection and breakthrough experiments to estimate parameters with sufficient accuracy and precision. We also found that modeling observation errors carefully is critical to obtain reasonable estimation.

DOI： 10.1016/j.chroma.2022.463703

Scopus

PubMed

Modeling and estimating kinetic parameters for CO<inf>2</inf> methanation from fixed bed reactor experiments Reviewed International journal

Tsuboi T., Yasuda S., Choi C., Zhang W., Machida H., Norinaga K., Yajima T., Kawajiri Y.

Journal of Advanced Manufacturing and Processing Vol. 5 ( 1 ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Advanced Manufacturing and Processing

CO2 methanation, which converts CO2 and hydrogen into methane as fuel, is one of the promising candidates for the development of CO2 utilization technologies. Recently, a highly active catalyst made of Ni/ZrO2 for methanation has been developed, and is currently investigated as a potential use in a high-performance reactor. However, design of reactor must be carried out carefully, since this reaction is highly exothermic, which may cause reactor runaway and deterioration of catalysts. For this problem, a mathematical model that can predict the behavior inside the reactor is necessary. In this work, we consider the methanation reaction of CO2 in a reactor model and estimate the kinetic parameters in the reaction rate model from experimental data. In the parameter estimation using literature values and Tikhonov regularization, eight kinetic parameters in the rate equations were identified from 64 data points with a wide range of conditions. We confirm that molar fractions at the reactor exit predicted by this reactor model are in good agreement with the experimental results. Furthermore, the developed model was validated to predict the compositions and temperature that were not used in the estimation. We expect the developed model will be a powerful tool for the reactor design.

DOI： 10.1002/amp2.10145

Scopus

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Papers - KAWAJIRI Yoshiaki