Faculty Profiles - NORINAGA Koyo

Papers - NORINAGA Koyo

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Changes in Intermolecular Interaction Forces Inducing Glass Transition Determined by Three-Dimensional Aggregated Structural Models of Coal Reviewed Open Access

Hata Yuki, Hayashizaki Hideyuki, Matsuzaki Yoichi, Morimoto Masato, Takanohashi Toshimasa, Takahashi Takafumi, Kanehashi Koji, Norinaga Koyo

ISIJ International Vol. 63 ( 9 ) page： 1433 - 1440 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan

<p>The three-dimensional aggregated structural models of two types of coals, A and B, were constructed. It is found that the density and the <i>T</i><sub>g</sub> of the models were qualitatively consistent with values obtained experimentally. The <i>T</i><sub>g</sub> of coals A and B calculated using the model structures are 315°C and 328°C, respectively. The effect of temperature on the distribution of cohesive energy was quantitatively elucidated using the three-dimensional aggregated structural models. The cohesive energy density (CED) of coal B was greater than that of coal A at temperatures <<i>T</i><sub>g</sub>. However, at temperatures ><i>T</i><sub>g</sub>, the CED of coal A is comparable to that of coal B. This implies that the molecules are more strongly aggregated in coal B than in coal A at low temperatures due to hydrogen bonding, and the intermolecular interaction is considered to have gradually relaxed above the <i>T</i><sub>g</sub>. It is concluded that differences in the molecular and cohesive structures of the coals led to differences in the distribution of van der Waals energy and electric energy at different temperatures. The van der Waals energy changed from attraction to repulsion at about 450°C and 285°C in coal A and B, respectively. Electric energy remained an attractive force as the temperature increased. The mechanism of the 13°C difference in the calculated <i>T</i><sub>g</sub> of each coal can be explained by the temperature change in the intermolecular force distribution. Therefore, this three-dimensional aggregated structural model can be used to understand the thermal behavior of aggregated molecules, such as coal thermoplasticity.</p>

DOI： 10.2355/isijinternational.ISIJINT-2022-547

Experimental Study on Quantitative Evaluation of Transferable Hydrogen in Possible Raw Materials for Metallurgical Cokes Including Bituminous, Sub-bituminous, Lignite Coals and Biomass Reviewed Open Access

Zhang Lijuan, Uehara Yusuke, Nakamura Maki, Choi Cheolyong, Liu Chong, Machida Hiroshi, Hayashizaki Hideyuki, Kawai Yuya, Hata Yuki, Norinaga Koyo

ISIJ International Vol. 63 ( 9 ) page： 1441 - 1450 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan

<p>Researchers have thoroughly studied coal pyrolysis over a long period, while the analysis of volatile evolution and the chemical structural changes of solid char were carried out individually in most of the studies. In this work, we quantified the chemical reactions to explain the different physical phenomena, such as softening and caking properties, exhibited by different ranks of coals during pyrolysis. Four typical carbonaceous feedstocks (bituminous, sub-bituminous, lignite coals, and biomass) were selected as test samples. The authors analyzed the generated gas during pyrolysis by using a quadrupole mass spectrometer (Q-MS) and the chemical structure of the pyrolyzed char via spectroscopic methods (NMR, FT-IR, CHNS, and XPS) to gain new insights into the pyrolysis mechanism of the carbonaceous feedstocks. Transferable hydrogen was introduced to define the hydrogen used to stable the free radicals formed during pyrolysis, which can be obtained by quantifying the conversion routes of hydrogen. The hydrogen released for the growth of aromatic clusters has three pathways, namely, (1) consumption by the hydrodeoxygenation reaction to produce pyrolytic vapor, (2) release as gaseous H<sub>2</sub>, and (3) transferable hydrogen. The calculation shows that the amount of transferable hydrogen during pyrolysis decreases as the coal rank gets lower. For pyrolysis up to 500°C, the amount of transferable hydrogen is 3.96, 2.32, and 1.36 mol/kg-coal for bituminous, sub-bituminous, and lignite coals, respectively. On the other hand, the transferable hydrogen of biomass needs to be further considered in terms of the effect of cellulose and hemicellulose’s structure.</p>

DOI： 10.2355/isijinternational.ISIJINT-2022-517

Large-eddy simulation of the non-adiabatic reforming process of hot coke oven gas using a flamelet-based approach Open Access

YU Panlong, YADAV Sujeet, HU Yong, KAI Reo, NORINAGA Koyo, KUROSE Ryoichi, WATANABE Hiroaki

Journal of Thermal Science and Technology Vol. 18 ( 2 ) page： 23-00279 - 23-00279 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers and The Heat Transfer Society of Japan

<p>Large-eddy simulation (LES) coupling with a non-adiabatic flamelet progress variable (NA-FPV) approach with reconstructed flamelet chemistry states is employed to simulate the hot coke oven gas (HCOG) reforming process. In the NA-FPV model, the chemistry states are first computed based on the correction factor for enthalpy defects and then modified by substituting the species statistics in the maximum heat loss state with those of less heat release to compensate for the unphysical results. The numerical results of LES coupling this NA-FPV model have been compared with the experimental measurement data in terms of temperature and yields, and reasonable agreements have been achieved. According to the LES results, it is seen O<sub>2</sub> only participates in the combustion process in the upper stream and the combustion process which mainly consumes H<sub>2</sub> and CO is to provide the other reforming process with heat and steam. In the upper and middle streams, the main HCOG jet is wrapped by the swirling high-temperature combustion products, and the reforming process primarily takes place by consuming CH<sub>4</sub>, polycyclic aromatic hydrocarbons (PAHs), and steam, while considerable H<sub>2</sub>, CO, and CO<sub>2</sub> are produced. It is observed that accompanying the reforming process C<sub>2</sub>H<sub>2</sub> is generated and it peaks in the middle stream, thus it is considered soot is formed in the complex reactions.</p>

DOI： 10.1299/jtst.23-00279

Development of a kinetic model for CO<sub>2</sub> methanation over a commercial Ni/SiO<sub>2</sub> catalyst in a differential reactor Reviewed

Khuenpetch, A; Choi, C; Reubroycharoen, P; Norinaga, K

ENERGY REPORTS Vol. 8 page： 224 - 233 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Energy Reports

Development of a kinetic model for CO2 methanation over a commercial nickel catalyst was performed to consider pathways of CO2 conversion via Sabatier and RWGS reactions. H2/CO2 ratio in the feed gas composition was varied at the stoichiometry of the Sabatier reaction assuming a fictitious CO2 conversion of 0 to 0.7. Non-stochiometric gas feeding and the addition of product gases, i.e., methane and steam, were also considered to examine reaction orders and inhibition effects. The kinetic tests were carried out at 300–350 °C and 0.1–0.9 MPa. GHSV corresponded to 37,494 h−1. The stable activity was achieved by forcibly stressing the catalyst under the equilibria at 500 °C for 35 h. The kinetic measurements were conducted at an isothermal differential fixed bed reactor in the absence of heat and mass transport limitations. The methanation reaction was first fitted with the power law and LH approaches by considering the Sabatier reaction. Then, the RWGS reaction was added to consider CO formation using the power law models. The results showed a better fitting of experimental observations by using the LH expression with the formation of formyl as RDS and the power law model with inhibiting influence of water.

DOI： 10.1016/j.egyr.2022.10.194

1-07 Highly selective electrochemical reduction of CO<sub>2</sub> into CO achieved via indium thin-layer on zinc nanosheet over Cu foam Reviewed

SIRISOMBOONCHAI Suchada, MACHIDA Hiroshi, NORINAGA Koyo

Proceedings of Conference on Coal Science Vol. 59 ( 0 ) page： 14 - 15 2022.10

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

<p>Electrochemical reduction (ECR) of CO<sub>2</sub> is one of the most promising technologies for electrification of the conversion process of CO<sub>2</sub> to obtain valuable chemicals/fuels without extreme condition requirements. Here, the performance of an electrocatalyst with the three-dimensional structure of indium thin-layer dispersed completely over Zn nanosheet structure growing on Cu/Cu foam (CF) is presented. This electrocatalyst was fabricated by electrodeposition of In and Zn over CF and exhibited a superior reduction at a Faradaic efficiency of 93.7% and an excellently long duration of 100h. Furthermore, owing to the synergy of the In thin layer, the Zn nanosheets provided a high active surface area and strong mechanical robustness during the reaction. Moreover, the InZnCu/CF catalyst presented low input energy of 2.90MWh for converting one ton of CO<sub>2</sub> into CO, that is an encouraging achievement toward a feasible large scale applications.</p>

DOI： 10.20550/jiesekitanronbun.59.0_14

2-26 Evaluation of lignin conversion into valuable chemicals via hydrogenation combined with fast pyrolysis processes Reviewed

ZHANG Lijuan, SIRISOMBOONCHAI Suchada, MACHIDA Hiroshi, NORINAGA Koyo

Proceedings of Conference on Coal Science Vol. 59 ( 0 ) page： 80 - 81 2022.10

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

<p>Lignin, as an important part of lignocellulosic biomass, should give more attention to promote the utilization of biomass. Being a polymer composed of phenylpropane units, lignin is regarded as a promising candidate for obtaining olefins and aromatic compounds. Herein, thermo-catalytic hydrogenation was used as a pretreatment process of lignin, after that more olefins and aromatics were obtained from the solid hydrogenated lignin via fast pyrolysis. This two-stage valorization process was techno-economically evaluated by Aspen plus and compared with the conventional fast pyrolysis process of lignin. Process simulation based on the experiment data suggested the significant economic benefit of this strategy to convert lignin into valuable chemicals, like olefins, aromatics, and phenolics.</p>

DOI： 10.20550/jiesekitanronbun.59.0_80

2-06 Numerical simulation of polycyclic aromatic hydrocarbons and soot formations from coal volatiles in a Two-stage Entrained Flow Gasifier with detailed chemistry Reviewed

LI Tailin, CHOI Cheolyong, FUKUMOTO Kazui, MACHIDA Hiroshi, NORINAGA Koyo

Proceedings of Conference on Coal Science Vol. 59 ( 0 ) page： 40 - 41 2022.10

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

<p>CO<sub>2</sub> recirculation in the oxy-fuel Integrated Coal Gasification Combined Cycle (IGCC) system is essential for continuous use of coal in the future. This study presents a detailed kinetic investigation into coal gasification under O<sub>2</sub>-N<sub>2</sub> and oxy-fuel (O<sub>2</sub>-H<sub>2</sub>O, O<sub>2</sub>-CO<sub>2</sub>) gasifying agents. The effects on polycyclic aromatic hydrocarbons (PAHs) and soot formation in the reductor of a two-stage entrained flow gasifier were simulated using CHEMKIN. The detailed chemical kinetic model includes 202 species, 1,351 gas-phase reactions, and 101 surface reactions. The numerical results showed that the oxy-fuel blown modes promoted tar reforming to complete elimination at 1,200°C (<1.5mg/Nm<sup><sub>3</sub></sup>). Because of a different tar conversion behavior, the O<sub>2</sub>-H<sub>2</sub>O blown mode provided a more potent tar-yield inhibition. In the case of soot formation, the amount of soot decreased under oxy-fuel blown modes. This behavior resulted from hydrogen abstraction and C<sub>2</sub>H<sub>2</sub> addition (HACA) surface growth, and nucleation rate reductions. Also, the PAHs condensation had a weak effect on the soot formation rate among different gasifying agents. This study promises a better gasification process design for a two-stage entrained flow gasifier in an oxy-IGCC system.</p>

DOI： 10.20550/jiesekitanronbun.59.0_40

Analysis of Low Temperature-oxidation Mechanism for Coal by Using High Resolution Solid State NMR and Gas Analysis Reviewed Open Access

Hata Yuki, Takahashi Takafumi, Sakuragi Kiyoshi, Yamaguchi Akimasa, Saito Koji, Norinaga Koyo

Tetsu-to-Hagane Vol. 108 ( 10 ) page： 693 - 702 2022.10

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan

<p>Spontaneous combustion property of low rank coal, an important issue in coal science, has been substantially studied. However, there are few studies discussing quantitative chemical structural changes of coal during its oxidization under 80°C.</p><p>In the present study, low rank coals of X and Y were oxidized in an adiabatic vessel where their temperature was increased due to spontaneous heating. Generated gases of H<sub>2</sub>O, CO<sub>2</sub>, and CO were analyzed by gas chromatography during the oxidization. As a result, coal Y, which was more easily oxidized than coal X, showed higher generation rate of CO<sub>2</sub> and CO gas than coal X. Some of H<sub>2</sub>O generated during the oxidation must have been remained in coal as adsorbed water since the amount of water in the oxidized coal was higher than that before oxidation.</p><p><sup>13</sup>C MAS NMR spectra of coal X and Y indicated that and chemical reaction producing carboxyl acid in coal Y is more activated than that in coal X. Furthermore, the number of aromatic carbon was reduced during the oxidization. It implied that the aromatic carbon might contribute to oxidization reaction. Coal Y before oxidation had smaller number of aromatic carbon per one cluster than coal X, while the structural parameters of aliphatic carbons in coal X and Y were almost the same. It is considered that smaller number of aromatic carbons more destabilize carbon radicals to generate “active” species. Such active carbon radicals are suggested to also react with oxygen in the atmosphere.</p>

DOI： 10.2355/tetsutohagane.TETSU-2022-010

Pretreatment of lignin by electrochemical hydrogenation to enhance the olefins and aromatic products during rapid pyrolysis Reviewed Open Access

Zhang, LJ; Sirisomboonchai, S; Choi, C; Machida, H; Norinaga, K

JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS Vol. 166 2022.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Analytical and Applied Pyrolysis

Lignin is one of the most promising biopolymers for producing hydrocarbons and aromatic compounds in nature. Electrochemical conversion of lignin is regarded as an attractive technology for producing various aromatic chemicals which are generally derived from fossil fuels. The author reports an electrochemical approach for hydrogenating alkaline lignin (AL), which uses relatively low-cost Ni foam as a working electrode under alkali electrolyte. The primary factors (such as power input, reactor type, temperature, reaction time, catalysts, and electrode substrates) of electrochemical hydrogenation were used to control the products' yield and features. The redox characteristics of the reaction system were directly compared with the cyclic voltammetry measurement under different parameters. After electrochemical hydrogenation (ECH), rapid pyrolysis was conducted on HAL samples to investigate the influence of electrochemical reactions on lignin. The maximum olefins and aromatics yield from HAL was increased to more than three times AL, accounting for 2.22 wt% and 4.07 wt%, respectively. Then, thermogravimetric analysis (TGA), elemental analysis (EA), Fourier-transform infrared spectroscopy (FTIR), and heteronuclear single quantum coherence (HSQC) NMR were employed to characterize hydrogenated lignin samples (HAL), as well as gas chromatography–mass spectrometry (GC-MS) was conducted to investigate the oil-phase products. This work focused on this electrochemical hydrogenation coupled with rapid pyrolysis process to give a possibility that converting lignin into not only liquid oil products, but solid hydrogenated lignin can be used to produce more olefins and aromatics in rapid pyrolysis, and presented the advantages and disadvantages of this two-stage process finally.

DOI： 10.1016/j.jaap.2022.105625

Efficient CO<sub>2</sub> Electrochemical Reduction by a Robust Electrocatalyst Fabricated by Electrodeposition of Indium and Zinc over Copper Foam Reviewed

Sirisomboonchai, S; Machida, H; Tran, KVB; Kawasumi, M; Norinaga, K

ACS APPLIED ENERGY MATERIALS Vol. 5 ( 8 ) page： 9846 - 9857 2022.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ACS Applied Energy Materials

Electrochemical reduction of CO2comprising the CO2reduction reactuib (CO2RR) and oxygen evolution reaction (OER) is one of the most promising technologies for electrification of the chemical process industry. Here, the performance of a electrocatalyst with a three-dimensional structure of InZnCu on Cu foam (CF) is presented. This electrocatalyst was fabricated by electrodeposition of In and Zn over Cu and exhibited a superior reduction of CO2to CO at a Faradaic efficiency of 93.7% at -0.7 V and an excellently long duration of 100 h. Due to the synergy of the thin In layer, the Zn nanosheets provided a high surface-active area and strong mechanical robustness during the reaction. Additionally, a two-electrode system was constructed based on the CF-modified surface, which provided valuable guidelines on the overall CO2RR-OER system for further evolution. Furthermore, due to the facile synthesis, the bimetal-layer double hydroxide (LDH) exhibited high conductivity and high OER performance. Hence, the two-electrode system assembled excellent electrocatalysts for the CO2RR-OER (InZnCu/CF||Cu(OH)2NWs@NiCo-LDH/CF) with high conversions of CO2to CO of 67% and 88% at 2 and 50 mA cm-2, respectively. Notably, the CO2RR-OER system exhibited excellent stability in a 40 h CO2conversion with a constant current density of 2 mA cm-2at an ultralow voltage of 1.59 V. Moreover, the calculation of the energy input converting CO per ton of CO2resulted in a low energy input range for further development in scalability. This overall CO2RR-OER proposes development in electrochemical CO2reduction for industrial applications.

DOI： 10.1021/acsaem.2c01564

Selective hydrogenation of furfural to tetrahydrofurfuryl alcohol in 2-butanol over an equimolar Ni-Cu-Al catalyst prepared by the co-precipitation method Reviewed Open Access

Rao, TU; Suchada, S; Choi, C; Machida, H; Huo, ZB; Norinaga, K

ENERGY CONVERSION AND MANAGEMENT Vol. 265 2022.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Energy Conversion and Management

In order to upgrade biomass-derived platform chemicals to high value-added chemicals and liquid fuels, it is highly advantageous and desirable to synthesize suitable non-precious bimetallic catalysts that are efficient and versatile in chemical reactions. Equal moles of Ni and Cu were dispersed on varying mole ratios of Al by the co-precipitation method to synthesize Ni-Cu alloy particles to obtain a maximum yield of tetrahydrofurfuryl alcohol (THFA) by the liquid phase hydrogenation of furfural. The nickel species were active for both the furan ring (C=C) and carbonyl group (C=O) of furfural molecule, while Cu species were highly active for only the carbonyl group of furfural molecule. Systematic characterization of the prepared catalysts by XRD, TPR, STEM-EDS, and XPS analysis revealed the formation of highly active Ni-Cu alloys and near-equal Ni/Cu surface contents were achieved for the equimolar catalyst, which showcased a maximum of 98 mol% yield of THFA at 140 °C, 30 bar, 4 h. The reaction pressure and temperature showed a substantial effect on the product yield. The solvent selection also influenced the product selectivity, particularly with 2-butanol, which promoted the reaction with its hydrogen donor capacity and supported the ring hydrogenation of FAL to THFA. Moreover, the reduced Ni1Cu1-Al1 catalyst displayed good recyclability for three runs and an equal activity to that of a fresh catalyst after the regeneration.

DOI： 10.1016/j.enconman.2022.115736

Understanding the involved chemistry and physics toward numerically simulating the reactors for carbon resources and carbon dioxide conversions Reviewed

NORINAGA Koyo

Proceedings of the Annual Conference of The Japan Institute of Energy Vol. 31 ( 0 ) page： xviii - xix 2022.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Japan Institute of Energy

<p>The recent approaches by the author and co-workers in understanding the involved chemistry and physics toward numerically simulating the chemical reactors are presented. The processes will include the gasification of solid fuels, coal tar reforming, and Sabatier reaction for producing carbon neutral synthetic methane.</p>

DOI： 10.20550/jietaikaiyoushi.31.0_xviii

CFD simulation of the Sabatier process in a shell-and-tube reactor under local thermal non-equilibrium conditions: Parameter sensitivity and reaction mechanism analysis Reviewed Open Access

Lin, YX; Zhang, W; Machida, H; Norinaga, K

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY Vol. 47 ( 34 ) page： 15254 - 15269 2022.4

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

The Sabatier process is a competitive technology applied for carbon capture and utilization. This process increases the risk of carbon deposition and catalyst thermal degradation because of its exothermic property. In this study, a CFD model verified through existing experimental data was established to systematically investigate the Sabatier process in a shell-and-tube reactor. The effects arising from several operating parameters (e.g., gas flow rate, feed gas composition, the thermal conductivity of catalyst pellet, the inlet temperature of cooling phase, as well as phase change refrigeration) on temperature profile and reaction performance were studied. Moreover, a mechanism of three reactions was investigated, including CO2 methanation, CO methanation, as well as RWGS reaction. Furthermore, the competition between CO2 methanation and RWGS reaction was explored. According to the further sensitivity analysis, increasing the thermal conductivity of the catalyst particles would be effective to inhibit hot spots, while keeping the carbon conversion rate unchanged.

DOI： 10.1016/j.ijhydene.2022.03.029

Catalytic transfer hydrogenation of ethyl levulinate into γ-valerolactone over air-stable skeletal cobalt catalyst Reviewed

Ren, DZ; Zhao, C; Zhang, NH; Norinaga, K; Zeng, X; Huo, ZB

JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING Vol. 10 ( 2 ) 2022.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Environmental Chemical Engineering

A fast and easy handled batch air diffusion method (BA) was developed to obtain a non-pyrophoric, air-stable skeletal Co catalyst (A-SCo) for catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL) into γ-valerolactone (GVL). A batch air diffusion method (BA) consumed the active adsorbed H2 on the surface of skeletal Co (SCo) but maintained structure catalyst and avoided excessive oxidation of metallic Co, Ni and Al. The 96% yield of GVL was obtained over the A-SCo and HZSM-5 at 140 °C. Further study of CTH process shows that metallic state of A-SCo provides important active sites for dehydrogenation of i-PrOH, which is critical step for hydrogenation of EL. This study provides a simple, efficient method to prepare an air-stable skeletal metal catalyst for CTH and hydrogenation process.

DOI： 10.1016/j.jece.2022.107188

A review of thermal catalytic and electrochemical hydrogenation approaches for converting biomass-derived compounds to high-value chemicals and fuels Reviewed Open Access

Zhang, LJ; Rao, TU; Wang, JY; Ren, DZ; Sirisommboonchai, S; Choi, C; Machida, H; Huo, ZB; Norinaga, K

FUEL PROCESSING TECHNOLOGY Vol. 226 2022.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Fuel Processing Technology

Major global issues such as greenhouse gas emissions and the excessive use of fossil fuels lead to looking for sustainable and clean energy resources. Lignocellulosic biomass is a prospective resource for sustainable carbon-based energy. The production of petroleum-based green fuels, chemicals, and solvents from biomass-derived products has garnered much attention in the recent past. The study of biomass derivatives hydrogenation improves the efficiency of generating high-value chemicals and provides much-needed insights into the primary reaction mechanism for the effective utilization of raw constituents or biomass. However, the existing thermochemical conversions of biomass and biomass-derived products such as thermal catalytic hydrogenation (TCH) involve energy-intensive and expensive processes. In this regard, sustainable energy generation attracts alternative conversion technologies, including electrochemical conversion (ECC), electrocatalytic hydrogenation (ECH), and photocatalytic conversions that can be directly integrated with renewable wind/solar technologies and operated at ambient or lower temperatures. The role of electrocatalyst and electrolyte is pivotal to achieve efficient and selective ECH of biomass organics. This review paper summarizes the utilization of TCH and ECH processes on cellulose/hemicellulose, lignin, and their derivatives/model compounds, including catalyst types, reaction conditions, hydrogenation efficiency, and technical limitations. The advantages and disadvantages of the two technologies for biomass utilization have also been compared, which provides a more favourable knowledge base and theoretical basis for the subsequent research work.

DOI： 10.1016/j.fuproc.2021.107097

Durability and fire-hazardous-risk evaluation of unique phase separation solvent using high-boiling-point amine and ether Reviewed

Maeda, N; Kishimoto, A; Machida, H; Yamaguchi, T; Yanase, K; Norinaga, K

INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL Vol. 114 2022.2

Language：English Publishing type：Research paper (scientific journal) Publisher：International Journal of Greenhouse Gas Control

Durability and fire hazard risk evaluations were conducted to determine the process feasibility of a unique phase separation solvent with a low regeneration temperature (90 °C) consisting of an amine, ether, and a small amount of water. The results are as follows. I) The amine degradation rate of the phase separation solvent was determined to be less than 1/10 of that of monoethanolamine, which was attributed to the high oxidative resistance and low regeneration temperature of the former. II) The composition of the gas that formed in the absorber was completely out of the combustible range during the treatment of 6% oxygen-containing gas on a dry basis. Therefore, we believe that this phase separation solvent is applicable to the treatment of exhaust gas from coal-fired thermal power plants and can realize stable operation with a small amount of amine required for replenishment.

DOI： 10.1016/j.ijggc.2021.103532

Fluctuation in diethylene glycol diethyl ether/water mixtures near the lower critical solution temperature studied by small- and wide-angle x-ray scattering and thermodynamic calculation Reviewed Open Access

Yanase, K; Tran, KVB; Yamaguchi, T; Machida, H; Norinaga, K

JOURNAL OF MOLECULAR LIQUIDS Vol. 346 2022.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Molecular Liquids

We studied local structure of diethylene glycol diethyl ether (DEGDEE)-water mixtures near the lower critical solution temperature (LCST) by means of simultaneous small- and wide-angle x-ray scattering measurement and thermodynamic calculation based on the activity coefficient model. Long-wavelength limits of structure factors SNN(0), SCC(0), and SNC(0), which respectively represent mean square fluctuations in the particle number, the concentration, and their cross correlation, are determined from scattering intensity extrapolated to the zero scattering vector and thermodynamic quantities according to the Bhatia and Thornton formula. SNN(0) and SCC(0) exhibit maxima near critical concentration. We found that difference between partial molar volumes of water and DEGDEE essentially results in SNN(0) values being one order of magnitude larger than SCC(0) values. Further, we determined Kirkwood-Buff (KB) integrals to clarify a mixing state of the solution from a mesoscopic point of view. The KB integrals also exhibit extrema near critical concentration. These results demonstrate self-segregations of both DEGDEE and water in a nanometer length scale even at homogeneous solution states, which can be regarded as a precursor of the macroscopic phase separation. Concentration dependence of the wide-angle scattering curve suggests that the short-range structure, whose length scale is sub-nanometer, moderately changes between the intrinsic bulk structures of DEGDEE and water. Comparison of the KB integrals with those determined by the activity coefficient model using non-random two-liquid equation is presented and effects of the fluctuation on the phase behavior are discussed.

DOI： 10.1016/j.molliq.2021.117830

Modeling the Chemical Structures of Coals with Different Classifications Using Mean Molecular Weights Reviewed Open Access

Hata Yuki, Hayashizaki Hideyuki, Takanohashi Toshimasa, Takahashi Takafumi, Kanehashi Koji, Norinaga Koyo

ISIJ International Vol. 62 ( 5 ) page： 948 - 956 2022

Language：English Publishing type：Research paper (scientific journal) Publisher：The Iron and Steel Institute of Japan

<p>The chemical structure models for the extractions and residues of two types of bituminous coals, A and B, were constructed. The molecular weights of the extractions were determined via gel permeation chromatography (GPC). New standard materials with structures similar to those of coal extraction (<i>i.e.</i>, 9, 10- diphenylanthracene, 5,6,11,12-tetraphenylnaphthracene, and chemical compounds A (Mw = 811) and B (Mw = 1135), which were synthesized using the coupling reaction) were adopted for GPC in order to obtain more accurate mean molecular weights than those in literature. Furthermore, a support program for constructing chemical structure models based on <sup>1</sup>H nuclear magnetic resonance (NMR) spectra was adopted. The coal models constructed suitably indicate the differences between the types of coal. In particular, it is found that a high pyridine-insoluble fraction extracted rate, which accounts for the most significant difference between the total extracted rates for coals A and B, enhance the coking property of coal A. In addition, the cluster size in the magic solvent-insoluble fraction might affect the softening property of coal.</p>

DOI： 10.2355/isijinternational.ISIJINT-2021-459

Determination of Kinetic Parameters for CO<sub>2</sub> Methanation (Sabatier Reaction) over Ni/ZrO<sub>2</sub> at a Stoichiometric Feed-Gas Composition under Elevated Pressure Reviewed

Choi, C; Khuenpetch, A; Zhang, W; Yasuda, S; Lin, YX; Machida, H; Takano, H; Izumiya, K; Kawajiri, Y; Norinaga, K

ENERGY & FUELS Vol. 35 ( 24 ) page： 20216 - 20223 2021.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Energy and Fuels

Methanation of CO2 using H2 obtained by renewable energy sources has been gaining attention as one of the promising options for utilizing captured CO2 and surplus power obtained when intermittent power sources such as solar and wind energy are used. Herein, kinetics of CO2 methanation over Ni/ZrO2 was studied using a tubular quartz reactor at 0.9 MPa. The Sabatier reaction (CO2 + 4H2 = CH4 + 2H2O, ΔHr298K = – 165 kJ mol–1) was carried out under stoichiometric gas feeding (CO2/H2 = 1/4 v/v to CH4/H2O = 1/2 v/v), and its reaction rate was determined. The exothermic nature of CO2 methanation and extremely high catalytic activities increased the reaction temperature to 400–600 °C even when the feed-gas temperature was as low as 250–400 °C, and the gas hourly space velocity was as high as 3 × 106 h–1. Nonlinear regression analyses based on one- and multistep kinetic models were used to investigate the reaction rates to estimate the kinetic parameters. Both models with optimized parameters can reproduce the experimentally obtained CH4 formation rates for the entire range of the feed-gas conversion with a coefficient of determination (R2) of over 0.98.

DOI： 10.1021/acs.energyfuels.1c01534

An Alternative CO<sub>2</sub> Capture with a Pressure Swing Amine Process Driven by Cryogenic Pumping with the Unused Cold Energy of Liquefied Natural Gas Reviewed

Machida, H; Hashiride, R; Niinomi, R; Yanase, K; Hirayama, M; Umeda, Y; Norinaga, K

ACS SUSTAINABLE CHEMISTRY & ENGINEERING Vol. 9 ( 47 ) page： 15908 - 15914 2021.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Sustainable Chemistry and Engineering

This paper presents an alternative concept of CO2 capture that can substantially reduce the energy required for CO2 capture by utilizing unused cold energy. The heat of vaporization of liquefied natural gas (LNG), of which the boiling point is 110 K, is a possible candidate for unused cold energy. This technology is based on a pressure swing amine process combined with a sublimation tank to cool CO2 released from a desorber into dry ice by exchanging the LNG cold energy. The feature of this technology is that pure CO2 is recovered mostly by a pressure swing that decreases the pressure in the desorber utilizing a cryogenic pump with CO2 sublimation instead of a mechanical pump. We developed an amine-based absorbent that can realize the proposed process for exhaust gas from a fossil fuel-fired power plant. A process simulation indicated that the required energy is as low as 0.25 GJ/ton CO2 when both the absorber and the desorber are operated at around 313 K, the desorber pressure is reduced to 1 kPa, and the sublimation tank is operated at 150 K.

DOI： 10.1021/acssuschemeng.1c05892

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