Faculty Profiles - NORINAGA Koyo

Papers - NORINAGA Koyo

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Gas-liquid flow characteristics in random packed columns with different packing diameters for a pressure-swing desorber Reviewed Open Access

Saito, Y; Tashiro, G; Chairunnisa; Miyazaki, T; Uehara, Y; Machida, H; Norinaga, K

CHEMICAL ENGINEERING SCIENCE Vol. 337 2027.1

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

Three-dimensional numerical simulations were conducted to investigate countercurrent gas–liquid flow in randomly packed beds with relevance to scale-up behavior of a pressure-swing CO<inf>2</inf> desorber. The effects of the packing diameter ((Formula presented), (Formula presented), and (Formula presented) mm) on the flow behavior, liquid distribution, gas–liquid interfacial area, and liquid holdup were systematically examined under reduced-pressure desorption conditions, while considering spatial variations in liquid properties associated with CO<inf>2</inf> release.The results showed a clear transition in the flow regime with increasing Dp[jls-end-space/]. Smaller packing diameters promoted the internal percolation flow, leading to a higher liquid holdup and larger gas–liquid interfacial area. In contrast, larger packing diameters induced gravity-dominated surface flow along packing elements owing to the reduced specific surface area, resulting in suppressed liquid dispersion and substantial decreases in the interfacial area and liquid holdup. Analysis of interfacial velocity distributions indicated that increasing Dp enhances the fraction of high-velocity interfacial regions, thereby promoting interfacial renewal despite a reduction in the total interfacial area. Consequently, an intermediate Dp achieved a qualitatively favorable balance between the interfacial area and interfacial renewal. Comparisons with conventional correlations confirmed the applicability of intermediate Dp under well-wetted conditions and revealed their limitations when gravity-dominated surface flow becomes pronounced. These findings provide insights into how packing diameter influences flow characteristics relevant to scale-up considerations.

DOI： 10.1016/j.ces.2026.124653

Resolving passive heat transfer and phase-change heat in cryogenic CO2 deposition (Desublimation) from CO2/N2 mixtures Reviewed Open Access

Xiao, SW; Machida, H; Norinaga, K

AICHE JOURNAL 2026.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Aiche Journal

In cryogenic CO<inf>2</inf> desublimation systems where phase change dominates both heat transfer and separation, conventional lumped thermal-resistance treatments embed interfacial latent heat into an overall heat-transfer coefficient, obscuring how phase-change heat is partitioned between the gas phase and the coolant and limiting diagnostic insight into energy efficiency. In this study, CO<inf>2</inf> desublimation experiments were conducted using CO<inf>2</inf>/N<inf>2</inf> mixtures, and a coupled heat- and mass-transfer model incorporating phase-change effects was developed. By explicitly treating the latent heat released at the gas–solid interface as an internal heat source within a thermal-resistance network, a heat-splitting performance index (HSPI) was introduced to quantify the fraction of latent heat coupled to the coolant side. The results show that both CO<inf>2</inf> recovery and coolant-side latent-heat utilization increase monotonically with the inlet CO<inf>2</inf> mole fraction, highlighting feed-gas composition as a key determinant of separation performance and energy efficiency in cryogenic CO<inf>2</inf> capture.

DOI： 10.1002/aic.70468

Numerical analysis of gas-liquid countercurrent flow in a pressure-swing CO2 desorber operated at reduced pressure Reviewed

Saito, Y; Tashiro, G; Chairunnisa; Miyazaki, T; Uehara, Y; Machida, H; Norinaga, K

CHEMICAL ENGINEERING SCIENCE Vol. 325 2026.5

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

Understanding fluid behavior in packed columns is essential for improving the efficiency of CO<inf>2</inf> capture processes. This study presents three-dimensional numerical simulations of gas–liquid countercurrent flow in a random packed bed of a desorber operated under reduced pressure in a pressure-swing mode. The applicability of existing correlations for liquid holdup, originally developed for absorbers, was evaluated under desorber conditions. A realistic random packing structure was numerically reconstructed, and variations in liquid viscosity and surface tension along the bed height were incorporated to represent CO<inf>2</inf> release during desorption. The results showed that liquid holdup increased with the progress of CO<inf>2</inf> desorption, while both liquid flux and the number of liquid nozzles had a strong influence on the gas–liquid interfacial area and liquid distribution. Numerical predictions of liquid holdup showed reasonable consistency with existing correlations, providing a comparative basis for discussing liquid distribution under desorber conditions. Overall, this study provides a quantitative framework for analyzing liquid flow behavior with property variations in random packed beds, contributing to the improved design and operation of CO<inf>2</inf> capture units.

DOI： 10.1016/j.ces.2026.123395

Engineering Bilayer Tandem Catalysts on Si-Based Photocathodes for High-performance CO2 Reduction to Produce Methane Reviewed Open Access

Wu, H; Si, SH; Wang, HT; Wang, CL; Dai, RC; Li, JN; Fukaya, S; Pan, ZH; Xiong, YJ; Usami, N; Norinaga, K; Kurokawa, Y; Sirisomboonchai, S; Liu, D; Wang, Q

ADVANCED MATERIALS Vol. 38 ( 15 ) page： e18249 2026.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Advanced Materials

Solar-powered CO<inf>2</inf> reduction through photoelectrochemical (PEC) approaches to produce hydrocarbon fuels, such as methane (CH<inf>4</inf>), is one of the most promising paths for supplying sustainable fuels. However, the limited light absorption capability and sluggish kinetics restrict the photocatalytic rate and selectivity for hydrocarbon production. Here, we introduce tandem catalysts on photocathodes designed to enhance controlled sequential reactions involving intermediates and thus the selectivity of CO<inf>2</inf> reduction. Specifically, when mounted on Cu/Ag-Cu bilayer catalysts, the p-type Si photocathode with a pyramid-structured surface dramatically improves CO<inf>2</inf>-to-CH<inf>4</inf> conversion, achieving a selectivity of 60.2 ± 3.4% and a working current density of −32.9 ± 1.9 mA cm<sup>−2</sup> at −1.1 V vs. RHE. As identified by operando Raman and synchrotron-radiation Fourier transform infrared spectroscopy and Density Functional Theory, the bottom layer of the Cu/Ag-Cu catalysts comprises Ag and Cu nanoparticles, which catalyse the initial reduction of CO<inf>2</inf> to form *CO and the creation of *H species dissociated from H<inf>2</inf>O, respectively. The top Cu layer subsequently enables the protonation of *CO to *CHO, ultimately yielding CH<inf>4</inf>. This design of tandem catalysts, coupled with a thorough investigation of the reaction mechanisms, offers a powerful approach toward high-performance and selective pathways for solar-powered CO<inf>2</inf> reduction to targeted products.

DOI： 10.1002/adma.202518249

Mechanistic and Stability Study of the Integrated CO2 Capture-Electroreduction Process in Ethanolamine Solution over Ni/NC Atomic Catalysts Reviewed Open Access

Dai, RC; Zhang, LJ; Yuan, XR; He, YT; Lin, YX; Wu, H; Wu, WJ; Machida, H; Norinaga, K

CARBON CAPTURE SCIENCE & TECHNOLOGY Vol. 18 2026.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon Capture Science and Technology

In recent years, the integrated systems for the cost-effective conversion of CO<inf>2</inf> into high-value products have emerged as a major research focus in advancing sustainable green chemistry. The integrated process not only addresses the high energy consumption during desorption but also simplifies the process and reduces costs. However, further improving CO<inf>2</inf> conversion efficiency and achieving system stability remain significant challenges. Here, we report an integrated CO<inf>2</inf> capture and electroreduction process (ICCE) using atomically dispersed Nickel catalysts (Ni/NC) for the direct electroreduction of CO<inf>2</inf> absorbed in 30 wt.% ethanolamine (MEA, MAE, EAE, DMEA) solutions to CO, achieving a high Faradaic efficiency of up to 91%. In addition, the authors compared the effects of different reaction temperatures and different partial pressures of CO<inf>2</inf> in the gas phase on the prolonged electroreduction reaction, and suggested that the integrated system maintaining a gas-liquid equilibrium, can be guaranteed to continuously electrolyze to produce CO at a high Faraday efficiency. Through multiple characterizations, like NMR spectroscopy and In-situ Raman spectroscopy, revealed that CO is primarily derived from interfacially regenerated free CO<inf>2</inf>, while carbamate species are not directly reduced but instead adsorb on the Ni/NC catalyst surface as inhibitory intermediates.

DOI： 10.1016/j.ccst.2026.100583

Numerical Analysis of CO<sub>2</sub> Deposition in a Sublimation Tank and Evaluation of Property Parameter Effects Reviewed Open Access

Saito, Y; Yamaguchi, H; Uehara, Y; Machida, H; Norinaga, K

JOURNAL OF THE JAPAN INSTITUTE OF ENERGY Vol. 105 ( 4 ) page： 85 - 95 2026

Mechanistic study on the roles of heteroatoms in Ni-based dual-atom catalysts for electrochemical CO2 reduction Reviewed Open Access

Park G.D., Norinaga K.

Carbon Resources Conversion 2026

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon Resources Conversion

The intrinsic catalytic activity of single-atom catalysts (SACs) can be enhanced by incorporating other elements. However, understanding the roles of these heteroatoms is crucial for maximizing catalytic efficiency. In this study, we focused on the electrochemical CO<inf>2</inf> reduction reaction (CO<inf>2</inf>RR) over Ni-based dual-atom catalysts (DACs) containing Zn or Mn using in situ Raman spectroscopy and ab initio molecular dynamics simulations. The NiZn DAC achieved a CO faradaic efficiency of > 99.8% up to a current density of − 300 mA cm<sup>−2</sup>. Compared with the Ni SAC and NiMn DAC, the NiZn DAC more effectively facilitated electron transfer by tuning the electronic structure of the catalytically active Ni center, stabilizing the chemisorbed CO<inf>2</inf> intermediates, and accelerating proton transfer by biasing the electron density of the chemisorbed CO<inf>2</inf> intermediates. This study provides insights into the roles of heteroatoms in catalytic activity and will aid the development of highly efficient catalysts.

DOI： 10.1016/j.crcon.2026.100446

Numerical Analysis of CO<sub>2</sub> Deposition in a Sublimation Tank and Evaluation of Property Parameter Effects Open Access

SAITO Yasuhiro, YAMAGUCHI Hiroyasu, UEHARA Yusuke, MACHIDA Hiroshi, NORINAGA Koyo

Journal of the Japan Institute of Energy Vol. 105 ( 4 ) page： 85 - 95 2026

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

<p>CO<sub>2</sub> deposition under low-pressure conditions plays a key role in sublimation-based CO<sub>2</sub> separation processes; however, numerical studies on this phenomenon remain limited. In this study, CO<sub>2</sub> deposition behavior was investigated using a combination of a global tank-scale model and a local model that resolves the growth of the dry-ice layer. The global model evaluated heat transfer and fluid flow inside the tank using CO<sub>2</sub> properties corresponding to 100 kPa and 1 kPa, while the local model analyzed the growth of the deposited layer and its influence on the near-wall temperature. Experiments conducted under reduced-pressure conditions provided two key datasets—the temporal evolution of gas temperature near the cold plate and the growth of the dry-ice layer—which were used as reference indicators for comparison with the simulations. Although the simulations reproduced the initial temperature decrease, they failed to capture the subsequent temperature rise observed experimentally, suggesting that heat release associated with CO<sub>2</sub> deposition significantly affects the thermal behavior. When this heat release was incorporated as an additional boundary condition, the characteristic temperature rise observed in the experiments was successfully reproduced. These results clarify the respective roles and limitations of the global and local models in representing CO<sub>2</sub> deposition behavior and provide guidance for developing more accurate numerical models.</p>

DOI： 10.3775/jie.105.85

O-23　Bioethanol Production from Non-Sterile Methane Fermentation Digestate Reviewed

TANIMURA Ayumi, KAKUZAWA Noriko, OBASE Kohei, TOJO Takayuki, HIROBE Tomoki, KIKUCHI Ryota, NORINAGA Koyo

Proceedings of the Conference on Biomass Science Vol. 21 ( 0 ) page： 49 - 50 2025.11

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

<p>This study explored the potential of producing bioethanol from non-sterile methane fermentation digestate supplemented with waste beverages. Several sucrose-fermenting yeast strains were tested, and <i>Saccharomyces </i><i>pastorianus</i><i> </i>NBRC 11024<sup>T</sup> showed the highest performance, reaching nearly 90% of the theoretical ethanol yield within 48 h. Interestingly, ethanol was not detected when sterilized digestate was used, suggesting that native microbial populations did not hinder fermentation and may have contributed to favorable conditions. Ethanol productivity decreased when the digestate proportion exceeded 70%, likely due to the accumulation of inhibitory compounds such as ammonia or volatile fatty acids. Microbial community analysis revealed that a bacterium belonging to lactic acid bacteria became dominant during fermentation, implying a role for indigenous bacteria in shaping the fermentation environment. These findings demonstrate the feasibility of low-cost and energy-efficient bioethanol production using unsterilized residues from biogas plants, offering a promising strategy for waste-to-biofuel conversion within circular bioresource systems.</p>

DOI： 10.20550/jiebiomassronbun.21.0_49

Facile Synthesis and Insight of Atomically Dispersed Ni Catalyst on N-Doped Carbonized Lignin for Highly Efficient Electrochemical CO<sub>2</sub> Reduction to CO (vol 16, e202300530, 2023) Reviewed Open Access

Park, GD; Sirisomboonchai, S; Norinaga, K

CHEMSUSCHEM Vol. 18 ( 17 ) 2025.9

Acetylene formation via oxidative coupling of methane over monolithic Pt/ Al<sub>2</sub>O<sub>3</sub> and Pt/ZrO<sub>2</sub> catalysts Reviewed Open Access

Schardt, S; Çelik, A; Bastian, S; Sirisomboonchai, S; Nakamura, M; Norinaga, K; Lott, P

APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE Vol. 23 2025.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Applications in Energy and Combustion Science

This study investigates the influence of key operational parameters – including space velocity, feed gas dilution with nitrogen, and the carbon-to-oxygen (C:O) ratio – on monolithic Pt/Al₂O₃ and Pt/ZrO₂ catalysts for the oxidative coupling of methane (OCM). Optimal operating conditions were identified that yielded high C₂ selectivities, with a notably large share of acetylene. Under ideal conditions, a Pt/ZrO₂ catalyst achieved a maximum C₂ selectivity of 11.3 %, with 84 % acetylene contribution and approximately 90 % methane conversion. Zirconia was found to be a superior support material compared to alumina in terms of catalyst stability and longevity. A number of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were applied and revealed significant morphological and structural changes in both catalyst types, induced by the harsh reaction conditions with temperatures exceeding 1200 °C. These findings contribute to the advancement of more robust catalyst formulations and optimized process conditions for the OCM reaction.

DOI： 10.1016/j.jaecs.2025.100357

Ethanol production from non-sterile methane fermentation residues for waste-to-biofuel conversion Reviewed Open Access

Tanimura, A; Kakuzawa, N; Obase, K; Tojo, T; Hirobe, T; Kikuchi, R; Norinaga, K

BIORESOURCE TECHNOLOGY REPORTS Vol. 31 2025.9

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

Effective valorization of food waste is essential for sustainable resource management. Methane fermentation residues, a byproduct of biogas production from food waste, are typically used as liquid fertilizer. However, their full potential as bioresource substrates remains underexplored. This study investigated the feasibility of producing bioethanol from non-sterile methane fermentation residues mixed with beverage waste under realistic, low-input conditions. Four sucrose-fermenting yeast strains were evaluated for ethanol production in a non-sterile medium composed of residue and deteriorated beverage (1:1, v/v). Ethanol was detected only under the non-sterile condition, not in filter-sterilized controls, suggesting that native microbial populations did not inhibit—and may have enhanced—fermentation. Saccharomyces pastorianus NBRC 11024<sup>T</sup> achieved the highest ethanol yield (27.4 g/L), reaching 89.4 % of the theoretical maximum within 48 h. Fermentation efficiency declined when the residue ratio exceeded 70 %, indicating possible inhibition due to nitrogen or volatile fatty acid accumulation. 16S rRNA amplicon sequencing revealed a marked shift in microbial community structure, with Leuconostoc species dominating at later stages. These findings suggest that methane fermentation residues can be used as functional co-substrates for ethanol production and may actively contribute to favorable fermentation conditions. In addition, commercially available beverages were shown to be a suitable model for waste beverages and provided practical insights into real-world applications. This approach offers a scalable, decentralized strategy for low-cost ethanol production and contributes to the development of circular bioresource systems.

DOI： 10.1016/j.biteb.2025.102285

P-4-5　Investigation of Numerical Conditions for Heat Transfer in A CO<sub>2</sub> Sublimation Tank Reviewed

CHIGA Kanako, TASHIRO Gentaro, YAMAGUCHI Hiroyasu, UEHARA Yusuke, MACHIDA Hiroshi, NORINAGA Koyo, SAITO Yasuhiro

Proceedings of the Annual Conference of The Japan Institute of Energy Vol. 34 ( 0 ) page： 224 - 225 2025.7

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

<p>Numerical simulations were conducted to investigate CO<sub>2</sub> gas cooling in a single-tube sublimation tank, focusing on how fins affect the internal temperature distribution and heat transfer performance. The results revealed that the presence of fins led to a more pronounced temporal expansion of the low-temperature region. Regardless of fin configuration, the heat transfer coefficient was consistently higher in the curved upper section of the U-shaped tube. These results suggest the need for optimal fin design according to cooling time and tube shape.</p>

DOI： 10.20550/jietaikaiyoushi.34.0_224

The Research and Development of Cryo-DAC<sup>®</sup>: A Direct Air Capture Technology Utilizing the Cryogenic Temperature of Liquefied Natural Gas Reviewed

NORINAGA Koyo

Nihon Enerugii Gakkai Kikanshi Enermix Vol. 104 ( 4 ) page： 381 - 386 2025.7

Numerical investigation of polycyclic aromatic hydrocarbons (PAHs) and soot formation from various coals in a two-stage entrained flow gasifier with detailed chemistry Reviewed

Li, TL; Fukumoto, K; Zhang, LJ; Lin, YX; Choi, C; Machida, H; Norinaga, K

JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS Vol. 188 2025.6

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

The substitution of air with O<inf>2</inf>/CO<inf>2</inf> atmosphere is a promising solution for CO<inf>2</inf> recirculation during coal gasification. However, a comprehensive understanding on the formation mechanism of PAHs and soot under different conditions is necessary to reduce their emissions. This work presents simulation results of a two-stage entrained flow coal gasifier in a 250 MW industrial-scale plant using detailed chemistry. The influences of reductor temperature (1000–1200 ℃) and coal types (bituminous coal, sub-bituminous coal, and lignite) on PAHs and soot formations from the coal volatiles in the reductor were simulated through a detailed chemical kinetic model under air and O<inf>2</inf>/CO<inf>2</inf> atmospheres. Results show that 2- and 3-ring aromatics are main PAHs products. Rising temperature has inhibitory effects on PAHs formation, especially for lignite. The O<inf>2</inf>/CO<inf>2</inf> condition reduces the PAHs yield compared with the air condition. Rate of production analysis reveals that conversion of major PAHs occurs mainly between PAHs and their radicals. Vinyl-naphthyl radical and indenyl radical play an important role in the acenaphthylene conversion. In addition, soot production increases with a higher temperature under both air and O<inf>2</inf>/CO<inf>2</inf> conditions. The O<inf>2</inf>/CO<inf>2</inf> condition effectively suppressed soot production through a weaker HACA surface growth route than the air condition. lignite produces the least soot, and sub-bituminous coal produces the most. This study deeply reveals the formation mechanisms of PAHs and soot in a two-stage entrained flow gasifier through detailed chemical kinetic modeling, giving an insight into the complex PAHs and soot formations to assess the design and the operating condition of gasifier with O<inf>2</inf>/CO<inf>2</inf> injection.

DOI： 10.1016/j.jaap.2025.107027

Coal Gasification in a Two-Stage Entrained Flow Gasifier under O<sub>2</sub>/CO<sub>2</sub> Conditions Reviewed

Li, TL; Choi, C; Fukumoto, K; Machida, H; Norinaga, K

ENERGY & FUELS Vol. 39 ( 20 ) page： 9345 - 9358 2025.5

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

Coal gasification in industrial gasifiers faces challenges related to tar and soot formation, which affect performance and emissions. This study proposes a new numerical approach for simulating coal gasification in a two-stage entrained flow gasifier under different O<inf>2</inf>/CO<inf>2</inf> ratios-blown conditions. The modeling framework incorporates a static simulation for the combustor and couples a multistep coal devolatilization model with an expanded gas-phase reaction model in the reductor. Model validation against experimental data showed prediction accuracies ranging from 4 to 20% for the devolatilization model and from 3 to 25% for the gas-phase reaction model across various species. The validated framework was employed to investigate the effect of varying O<inf>2</inf>/CO<inf>2</inf> ratios in gasifying agents on the gasification performance. Results showed that increasing the O<inf>2</inf>/CO<inf>2</inf> ratio from 30% to 50% increased H<inf>2</inf> production from 3.69% to 13.03% and CO from 34.40% to 55.04% while reducing CO<inf>2</inf> from 48.27% to 19.96%. Higher O<inf>2</inf>/CO<inf>2</inf> ratios inhibited soot formation but increased the tar yield, although the final tar concentration remained well below 1 mg/Nm<sup>3</sup>. This study highlights the potential of using oxy-fuel gasification with CO<inf>2</inf> recirculation for optimizing syngas quality and advancing CO<inf>2</inf> capture, offering valuable insights for industrial gasifier design and operation within oxy-fuel IGCC systems.

DOI： 10.1021/acs.energyfuels.5c00098

Mechanism investigation of direct electrochemical reduction of CO<sub>2</sub>-loaded 2-(ethylamino)ethanol solution into CO Reviewed

Dai, RC; Zhang, LJ; Tran, KVB; Sirisomboonchai, S; Machida, H; Norinaga, K

SEPARATION AND PURIFICATION TECHNOLOGY Vol. 355 2025.3

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

Carbon capture and utilization (CCU) has attracted considerable interest recently as CO<inf>2</inf> emission and global warming have greatly affected various aspects of the environment, economy, and society. However, energy consumption during CCU must be substantially reduced. In this study, we propose an alternative approach using electrochemical reduction to directly convert CO<inf>2</inf>-loaded amine solutions into CO. The effects of the electrodes, temperature, potential, and CO<inf>2</inf> loading on the Faradaic efficiency (FE) of CO were comprehensively investigated. The Ag NPs/CP electrode showed good catalytic performance on the electrochemical reduction of CO<inf>2</inf>-loaded amine solution to CO. By comparing the chemical composition in the solution before and after the electrochemical reaction, we determined that the main source of CO might be free CO<inf>2</inf>, which is mainly converted from bicarbonate rather than carbamate. In addition, electrochemical impedance spectroscopy was used to investigate the resistance during the reaction. The electric double-layer was found over the electrode surface when different amine solutions were used as the electrolyte. The spatial structure of ammonium cations and carbamate plays a key role in the FE of CO in this process.

DOI： 10.1016/j.seppur.2024.129575

Design of an efficient CO<sub>2</sub> methanation process and techno-economic analysis with CO<sub>2</sub> capture from the flue gas of automotive shredder residue Reviewed Open Access

Wasnik, CG; Nakamura, M; Machida, H; Ito, J; Shiratori, K; Norinaga, K

CHEMICAL ENGINEERING JOURNAL Vol. 507 2025.3

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

Recycling and utilizing automotive shredder residue (ASR) is necessary for realizing a sustainable automotive industry. This study conducted a feasibility analysis using a process simulator for Case I, where fuel gas is produced through the gasification of ASR followed by combined heat and power generation using a gas engine, CO<inf>2</inf> capture from exhaust gas through chemical absorption, and production of synthetic methane (CH<inf>4</inf>) using the captured CO<inf>2</inf> and renewable hydrogen produced via water electrolysis powered by renewable energy sources. This process produces not only CH<inf>4</inf> but also surplus electricity, which can be used to produce H<inf>2</inf> or power adjacent equipment. Case II, where fuel gas obtained from ASR gasification was directly methanated, was considered for comparison. This study compared the economic potential of both processes for kiln-type ASR gasification that can process 1,200 kg-ASR/h to produce 3,350 Nm<sup>3</sup>/h of fuel gas. Case I produced 4,800 tons/year of CH<inf>4</inf> with an energy efficiency of 46.5 %, whereas Case II produced 2,720 tons/year. The levelized production cost of methane in 2050 can be estimated at $1,241/ton and $1,568/ton for Cases I and II, respectively, which are lower than the expected cost of natural gas in market environments by 2050. This study highlights the potential of ASR-derived CO<inf>2</inf> methanation as a carbon–neutral technology that can effectively achieve carbon conversion while producing high-value synthetic methane.

DOI： 10.1016/j.cej.2025.160737

CO<sub>2</sub> methanation over low-loaded Ni-M, Ru-M (M = Co, Mn) catalysts supported on CeO<sub>2</sub> and SiC Reviewed Open Access

Wasnik, CG; Nakamura, M; Shimada, T; Machida, H; Norinaga, K

CARBON RESOURCES CONVERSION Vol. 8 ( 1 ) 2025.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon Resources Conversion

The concentration of the major greenhouse gas CO<inf>2</inf> is rapidly increasing in the atmosphere, leading to global warming and a range of environmental issues. An efficient circulation and utilization of CO<inf>2</inf> is critical in the current environmental context. Methanation, an exothermic process, emerges as a critical strategy for effective CO<inf>2</inf> utilization. On this front, there is a significant demand for rational design of catalysts that maintain high activity and methane selectivity over a wide temperature range (250–550 °C). The catalyst that can promise a consistent reaction even at 500 °C under an atmospheric pressure is thus obliged. The present study investigated bimetallic catalysts with SiC, which is known for its exceptional thermal conductivity, and CeO<inf>2</inf>, which is characterized by its CO₂ affinity, as base materials. We incorporated Ni-M and Ru-M (M = Co and Mn) as the active metals, each loaded at 2 %. Impressively, with merely 20 mg, the Ni-Co/SiC catalyst achieved a CO<inf>2</inf> conversion rate of 77 % and CH₄ selectivity of 88 % at 500 °C, in a fixed-bed tubular reactor system with conditions of H<inf>2</inf>/CO<inf>2</inf> = 4, a total flow rate of 70 ml min<sup>−1</sup>, and a steady GHSV of 12,000 h<sup>−1</sup>. Moreover, 2Ni-2Co/CeO<inf>2</inf> catalyst demonstrated exceptional performance with a 76 % conversion of CO<inf>2</inf> and a 83 % selectivity for CH<inf>4</inf>, all under identical conditions. The catalyst's durability was confirmed by a subsequent 40-hour stability test, which showed only a 3–5 % degradation. The developed catalysts were comprehensively characterized by BET/BJH, CO pulse chemisorption, H<inf>2</inf>-TPR, HAADF-STEM-EDS, SEM-EDS and XRD etc. to unveil their physicochemical and surface traits. It was found that Co and Mn, when integrated, effectively restrained the agglomeration of Ni and Ru particles, ensuring optimal metal dispersion on the support. In conclusion, our synthesized bimetallic catalysts shown a sustained catalytic capability, even in the high-temperature environment.

DOI： 10.1016/j.crcon.2024.100241

A New Method to Observe the Internal Amine Distribution in an Amine-Functionalized Resin Sorbent Particle Reviewed

Xu, CH; Liu, PB; Peng, YL; Dou, MY; Jiang, QQ; Jia, XH; Zhang, YM; Norinaga, K

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH Vol. 64 ( 10 ) page： 5596 - 5601 2025.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Industrial and Engineering Chemistry Research

Understanding the amine distribution within solid amine sorbents is crucial for enhancing their amine utilization and ultimately improving the CO<inf>2</inf> adsorption capacity. However, suitable characterization methods are lacking. To address this, a novel method was proposed to visualize the distributions of total and accessible amine content within the sorbent particles. In this method, SO<inf>2</inf> was selected to label the accessible amine, while scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) were used to measure the nitrogen and sulfur content, which were further used to calculate the total amine and accessible amine content, respectively. By this method, the total amine content is found to be evenly distributed, which is also higher than the accessible amine content due to the utilization of nitrogen for cross-linking and the diffusion resistance within the particles. For particle sizes larger than a critical size, accessible amine content is higher near the wall and lower at the core. This gradient becomes less pronounced as particle size decreases and becomes uniform when particle size is below this critical size. Therefore, reducing the particle size of solid amine sorbents to below the critical size range (e.g., 250-338 μm in this study) can effectively enhance CO<inf>2</inf> adsorption capacity by maximuming the accessible amine cont within the sorbent particles.

DOI： 10.1021/acs.iecr.4c05007

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