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Tuning surface-active sites of Ru catalysts for the selective deoxygenation of lignin monomers to fuels and chemicals

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Science China Chemistry 2025年

作者： Rizky Gilang Kurniawan Jongho choi Neha Karanwal seung Min Kim Seok Ki Kim Deepak Verma Jaehoon Kim School of Chemical Engineering Sungkyunkwan University School of Mechanical Engineering Sungkyunkwan University SKKU Advanced Institute of Nanotechnology (SAINT) Sungkyunkwan University Institute of Advanced Composite Materials Korea Institute of Science and Technology Department of Chemical Engineering Ajou University

Cycloalkanes and cyclohexanols find diverse applications, including sustainable aviation fuel, fuel additives, and value-added chemicals. These compounds can be produced via complete or selective hydrodeoxygenation（HDO） of lignin-derived phenolic monomers. In this study, a urea-assisted method was employed to control the size of Ru nanoparticles（NPs） and tune the surfaceactive sites on Ru metal supported on CNx. By adjusting the Ru-to-urea molar ratio, both the size of Ru NPs and the metallic-tooxide ratio of Ru were controlled, along with the incorporation of N atoms into the RuO2surface coordination. In the absence of urea, the Ru/CNx（1:0） catalyst, containing 4.8 nm Ru NPs, achieved complete HDO of 4-propyl guaiacol to n-propyl cyclohexane through ring saturation, followed by hydro-demethoxylation of the C–OCH3group, and hydrogenolysis of the –OH group, with a 97.0% yield at an initial H2pressure of 1.5 MPa, 200 °C, and 20 h in water. The final hydrogenolysis step was inhibited over the urea-assisted catalysts. The Ru/CNx（1:8） catalyst, containing 3.1 nm Ru NPs, achieved a maximum selectivity of 67.6% for n-propyl cyclohexanol, along with complete conversion of 4-propyl guaiacol. Similar trends were observed in the product distribution when upgrading reductive catalytic fractionation bio-oil over Ru/CNx（1:0） and Ru/CNx（1:8）.

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Ex situ aging effect on sulfonated poly(ether ether ketone) membrane:Hydration-dehydration cycling and hydrothermal treatment

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Journal of Energy Chemistry 2022年第7期31卷 583-592,I0014页

作者： seung-Young choi Kyeong Sik Jin Polymer&Materials Chemistry Department of ChemistryLund UniversitySE-22100Sweden Center for Hydrogen·Fuel Cell Research Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Pohang Accelerator Laboratory Pohang University of Science and Technology(POSTECH)PohangKyungbuk 37673Republic of Korea

Prolonged hydrothermal treatment for sulfonated poly(ether ether ketone) membranes induces mechanical degradation and developing hydrophilic-hydrophobic phase separation, simultaneously. The enhanced phase separation provides incremental proton conductivity to the membranes, whereas mechanical degradation drastically reduces device stability. On this basis, we describe here the effects of two different ex situ aging processes on sulfonated poly(ether ether ketone) membranes: hydrationdehydration cycling and prolonged hydrothermal treatment. Both aged membranes exhibited enhanced phase separation under the hydrated conditions, as characterized by small angle X-ray ***, when the aged membranes were dried again, the nanostructure of the membranes aged via the hydration-dehydration cycling was recoverable, whereas that of the membranes aged via prolonged hydrothermal treatment was irreversible. Furthermore, the two differently aged membranes showed clear differences in thermal, mechanical, and electrochemical properties. Finally, we implemented both aged membranes in fuel cell application. The sample aged via hydration-dehydration cycling maintained its improved cell performance, whereas the sample aged via hydrothermal treatment showed drastically reduced cell performance after durability test for 50 h.

关键词： Sulfonated poly(ether ether ketone) Humidity cycle test Ex situ aging Proton exchange membrane Fuel cell

A digital application for implementing the ICD-11 traditional medicine chapter

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Journal of Integrative Medicine 2020年第6期18卷 455-458页

作者： seung-hoon choi Department of Life Convergence Graduate SchoolDankook UniversityYonginGyeonggi-do 16890Republic of Korea

On May 25,2019,the World Health Assembly approved the eleventh revision of the International Statistical Classification of Diseases and Related Health Problems(ICD-11),containing a chapter on traditional *** means that the traditional East Asian medicine(TEAM)is now officially recognized as a part of mainstream medical ***,the patterns presented in the ICD-11 traditional medicine chapter are only the tip of the iceberg of TEAM clinical practice,and it will be necessary to supplement and upgrade the *** order to implement this,objectification and standardization of TEAM must be premised,and grafting with proper modern science and technology is *** Identification and Prescription Expert-11(PIPE-11),which is a TEAM clinical decision support system,adopts vastly from clinical literature on pattern identification and the *** adopting the rule-based reasoning method,the way of diagnosis and prescription by a TEAM practitioner in actual clinical practice is implemented as it ***-11 could support to improve both the accuracy of medical diagnosis and the reliability of the medical treatment of TEAM in clinical *** the field of research,it might facilitate the usage for reliable reference for symptoms and signs retrieval and patient *** the field of education,it can provide a high level of training for learning pattern identification and prescription,and further be used to reinforce skills of diagnosis and prescription by providing self-simulation ***,PIPE-11 as a digital application is expected to support the traditional medicine chapter of ICD-11 to successfully contribute to the improvement of human health.

关键词： ICD-11 PIPE-11 Traditional medicine Clinical decision support system Formula Pattern

Evaluation of Mechanical Properties According to Nb Content of High Strength Steel Manufactured in VIM

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Journal of Materials Science & Technology 2008年第5期24卷 793-796页

作者： Byung-hui choi Byung-Ki choi Department of Mechanical Engineering Graduate SchoolChosun UniversityKorea Department of Mechanical Engineering Chosun UniversityGwang-ju 501-750Korea

As the aircraft and aerospace industry and the automobile industry are developed, the demand of reliable materials with high strength and high toughness is steadily increased. The grain miniature method which improves the ductility and the toughness simultaneously under high strength is the miniature of the casting microstructure. In this paper, the Nb which affects the austenite grain miniature is added by 0.00%, 0.03% and 0.06% in this steel and the ingot is manufactured in a vacuum induction melting furnace （VIM）. The casting microstructure and the mechanical property of the maraging steel according to Nb contents are analyzed by conducting the solution annealing and the age hardening after hot rolling. In this result, a specimen containing 0.03% Nb is most miniature. When it does the long time age hardening, the precipitation estimated as the carbide is appeared. The mechanical properties are excellent if a specimen containing 0.06% Nb does the age hardening during 8 h in 482℃.

关键词： High strength steel Maraging steel Nb Vacuum induction melting furnace (VIM)

Short-circuit Current Characteristics of Wind Generators

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电力系统自动化 2012年第8期36卷 110-114页

作者： seung-Jae LEE Myeon-Song choi Department of Electrical Engineering Myongji University

To study the effects of wind generators on distribution system protection,the short-circuit current(SCC) characteristics of wind generators is *** there are many researches on the issue,a clear agreement has not been reached so *** SCC characteristics for different wind generators are *** simulation is performed in the same system integrated with different kinds of wind generators,and their results are compared with those reported in IEEE *** detection possibility by overcurrent relay(OCR)is discussed based on the simulation results.

关键词：风力发电机组短路电流电流特性配电系统 PSCAD 过流继电器 IEEE 通过检测

Influence of the wastewater composition on denitrification and biological P-removal in the S-DN-P process: (c) Dissolved and undissolved substrates

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Journal of Environmental Sciences 2009年第8期21卷 1074-1079页

作者： Hee-Jeong choi Chul-Ho choi seung-Mok Lee Diwakar Tiwari Department of Environmental Engineering Kwandong University Department of Chemistry School of Physical Sciences Mizoram University

The denitdfication and P-removal in the sorption-denitrification-P-removal （S-DN-P） process were carded out under various wastewater compositions. It is noted that P-removal largely depends on the wastewater composition as well to the quantity of the substrates present in wastewater fraction. Three different wastewater fractions are obtained as： raw wastewater, dissolved wastewater （obtained with filtration using 0.45 μm filter）, and undissolved wastewater （i.e., infiltrate obtained by above filtration）. The ratio of P-release/CODtotal-consumption clearly inferred that undissolved wastewater possess very low value i.e., 0.0008 followed by raw wastewater 0.008 and dissolved wastewater 0.03. When this ratio was nearby 0.01, enhanced P-removal was observed. Moreover, the ratio of P-uptake to NO3^--N decomposition for raw wastewater was two times for dissolved wastewater. Interestingly, it was observed that the P-removal and denitrification depend not only on the dissolved substrates but also the undissolved substrates present in the wastewater. The result of the P-removal obtained with this S-DN-P process did not show a big difference of 36%, 34% and 30%, respectively, for raw, dissolved and undissolved wastewater.

关键词： denitrification polyhydroxybutyrate sequencing batch biofilm reactor sorption denitrification P-removals

Aerosol-assisted rapid synthesis of SnS-C composite microspheres as anode material for Na-ion batteries

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Nano Research 2015年第5期8卷 1595-1603页

作者： seung Ho choi Yun Chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea

SnS-C composite powders were prepared through one-pot spray pyrolysis for use as anode materials for Na-ion batteries. C microspheres with uniformly attached cubic-like SnS nanocrystals, which have an amorphous C coating layer, were formed at a preparation temperature of 900 ℃. The initial discharge capacities of the bare SnS and SnS-C composite powders at a current density of 500 mA·g^-1 were 695 and 740 mA·h·g^-1, respectively. The discharge capacities after 50 cycles and the capacity retentions measured from the second cycle of the bare SnS and SnS-C composite powders were 25 and 433 mA.h.g-1 and 5 and 89%, respectively. The prepared SnS-C composite powders with high reversible capacities and good cycle performance can be used as Na-ion battery anode materials.

关键词： tin sulfide anode material carbon composite sodium battery energy storage

Enhanced Li^＋ storage properties of few-layered MoS2-C composite microspheres embedded with Si nanopowder

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Nano Research 2015年第8期8卷 2492-2502页

作者： seung Ho choi Yun Chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seoul 136-713 Republic of Korea

A few-layered MoS2-C composite material is studied as a supporting material for silicon nanopowder. Microspheres of the few-layered MoS2-C composite embedded with 30 wt.% Si nanopowder are prepared by one-pot spray pyrolysis. The Si nanopowder particles with high capacity are completely surrounded by the few-layered MoS2-C composite matrix. The discharge capacities of the MoS2-C composite microspheres with and without 30 wt.% Si nanopowder after 100 cycles are 1,020 and 718 mAh·g^-1 at a current density of 1,000 mA·g^-1 respectively. The spherical morphology of the MoS2-C composite microspheres embedded with Si nanopowder is preserved even after 100 cycles because of their high structural stability during cycling. The MoS2-C composite layer prevents the formation of unstable solid-electrolyte interface （SEI） layers on the Si nanopowder. Furthermore, as the MoS2-C composite matrix exhibits high capacity and excellent cycling performance, these characteristics are also reflected in the MoS2-C composite microspheres embedded with 30 wt.% Si nanopowder.

关键词： molybdenum sulfide silicon anode material lithium batteries spray pyrolysis

ON THE ASYMPTOTIC DYNAMICS OF THE VLASOV-YUKAWA-BOLTZMANN SYSTEM NEAR VACUUM

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Acta Mathematica Scientia 2015年第4期35卷 887-905页

作者： Sun-Ho choi seung-Yeal HA Department of Mathematical Sciences KAIST Department of Mathematical Sciences and Research Institute of Mathematics Seoul National University

In this pape,~ we study uniform L1-stability and asymptotic completeness of the Vlasov-Yukawa-Boltzmann （V-Y-B） system. For a sufficiently small rand smooth initial data, we show that classical solutions exist globally and satisfy dispersion estimates, uniform L1-stability with respect to initial data and scattering type estimate. We show that the short range nature of interactions due to the Yukawa potential enables us to construct robust Lyapunov type functional to derive scattering states. In the zero mass limit of force carrier particles, we also show that the classical solutions to the V-Y-B system converge to that of the Vlasov-Poisson-Boltzmann （V-P-B） system in any finite time interval

关键词： asymptotic completeness collision operator the Vlasov-Yukawa-Boltzmannsystem uniform L1-stability