61 results on '"Jung-Il Yang"'
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2. Biogas Technology Development Trend for Transportation Fuel and Green Hydrogen Productions
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Shin-Wook Kang, Hack-Keun Lee, Ji-Chan Park, Su Ha, Se Hoon Kim, and Jung-Il Yang
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Automotive Engineering - Published
- 2022
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3. Automated synthesis and data accumulation for fast production of high-performance Ni nanocatalysts
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Shin Wook Kang, Ji Chan Park, Chang Seop Hong, Taewaen Lim, Gyeongjin Nam, Jung-Il Yang, Kyung Hee Oh, Hack-Keun Lee, and Sang Ho Lee
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Materials science ,Chemical engineering ,Activated charcoal ,law ,General Chemical Engineering ,Reactor system ,Critical factors ,Nanoparticle ,Calcination ,Particle size ,Nanomaterial-based catalyst ,Catalysis ,law.invention - Abstract
Diverse methods have been developed for the synthesis of active nanocatalysts involving various heterogeneous catalytic reactions. Thus far, numerous trial-and-error runs have been done to find the effective and practical ways. In the present work, the All-In-One (AIO) reactor system with a well-designed synthesis program, now in pilot stage, was first exploited as a reliable synthesis tool to find the optimum conditions for the production of Ni nanocatalysts. Using an activated charcoal support, active Ni nanoparticles of 7.8–11.8 nm (labeled A001–A007 in the program) were produced. These were achieved using a melt-impregnation process, which was controlled by variations in the applied gas (N2 and H2) and temperature (400 °C, 450 °C, and 500 °C) used as critical factors in the calcination step. Based on the optimization of the reaction sequence, each Ni nanocatalyst could be prepared within 5 h and 22 min. In particular, the optimum Ni nanocatalyst (A006) with the smallest particle size (7.8 nm), prepared under H2 flow at 400 °C, exhibits the highest catalytic activity (0.748 mmol4-NP·gcat-1·s-1) among the Ni catalysts for 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP). This activity is much higher than that of conventional supported Ni nanocatalysts (0.551 mmol4-NP·gcat-1·s-1) produced using the wetness method.
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- 2022
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4. Efficient catalyst by a sequential melt infiltration method to achieve a high loading of supported nickel nanoparticles for compact reformer
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Su Ha, Ji Chan Park, Jung-Il Yang, Shin Wook Kang, Hack-Keun Lee, and Kyung Hee Oh
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Reaction rate ,Nickel ,Materials science ,chemistry ,Hydrogen ,Chemical engineering ,General Chemical Engineering ,chemistry.chemical_element ,Nanoparticle ,Thermal stability ,Dispersion (chemistry) ,Catalysis ,Hydrogen production - Abstract
The development of high-performance Ni catalysts including the formation and stabilization of active Ni nanoparticles with high surface areas by increasing their metal dispersion at the high metal loading have been major issues in the design of a compact reformer for hydrogen production. Herein, we first report a facile method based on the sequential melt infiltration process for creating highly dispersed Ni nanoparticles (~7.5 nm) incorporated into alumina support (Ni/Al2O3) with high Ni load (45 wt%). They showed much higher hydrogen productivity and reaction rate than that of the incipient wet-impregnated Ni catalyst and commercial Ni catalyst as well as good thermal stability in steam-methane reforming under harsh conditions.
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- 2021
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5. A New Automated Synthesis of Coke-Resistant Cs-Promoted Ni-Supported Nanocatalyst for Sustainable Dry Reforming of Methane
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Kyung Hee Oh, Jin Hee Lee, Kwangsoo Kim, Hack-Keun Lee, Shin Wook Kang, Jung-Il Yang, Jong-Ho Park, Chang Seop Hong, Byung-Hyun Kim, and Ji Chan Park
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- 2022
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6. A new systematic synthesis of ultimate nickel nanocatalysts for compact hydrogen generation
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Shin Wook Kang, Hack-Keun Lee, Jung Taesung, Heon Jung, Jungmin Ban, Dong Hyun Chun, Jung-Il Yang, Dawon Oh, Ji Chan Park, and Jin Hee Lee
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inorganic chemicals ,Fluid Flow and Transfer Processes ,Materials science ,Hydrogen ,Process Chemistry and Technology ,chemistry.chemical_element ,Nanoparticle ,Catalysis ,Nanomaterial-based catalyst ,Steam reforming ,Nickel ,chemistry ,Chemical engineering ,Chemistry (miscellaneous) ,Chemical Engineering (miscellaneous) ,Dispersion (chemistry) ,Hydrogen production - Abstract
Nickel (Ni)-based materials have been shown as good catalysts for hydrogen production by steam reforming of methane, but the hydrogen productivity has been restricted due to agglomeration among particles on Ni loaded catalysts. A new strategy is demonstrated by which to produce ultimate nickel nanocatalysts with high particle dispersion and high metal loading by using automated and systematic synthesis tools based on a simple melt-infiltration process and thermal treatment. The systematic sequence can yield highly dispersed Ni nanoparticles (4.5 nm) with high metal loading (25 wt%) on porous alumina (u-Ni/Al2O3) as an ultimate catalyst.
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- 2020
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7. Extremely productive iron-carbide nanoparticles on graphene flakes for CO hydrogenation reactions under harsh conditions
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Jung-Il Yang, Heon Jung, Dong-Wook Lee, Jong Hyuk Seo, Geun Bae Rhim, Ji Chan Park, Heon-Do Jeong, Min Hye Youn, Dong Hyun Chun, Hack-Keun Lee, Jin Hee Lee, and Shin Wook Kang
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chemistry.chemical_classification ,010405 organic chemistry ,Chemistry ,Graphene ,Nanoparticle ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Carbide ,law.invention ,Metal ,Hydrocarbon ,Chemical engineering ,law ,visual_art ,visual_art.visual_art_medium ,Thermal stability ,Physical and Theoretical Chemistry ,Dispersion (chemistry) - Abstract
For the highly productive nanocatalyst synthesis, ensuring the formation and stabilization of active nanoparticles with enlarged surface areas by increasing their metal loading and dispersion have been major issues. Herein, we report a facile method based on a simple melt-infiltration process for creating extremely productive Fe5C2 nanoparticles (∼14 nm) incorporated into graphene flakes (Fe5C2/G) with a stable and high Fe load (∼35 wt%). They showed extremely high C5+ hydrocarbon productivity (4.41 gC5+HC gcat−1 h−1), CO conversion (91.8%), and Fe time yield (6.5 × 10−4 molCO gFe−1 s−1) as well as good thermal stability in CO hydrogenation reactions under harsh conditions.
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- 2019
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8. Phase-controlled synthesis of thermally stable nitrogen-doped carbon supported iron catalysts for highly efficient Fischer-Tropsch synthesis
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Jung-Il Yang, Shin Wook Kang, Jin Hee Lee, Ji Chan Park, Heon Jung, Hyunkyung Choi, Dong Hyun Chun, Hack-Keun Lee, Heon-Do Jeong, Min Hye Youn, Geun Bae Rhim, and Chul Sung Kim
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chemistry.chemical_classification ,Materials science ,Nanoparticle ,chemistry.chemical_element ,Fischer–Tropsch process ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Chemical synthesis ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Catalysis ,Hydrocarbon ,chemistry ,Chemical engineering ,Phase (matter) ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,Dispersion (chemistry) ,Carbon - Abstract
Iron-based nanoparticles with uniform and high particle dispersion, which are supported on carbon structures, have been used for various applications. However, their preparation still suffers from complicated synthesis involving multiple steps and from the high price of precursors and solvents. In the present work, a new carbon encapsulated iron-carbide nanoparticle supported on nitrogen-doped porous carbon (Fe5C2@C/NPC) structure was introduced. It was made using a simple solid-state reaction with sequential thermal treatments. Fe5C2@C/NPC is a highly active and stable catalyst for the high-temperature Fischer-Tropsch synthesis reaction. It showed very high hydrocarbon productivity (4.71 gHC·gcat−1·h−1) with high CO conversions (up to 96%).
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- 2019
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9. Effect of cobalt metal loading on Fischer–Tropsch synthesis activities over Co/γ-Al2O3 catalysts: CO conversion, C5+ productivity, and α value
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Chang Hyun Ko and Jung-Il Yang
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inorganic chemicals ,Materials science ,010405 organic chemistry ,Oxide ,chemistry.chemical_element ,Fischer–Tropsch process ,General Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Adsorption ,chemistry ,Particle ,Particle size ,Cobalt oxide ,Cobalt ,Nuclear chemistry - Abstract
This study investigates the effect of cobalt loading (5–20 wt% Co) on the physical properties of the alumina support and cobalt particle size of Co/γ-Al2O3 catalysts for Fischer–Tropsch synthesis (FTS) reaction (T = 210 °C (set), P = 20 bar, H2/CO = 2). To characterize the catalysts and correlate these characteristics with their catalytic activities in FTS, N2 adsorption, inductively coupled plasma, X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) studies were conducted. N2 adsorption and XRD analyses showed that as the cobalt loading was increased up to 15 wt%, the number of cobalt oxide particles increased by the direct interaction between cobalt oxide and the alumina support surface, but that when the cobalt loading was further increased to 20 wt%, the particle size of the cobalt oxide increased abruptly due to the additional cobalt loading on the previously loaded cobalt oxide. These physical properties of the supported cobalt catalysts were attributed to the pore structure of the alumina support. From the TEM micrographs, the size of cobalt particles was roughly estimated to increase from 20 to 50 nm at a cobalt loading up to 15 wt% Co/γ-Al2O3 to 70–100 nm at 20 wt% cobalt loading. For the 5–15 wt% Co/γ-Al2O3 catalysts, CO conversion and C5+ liquid oil productivity increased with increasing cobalt loading because they were strongly proportional to the number of cobalt particle active sites. However, the 20 wt% Co/γ-Al2O3 catalyst showed the highest value of α because the larger cobalt particles increased the opportunity for chain growth. The XPS data also supported the greater reducibility of the cobalt species in 20 wt% Co/γ-Al2O3 and hence its larger size compared to that at low cobalt loading.
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- 2019
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10. Facile Synthesis of a High Performance NiPd@CMK-3 Nanocatalyst for Mild Suzuki-Miyaura Coupling Reactions
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Ji Chan Park, Sanha Jang, Shin Wook Kang, Chan-Woo Lee, Byung-Hyun Kim, A-Ram Kim, Jung-Il Yang, and Kang Hyun Park
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Materials science ,Organic Chemistry ,Alloy ,chemistry.chemical_element ,engineering.material ,Combinatorial chemistry ,Catalysis ,Coupling reaction ,Inorganic Chemistry ,Nickel ,chemistry ,Suzuki reaction ,engineering ,Physical and Theoretical Chemistry ,Bimetallic strip ,Palladium - Published
- 2019
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11. A durable nanocatalyst of potassium-doped iron-carbide/alumina for significant production of linear alpha olefins via Fischer-Tropsch synthesis
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Geun Bae Rhim, Heon-Do Jeong, Min Hye Youn, Jin Hee Lee, Kee Young Koo, Hyunkyoung Choi, Ho-Tae Lee, Shin Wook Kang, Dong-Wook Lee, Jung-Il Yang, Ji Chan Park, Chul Sung Kim, Sanha Jang, Heon Jung, and Dong Hyun Chun
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chemistry.chemical_classification ,Base (chemistry) ,010405 organic chemistry ,Process Chemistry and Technology ,Potassium ,chemistry.chemical_element ,Fischer–Tropsch process ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Carbide ,Hydrocarbon ,chemistry ,Chemical engineering ,Selectivity ,Space velocity - Abstract
Improvement of activity, selectivity, and stability of the catalyst used in Fischer-Tropsch synthesis (FTS) to produce targeted hydrocarbon products has been a major challenge. In this work, the potassium-doped iron-carbide/alumina (K-Fe5C2/Al2O3), as a durable nanocatalyst containing small iron-carbide particles (∼ 10 nm), was applied to high-temperature Fischer-Tropsch synthesis (HT-FTS) to optimize the production of linear alpha olefins. The catalyst, suitable under high space velocity reaction conditions (14–36 N L gcat−1 h−1) based on the well-dispersed potassium as an efficient base promoter on the active iron-carbide surface, shows very high CO conversion (up to ∼90%) with extremely high activity (1.41 mmolCO gFe−1 s−1) and selectivity for C5–C13 linear alpha olefins.
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- 2018
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12. Reverse water gas shift reaction over CuFe/Al2O3 catalyst in solid oxide electrolysis cell
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Kai Zhao, Jung-Il Yang, Qusay Bkour, Ji Chan Park, Su Ha, Xiaoxue Hou, M. Grant Norton, and Shin Wook Kang
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Materials science ,Hydrogen ,Electrolytic cell ,General Chemical Engineering ,Inorganic chemistry ,Oxide ,chemistry.chemical_element ,Selective catalytic reduction ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,Water-gas shift reaction ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,High-temperature electrolysis ,Environmental Chemistry ,0210 nano-technology ,Space velocity - Abstract
Catalytic reduction by the reverse water gas shift (RWGS) reaction is an efficient way to utilize carbon dioxide and reduce its environmental impact as a greenhouse gas. In this research, an active CuFe/Al 2 O 3 nano powder was developed as a high temperature reforming catalyst for the RWGS reaction. The powder was synthesized by a wet-impregnation method and the copper alloy was uniformly dispersed on the γ-Al 2 O 3 support. At a gas space velocity of 60,000 h −1 , the conversion of carbon dioxide was 42% at 700 °C, which is very close to the equilibrium conversion of 44%. The results indicated excellent reforming activity of the CuFe/Al 2 O 3 catalyst for the high temperature RWGS reaction. In addition, the catalyst was applied in the form of a reforming layer over a conventional Ni-based electrode of a solid oxide electrolysis cell (SOEC) for an integrated SOEC-RWGS system. Hydrogen produced from steam electrolysis over the Ni-based cathode can be efficiently utilized to reduce the carbon dioxide by the RWGS reaction over the CuFe/Al 2 O 3 -based reforming layer. In this bilayer design, the reforming layer maintained the high surface area necessary for achieving good reforming activity, while the electrode layer possessed a high degree of sintering to enhance its electrochemical function. A high conversion of carbon dioxide (37% at 700 °C) was obtained in our bilayer SOEC-RWGS system. This promising result suggests the feasibility of the integrated SOEC-RWGS system for an efficient co-electrolysis device.
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- 2018
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13. A Thermally Stable Co@pSiO2 Yolk-Shell Nanocatalyst for High-Temperature Fischer-Tropsch Synthesis
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Ho-Tae Lee, Jae In Kwon, Shin Wook Kang, Ji Chan Park, Jung-Il Yang, Dong Hyun Chun, and Heon Jung
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Materials science ,food.ingredient ,food ,Chemical engineering ,Yolk ,Biomedical Engineering ,Shell (structure) ,General Materials Science ,Bioengineering ,Fischer–Tropsch process ,General Chemistry ,Condensed Matter Physics - Published
- 2017
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14. High-performance Fe 5 C 2 @CMK-3 nanocatalyst for selective and high-yield production of gasoline-range hydrocarbons
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Dong Hyun Chun, Jeong Woo Han, Sang Hoon Joo, Chul Sung Kim, Heon Jung, Ji Chan Park, Ho-Tae Lee, Jung-Il Yang, Shin Wook Kang, Chan-Woo Lee, Kyeounghak Kim, Sanha Jang, and Jung Tae Lim
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Chemistry ,Inorganic chemistry ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Mesoporous carbon ,Physical and Theoretical Chemistry ,Gasoline ,0210 nano-technology ,Selectivity ,Nuclear chemistry - Abstract
Highly-loaded and well-dispersed Fe 5 C 2 nanoparticles within ordered mesoporous carbon CMK-3 (Fe 5 C 2 @CMK-3) were prepared via a simple melt infiltration method. They were successfully applied to high-temperature Fischer-Tropsch synthesis, and showed high CO conversion (91%) and activity (5.1 × 10 −4 mol co g Fe −1 s −1 ) as well as good selectivity (38 wt%) for gasoline-range hydrocarbons (C 5 –C 12 ). The catalytic property of Fe 5 C 2 @CMK-3 was newly interpreted, based on theoretical data obtained by computational simulations.
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- 2017
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15. Elucidating the Influence of Electric Fields toward CO2 Activation on YSZ (111)
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Fanglin Che, Jean-Sabin McEwen, Su Ha, Jung-Il Yang, and Nisa Ulumuddin
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Materials science ,Field (physics) ,Strong interaction ,02 engineering and technology ,lcsh:Chemical technology ,010402 general chemistry ,01 natural sciences ,Catalysis ,lcsh:Chemistry ,Physisorption ,Electric field ,lcsh:TP1-1185 ,yttria stabilized zirconia ,Physical and Theoretical Chemistry ,density functional theory ,CO2 reduction ,021001 nanoscience & nanotechnology ,Antibonding molecular orbital ,electric field ,0104 chemical sciences ,lcsh:QD1-999 ,Chemical physics ,Chemisorption ,Density of states ,Density functional theory ,0210 nano-technology - Abstract
Despite its high thermodynamic stability, the presence of a negative electric field is known to facilitate the activation of CO2 through electrostatic effects. To utilize electric fields for a reverse water gas shift reaction, it is critical to elucidate the role of an electric field on a catalyst surface toward activating a CO2 molecule. We conduct a first-principles study to gain an atomic and electronic description of adsorbed CO2 on YSZ (111) surfaces when external electric fields of +1 V/Å, 0 V/Å, and −1 V/Å are applied. We find that the application of an external electric field generally destabilizes oxide bonds, where the direction of the field affects the location of the most favorable oxygen vacancy. The direction of the field also drastically impacts how CO2 adsorbs on the surface. CO2 is bound by physisorption when a +1 V/Å field is applied, a similar interaction as to how it is adsorbed in the absence of a field. This interaction changes to chemisorption when the surface is exposed to a −1 V/Å field value, resulting in the formation of a CO3− complex. The strong interaction is reflected through a direct charge transfer and an orbital splitting within the Olatticep-states. While CO2 remains physisorbed when a +1 V/Å field value is applied, our total density of states analysis indicates that a positive field pulls the charge away from the adsorbate, resulting in a shift of its bonding and antibonding peaks to higher energies, allowing a stronger interaction with YSZ (111). Ultimately, the effect of an electric field toward CO2 adsorption is not negligible, and there is potential in utilizing electric fields to favor the thermodynamics of CO2 reduction on heterogeneous catalysts.
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- 2021
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16. Synthesis of Co/SiO2 hybrid nanocatalyst via twisted Co3Si2O5(OH)4 nanosheets for high-temperature Fischer–Tropsch reaction
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Ho-Tae Lee, Mijong Kim, Ji Chan Park, Sanha Jang, Jeong-Chul Kim, Jae In Kwon, Jung-Il Yang, Shin Wook Kang, Heon Jung, Hyunjoon Song, Geun Bae Rhim, and Dong Hyun Chun
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chemistry.chemical_classification ,Materials science ,Hydrogen ,010405 organic chemistry ,Hydrothermal reaction ,Inorganic chemistry ,chemistry.chemical_element ,Fischer–Tropsch process ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,Chemical synthesis ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Hydrocarbon ,chemistry ,High activity ,General Materials Science ,Thermal stability ,Electrical and Electronic Engineering ,Cobalt ,Nuclear chemistry - Abstract
A cobalt-silica hybrid nanocatalyst bearing small cobalt particles of diameter ~5 nm was prepared through a hydrothermal reaction and hydrogen reduction. The resulting material showed very high CO conversion (>82%) and high hydrocarbon productivity (~1.0 gHC·g−1 cat·h−1) with high activity (~8.5 × 10−5 molCO·g Co −1 ·s−1) in the Fischer–Tropsch synthesis reaction.
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- 2017
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17. Large-scale synthesis of uniformly loaded cobalt nanoparticles on alumina for efficient clean fuel production
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Ji Chan Park, Ho-Tae Lee, Dong Hyun Chun, Shin Wook Kang, Jae In Kwon, Heon Jung, and Jung-Il Yang
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inorganic chemicals ,chemistry.chemical_classification ,Materials science ,010405 organic chemistry ,General Chemical Engineering ,Inorganic chemistry ,Salt (chemistry) ,chemistry.chemical_element ,Nanoparticle ,General Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Liquid fuel ,Catalysis ,Metal ,Hydrocarbon ,chemistry ,visual_art ,visual_art.visual_art_medium ,Hydrate ,Cobalt - Abstract
Large-scale synthesis of cobalt nanoparticles supported on alumina (Co/Al2O3), which has well dispersed metallic cobalt around 15 nm, was conducted via a simple melt infiltration process of a cobalt hydrate salt and subsequent thermal reduction. The catalytic performance of Co/Al2O3 was studied for Fischer–Tropsch synthesis in order to optimize the liquid fuel productivity for target hydrocarbon products controlled by reaction pressures and temperatures. The catalyst showed promising CO conversions up to 76% with high hydrocarbon productivity (∼1.0 gHC gcat−1 h−1) and good stability.
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- 2017
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18. Robust iron-carbide nanoparticles supported on alumina for sustainable production of gasoline-range hydrocarbons
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Shin Wook Kang, Sanha Jang, Heon Jung, Ki Min Nam, Jung-Il Yang, Heon-Do Jeong, Dong Hyun Chun, Ho-Tae Lee, and Ji Chan Park
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chemistry.chemical_classification ,Hydrogen ,Chemistry ,Catalyst support ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Hydrocarbon ,Chemical engineering ,Materials Chemistry ,medicine ,Organic chemistry ,Carbon nanotube supported catalyst ,0210 nano-technology ,Carbon monoxide ,Activated carbon ,medicine.drug - Abstract
The high-temperature Fischer–Tropsch synthesis reaction has been exploited to selectively produce lower-olefins and gasoline-range hydrocarbons (C5–C12) from a mixture of carbon monoxide and hydrogen, using iron-based catalysts. For this reaction, improving the selectivity and stability of the catalyst has been a major challenge, as has enhancing the activity. In the present work, we introduce iron-carbide nanoparticles supported on a porous gamma-alumina framework as a robust catalyst, prepared via a simple melt infiltration process and subsequent thermal treatment, for high-temperature Fischer–Tropsch synthesis. The iron-carbide/alumina catalyst showed much better catalytic performance, with a higher stability for producing gasoline-range hydrocarbon products, than did iron-carbide/mesoporous silica (SBA-15) and iron-carbide/activated carbon (AC).
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- 2017
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19. MoO2-based cathode for CO2 and H2O electrolysis
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Kai Zhao, Su Ha, Xiaoxue Hou, and Jung-Il Yang
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Electrolysis ,Materials science ,Renewable Energy, Sustainability and the Environment ,Open-circuit voltage ,Oxide ,Energy Engineering and Power Technology ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrochemistry ,01 natural sciences ,Cathode ,0104 chemical sciences ,law.invention ,Dielectric spectroscopy ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Chemical engineering ,law ,0210 nano-technology ,Polarization (electrochemistry) ,Polymer electrolyte membrane electrolysis - Abstract
This short communication describes a novel MoO2-based cathode and its potential application for solid oxide electrolysis cells. Electrochemical performances of the MoO2-based cathode are investigated with respect to a commercial Ni/YSZ-based cathode for both co-electrolysis (of H2O and CO2) and electrolysis of only CO2 at 750 °C. Under the co-electrolysis mode, the MoO2-based cell and the Ni/YSZ cell show a similar electrochemical performance, while in the CO2 electrolysis mode, the MoO2-based cell demonstrates a much improved electrocatalytic activity compared with the Ni/YSZ cell. This improved electrochemical activity of the MoO2-based cathode under the CO2 electrolysis mode is further investigated by its electrochemical impedance spectroscopy (EIS) study. According to our EIS study, the polarization resistance of the MoO2-based cell is 67% lower than that of the Ni/YSZ-based cell under the open circuit potential. A performance stability study indicates that the MoO2-based cell exhibits a relatively low performance degradation under the CO2 electrolysis mode during its 10-h constant voltage test, and low carbon amount (6.6 wt.%) is detected after the performance stability measurement. These findings suggest the advantages of applying the MoO2-based cathode for the CO2 electrolysis.
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- 2016
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20. Development of a stand-alone steam methane reformer for on-site hydrogen production
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Ji Chan Park, Dong Hyun Chun, Jung-Il Yang, Tak-Hyoung Lim, Tae Wan Kim, and Heon Jung
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Exothermic reaction ,Methanol reformer ,Methane reformer ,Renewable Energy, Sustainability and the Environment ,Chemistry ,020209 energy ,Energy Engineering and Power Technology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Catalysis ,Steam reforming ,Fuel Technology ,Chemical engineering ,0202 electrical engineering, electronic engineering, information engineering ,Small stationary reformer ,0210 nano-technology ,Space velocity ,Hydrogen production - Abstract
A small, stationary reformer designed as a stand-alone and self-sustaining type was developed for on-site hydrogen (H2) production. We created a compact reformer to produce H2 at a rate of 1 Nm3/h using the previously reported reaction kinetics of steam methane reforming (SMR). Both catalysts for the compact reformer - i.e., 15 wt% and 20 wt% Ni/γ-Al2O3 - showed good activity, with CH4 conversion exceeding 90% at 655 °C and a contact time of 3.0 gcath/mol, which were considered critical thresholds in the development of a small, compact stationary reformer. At an H2 production rate of 1 Nm3/h, the catalyst amount was calculated to be 167.8 g and the reformer length required to charge the catalyst was 613 mm, with a diameter of 1 inch. The CH4 conversion and H2 production rates achieved with the compact reformer using the 20 wt% Ni/γ-Al2O3 catalyst at 738 °C were 97.9% and 1.22 Nm3/h, respectively. Furthermore, a heat-exchanger type reformer was developed to efficiently carry out the highly endothermic SMR reaction for on-site H2 production. This reformer comprised a tube side (in which the catalysts were charged and the SMR reaction took place by feeding the reactants) and a shell side (in which the heat for the endothermic reaction was supplied by CH4 combustion). Reforming activities were evaluated using the active 20 wt% Ni/γ-Al2O3 catalyst, depending on the reactants' gas hourly space velocity (GHSV). The H2 production rate increased as the GHSV increased. Finally, the reformer produced a CH4 conversion of 98.0% and an H2 production rate of 1.97 Nm3/h at 745 °C, as well as a high reactants' GHSV of 10,000 h−1. Therefore, the heat-exchanger type reformer proved to be an effective system for conducting the highly endothermic SMR reaction with a high reactants' GHSV to yield a high rate of H2 production.
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- 2016
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21. Nanocrystalline Iron-Ore-Based Catalysts for Fischer-Tropsch Synthesis
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Ho-Tae Lee, Jung-Il Yang, Sungjun Hong, Heon Jung, Ji Chan Park, Seok Yong, and Dong Hyun Chun
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chemistry.chemical_classification ,Materials science ,Biomedical Engineering ,Bioengineering ,Fischer–Tropsch process ,02 engineering and technology ,General Chemistry ,Raw material ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Nanocrystalline material ,0104 chemical sciences ,Catalysis ,Hydrocarbon ,Iron ore ,Chemical engineering ,chemistry ,engineering ,General Materials Science ,Nanometre ,Crystallite ,0210 nano-technology - Abstract
Nanocrystalline iron ore particles were fabricated by a wet-milling process using an Ultra Apex Mill, after which they were used as raw materials of iron-based catalysts for low-temperature Fischer-Tropsch synthesis (FTS) below 280 degrees C, which usually requires catalysts with a high surface area, a large pore volume, and a small crystallite size. The wet-milling process using the Ultra Apex Mill effectively destroyed the initial crystallite structure of the natural iron ores of several tens to hundreds of nanometers in size, resulting in the generation of nanocrystalline iron ore particles with a high surface area and a large pore volume. The iron-ore-based catalysts prepared from the nanocrystalline iron ore particles effectively catalyzed the low-temperature FTS, displaying a high CO conversion (about 90%) and good C5+ hydrocarbon productivity (about 0.22 g/g(cat)(-h)). This demonstrates the feasibility of using the iron-ore-based catalysts as inexpensive and disposable catalysts for the low-temperature FTS.
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- 2016
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22. Nanocrystalline Ferrihydrite-Based Catalysts for Fischer-Tropsch Synthesis: Part I. Reduction and Carburization Behavior
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Dong Hyun Chun, Ji Chan Park, Geun Bae Rhim, Ho-Tae Lee, Jung-Il Yang, SungJun Hong, and Heon Jung
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Materials science ,Biomedical Engineering ,Bioengineering ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Catalysis ,Metal ,chemistry.chemical_compound ,Ferrihydrite ,General Materials Science ,Wüstite ,Magnetite ,Fischer–Tropsch process ,General Chemistry ,Hematite ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,engineering ,Fayalite ,0210 nano-technology - Abstract
Temperature-programmed reduction using H2 (H2-TPR) and CO (CO-TPR) was carried out to investigate the reduction and carburization behavior of nanocrystalline ferrihydrite-based Fe/Cu/K/SiO2 catalysts for use in Fischer-Tropsch synthesis (FTS). Unlike pure ferrihydrite, the ferrihydrite-based catalysts did not pass through the intermediate decomposition step of ferrihydrite (Fe9O2(OH)23) into hematite (a-Fe2O3) as they were reduced into magnetite (Fe3O4). This is attributed to the enhanced thermal stability induced by SiO2. For the ferrihydrite-based catalysts, the reduction of ferrihydrite into magnetite occurred in two stages because the reduction promoter, Cu, is not homogeneously distributed on the catalyst surfaces. The Cu-rich sites are likely to be reduced in the first stage, and the Cu-lean sites may be reduced in the second stage. After the ferrihydrite is reduced to magnetite, the reduction process of magnetite was similar to that for conventional hematite-based FTS catalysts: 'magnetite --> metallic iron' and 'magnetite --> wustite (FeO) or fayalite (Fe2SiO4) --> metallic iron' in the H2 atmosphere; 'magnetite --> iron carbides' in the CO atmosphere.
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- 2016
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23. Estimating surface electric fields using reactive formic acid probes and SEM image brightness analysis
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Kriti Agarwal, Su Ha, Jake T. Gray, Jung Il Yang, and Jeong Hyun Cho
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Brightness ,Materials science ,Field (physics) ,Formic acid ,General Chemical Engineering ,Biasing ,Field strength ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Electric field ,Environmental Chemistry ,Composite material ,0210 nano-technology ,Selectivity - Abstract
By changing the electrical bias imposed on a Ni catalyst attached to an external circuit, the selectivity of catalytic formic acid decomposition is shown to change—favoring CO2/H2 production under negative bias and CO/H2O production under positive bias. A method for estimating the strength of externally generated surface electric fields by measuring this selectivity change is presented and used to approximate field strengths on the order of 0.20 V/nm. A COMSOL model of the catalyst was created which indicated that the presence of Ni particles increased field strength and uniformity across the catalyst. Comparing this model to SEM imaging of the catalyst verified that the field strengths are highest on the surface of the catalyst particles, pore edges, and microscopic defects. The methods developed herein may be useful to future reaction engineers seeking to incorporate applied electric fields into process designs.
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- 2020
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24. Unravelling the reaction mechanism of gas-phase formic acid decomposition on highly dispersed Mo2C nanoparticles supported on graphene flakes
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Norbert Kruse, Shin Wook Kang, Jean-Sabin McEwen, Su Ha, Jake T. Gray, Jung-Il Yang, and Ji Chan Park
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Reaction mechanism ,Graphene ,Formic acid ,Decarboxylation ,Process Chemistry and Technology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,medicine.disease ,01 natural sciences ,Decomposition ,Catalysis ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,medicine ,Dehydration ,0210 nano-technology ,Selectivity ,Chemical decomposition ,General Environmental Science - Abstract
Mo2C/graphene nanostructures were used to investigate the nature of gas-phase formic acid decomposition into either CO/H2O or CO2/H2 products. The experimental data show that the Mo2C/graphene can facilitate both decarboxylation and dehydration pathways for the formic acid decomposition reaction. Its selectivity is strongly influenced by the reaction temperature where the decarboxylation predominates at a low temperature (e.g., ≤ 280 °C) and the dehydration predominates at a high temperature (e.g., ≥ 370 °C). These experimental data are compared to Monte Carlo simulations. It was found that the decarboxylation pathway for the production of CO/H2O can be simulated and explained by an Eley-Rideal type mechanism that involves interaction of gas-phase HCOOH with surface H*. Furthermore, the dehydration pathway for the production of CO2/H2 can be simulated and explained by a Langmuir-Hinshelwood type mechanism that involves unimolecular decomposition of surface HCO*O* to form CO2 and H*.
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- 2020
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25. Highly productive cobalt nanoparticles supported on mesocellular silica foam for the Fischer–Tropsch reaction
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Shin Wook Kang, Ji Chan Park, Jae In Kwon, Ho-Tae Lee, Heon Jung, Jung-Il Yang, and Dong Hyun Chun
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chemistry.chemical_classification ,Nanoparticle ,chemistry.chemical_element ,Fischer–Tropsch process ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Catalysis ,Nanomaterial-based catalyst ,0104 chemical sciences ,Hydrocarbon ,chemistry ,Pulmonary surfactant ,Chemical engineering ,Materials Chemistry ,Organic chemistry ,0210 nano-technology ,Selectivity ,Cobalt - Abstract
We prepared highly productive Co/MCF nanocatalysts by a facile melt infiltration process using a hydrated Co precursor. The highly loaded Co particles (30 wt%) were uniformly dispersed in the large pores (30 nm) of the MCF support. The Co particles had an average diameter of 17 nm and clean surfaces without any surfactant. The Co/MCF catalyst exhibited very high hydrocarbon productivity (∼0.98 gtotal HC gcat−1 h−1) with high activity (CO conversion = 77%, CTY = 7.6 × 10−5 molCO gCo−1 s−1) and good selectivity for C5+ long chain hydrocarbons (∼81%) in Fischer–Tropsch synthesis.
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- 2016
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26. The kinetics of steam methane reforming over a Ni/γ-Al2O3 catalyst for the development of small stationary reformers
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Tae Wan Kim, Tak-Hyoung Lim, Jung-Il Yang, Heon Jung, Dong Hyun Chun, Sungjun Hong, Ho Tae Lee, and Ji Chan Park
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Renewable Energy, Sustainability and the Environment ,Chemistry ,Diffusion ,Kinetics ,Metallurgy ,Pre-exponential factor ,Energy Engineering and Power Technology ,Activation energy ,Condensed Matter Physics ,Catalysis ,Steam reforming ,Chemical kinetics ,Fuel Technology ,Chemical engineering ,Particle size - Abstract
To develop small stationary reformers for on-site H 2 production, the active catalyst and its reaction kinetics were examined in order to study the steam methane reforming reaction. A 20 wt% Ni/γ-Al 2 O 3 was found to be a highly active catalyst within the investigated range of contact time from 1.16 to 3.64 g cat h/mol, which was good for developing the small stationary reformers. BET, XRD, and TEM analysis revealed that the high activity of the 20 wt% Ni/γ-Al 2 O 3 catalyst compared to the 15 wt% Ni/γ-Al 2 O 3 catalyst was strongly ascribed to the high number of Ni metal particles and the ratio of the number of the Ni metal species between the catalysts was calculated to be 1.33. Furthermore, the SMR reaction kinetics of the reversible first-order reaction between reactants and products was applied. This showed that the activation energies obtained by the two catalysts were the same because of the similar pore diffusion and heat transfer restrictions, and the similar Ni particle size in the catalyst pores. Also, it was found that the ratio of the pre-exponential factor was 1.30, which was exactly proportional to the ratio of Ni loading in the catalysts because it was strongly related to the collision density.
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- 2015
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27. A new synthesis of carbon encapsulated Fe5C2 nanoparticles for high-temperature Fischer–Tropsch synthesis
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Jung-Il Yang, Seok Yong Hong, Chul Sung Kim, Ho-Tae Lee, Sanha Jang, Dong Hyun Chun, Ji Chan Park, Sungjun Hong, Heon Jung, and Jung Tae Lim
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Materials science ,Hydrothermal reaction ,Inorganic chemistry ,Nanoparticle ,chemistry.chemical_element ,Fischer–Tropsch process ,Thermal treatment ,Chemical engineering ,chemistry ,Iron oxalate ,High activity ,General Materials Science ,Mesoporous material ,Carbon - Abstract
Using a simple thermal treatment under a CO flow, uniform micrometer-sized iron oxalate dihydrate cubes prepared by hydrothermal reaction were transformed into Fe5C2@C nanoparticles to form a mesoporous framework; the final structure was successfully applied to the high-temperature Fischer-Tropsch reaction and it showed high activity (CO conversion = 96%, FTY = 1.5 × 10(-4) molCO gFe(-1) s(-1)) and stability.
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- 2015
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28. Cs promoted Fe5C2/charcoal nanocatalysts for sustainable liquid fuel production
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Ho-Tae Lee, Jung-Il Yang, Dong Hyun Chun, Heon Jung, Ji Chan Park, Geun Bae Rhim, Sungjun Hong, and Sanha Jang
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Materials science ,Chemical engineering ,General Chemical Engineering ,visual_art ,visual_art.visual_art_medium ,General Chemistry ,Selectivity ,Charcoal ,Nanomaterial-based catalyst ,Liquid fuel ,Carbide - Abstract
Cs promoted Fe5C2/charcoal nanocatalysts bearing small iron carbide particles of 8.5 and 14 nm were prepared through a simple melt-infiltration process and a wetness impregnation method; the resulting materials showed very high CO conversion (>95%) and good selectivity, especially at Cs/Fe = 0.025, resulting in a high liquid oil productivity (∼0.4 gliq gcat−1 h−1) in high-temperature Fischer–Tropsch synthesis.
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- 2015
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29. A new systematic synthesis of ultimate nickel nanocatalysts for compact hydrogen generation.
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Hack-Keun Lee, Shin Wook Kang, Jung-Il Yang, Dong Hyun Chun, Jin Hee Lee, Dawon Oh, Jungmin Ban, Taesung Jung, Heon Jung, and Ji Chan Park
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- 2020
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30. Effects of SiO2 Incorporation Sequence on the Catalytic Properties of Iron-Based Fischer–Tropsch Catalysts Containing Residual Sodium
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Ho-Tae Lee, Dong Hyun Chun, Ji Chan Park, Jung-Il Yang, Heon Jung, and Sungjun Hong
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Precipitation (chemistry) ,Sodium ,Inorganic chemistry ,chemistry.chemical_element ,Fischer–Tropsch process ,General Chemistry ,Catalysis ,chemistry.chemical_compound ,chemistry ,Selectivity ,Dispersion (chemistry) ,Sodium carbonate ,Organometallic chemistry - Abstract
Fischer–Tropsch synthesis was carried out over industrially important Fe/Cu/K/SiO2 catalysts containing a small amount of residual sodium which originated from the sodium carbonate solution used as a precipitating agent. The structural promoter, SiO2, was incorporated by two comparative sequences: immediately after precipitation (AP) or after a subsequent wash (AW). Whereas AW exhibited severe deactivation during the reaction, AP displayed high and stable catalytic activity for the entire reaction time. Furthermore, AP showed higher selectivity of liquid hydrocarbons, in particular heavy hydrocarbons, than AW. We attribute the advantageous catalytic performance observed in AP to the enhanced reducibility and higher surface basicity of AP, potentially induced by higher dispersion of catalysts and promoters.
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- 2013
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31. A Facile Synthesis of SiO2@Co/mSiO2 Egg-Shell Nanoreactors for Fischer-Tropsch Reaction
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Kwan Young Lee, Ji Chan Park, Jae In Kwon, Tae Wan Kim, and Jung-Il Yang
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Materials science ,Inorganic chemistry ,Biomedical Engineering ,Nanoparticle ,chemistry.chemical_element ,Bioengineering ,Fischer–Tropsch process ,02 engineering and technology ,General Chemistry ,Nanoreactor ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Chemical synthesis ,Nanomaterial-based catalyst ,0104 chemical sciences ,Catalysis ,Chemical engineering ,chemistry ,General Materials Science ,0210 nano-technology ,Cobalt - Abstract
Recently, a convenient melt-infiltration method, using a hydrated metal salt with porous support, was developed to prepare various metal/metal-oxide nanocatalysts. Until now, millimeter-scale, bead-shaped, cobalt egg-shell catalysts have been used to enhance the rate of reactant diffusion and catalyst performance. In the present work, new SiO2@Co/mSiO2 egg-shell nanoreactors (~300 nm) were synthesized with controlled Co content of 10 and 20 wt%. This was accomplished using a selective melt-infiltration process with porous silica shells around solid-silica cores. The SiO2@Co(10 wt%)/mSiO2 egg-shell catalyst that bears small cobalt nanoparticles of -2 nm was successfully employed for the industrially valuable Fischer-Tropsch synthesis reaction, showing the high activity of -8.0 x 10(-5) mol(CO) x gCo(-1) x S(-1).
- Published
- 2016
32. Interaction between partitioning porous plate and rising bubbles in a trayed bubble column
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Jung-Il Yang, Hak-Joo Kim, Seung Bin Park, Ji Chan Park, Junghoon Yang, Heon Jung, Young Gul Hur, Dong Hyun Chun, and Ho-Tae Lee
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Pore size ,Bubble column ,Chromatography ,Gas velocity ,Chemistry ,General Chemical Engineering ,Bubble ,General Chemistry ,Mechanics ,law.invention ,Physics::Fluid Dynamics ,Sieve ,Tray ,law ,Drag ,Porosity - Abstract
In a trayed bubble column, the structure of the partitioning plate plays an important role on the bubble behavior. This study examined the effect of the opening ratio and pore size of the plate on the bubble break-up frequency and bubble size distribution. The sieve tray was used as the partitioning plate. The opening ratio was closely related to gas cap development. The stagnation of bubble flow and a gas cap were observed with an opening ratio less than 48.5%. The gas cap increased with decreasing opening ratio and increasing superficial gas velocity. The main effect of the sieve tray could be categorized into the additional drag force and bubble break-up depending on the sieve pore size. When the sieve pore size was smaller than the Sauter diameter of the bubble swarm, the movement of rising bubbles was interrupted by the drag force applied by the surrounding mesh lines. On the other hand, when the sieve pore size was larger than the Sauter diameter, the bubbles were affected by the additional bubble break-up. After the bubbles penetrated the sieve tray, the bubble size distribution shifted to a smaller one and the Sauter diameter decreased.
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- 2012
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33. Kinetic Study of the Fischer-Tropsch Synthesis and Water Gas Shift Reactions over a Precipitated Iron Catalyst
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Heon Jung, Dong Hyun Chun, Jung-Il Yang, and Ji Chan Park
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Kinetic model ,Chemistry ,General Chemical Engineering ,Inorganic chemistry ,Physical chemistry ,Fischer–Tropsch process ,Kinetic energy ,Iron catalyst ,Water-gas shift reaction - Abstract
철 촉매를 이용한 Fischer-Tropsch 합성 반응과 수성 가스 전환 반응에 대한 반응 메커니즘과 반응 속도식을 5 채널 고정층 반응기를 이용하여 조사하였다. 실험 조건은, 반응물 합성가스 $H_2$ /CO 비 0.5~2, 반응물 공급 유량 60~80 ml/min, 반응 온도 $255{\sim}275^{\circ}C$ 로서 반응 압력은 1.5 MPa을 유지하였다. F-T 합성 반응의 반응 속도식( $r_{FT}$ )은 반응 속도 결정 단계로서 분자로 흡착된 CO와 기상의 수소 분자와의 반응을 바탕으로 하는 Eley-Rideal 반응 메카니즘을 통해 계산되었고, WGS 반응의 반응 속도식( $r_{WGS}$ )은 formate 중간체 생성 반응을 반응 속도 결정 단계로 가정하여 결정되었다. 실험 결과, F-T 합성 반응의 반응 속도식과 WGS 반응의 반응 속도식은 각각 탄화수소 생성과 $CO_2$ 생성에 대한 반응 속도 실험값을 잘 모사하였고, 또한 power law에 근거한 CO 전환 반응에 대한 반응 속도식도 실험값과 잘 일치하였다. 이처럼, 각각의 반응 메카니즘을 바탕으로 도출된 반응 속도식( $r_{FT}$ , $r_{WGS}$ , $-r_{CO}$ )은 실험값과 여러 가지 기존 문헌에서 보고된 반응 속도식 모델과 잘 일치하였다. 【The kinetics of the Fischer-Tropsch synthesis and water gas shift reactions over a precipitated iron catalyst were studied in a 5 channel fixed-bed reactor. Experimental conditions were changed as follows: synthesis gas $H_2$ /CO feed ratios of 0.5~2, reactants flow rate of 60~80 ml/min, and reaction temperature of $255{\sim}275^{\circ}C$ at a constant pressure of 1.5 MPa. The reaction rate of Fischer-Tropsch synthesis was calculated from Eley-Rideal mechanism in which the rate-determining step was the formation of the monomer species (methylene) by hydrogenation of associatively adsorbed CO. Whereas water gas shift reaction rate was determined by the formation of a formate intermediate species as the rate-determining step. As a result, the reaction rates of Fischer-Tropsch synthesis for the hydrocarbon formation and water gas shift for the $CO_2$ production were in good agreement with the experimental values, respectively. Therefore, the reaction rates ( $r_{FT}$ , $r_{WGS}$ , $-r_{CO}$ ) derived from the reaction mechanisms showed good agreement both with experimental values and with some kinetic models from literature.】
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- 2012
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34. Negative Effects of CO2 in the Feed Stream on the Catalytic Performance of Precipitated Iron-Based Catalysts for Fischer–Tropsch Synthesis
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Ji Chan Park, Ho-Tae Lee, Junghoon Yang, Hak-Joo Kim, Byeong-Kwon Kim, Jung-Il Yang, Heon Jung, and Dong Hyun Chun
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Reaction rate ,chemistry.chemical_classification ,Adsorption ,Hydrocarbon ,chemistry ,Desorption ,Inorganic chemistry ,Fischer–Tropsch process ,General Chemistry ,Partial pressure ,Selectivity ,Catalysis - Abstract
Fischer–Tropsch synthesis was carried out over precipitated iron-based catalysts with different amounts of CO2 in the feed stream while maintaining both total reaction pressure (1.5 MPa) and partial pressure of H2 + CO (0.75 MPa) using an inert balance gas, N2. The CO2 in the feed stream decreased the rate of hydrocarbon formation, but it had no significant influence on the carbon number distribution of hydrocarbons. The CO2 in the feed stream also suppressed CO2 formation, decreasing both CO conversion and CO2 selectivity. We attribute the decreased reaction rate to the partial competition in the adsorption behavior between CO and CO2 as revealed in the temperature-programmed desorption.
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- 2012
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35. Combined pre-reformer/reformer system utilizing monolith catalysts for hydrogen production
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Junghoon Yang, Dong Hyun Chun, Nam Jo Jung, Jae Hong Ryu, Hak-Joo Kim, In-Ho Cho, Ji Chan Park, Ho Tae Lee, Heon Jung, Jung Il Yang, and Kwan Young Lee
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chemistry.chemical_classification ,geography ,geography.geographical_feature_category ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Condensed Matter Physics ,Catalysis ,Steam reforming ,chemistry.chemical_compound ,Fuel Technology ,Hydrocarbon ,Chemical engineering ,Propane ,Monolith ,Nuclear chemistry ,Syngas ,Hydrogen production - Abstract
The pre-reforming of higher hydrocarbon, propane, was performed to generate hydrogen from LPG without carbon deposition on the catalysts. A Ru/Ni/MgAl2O4 metallic monolith catalyst was employed to minimize the pressure drop over the catalyst bed. The propane pre-reforming reaction conditions for the complete conversion of propane with no carbon formation were identified to be the following: space velocities over 2400 h−1 and temperatures between 400 and 450 °C with a H2O/C1 ratio of 3. The combined pre-reformer and the main reformer system with the Ru/Ni/MgAl2O4 metallic monolith catalyst was employed to test the conversion propane to syngas where the reaction heat was provided by catalytic combustors. Propane was converted in the pre-reformer to 52.5% H2, 27.0% CH4, 17.5% CO, and 3.0% CO2 with a 331 °C inlet temperature and a 482 °C catalyst outlet temperature. The main steam reforming reactor converted the methane from the pre-reformer with a conversion of higher than 99.0% with a 366 °C inlet temperature and an 824 °C catalyst outlet temperature. With a total of 912 cc of the Ru/Ni/MgAl2O4 metallic monolith catalyst in the main reformer, the H2 production from the propane reached an average of 3.25 Nm3h−1 when the propane was fed at 0.4 Nm3h−1.
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- 2011
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36. Catalytic process for decolorizing yellow plume
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Junghoon Yang, Ho-Tae Lee, Hak-Joo Kim, Jung-Il Yang, Heon Jung, and Dong Hyun Chun
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chemistry.chemical_compound ,Diesel fuel ,Chemical engineering ,Chemistry ,Reducing agent ,General Chemical Engineering ,Exhaust gas ,Nitrogen dioxide ,General Chemistry ,Methanol ,Carbon monoxide ,Catalysis ,Plume - Abstract
Yellow-colored exhaust gas streams from internal engines or gas turbines, frequently referred to as “yellow plume,” contain nitrogen dioxide (NO2) at concentrations as low as 15 ppm. The process developed in this work for decolorizing the yellow plume is based on reduction of NO2 to NO utilizing a combination of a Pt catalyst and a reducing agent. A stoichiometric excess of carbon monoxide, diesel oil, methanol or ethanol were used as reducing agents. Depending on the type of the reductant, the active temperature window of NO2 reduction was varied with methanol and CO being active at lower temperatures and ethanol and diesel oil at higher temperatures. By changing the Pt loading of the catalysts the active temperature window of NO2 reduction was also changed, higher loading Pt catalysts being active at lower temperatures. This scheme of NO2 reduction process was verified in a pilot-scale test with the real exhaust gas from the gas turbine power plant, showing 96% of NO2 reduction at the stack temperatures of 102–123 °C and at space velocities of 28,000–95,000 h−1 with inherent CO in the exhaust gas as the reducing agent.
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- 2011
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37. Partial oxidation of n-hexadecane into synthesis gas over a Pd-based metal monolith catalyst for an auxiliary power unit (APU) system of SOFC
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Hak-Joo Kim, Jung-Il Yang, and Heon Jung
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geography ,geography.geographical_feature_category ,Process Chemistry and Technology ,chemistry.chemical_element ,Redox ,Catalysis ,Diesel fuel ,chemistry ,Chemical engineering ,Partial oxidation ,Monolith ,General Environmental Science ,Palladium ,Space velocity ,Syngas - Abstract
The developed diesel fuel reformer presented in this study consists of three components: a fuel injection part working with an air-blown nozzle; a fuel vaporizing part; catalytic converting part. The injected diesel fuel was vaporized on the surface of the electrically heated cylindrical metallic monolith cell (EHC; electrically heated cell). With our injection and vaporization systems, fast start-ups within 4 min were accomplished at low energy consumption in the stand-alone mode; this proved practicable for transportation applications. The palladium-based catalyst was prepared by the dip coating method. All SEM, TEM, and XPS analyses showed that an intensive and uniform catalyst layer was formed on the metallic monolith surface, composed of palladium oxide crystallite impregnated on alumina support. The catalytic partial oxidation of n-hexadecane was carried out by varying the C/O ratio and steam/C ratio within the GHSV in the range of 30,000–100,000 h−1. Both TPO and XPS analyses were performed for tracing the reaction mechanism of the partial oxidation of n-hexadecane into synthesis gas under the palladium-based catalyst. Partial oxidation over the palladium catalyst was proposed to proceed via the Mars & van Krevelen two-stage redox mechanism. Addition of CeO2, BaO, and SrO promoters to the Pd/Al2O3 catalyst improved thermal stability, as well as the ability of instant re-oxidation of metallic Pd to PdO during the redox cycles, which gave rise to an increase in catalytic activity for higher synthesis gas productivity of higher H2/CO ratios and lower CO2 selectivity.
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- 2011
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38. Two regime transitions to pseudo-homogeneous and heterogeneous bubble flow for various liquid viscosities
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Ho-Tae Lee, Heon Jung, Jung-Il Yang, Hak-Joo Kim, Junghoon Yang, and Dong Hyun Chun
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Bubble column ,Gas velocity ,Turbulence ,Chemistry ,Process Chemistry and Technology ,General Chemical Engineering ,Bubble ,Energy Engineering and Power Technology ,Thermodynamics ,General Chemistry ,Industrial and Manufacturing Engineering ,Physics::Fluid Dynamics ,Homogeneous ,Bubble flow ,Particle-size distribution ,Two-phase flow - Abstract
The gas hold-up variation and regime transition were investigated with different liquid viscosities ranging from 1.0 mPa s to 31.5 mPa s using a 0.15-m-in-diameter bubble column. In contrast to common observations, the gas hold-up graph with the superficial gas velocity could be categorized into three flow regimes: homogeneous, pseudo-homogeneous and heterogeneous flow regimes. The formation of large bubbles caused a transition from the homogeneous to the pseudo-homogenous flow regime, in which large bubbles rose vertically without oscillatory turbulence. According to the results from the dynamic gas disengagement (DGD) technique, large bubbles began to form at the transition superficial gas velocity to the pseudo-homogeneous flow regime. The transition to a heterogeneous flow regime was initiated by the turbulent movement of large bubbles. The transition superficial velocities to pseudo-homogeneous and heterogeneous flow regimes, u t1 and u t2 , decreased with increasing liquid viscosity below a critical viscosity and converged to a certain value above that viscosity. However, the correlations from the literatures could not make a reasonable estimation of the transition superficial velocities because they did not consider the possible transition to a pseudo-homogeneous flow regime. Therefore, the two transition points should be predicted separately.
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- 2010
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39. Mass transfer limitations on fixed-bed reactor for Fischer–Tropsch synthesis
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Ho-Tae Lee, Hak-Joo Kim, Jung-Il Yang, Junghoon Yang, Heon Jung, Jai-Chang Hong, and Dong Hyun Chun
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inorganic chemicals ,chemistry.chemical_classification ,Olefin fiber ,Superficial velocity ,General Chemical Engineering ,Energy Engineering and Power Technology ,Fischer–Tropsch process ,Catalysis ,Fuel Technology ,Hydrocarbon ,chemistry ,Chemical engineering ,Mass transfer ,Pellet ,Organic chemistry ,Syngas - Abstract
Mass transfer limitations on fixed-bed for Fischer–Tropsch synthesis were investigated by changing synthesis gas superficial velocity, catalyst pellet size, and catalyst amount. To study external mass transfer limitation, synthesis gas superficial velocity was changed from 8.47 × 10 − 4 m s − 1 to 3.39 × 10 − 3 m s − 1 . As a result, the synthesis gas superficial velocity of 3.39 × 10 − 3 m s − 1 was most suitable for hydrocarbon chain growth resulting to liquid hydrocarbon formation. In case of internal mass transfer limitations, the effects of catalyst pellet size and catalyst amount ( W cat / F ) were discussed. The large catalyst pellet showed higher C 5+ selectivity and a lower α value compared to the small pellet because of more severe internal mass transfer limitations of α -olefin and long-chained hydrocarbons in the large pellet, respectively. Catalyst amount ( W cat / F ) was inversely proportional to the internal mass transfer limitation because increased catalyst amount gave more time for liquid hydrocarbon products to diffuse from the catalyst pellet and, therefore, the catalyst amount of 4.5 g ( W cat / F = 45 g cat min L − 1 ) was most appropriate for liquid hydrocarbon formation.
- Published
- 2010
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40. Highly effective cobalt catalyst for wax production in Fischer–Tropsch synthesis
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Junghoon Yang, Jung-Il Yang, Heon Jung, Hak-Joo Kim, Ho-Tae Lee, and Dong Hyun Chun
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chemistry.chemical_classification ,Wax ,General Chemical Engineering ,Catalyst support ,Organic Chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Mineralogy ,Fischer–Tropsch process ,Catalyst poisoning ,Catalysis ,Fuel Technology ,Hydrocarbon ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,Cobalt ,Cobalt oxide - Abstract
Fischer–Tropsch synthesis (FTS) was carried out in a fixed bed reactor with a highly effective cobalt catalyst for wax production. The procedure for reducing the inactive cobalt oxide to the active cobalt catalyst was examined by X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The results showed that 300 ml/min H 2 at 350 °C for 16 h was suitable for reducing the inactive Co oxides to active metallic Co sites. In the case of the powder and pellet type cobalt catalysts with a reactant (H 2 /CO = 2:1) flow rate of 15 g cat min L −1 , catalyst deactivation occurred as a result of mass transfer limitations of the hydrocarbon and water produced on the catalyst. On the other hand, the pellet type cobalt catalyst with a reactant flow rate of 45 g cat min L −1 showed activity not only for liquid hydrocarbon (C 5+ ) formation but also for gas product (CH 4 and CO 2 ) formation. In particular, the methane yield reached almost 20% due to heat transfer limitation in the catalyst. Considering the heat and mass transfer limitations in the cobalt catalyst, a Co-foam catalyst with an inner metallic foam frame and an outer cobalt catalyst was developed. SEM–EDS Co-mapping revealed the cobalt atoms to be distributed equally over the surface of the Co-foam catalyst. The Co-foam catalyst was highly selective toward liquid hydrocarbon production and the liquid hydrocarbon productivity at 203 °C was 52.5 ml kg cat - 1 h −1 , which was higher than that by the Co-pellet. In addition, the chain length probability, α , by the Co-foam catalyst was 0.923 and wax formation was especially favored.
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- 2010
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41. The effect of temperature on NOx reduction by H2 in the presence of excess oxygen on a Pt/Al2O3 monolithic catalyst
- Author
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Heon Jung and Jung-Il Yang
- Subjects
General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Atmospheric temperature range ,Oxygen ,Industrial and Manufacturing Engineering ,Catalysis ,Reaction rate ,chemistry ,Oxidation state ,Chemisorption ,Environmental Chemistry ,Selective reduction ,NOx - Abstract
This study examined the reduction of NO x by H 2 over a Pt/Al 2 O 3 catalyst coated onto a monolith as a function of temperature. The formation of N 2 O began at a low temperature due to the chemisorption of NO on Pt metal and its resulting oxidation at the Pt active sites. The formation of N 2 was possible at higher temperatures because at the high temperatures, the reaction rate for N 2 formation was higher than the reaction rate for N 2 O formation. The formation of NO 2 was predominant above 150 °C due to the excessive oxidation activity of the catalyst. The formation of N 2 O at low temperatures and that of N 2 at high temperatures were found to be strongly related to the Pt loading and the temperature range in which the reductive activity was obtained, respectively. Therefore, both reductive conditions and an adequate reaction temperature are important factors for the selective formation of N 2 from the reduction of NO on a Pt catalyst. The temperature-dependent change in the oxidation state of Pt during the reduction of NO was also examined to determine the mechanism for the reduction of NO x by H 2 . In addition, the reaction conditions for the selective reduction of NO x to N 2 were determined.
- Published
- 2009
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42. Mass- and heat-transfer-enhanced catalyst system for Fischer-Tropsch synthesis in fixed-bed reactors
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Heon Jung, Hak-Joo Kim, Jung-Il Yang, Hyunku Joo, Jae-Hong Ryu, and Jaekyung Yoon
- Subjects
Exothermic reaction ,geography ,Degree of reaction ,geography.geographical_feature_category ,Chemistry ,Fischer–Tropsch process ,General Chemistry ,Catalysis ,law.invention ,Diesel fuel ,Chemical engineering ,law ,Organic chemistry ,Monolith ,Selectivity ,Distillation - Abstract
Fischer-Tropsch synthesis (FTS) was carried out using Al2O3-supported Co catalyst coated on metallic monolith. Considering the liberation of a large amont of heat from the highly exothermic FTS reaction, catalytic activity of Co catalyst coated on metallic monolith was tested and compared with that of pellet-type catalysts. The reaction was carried out in a conventional tubular fixed-bed reactor and simulated distillation (SIMDIS) analysis method was used to determine the liquid products distribution. Proper control of degree of reaction, as well as the reaction temperature gave rise to a shift of products selectivity toward higher hydrocarbons, especially C13−C18 diesel range hydrocarbons.
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- 2008
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43. Autothermal reforming of methane to syngas for Fischer-Tropsch synthesis with promoted palladium and a fast start-up device
- Author
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Kyoungmo Koo, Hyunku Joo, Jung-Il Yang, Jaekyung Yoon, and Hak-Joo Kim
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geography ,geography.geographical_feature_category ,Methane reformer ,Chemistry ,Inorganic chemistry ,Fischer–Tropsch process ,General Chemistry ,Syngas to gasoline plus ,Methane ,Catalysis ,chemistry.chemical_compound ,Chemical engineering ,Monolith ,Space velocity ,Syngas - Abstract
In this study, a Pd catalyst was prepared with promoters such as CeO2, BaO and SrO in a washcoated form on a metallic monolith for autothermal reforming of methane to syngas for the Fischer-Tropsch synthesis. A reactor was installed with an electric heater in the form of the metallic monolith as a start-up device instead of a burner with which stable and fast start-ups (within 4 min) were achieved. Gas hourly space velocity and O2/CH4 governed, methane conversion, while H2O/CH4 controlled H2/CO ratio. A methane conversion of approx. 96%, H2+CO selectivity of approx. 85%, and H2/CO of approx. 2.6 were obtained under the conditions of gas hourly space velocity (GHSV) at 103000 h−1, O2/CH4=0.7 and H2O/CH4=0.35.
- Published
- 2008
- Full Text
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44. Esterification of Acrylic Acid with 1,4-Butanediol in a Batch Distillation Column Reactor over Amberlyst 15 Catalyst
- Author
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Jung Il Yang, Soon Haeng Cho, Jongki Park, and Kwan Young Lee
- Subjects
Reaction rate ,chemistry.chemical_compound ,Acrylate ,Chromatography ,Batch distillation ,chemistry ,Polymerization ,General Chemical Engineering ,Reactive distillation ,1,4-Butanediol ,Acrylic acid ,Catalysis - Abstract
The esterification reaction of acrylic acid (AA) with 1,4-butanediol (BD) to produce 4-hydroxybutyl acrylate (HBA) was carried out in a batch reactive distillation mode over the Amberlyst 15 catalyst. The reactive distillation was highly desirable to increase the reaction rate of BD and eventually to obtain the high purity of HBA because the unreacted BD was not easily separable to the produced HBA after the reaction. The reaction pressure below 760 mm Hg was used to remove the by-product water from the reaction zone. The air-bubbling operation was successfully applied to prevent the polymerization of reactants and products under the vacuum condition (400 ∼ 760 mm Hg). The reaction rates were strongly dependent on the reaction pressure, especially, the reaction rate of BD disappearance. The increased reaction rate of BD by the reactive distillation enabled to produce a high purity of HBA.
- Published
- 2008
- Full Text
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45. Production of 4-Hydroxybutyl Acrylate and Its Reaction Kinetics over Amberlyst 15 Catalyst
- Author
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Hak-Joo Kim, Soon Haeng Cho, Heon Jung, Jung Il Yang, Kwan Young Lee, and Hyunku Joo
- Subjects
Reaction rate ,Chemical kinetics ,chemistry.chemical_compound ,Acrylate ,Acid catalysis ,Reaction rate constant ,Chemistry ,Stereochemistry ,General Chemical Engineering ,Activation energy ,Nuclear chemistry ,Acrylic acid ,Catalysis - Abstract
Esterification of acrylic acid (AA) with 1,4-butanediol (BD) was carried out over a solid acid catalyst to produce 4-hydroxybutyl acrylate (HBA), an environmentally benign coating agent. The Amberlyst 15 catalyst was more active for the reaction than other ion exchanged resin catalysts such as Amberlyst 35 and DOWEX HCR-S(E). The quasi-homogeneous model was chosen to express the esterification reaction kinetics over Amberlyst 15. The stirring speed was changed from 300 rpm to 750 rpm and the reaction rate showed no influence of external mass transfer. The reaction temperature was varied from 100°C to 120°C to calculate activation energies of the reactions. The calculated activation energies were 58.3 kJ/mol and 86.7 kJ/mol for HBA and BDA (1,4-butanediol diacrylate, by-product) productions, respectively. The catalyst concentration was also changed from 0.0043 g/ml to 0.0171 g/ml to find its effect on the rate constant. The complete kinetic equation of esterification to produce HBA over the Amberlyst 15 catalyst based on the quasi-homogeneous model was developed.
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- 2008
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46. Promotion of palladium-based catalysts on metal monolith for partial oxidation of methane to syngas
- Author
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Jung Il Yang, Kwan Young Lee, Hak-Joo Kim, Heon Jung, and Jae Hong Ryu
- Subjects
Chemistry ,Process Chemistry and Technology ,Inorganic chemistry ,Sintering ,chemistry.chemical_element ,Heterogeneous catalysis ,Catalysis ,Transition metal ,Thermal stability ,Partial oxidation ,General Environmental Science ,Palladium ,Syngas - Abstract
Four different modifications of alumina were prepared for use as the support for a Pd catalyst used for the partial oxidation of methane to syngas. The catalysts were washcoated on a metallic monolith in order to determine their activities at high gas flow rates. Compared with the Pd/Al 2 O 3 catalyst, enhanced partial oxidation activities were observed with the Pd/CeO 2 /Al 2 O 3 , Pd/CeO 2 /BaO/Al 2 O 3 and Pd/CeO 2 /BaO/SrO/Al 2 O 3 catalysts. The palladium particles were better dispersed in the presence of CeO 2 and SrO. Adding BaO, CeO 2 and BaO–CeO 2 to γ-Al 2 O 3 prevented the transformation of the alumina phase during the 3-day aging process at 1000 °C, providing the support with some level of thermal stability. The addition of small amounts of SrO to the CeO 2 /BaO/Al 2 O 3 support enhanced the thermal stability of the Pd particles and minimized their sintering. The triply promoted Pd catalyst studied in this work was effective in carrying out partial oxidation at high temperatures, with BaO and CeO 2 promoting the thermal stability of the support, CeO 2 and SrO dispersing the Pd particles and SrO anchoring the Pd particles strongly to the support. The composition of the catalyst which gave both the highest partial oxidation activity and the best thermal stability was Pd(2)/CeO 2 (23)/BaO(11)/SrO(0.8)/Al 2 O 3 .
- Published
- 2008
- Full Text
- View/download PDF
47. Ni catalyst wash-coated on metal monolith with enhanced heat-transfer capability for steam reforming
- Author
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Jae Hong Ryu, Heon Jung, Howon La, Hak-Joo Kim, Kwan Young Lee, and Jung Il Yang
- Subjects
geography ,geography.geographical_feature_category ,Methane reformer ,Renewable Energy, Sustainability and the Environment ,Chemistry ,Catalyst support ,Inorganic chemistry ,Energy Engineering and Power Technology ,engineering.material ,Methane ,Catalysis ,Steam reforming ,chemistry.chemical_compound ,engineering ,Noble metal ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Monolith ,Space velocity - Abstract
A commercial Ni-based catalyst is wash-coated on a monolith made of 50 μm-thick fecralloy plates. Compared with the same volume of coarsely powdered Ni catalysts, the monolith wash-coated Ni catalysts give higher methane conversion in the steam reforming reaction, especially at gas hourly space velocities (GHSV) higher than 28,000 h −1 , and with no pressure drop. A higher conversion of the monolith catalyst is obtained, even though it contains a lower amount of active catalyst (3 g versus 17 g for a powdered catalyst), which indicates that the heat-transfer capability of the wash-coated Ni catalyst is significantly enhanced by the use of a metal monolith. The efficacy of the monolith catalyst is tested using a shell-and-tube type heat-exchanger reactor with 912 cm 3 of the monolith catalyst charged on to the tube side and hot combusted gas supplied to the shell side in a counter-current direction to the reactant flow. A methane conversion greater than 94% is obtained at a GHSV of 7300 h −1 and an average temperature of 640 °C. Nickel catalysts should first be reduced to become active for steam reforming. Doping a small amount (0.12 wt.%) of noble metal (Ru or Pt) in the commercial Ni catalyst renders the wash-coated catalyst as active as a pre-reduced Ni catalyst. Thus, noble metal-doped Ni appears useful for steam reforming without any pre-reduction procedure.
- Published
- 2007
- Full Text
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48. Hydrotalcites for adsorption of CO2 at high temperature
- Author
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Jung-Il Yang and Jong-Nam Kim
- Subjects
Preparation method ,Supersaturation ,chemistry.chemical_compound ,Adsorption ,Hydrotalcite ,Chemistry ,General Chemical Engineering ,Inorganic chemistry ,Carbon dioxide ,Gravimetric analysis ,General Chemistry ,Nuclear chemistry ,Catalysis - Abstract
Adsorption of carbon dioxide by hydrotalcites was investigated by using a gravimetric method at 450 ‡C. Hydrotalcites possessed higher adsorption capacity of CO2 than other basic materials such as MgO and Al2O3. Two different preparation methods of hydrotalcite with varying Mg/Al ratio were employed to determine their effects on the adsorption capacity of CO2. In addition, varying amounts of K2CO3 were impregnated on the hydrotalcite to further increase its adsorption capacity of CO2. The hydrotalcite prepared by the high supersaturation method with Mg/Al=2 showed the most favorable adsorption-desorption pattern with high adsorption capacity of CO2. K2CO3 impregnation on the hydrotalcite increased the adsorption capacity of CO2 because it changed both the chemical and the physical properties of the hydrotalcite. The optimum amount of K2CO3 impregnation was 20 wt%. The hydrotalcite prepared by the high supersaturation method with Mg/Al=2 and 20 wt% K2CO3 impregnation has the highest adsorption capacity of CO2 with 0.77 mmol CO2/g at 450 ‡C and 800 mmHg.
- Published
- 2006
- Full Text
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49. Recovery of Rare-Earth Minerals from the Feldspar By-Product
- Author
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Jai Koo Park, Joon Soo Kim, Moon Young Jung, Jung Il Yang, and Hee Young Shin
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Environmental Engineering ,Oxide ,Mineralogy ,Feldspar ,Pollution ,Sulfide minerals ,chemistry.chemical_compound ,chemistry ,Monazite ,visual_art ,By-product ,visual_art.visual_art_medium ,Composition (visual arts) ,Xanthate ,Waste Management and Disposal ,Mineral processing ,Geology - Abstract
This paper was focused on recovering rare-earth minerals from tailing of Boo-yeo feldspar mine using mineral processing technologies. The tailing, that is feldspar by-product, consisted of light minerals, sulfide minerals, heavy minerals and a little rare-earth minerals. In field, gravity concentration was conducted to reject the light minerals from the tailing sample. In laboratory, sulfide minerals were firstly removed from the head sample by bulk flotation with amyl xanthate at pH 4. Magnetic separations were conducted to recover the rare-earth minerals from the concentrate of bulk flotation. The highest grade concentrate for rare-earth minerals were recovered in the range of 5,500~7,000 Gauss. The final concentrate obtained in several stage mineral processing techniques mostly consisted of monazite with 2.65 wt.% yield and contained total rare-earths oxide composition of 53.58 wt.%. Especially, rare-earths oxide composition of the final concentrate was 36 times for CeO2 and 192 times for Y2O3...
- Published
- 2000
- Full Text
- View/download PDF
50. Selective and high catalytic activity of CsnH4−nPMo11VO40 (n≥3) for oxidation of ethanol
- Author
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Jung-Il Yang, Kwan Young Lee, Jinhyuk Lee, Jae Chun Hyun, and Daewon Lee
- Subjects
Acid catalysis ,chemistry.chemical_compound ,Ethanol ,Ethylene ,Chemistry ,Process Chemistry and Technology ,Acetaldehyde ,Organic chemistry ,Alcohol ,Diethyl ether ,Heterogeneous catalysis ,Catalysis - Abstract
Oxidation of ethanol has been performed over CsnH4−nPMo11VO40 (0 ≤ n ≤ 4) catalysts in order to investigate the oxidation property of acidic Cs salts of molybdovanadophosphoric acid. A flow-type packed bed reactor was used for the reaction. Acetaldehyde was produced by oxidation catalysis, while ethylene and diethyl ether were produced by acid catalysis. The yields of these products were strongly dependent on the amount of Cs contained. Acid catalysis was dominant in n
- Published
- 2000
- Full Text
- View/download PDF
Catalog
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