• Title/Summary/Keyword: Carbon-based Catalyst

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Valorizing Cattle Manure to Syngas via Catalytic Pyrolysis with CO2 (이산화탄소-촉매 열분해 활용 우분 유래 합성가스 증대 연구)

  • Lee, Dong-Jun;Jung, Jong-Min;Kim, Jung Kon;Lee, Dong-Hyun;Kim, Hyunjong;Park, Young-Kwon;Kwon, Eilhann E.
    • Journal of the Korea Organic Resources Recycling Association
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    • v.30 no.4
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    • pp.141-150
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    • 2022
  • To abate the environmental burden derived from the massive generation of cattle manure (CM), pyrolysis of CM was suggested as one of the methods for manure treatment. In respect of carbon utilization, pyrolysis has an advantage in that it can produce usable carbon-based chemicals. This study was conducted to investigate a syngas production from pyrolysis of CM in CO2 condition. In addition, mechanistic functionality of CO2 in CM pyrolysis was investigated. It was found that the formation of CO was enhanced at ≥ 600 ℃ in CO2 environment, which was attribute to the homogeneous reactions between CO2 and volatile matters (VMs). To expedite reaction kinetics for syngas production during CM pyrolysis, Catalytic pyrolysis was carried out using Co/SiO2 as a catalyst. The synergistic effects of CO2 and catalyst accelerate the formation of H2 and CO at entire temperature range. Thus, this result offers that CO2 could be a viable option for syngas production with the mitigation of greenhouse gas.

Template-Based Carbon Nanotubes Field Emitter

  • Jeong, Soo-Hwan;Lee, Ok-Joo;Hwang, Sun-Kyu;Lee, Kun-Hong
    • Journal of Information Display
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    • v.2 no.3
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    • pp.78-85
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    • 2001
  • The growth of carbon nanotubes(CNTs) in anodic aluminum oxide(AAO) template and their application to a field emitter are described. AAO templates were fabricated by anodizing bulk aluminum and sputtered thin Al film on Nb-coated Si wafers. After Co catalyst had been electrochemically deposited into the bottom of the pores in AAO template, CNTs were grown by pyrolyzing $C_2H_2$. Depending on the reaction conditions, CNTs grew up to or over the top of the pores in AAO template with different structures. The morphology and structure of CNTs were observed with a scanning electron microscope and a transmission electron microscope. The diameter of CNTs strongly depended on the size of the pores in AAO template and the growing conditions. The electron field emission measurement of the samples resulted in the turn-on field of 1.9-2.2 $V/{\mu}m$ and the field enhancement factor of 2450-5200. The observation of high field enhancement factors is explained in terms of low field screening effect.

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Removal of Sulfur Compounds from Anaerobic Digestion Gas (혐기성 소화 가스로부터 황화합물의 제거)

  • Choi, Do-Young;Jang, Seong-Cheol;Ahn, Byoung-Sung;Choi, Dae-Ki
    • Applied Chemistry for Engineering
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    • v.19 no.1
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    • pp.31-36
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    • 2008
  • In hydrogen production for fuel cell by reforming ADG, sulfur compounds, odorant in ADG, are detrimental to reforming catalyst and fuel cell electrodes. We prepared alkali metal impregnated activated carbon to remove sulfur compounds in ADG by adsorption. The sulfur breakthrough adsorption capacity was changed depending on the oxygen concentration and relative humidity. Oxygen 0.2 vol% and RH 90% showed the highest sulfur breakthrough capacity. Adsorption characteristics of $H_2S$ on KI impregnated activated carbon were evaluated using dynamic adsorption method in a fixed bed. Based on the results, adsorption tower was designed and field-tested.

Structural and Field-emissive Properties of Carbon Nanotubes Produced by ICP-CVD: Effects of Substrate-Biasing (ICP-CVD 방법으로 성장된 탄소 나노튜브의 구조적 특성 및 전계방출 특성: 기판전압 인가 효과)

  • Park, C.K.;Kim, J.P.;Yun, S.J.;Park, J.S.
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.1
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    • pp.132-138
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    • 2007
  • Carbon nanotubes (CNTs) arc grown on Ni catalysts employing an inductively-coupled plasma chemical vapor deposition (ICP-CVD) method. The structural and field-emissive properties of the CNTs grown are characterized in terms of the substrate-bias applied. Characterization using the various techniques, such as field-omission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Auger spectroscopy (AES), and Raman spectroscopy, shows that the structural properties of the CNTs, including their physical dimensions and crystal qualities, as well as the nature of vertical growth, are strongly dependent upon the application of substrate bias during CNT growth. It is for the first time observed that the provailing growth mechanism of CNTs, which is either due to tip-driven growth or based-on-catalyst growth, may be influenced by substrate biasing. It is also seen that negatively substrate-biasing would promote the vertical-alignment of the CNTs grown, compared to positively substrate-biasing. However, the CNTs grown under the positively-biased condition display a higher electron-emission capability than those grown under the negatively-biased condition or without any bias applied.

Optimization of Reaction Conditions for High Yield Synthesis of Carbon Nanotube Bundles by Low-Temperature Solvothermal Process and Study of their H2 Storage Capacity

  • Krishnamurthy, G.;Agarwal, Sarika
    • Bulletin of the Korean Chemical Society
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    • v.34 no.10
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    • pp.3046-3054
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    • 2013
  • Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of $180^{\circ}C$. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based $N_2$ gas adsorption studies have been made to obtain BET surface area and $H_2$ storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

Improvement of Thermal Efficiency using Atkinson Cycle in a High-Compression Ratio, Spark-Ignition, Natural Gas Engine for Power Generation (고압축비 전기점화 천연가스 발전용 엔진에서 앳킨슨 사이클 적용을 통한 열효율 향상)

  • Junsun Lee;Hyunwook Park;Seungmook Oh;Changup Kim;Yonggyu Lee;Kernyong Kang
    • Journal of ILASS-Korea
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    • v.28 no.2
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    • pp.55-61
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    • 2023
  • Natural gas is a high-octane fuel that is effective in controlling knocking combustion. In addition, as a low-carbon fuel with a high hydrogen-carbon ratio, it emits less carbon dioxide and almost no particulate matter compared to conventional fossil fuels. Stoichiometric combustion engines equipped with a three-way catalyst are useful in various fields such as transportation and power generation because of their excellent exhaust emission reduction performance. However, stoichiometric combustion engines have a disadvantage of lower thermal efficiency compared to lean combustion engines. In this study, a combination of high compression ratio and Atkinson cycle was implemented in a 11 liter, 6-cylinder, spark-ignition engine to improve the thermal efficiency of the stoichiometric engine. As a result, pumping and friction losses were reduced and the operating range was extended with optimized Atkinson camshaft. Based on the exhaust gas limit temperature of 730℃, the maximum load and thermal efficiency were improved to BMEP 0.66 MPa and BTE 35.7% respectively.

Modeling of Liquid Hold-up in Fixed-bed Reactor for Fischer-Tropsch Synthesis (고정층 Fischer-Tropsch 반응기의 액상 왁스 정체 현상 모델링)

  • Park, Chansaem;Jung, Ikhwan;Park, Seongho;Na, Jonggeol;Kshetrimayum, Krishnadash;Han, Chonghun;Lee, Jong Yeol;Jung, Jongtae
    • Journal of the Korean Institute of Gas
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    • v.18 no.4
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    • pp.63-67
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    • 2014
  • Fischer-Tropsch synthesis mainly produces a wax which is a viscous liquid for long carbon chain. When a catalytic fixed-bed reactor is used for Fischer-Tropsch synthesis, the wax generated on a catalyst surface can keep adsorbing on the catalyst surface. This liquid hold-up causes significant pressure drop and clogging problems through the reactor. Thus, the model for liquid hold-up is required to design the size of reactor and catalyst particles. In this study, the liquid hold-up model considering structural and operational conditions was proposed based on empirical equations for convective mass transfer between the syngas flow and the wax-adsorbed catalyst. The developed model was validated by comparing with the experimental data from Knochen's work (2010). The influence of reactor length and coross section on the wax hold-up in reactor were analyzed and the optimal reactor size were proposed.

Growing Behaviors in Colloidal Solution of Pt Crystal for PEMFC Cathode (콜로이드 용액 내의 수소연료전지 공기극 촉매용 백금 입자 성장 속도 관찰)

  • Ham, Kahyun;Chung, Sunki;Choi, Mihwa;Yang, Seugran;Lee, Jaeyoung
    • Applied Chemistry for Engineering
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    • v.30 no.4
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    • pp.493-498
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    • 2019
  • In polymer exchange membrane fuel cells, it is crucial to fabricate a highly active and thin Pt catalyst layer for the smooth mass transport of dissolved oxygen and water. Although a highly loaded platinum (Pt) catalyst based on the hydrothermal synthesis has been reported in several studies, its growing behaviors and kinetics were yet to be understood. In this study, we investigated the growth of Pt crystal in suspension after the reduction step depending on a stirring time and evaluated the electrochemical activity. For only a couple of hours in the early stage, Pt colloids were adsorbed on the Pt-carbon catalyst and the Pt crystal was grown. After that, the small Pt colloid was formed by another nucleation step, which did not involve the growth of Pt crystal. We reveal that the Pt-Carbon catalyst with stirring for 6 h showed a high activity toward the oxygen reduction reaction.

A Study on Catalytic Pyrolysis of Polypropylene with Mn/sand (Mn/sand 촉매를 활용한 폴리프로필렌 촉매 열분해 연구)

  • Soo Hyun Kim;Seung Hun Baek;Roosse Lee;Sang Jun Park;Jung Min Sohn
    • Clean Technology
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    • v.29 no.3
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    • pp.185-192
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    • 2023
  • This study was conducted to obtain basic process simulation data before conducting pyrolysis experiments for the development of a thermochemical conversion system by recirculation of heat carrier and gases thereby. In this study, polypropylene (PP) was used as a pyrolysis sample material as an alternative to waste plastics, and fluid sand was used as a heat transfer medium in the system. Manganese (Mn) was chosen as the catalyst for the pyrolysis experiment, and the catalyst pyrolysis was performed by impregnating it in the sand. The basic properties of PP were analyzed using a thermogravimetric analyzer (TGA), and liquid oil was generated through catalytic pyrolysis under a nitrogen atmosphere at 600℃. The carbon number distribution of the generated liquid oil was confirmed by GC/MS analysis. In this study, the effects of the presence and the amount of Mn loading on the yield of liquid oil and the distribution of hydrocarbons in the oil were investigated. When Mn/sand was used, the residue decreased and the oil yield increased compared to pyrolysis using sand alone. In addition, as the Mn loading increased, the ratio of C6~C9 range gasoline in the liquid oil gradually increased, and the distribution of diesel and heavy oil with more carbon atoms than C10 in the oil decreased. In conclusion, it was found that using Mn as a catalyst and changing the amount of Mn could increase the yield of liquid oil and increase the gasoline ratio in the product.

Fabrication of a nano-sized conical-type tungsten field-emitter based on carbon nanotubes (탄소나노튜브를 이용한 텅스텐 나노팁 전계방출기 제작)

  • Park, Chang-Kyun;Kim, Jong-Pil;Kim, Young-Kwang;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1220-1221
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    • 2008
  • Submicron-sized conical-type tungsten(W) field-emitters based on carbon nanotubes(CNTs) are fabricated with the configuration of CNTs/catalyst(Ni)/buffer(Al/Ni/TiN)/W-tip. This study focuses on elucidating how the Al/Ni/TiN stacked buffer layer affects the structural properties of CNTs and the electron-emission characteristics of CNT-emitters. Field-emission scanning electron microscopy(FESEM), high-resolution transmission electron microscopy(HRTEM), and x-ray photoelectron spectroscopy(XPS) are used to monitor the nanostructures, surface morphologies, chemical bonds of all the catalysts and CNTs grown. The crystalline structure of CNTs is also characterized by Raman spectroscopy. Furthermore, the measurement of field-emission characteristics for the field-emitters fabricated shows that the emitter using the Al/Ni/TiN stacked buffer reveals the excellent performances.

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