• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.908-916
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• 2010

Fullerene-60 nanoparticles were used for studying their effect on the low-density polyethylene (LDPE) biodegradation efficiency of two potential polymer-degrading consortia comprising three bacterial strains each. At a concentration of 0.01% (w/v) in minimal broth lacking dextrose, fullerene did not have any negative influence upon the consortia growth. However, fullerene was found to be detrimental for bacterial growth at higher concentrations (viz., 0.25%, 0.5%, and 1%). Although addition of 0.01% fullerene into the biodegradation assays containing 5mg/ml LDPE subsided growth curves significantly, subsequent analysis of the degraded products revealed an enhanced biodegradation. Fourier transform infrared spectroscopy (FT-IR) revealed breakage and formation of chemical bonds along with the introduction of ${\nu}C$-O frequencies into the hydrocarbon backbone of LDPE. Moreover, simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) revealed a higher number of decomposition steps along with a 1,000-fold decrease in the heat of reactions (${\Delta}H$) in fullerene-assisted biodegraded LDPE, suggesting the probable formation of multiple macromolecular byproducts. This is the first report whereby fullerene-60, which is otherwise considered toxic, has helped to accelerate the polymer biodegradation process of bacterial consortia.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1607-1610
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• 2009

The carbon-coated Si/Cu powder has been prepared by mechanical ball milling and hydrocarbon gas decomposition methods. The phase of Si/Cu powder was analyzed using X-ray diffraction (XRD), dispersive Raman spectroscopy, electron probe microanalysis (EPMA) and transmission electron microscope (TEM). The carbon-coated Si/Cu powders were used as anode active material for lithium-ion batteries. Their electrochemical properties were investigated by charge/discharge test using commercial LiCo$O_2$ cathode and lithium foil electrode, respectively. The surface phase of Si/Cu powders consisted of carbon phase like the carbon nanotubes (CNTs) with a spacing layer of 0.35 nm. The carbon-coated Si/Cu/graphite composite anode exhibited a higher capacity than commercial graphite anode. However, the cyclic efficiency and the capacity retention of the composite anode were lower compared with graphite anode as cycling proceeds. This effect may be attributed to some mass limitations in LiCo$O_2$ cathode materials during the cycling.

• Journal of the Korean institute of surface engineering
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• v.50 no.6
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• pp.516-522
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• 2017

We report the growth of carbon nanotubes (CNT) on Invar-42 plates using coal tar pitch (CTP) by chemical vapor deposition (CVD) method. The solid phase CTP is used as an inexpensive carbon source since it produces a bunch of hydrocarbon gases such as $CH_4$ and other $C_xH_v$ by thermal decomposition over $450^{\circ}C$. The Invar-42 is a representative Ni-based ferrous alloy and can be used repetitively as a substrate for CNT growth because Ni and Fe are used as very active catalytic elements. We changed mixing ratio of carrier gases, argon and hydrogen, and temperature of growth region. It was found that the optimum gas ratio and temperature for high quality CNT growth are $Ar:H_2=400:400$ sccm and $1000^{\circ}C$, respectively. In addition, the carbon nanoball (CNB) was also obtained by just changing the mixing ratio to $Ar:H_2=100:600$ sccm. Finally, CTP can be employed as a versatile carbon source to produce various carbon-based nanomaterials, such as CNT and CNB.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.175-188
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• 2023

Global interest in hydrogen energy is increasing as an eco-friendly future energy that can replace fossil fuels. Accordingly, a next-generation hydrogen production technology using microorganisms, nuclear power, etc. is being developed, while a lot of time and effort are still required to overcome the cost of hydrogen production based on fossil fuels. As a way to minimize greenhouse gas emissions in the hydrocarbon-based hydrogen production process, methane direct decomposition technology has recently attracted attention. In order to improve the economic feasibility of the process, the simultaneous production of value-added carbon materials with hydrogen can be one of the most essential aspects. For that purpose, various studies on catalysis related to the quality and yield of high-value carbon materials such as carbon nanotubes (CNTs). In terms of process technology, a number of the research and development of fluidized-bed reactors capable of continuous production and improved gas-solid contact efficiency has been attempted. Recently, methane direct decomposition technology using a fluidized bed has been developed to the extent that it can produce 270 kg/day of hydrogen and 1000 kg/day of carbon. Plus, with the development of catalyst regeneration, separation and recirculation technologies, the process efficiency can be further improved. This review paper investigates the recent development of catalysts and fluidized bed reactor for methane direct pyrolysis to identify the key challenges and opportunities.

• Resources Recycling
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• v.20 no.3
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• pp.62-67
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• 2011

This study has been investigated for characteristic of removal on the effect of changes in soil moisture, microwave power, and temperature through the decomposition of oil-contaminated soil under high temperature conditions with high temperature heating elements and microwave. A lubricating oil having long carbocyclic(C18-C50) commonly known as a non-resolvable material was treated and the efficient for removal of TPH(Total Petroleum Hydrocarbon) obtained 85.2% at 6 kW and $700^{\circ}C$ and thus the contaminant was found to be removed to 1788 mg/kg for 40 minutes. In case of contaminated soil by light oil and gasoline, the amount of removal was achieved with 567 mg/kg at 6 kW, 500 for 20 minutes that corresponds to reach 98.4% of treatment efficient. In addition, non-resolvable materials contaminated by oil reached TPH concentration on 2,000 mg/kg of worrisome level of soil contamination in the 3-zone at 6kW, $700^{\circ}C$, and 30 minutes, and processing cost at this time was about 8,173 won per ton.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.672-677
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• 2014

Torrefaction is a thermal treatment process to pre-treat biomass at temperature of $200{\sim}300^{\circ}C$ under an inert atmosphere. It was known that torrefaction process strongly depended on the decomposition temperature of the lignocellulosic constituents in biomass. In this work, the torrefaction characteristics of baggase has been studied. This study focuses on the relation between the energy yields, heating values, gas emission, volatile and ash constituents with torrefaction temperatures and times. The activation energies of baggase torrefaction has been studied by using TGA (Thermogravimetric Analyzer). From this work, it was seen that ash constituents and heating values were increased with torrefaction temperature, while volatile constituents and energy yields decreased. It was also found that carbon monoxide containing oxygen were decomposed at a lower temperature than those of hydrocarbon compounds, $C_xH_y$.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.1-9
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• 2011

Researches on hypersonic aircraft technologies have been carried out to increase flight speeds. However, increase in flight speeds causes heat loads that could lead structural change of aircraft's component. Researches on cooling technologies using endothermic fuels are progressing in the USA, France and Russia to treat the heat loads. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. In this study, methylcyclohexane, n-octane, and n-dodecane were selected as model endothermic fuels and experiments in endothermic properties were implemented. Experimental conditions were supercritical condition of each model fuels in which actual endothermic fuels were exposed. The object of this study is to identify endothermic properties of the model endothermic fuels and to predict endothermic properties of actual fuels such as kerosene fuels.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.638-641
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• 2005

수소는 자원이 무한하고 청결한 에너지이다. 수소는 무공해 청정 대체연료로 사용될 수 있을 뿐만 아니라 풍부한 자원으로부터 얻을 수 있다. 수소에너지는 물을 분해하여 얻거나 화석연료를 수증기개질 또는 부분산화 시킴으로써 얻을 수가 있다. 수소에너지는 1차 에너지를 변환시켜 얻을 수 있는 2차 에너지로서 환경에 대한 부하가 거의 없어 향후 화석연료를 대체할 수 있는 가장 가능성이 높은 에너지이며, 연료전지의 상용화를 앞두고 있어 중요성이 더욱 증대되고 있다. 수소를 생산하는 방법 중 가장 이상적인 방법으로는 물분해함으로써 수소를 제조하는 방법이 있다. 그러나 물분해에 의한 수소생산은 제조비용이 비싸 경제성이 떨어진다는 점과 수소의 대량생산에 필요한 기술확보가 여의치 않아 어렵다. 그러므로 수소를 저 비용으로 대량 생산할 수 있는 수소 제조 기술의 확보가 선행되어야 할 것이다. 현재 상용화되어 있는 수소제조방법은 거의 석유나 천연가스의 수증기 개질에 의한 수소 제조 방법이다. 그러나 이러한 방법은 유해 환경 물질인 CO나 $CO_2$를 배출하는 단점을 지니고 있다. 이러한 단점을 보완키 위한 수소 제조공정의 대안 중 하나는 탄화수소연료의 수소와 탄소로의 직접분해에 의한 수소생산이다. 이 중 원하는 생성물인 수소 외에 부산물이 카본이 동시에 얻을 수 있는 메탄분해에 의한 수소생산방법은 생산된 수소의 약 15%만 연소시킴으로서 필요한 에너지를 공급할 수 있으며, 동시에 지구온난화의 주범인 CO 또는 $CO_2$가 생성되지 않는 장점이 있다. 하지만 메탄을 분해하기 위해서는 매우 높은 에너지가 필요로 하게 된다. 이에 반해 프로판은 메탄보다 낮은 열원에서 분해할 수 있는 장점을 지니고 있다. 본 연구에서는 메탄보다 분해하기 쉬운 프로판을 직접 분해하여 수소를 생산하고자 하였다. 프로판 직접분해반응는 $500\sim750^{\circ}C$의 온도 범위에서 이루어 졌으며, 촉매로서는 국내에서 생산되는 상용촉매인 카본블랙을 이용하였다.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.216-219
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• 2000

Pyrolysis products of woody biomass were consistedofvarious linear hydrocarbon, aromatics or condensed cyclic compounds. In order to obtain biomass pyrolysis products, more equipments and time were needed. But solvolysis of woody biomass with acetone easily obtained decomposition products and enhanced conversion rate(18.72%, max.) from woody biomass than pyrolysis of woody biomass. Beacause solvolysis with acetone improved conversion rate (26.64%, max.) of lignin. the whole conversion rate was improved. But above $300^{\circ}C$, lignin showed lower conversion rate, so the whole conversion rate decreased. Solvolysis products of woody biomass with acetone were same as pyrolysis products. Above $400^{\circ}C$, methoxy phenols were completely disappeared.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.468-473
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• 2018

In this study, the reforming reaction of vacuum residues (VR), high viscosity oil residues produced from vacuum distillation process of petroleum oil, was carried out using catalytic aquathermolysis reaction. VR showed a prone to decrease the amount of resins and asphaltenes in the constituents, and to increase saturates and aromatics when reacting with steam at 30 bar and above $300^{\circ}C$ for 24 h. When the amount of steam is not enough at this reaction, the asphaltene content in the products was rather increased after the reaction. As a result of the catalytic aquathermolysis using the metal oxide-zeolite catalyst with the decaline as a hydrogen donor, a 10% decrease in resin and asphaltene as well as a 10% increase in the aromatic hydrocarbon were observed. Consequently, the viscosity of VR decreased by 70% after the reaction. GC-Mass spectroscopy showed that the aquathermolysis of VR resulted in the decomposition of the resins and asphaltens into a low molecular weight material.