• 청정기술
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• 제20권1호
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• pp.72-79
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• 2014

본 연구에서는 갈탄에 폐촉매(I, II, III) 및 $K_2CO_3$를 이용한 $CO_2$ 가스화의 반응속도상수 및 활성화 에너지를 조사하였다. 가스화 실험은 1 wt%, 5 wt%, 10 wt%의 촉매를 물리적으로 혼합한 갈탄을 열중량분석(Thermogravity analysis, TGA)을 이용하여 가스화 온도 $800^{\circ}C$, $850^{\circ}C$, $900^{\circ}C$ 범위에서 수행하였다. 실험 데이터를 세 가지 반응속도 모델(volumetric reaction model, VRM; shrinking core model, SCM; modified volumetric reaction model, MVRM)에 적용한 결과 MVRM이 가장 적합하였다. 가스화 속도는 온도가 높아짐에 따라 증가하는 것으로 관찰되었으며, 모든 실험 온도에서 폐촉매를 이용한 가스화 반응의 활성화 에너지는 촉매를 혼합하지 않은 갈탄 보다 낮게 나타났다. 특히, 폐촉매 III 10 wt%의 경우 활성화 에너지가 92.37 kJ/mol로 가장 낮게 얻어졌다.

• Carbon letters
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• 제28권
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• pp.116-120
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• 2018

Nitrogen-doped carbons have attracted much attention due to their novel application in relation to gas storage. In this study, nitrogen-doped porous carbons were synthesized using SBA-15 as a template, polypyrrole as the carbon and nitrogen precursor, and KOH as an activating agent. The effect of the activation temperature ($600-850^{\circ}C$) on the $CO_2$ adsorption capacity of the obtained porous carbons was studied. Characterization of the resulting carbons showed that they were micro-/meso-porous carbon materials with a well-developed pore structure that varied with the activation temperature. The highest surface area of $1488m^2g^{-1}$ was achieved at an activation temperature of $800^{\circ}C$ (AC-800). The nitrogen content of the activated carbon decreased from 4.74 to 1.39 wt% with an increase in the activation temperature from 600 to $850^{\circ}C$. This shows that nitrogen is oxidized and more easily removed than carbon during the activation process, which indicates that C-N bonds are more easily ruptured at higher temperatures. Furthermore, $CO_2$ adsorption isotherms showed that AC-800 exhibited the best $CO_2$ adsorption capacity of $110mg\;g^{-1}$ at 298 K and 1 bar.

• 한국세라믹학회지
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• 제36권10호
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• pp.1016-1021
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• 1999

활상탄소섬유는 입상 활성탄에 비해 빠른 흡 · 탈착 속도와 높은 흡착량을 갖기 때문에 흡착재, 촉매, 분자체와 같은 환경 신소재로서 큰 주목을 받고 있다. 본 연구에서는 안정화 PAN계 탄소섬유를 수증기와 CO2를 이용한 물리적 활성화에 의해 여러 등급의 활성탄소섬유를 제조하였고, 비표면적, 요오드 흡착량, 세공구조 등을 측정하였다. 수증기 활성화에서 77%의 burn-off에서 비표면적이 1019 m2/g을 나타내었고, 반면에 CO2 활성화에서는 52%의 burn-off에서 7168m2/g의 비표면적을 갖는 활성탄소섬유가 제조되었다 그러나, 비슷한 burn-off에서는 CO2로 활성화한 경우에서 세공용적이 0.37 cc/g이고, 요오드 흡착량이 1589 mg/g으로서 수증기 활성화보다 더 큰 세공용적과 요오드 흡착량을 나타내었다. 또한 제조된 활성탄소섬유의 질소 흡착등온선들은 Brunaner-Deming-Deming-Teller의 분류에 따르면 모두 type I으로 주로 미세공들로 이루어져 있음을 알 수가 있었다.

• 대한화학회지
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• 제34권2호
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• pp.117-122
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• 1990

몇 가지 온도와 압력 하에서 $trans-[CoETECl_2]^+$와 $cis-{\beta}-[CoTETCl_2]^+$ 착이온의 수화반응과 $trans-[CoETEClOH_2]_2^+$착이온의 이성질화반응의 반응속도를 분광광도법으로 측정하여 이들 착물의 반응메카니즘을 규명하였다. $trans-[CoETECl_2]^+$와 $cis-{\beta}-[CoTETCl_2]^+$ 착이온의 수화반응에 대한 활성화엔트로피, ${\Delta}S{\neq}$는 각각 4.0 eu 및 5.3 eu이고 활성화부피, ${\Delta}V{\neq}$는 각각 $-5.8 cm^3mol^{-1}$ 및 $-6.6 cm^3mol^{-1}(40^{\circ}C$)이었다. 이들 데이타로부터 수화반응위 메카니즘은 해리(D)메카니즘으로 추정할 수 있었다. $trans-[CoETEClOH_2]^{2+}$ 착이온의 $cis-{beta}-[CoETEClOH_2]^2+$ 로의 이성질화반응에 대한 활성화엔트로피, ${\Delta}S^{\neq}$와 활성화부피, ${\Delta}V^{\neq}$는 각각 9.5 eu 및 $8.4 cm^3mol^{-1}(30^{\circ}C$)이었다. 이들 데이타로부터 이성질화반응의 메카니즘은 $H_2O$가 해리된 후 이성질화가 일어나는 해리(D)메카니즘인 것으로 추정할 수 있었다.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1086-1092
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• 2012

본 촉매가스화 실험에서 촉매로서 가치가 있는 천연광물과 순수촉매를 사용하여 저급석탄의 $CO_2$분위기하 활성화 에너지 및 생성된 합성가스의 성분을 분석하였다. 먼저 공업 분석과 원소 분석을 통해 6가지 저급석탄의 회분과 황 함유량을 측정하였다. 그 후 Thermogravimetric Analyzer (TGA)를 통해 저급석탄 열분해반응 특성을 고려하여 실험에 가장 적합한 저급석탄을 선정하였다. 선정된 삼화 저급석탄은 촉매와 섞어 $CO_2$분위기하 TGA실험을 진행하였으며, 결과를 토대로 Kissinger 방법을 이용한 활성화 에너지를 구하였다. 또한 shrinking core model을 이용해 활성화 에너지를 구하여 Kissinger 방법과 비교하였다. 그리고 반응기에서 이산화탄소 분위기하 생성된 합성가스는 Gas Chromatography (GC)를 이용하여 분석하였다. 가스를 분석한 결과 수소의 생성량은 $K_2CO_3$를 촉매로 사용하였을 경우 가장 크게 나타났으며, 앞서 구한 활성화 에너지 결과와 일치하는 경향을 나타내었다.

• Reproductive and Developmental Biology
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• 제36권3호
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• pp.141-145
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• 2012

The present study was conducted to develop a simple method for porcine oocyte maturation without $CO_2$ regulation. In experiment 1, we evaluated that the effect of $CO_2$ non-supplement on porcine oocyte maturation. Cumulusoocyte complexes (COCs) were collected from 2~6 mm follicles and divided into three groups (Control, tube-$CO_2$, and tube-non-$CO_2$). For control, COCs were cultured in 4-well multidish in a $CO_2$ incubator. For tube-$CO_2$, COCs were cultured in a round-bottom tube in a $CO_2$ incubator, and for tube-non-$CO_2$, COCs were cultured in a round-bottom tube sealed tightly without $CO_2$ supplement in a dry incubator. The proportion of oocytes reached to metaphase II (M-II) was not significantly different among three groups (87.9% to 91.4%). In experiment 2, we evaluated the effect of $CO_2$ non-supplement during oocyte maturation on development of embryos. Oocytes with a polar body were divided into two groups (Control and tube-non-$CO_2$) and applied 1.1 kV/cm or 1.2 kV/cm voltages for parthenogenetic activation. After activation, embryos were cultured for 6 days and examined the development. The proportion of embryos cleaved was not significantly different among treatment (86.3% to 91.5%). The proportion of embryo reached to blastocyst stage was not significantly different among treatment (13.9% to 25.2%). The cell number of blastocysts was not significantly different among treatment (29.0 to 32.4). In conclusion, oocytes cultured in a dry incubator without $CO_2$ supplement have enough competence to development after parthenogenetic activation. These results would be useful for transporting oocytes or embryos a long distance.

• 한국세라믹학회지
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• 제19권4호
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• pp.309-315
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• 1982

$FeAl_2O_4$ was formed from the starting material of $Fe_2O_3$ and $Al_2O_3$ by controlling the oxygen partial pressure using $H_2-CO_2$ gas mixture, over the temperature range of 800~120$0^{\circ}C$. The formation mechanism of $FeAl_2O_4$ was found to be a second order chemical reaction, and the activation energy of formation was observed as 39.97 kcal/mole. Vaporization behavior of $FeAl_2O_4$ under $CO_2$ atmosphere was observed over the temperature range of 800~120$0^{\circ}C$. $FeAl_2O_4$ was vaporized by a second order chemical reaction and the activation energy was found to be 21.8kcal/mole. Electrical conductivity of $FeAl_2O_4$ was also measured.

• Genomics & Informatics
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• 제21권1호
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• pp.2.1-2.14
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• 2023

Microglia, similar to peripheral macrophages, are the primary immune cells of the central nervous system (CNS). Microglia exist in the resting state in the healthy CNS, but can be activated and polarized into either M1 or M2 subtypes for immune defense and the maintenance of CNS homeostasis by multiple stimuli. Several long noncoding RNAs (lncRNAs) mediate human inflammatory diseases and neuropathologies by regulating their target genes. However, the function of common lncRNAs that contribute to microglial activation remains unclear. Thus, we used bioinformatic approaches to identify common lncRNAs involved in microglial activation in vitro. Our study identified several lncRNAs as common regulators of microglial activation. We identified 283 common mRNAs and 53 common lncRNAs during mouse M1 microglial activation processes, whereas 26 common mRNAs and five common lncRNAs were identified during mouse M2 microglial activation processes. A total of 648 common mRNAs and 274 common lncRNAs were identified during the activation of human M1 microglia. In addition, we identified 1,920 common co-expressed pairs in mouse M1 activation processes and 25 common co-expressed pairs in mouse M2 activation processes. Our study provides a comprehensive understanding of common lncRNA expression profiles in microglial activation processes in vitro. The list of common lncRNAs identified in this study provides novel evidence and clues regarding the molecular mechanisms underlying microglial activation.

• 유기물자원화
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• 제25권3호
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• pp.63-71
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• 2017

본 연구에서는 활성탄 제조에 널리 이용되고 있는 KOH 활성화법으로 활성화된 활성탄의 표면적 증가를 위하여 세척시간, 교반속도, 세척횟수 등의 변수들에 대한 활성탄 세척공정 최적화 연구를 수행하였다. 연구결과, 활성탄의 표면적은 세척효율이 증가됨에 따라 뚜렷하게 증가되었는데, 90% 이상의 세척효율을 얻기 위해서는 활성탄의 복잡한 세공구조에 따른 세공 내 확산메커니즘이 제어인자로 작용함을 알 수 있었다. 또한, 세척액의 증발을 통하여 $K_2CO_3$를 얻을 수 있었고 이를 이용한 활성화실험이 이루어졌다. 그 결과, 비표면적 $2,219m^2/g$의 제조가 가능하였다. $K_2CO_3$가 KOH의 효과적인 대안이라는 것을 고려할 때, 활성탄 제조공정에서 폐수 재이용은 무배출 폐기물 공정에 적용 할 수 있음을 보여주었다.

• Carbon letters
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• 제2권3_4호
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• pp.176-181
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• 2001

A series of activated carbons were prepared from coconut shells and coal-tar pitch binder by physical activation with steam in this study. The effect of variable processes such as activation temperature, activation time and ratio of mixing was investigated for optimizing those preparation parameters. The activation processes were carried out continuously. The nitrogen adsorption isotherms at 77 K on pellet-shaped activated carbons show the same trend of Type I by IUPAC classification. The average pore sizes were about 19-21${\AA}$. The specific surface areas ($S_{BET}$) of pellet typed ACs increased with increasing the activation temperature and time. Specific surface area of AC treated for 90 min at temperature $900^{\circ}C$ was 1082 $m^2/g$. The methylene blue numbers continuously increased with increasing the activation temperature and time. On the other hand, iodine numbers highly increased till activation time of 60 min, but the rate of increase of iodine numbers decreased after that time. This indicates that new micropores were created and the existing micropores turned into mesopores and macropores because of increased reactivity of carbon surface and $H_2O$.