• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.653-657
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• 2011

Conversion characteristics of $CH_4$ and $CO_2$ was studied using an atmospheric pressure plasma for the preparation of synthesis gas composed of $H_2$ and CO. The effects of delivered power, total gas flow rate, and gas residence time in the reactor on the conversion of $CH_4$ and $CO_2$ were evaluated in a plasma reactor with the type of dielectric barrier discharge. The increase of reactor temperature did not affect on the increase of conversion if the temperature does not reach to the appropriate level. The conversion of $CH_4$ and $CO_2$ largely increased with increasing the delivered power. As the $CH_4/CO_2$ ratio increased, the $CH_4$ conversion decreased, whereas the $CO_2$ conversion increased. Generally, the $CH_4$ convesion was higher than the $CO_2$ conversion through the variation of the process parameters.

• Clean Technology
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• v.9 no.3
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• pp.125-132
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• 2003

Activity improvement of Ni metal catalysts for carbon dioxide reforming was studied using HY-zeolite as the main supporter. As the reaction temperature increased, $CH_4$ and $CO_2$ conversions increased, and conversions higher than 80% was obtained above $700^{\circ}C$. As the Ni loading increased, the catalyst activity increased, and the highest activity was shown for the Ni loading of 13wt%. The HY-zeolite support showed the highest intial conversions of $CH_4$ and $CO_2$, but it showed faster deactivation than a ${\gamma}-Al_2O_3$ support. Nevertheless, it maintained the $CH_4$conversion higher than 80% after 24 hr reaction. The effect of promoters such as Mg, Mn, K, and Ca was also studied. It was observed that the Mg promotor exhibited the highest catalyst activity and less deactivation compared with Mn, K and Ca. After 24hr reaction, The optimum Mg content was found to be 5wt%.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.347-354
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• 2013

This study was carried out to examine different mole ratio of $H_2/CO_2$ and EBCT using the continuous system in the lab scale throughout biological methods with accumulated hydrogenotrophic methanogen that can convert $CO_2$ to $CH_4$. The experimental-based results with various gas mixtures of mole ratio of 4:1($H_2/CO_2$) and 5:1($H_2/CO_2$), $H_2$ was converted more than 99% conversion rate. In case of $CO_2$, 4:1($H_2/CO_2$) and 5:1($H_2/CO_2$) were $74.45{\pm}0.33%$, $95.8{\pm}10.7%$, respectively, in addition, the study was confirmed that the amount of $H_2$ was more needed than stoichiometric equations, where approach methods are empirical versus theoretical frameworks, for converting total $CO_2$. As such, we have noticed that $H_2$ was used for energy source of hydrogenotrophic methanogen for maintaining life. Regarding the results of the ratio of treatment by retention time, limitation of treatment capacity showed that $H_2$(99.9%) and $CO_2$(96.23%) at EBCT 3.3 hrs indicated stable conversion ratio, as well as appeared that methane production rate and $CO_2$ fixation rate were investigated $1.15{\pm}0.02m^3{\cdot}m^{-3}{\cdot}day^{-1}$ and $2.01{\pm}0.04kg{\cdot}m^{-3}{\cdot}day^{-1}$, respectively.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.205-209
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• 2015

CCU (Carbon Capture & Utilization) has a potential technology for the reduction and usage of carbon dioxide which is greenhouse gas emitting from a fossil fuel buring. To decompose the carbon dioxide, a three phase gliding arc plasma-catalytic reactor was designed and manufactured. Experiments of carbon dioxide reduction was performed by varying the gas flow rate with feeding the $CO_2$ only as well as the input power, the catalyst type and steam supply with respect to the injection of the mixture of $CO_2$ and $CH_4$. The $CO_2$ decomposition rate was 7.9% and the energy efficiency was $0.0013L/min{\cdot}W$ at a $CO_2$ flow rate of 12 L/min only. Carbon monoxide and oxygen was generated in accordance with the destruction of carbon dioxide. When the injection ratio of $CH_4/CO_2$ reached 1.29, the $CO_2$ destruction and $CH_4$ conversion rates were 37.8% and 56.6% respectively at a power supply of 0.76 kW. During the installation of $NiO/Al_2O_3$ catalyst bed, the $CO_2$ destruction and $CH_4$ conversion rates were 11.5% and 9.9% respectively. The steam supply parameter do not have any significant effects on the carbon dioxide decomposition.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.624-628
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• 1998

The aromatic organic solvents(BTX) were decomposed in the fixed bed reactor packed with a 0.5% $Pt/{\gamma}-Al_2O_3$ catalyst, then, supercritical carbon dioxide(SC-$CO_2$) was used as the reaction media. And the conversion was dependent on the inlet concentration of BTX and the molar density of SC-$CO_2$. The conversion of BTX was decreased with increasing of inlet concentration, and was increased with temperature and pressure. The maximum conversion of benzene was 98.5% at $300^{\circ}C$ and 204.1 atm, and that of toluene and xylene were 82.0 and 76.5%, respectively, at $350^{\circ}C$ and 204.1 atm. The intermediate products of partial oxidation were identified as benzaldehyde, phenol, benzenemethanol, and so on. The BTX can be effectively converted into harmless $CO_2$ and $H_2O$ at appropriate operating condition. Thus, the nontoxic recovery process was suggested as the removal method of BTX.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.526-529
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• 2007

본 연구에서는 일정선량(600kGy)에서 전자빔 에너지(0.7, 1, 2 MeV)를 달리하여 조사한 $Ni/g-Al_2O_3$ 촉매를 이용하여 세 가지 다른 종류의 합성가스 전환반응(메탄의 이산화탄소 개질반응, 메탄의 수증기 개질반응, 메탄의 부분산화반응)을 수행하였다. 전자빔 조사는 He 분위기, 실온에서 수행하였으며, 조사된 촉매의 표면상태 변화를 살펴보기 위하여 XRD, XPS 분석을 수행하였다. 고에너지 전자빔 처리된 $Ni/g-Al_2O_3$ 촉매의 표면 특성분석 결과 촉매 표면의 Ni종은 metallic Ni, NiO, $NiAl_2O_4$의 3가지 상태로 존재함을 알 수 있었으며, 전자빔 에너지 증가에 따라 촉매 표면의 전체적인 Ni 함량과 촉매 표면의 Ni 분산도를 나타내는 Ni/Al ratio가 증가하였다. 또한, 전자빔 에너지 증가에 따라 Ni에 결합된 산소가 더 크게 감소되어 표면에서 산소 vacancy가 증가하는 결과를 가져왔으며, 이는 결국 세 가지 Ni의 상태 중 metallic Ni과 $NiAl_2O_4$를 증가시켰다. 이러한 결과들은 메탄의 이산화탄소 개질 반응과 메탄의 수증기 개질반응에서 반응물($CH_4$, $CO_2$)의 전환율과 생성물(CO, $H_2$)의 수득율을 증가시켰으며 메탄의 부분산화반응은 반응의 특성상 메탄의 전환율은 증가하나 생성물인 CO, $H_2$는 오히려 감소하는 결과를 가져옴을 알 수 있었다.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.323-327
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• 2020

The reaction characteristics of Ni/CeO_2-X which is highly efficient at a low temperature was investigated for an application to carbon dioxide methanation process. The CeO_2-X support was obtained by the heat treatment of Ce(NO₃)₃ at 400 ℃ and the catalyst was prepared by impregnation process. The operating parameters of the experiment were the internal pressure of the reactor, the composition of oxygen, methane, and hydrogen sulfide in the inlet gas and the reaction temperature. When Ni/CeO_2-X was used for the carbon dioxide methanation reaction, the CO₂ conversion rate increased by more than 25% as the pressure increased from 1 to 3 bar. The increase was large at a low reaction temperature. When both oxygen and methane were in the inlet gas, the CO₂ conversion rate of the catalyst decreased by up to 16 and 4%, respectively. As the concentration of oxygen and methane increased, the reduction rate of the CO₂ conversion rate tended to increase. In addition, the hydrogen sulfide in the inlet gas reduced the CO₂ conversion rate by up to 7% and caused catalyst deactivation. The results of this study will be useful as basic data for the carbon dioxide methanation process.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.71.2-71.2
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• 2013

천연가스를 화학적 전환에 의해 부가가치를 높이기 위해서는 리포밍에 의해 합성가스(CO/H2)를 경유하는 간접전환경로가 현재로서는 가장 현실적인 방법이라 할 수 있다. 천연가스를 이용한 합성가스 제조기술은 수증기개질법(SRM), 이산화탄소 개질법(CDR, dry reforming), 부분산화법, 촉매 부분 산화법, 자열개질법 등으로 구분되며, 최근에는 각각의 제조방법의 장점을 고려하여 혼합개질법 또는 일련의 리포머 조합 방법이 개발되고 있다. CDR은 촉매 하에서 메탄과 이산화탄소의 직접접촉에 의해 반응이 일어나며, 수소와 일산화탄소의 비가 같은 합성가스가 제조된다. SRM에 비하여 고온에서 반응이 일어나고 전환율이 더 낮으므로 에너지 소비가 상대적으로 높다. 하지만, SRM과 함께 사용하면 합성가스 비율을 F-T합성이나 메탄올 합성에 적절한 비율로 조절이 가능한 장점이 있으며, 온실가스를 저감시킬 수 있는 전환기술로도 각광받고 있다. 본 발표에서는 최근의 CDR을 이용한 가스로부터 합성석유(GTL)와 메탄올을 고효율로 생산하는 기술 개발 동향에 대해서 소개하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.73.2-73.2
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• 2011

합성천연가스(SNG: Synthetic Natural Gas)를 얻기 위해, 석탄 가스화로부터 얻은 합성가스는 일반적으로 수소와 일산화탄소의 비가 3.0($H_2$/CO)이 되도록 수성가스전환(WGS)반응을 거친 후 메탄화반응기로 유입되며, 가능하면 낮은 온도에서 메탄 전환율이 높은 메탄화 반응의 특성상 강한 발열반응이 수반되므로 이를 낮추는 것이 중요하다. 또한, 최종생성물내의 메탄 농도를 높이기 위해 WGS 이후 탈황과 동시에 이산화탄소를 제거하기 위한 공정이 요구된다. 본 연구에서는 정제된 합성가스의 WGS와 이산화탄소 제거가 생략된 공정을 개발하기 위해, 상업용 촉매에 대하여 수소의 농도가 낮은 합성가스를 이용하여 스팀과 이산화탄소에 대한 메탄화반응 특성을 평가하였다. 또한, 이산화탄소의 존재여부에 따라 스팀으로 메탄화반응과 WGS가 동시에 일어날 수 있는 최적의 운전조건을 얻고자 하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.53-56
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• 2007

미량의 Ru을 증진제로 첨가하여 니켈 촉매의 반응 활성을 증진시킴으로써, 저온 환원성과 장시간 반응에 대한 안정성을 확보하고자 하였다. Ni의 담지량은 12 wt%로 고정하였으며 이에 Ru을 각각 0.1, 0.3, 0.5 wt%로 변화시켜 2차 담지하였다. 메탄의 수증기/이산화탄소 복합 개질 반응에 있어 니켈 촉매에 Ru을 2차 담지 한 촉매는 800 $^{\circ}C$, GHSV(gas hourly space velocity) 265,000 $h^{-1}$ 하에서 100 %에 가까운 $CH_{4}$ 전환율을 보였으며, GHSV 1,060,000 $h^{-1}$ 일 때에도 10시간 동안 90 %의 $CH_{4}$ 전환율을 기록하였다. 또한 이 중 0.3 wt%의 Ru를 담지한 경우가 1,060,000 $h^{-1}$의 조건하에서도 95 %이상으로 가장 높은 $CH_{4}$ 전환율로 유지되었다. $H_{2}-TPR$ 분석 결과, Ni(12)/$MgAl_{2}O_{4}$ 와 비교해 볼 때 Ru(0.5)/Ni(12)/$MgAl_{2}O_{4}$와 Ru(0.3)/Ni(12)/$MgAl_{2}O_{4}$ 촉매의 경우 150 $^{\circ}C$에서 저온 환원이 가능한 $RuO_{2}$의 존재를 확인할 수 있었다.