• 한국수소및신에너지학회논문집
• /
• 제23권2호
• /
• pp.173-182
• /
• 2012

Effects of temperature, pressure, and gas residence time on methane combustion characteristics of mass produced oxygen carrier particle (OCN706-1100) were investigated in a pressurized fluidized bed reactor using methane and air as reactants for reduction and oxidation, respectively. The oxygen carrier showed high fuel conversion, high $CO_2$ selectivity, and low CO concentration at reduction condition and very low NO emission at oxidation condition. Moreover OCN706-1100 particle showed good regeneration ability during successive reduction-oxidation cyclic tests up to the 10th cycle. Fuel conversion and $CO_2$ selectivity decreased and CO emission increased as temperature increased. These results can be explained by trend of calculated equilibrium CO concentration. However, $CO_2$ selectivity increased as pressure increased and fuel conversion increased as gas residence time increased.

• 한국수소및신에너지학회논문집
• /
• 제18권2호
• /
• pp.132-139
• /
• 2007

Popular techniques for producing synthesis gas by converting methane include steam reforming and catalyst reforming. However, these are high temperature and high pressure processes limited by equipment, cost and difficulty of operation. Low temperature plasma is projected to be a technique that can be used to produce high concentration hydrogen from methane. It is suitable for miniaturization and for application in other technologies. In this research, the effect of changing each of the following variables was studied using an AC Glidarc system that was conceived by the research team: the gas components ratio, the gas flow rate, the catalyst reactor temperature and voltage. Glidarc plasma reformer was consisted of 3 electrodes and an AC power source. And air was added for the partial oxidation reaction of methane. The result showed that as the gas flow rate, the catalyst reactor temperature and the electric power increased, the methane conversion rate and the hydrogen concentration also increased. With $O_2/C$ ratio of 0.45, input flow rate of 4.9 l/min and power supply of 1 kW as the reference condition, the methane conversion rate, the high hydrogen selectivity and the reformer energy density were 69.2%, 36.2% and 35.2% respectively.

• 실내환경 및 냄새 학회지
• /
• 제16권2호
• /
• pp.139-149
• /
• 2017

In order to reduce odor and methane emission from the landfill, open biocovers and a closed biofilter were applied to the landfill site. Three biocovers and the biofilter are suitable for relatively small-sized landfills with facilities that cannot resource methane into recovery due to small volumes of methane emission. Biocover-1 consists only of the soil of the landfill site while biocover-2 is mixed with the earthworm casts and artificial soil (perlite). The biofilter formed a bio-layer by adding mixed food waste compost as packing material of biocover-2. The removal efficiency decreased over time on biocover-1. However, biocover-2 and the biofilter showed stable odor removal efficiency. The rates of methane removal efficiency were in order of biofilter (94.9%)>, biocover-1(42.3%)>, and biocover-2 (37.0%). The methane removal efficiency over time in biocover-1 was gradually decreased. However, drastic efficiency decline was observed in biocover-2 due to the hardening process. As a result of overturning the surface soil where the hardening process was observed, methane removal efficiency increased again. The biofilter showed stable methane removal efficiency without degradation. The estimate methane oxidation rate in biocover-1 was an average of 10.4%. Biocover-2 showed an efficiency of 46.3% after 25 days of forming biocover. However, due to hardening process efficiency dropped to 4.6%. After overturn of the surface soil, the rate subsequently increased to 17.9%, with an evaluated average of 12.5%.

• Korean Chemical Engineering Research
• /
• 제50권1호
• /
• pp.41-49
• /
• 2012

본 연구는 메탄 부분산화에 의한 메탄올 직접 합성을 위한 촉매 개발을 목표로 수행되었다. 이를 위하여 Mo-Bi-V-Al 복합 산화물 촉매를 제조하였으며, 제조 방법에 따른 촉매 물성을 비교하고, 제조한 촉매를 이용하여 메탄올 합성반응을 수행하여 그 결과를 검토하여 보았다. 졸-겔법으로 제조한 촉매가 공침법으로 제조한 촉매보다 비표면적이 훨씬 컸다. 입자가 작고 표면적이 클수록 부분산화반응보다는 완전산화반응이나 메탄올 산화반응이 더 잘 진행되어 메탄올의 선택도는 낮아지고 이산화탄소의 선택도는 증가하였다. 졸-겔법으로 제조한 촉매가 공침법으로 제조한 촉매보다 약 $20^{\circ}C$ 정도 더 낮은 온도에서 더 높은 메탄올 선택도(13%)를 보였다. 두 방법으로 제조한 촉매의 XRD 분석 결과 두 촉매의 결정 구조가 서로 달랐다. 본 반응에서 압력이 증가할수록 완전산화 반응이 억제되고 부분산화 반응이 일어나서 메탄올의 선택도는 증가하였고 이산화탄소의 선택도는 감소하였다.

• 열처리공학회지
• /
• 제14권2호
• /
• pp.103-109
• /
• 2001

Plasma nitrocarburising and post oxidation were performed on SM45C steel using a plasma nitriding unit. Nitrocarburising was carried out with various methane gas compositions with 4 torr gas pressure at $570^{\circ}C$ for 3 hours and post oxidation was carried out with 100% oxygen gas atmosphere with 4 torr at different temperatures for various times. It was found that the compound layer produced by plasma nitrocarburising consisted of predominantly ${\varepsilon}-Fe_{2-3}(N,C)$ and a small proportion of ${\gamma}-Fe_4(N,C)$. With increasing methane content in the gas mixture, ${\varepsilon}$ phase compound layer was favoured. In addition, when the methane content was further increased, cementite was observed in the compound layer. The very thin oxide layer on top of the compound layer was obtained by post oxidation. The formation of Oxide phase was initially started from the magnetite($Fe_3O_4$) and with increasing oxidation time, the oxide phase was increased. With increasing oxidation temperature, oxide phase was increased. However the oxide layer was split from the compound layer at high temperature. Corrosion resistance was slightly influenced by oxidation times and temperatures.

• 한국수소및신에너지학회논문집
• /
• 제22권2호
• /
• pp.168-177
• /
• 2011

A set of kinetics study on the reduction with $CH_4$, oxidation with steam and oxidation with air was performed for $Fe_2O_3/ZrO_2$. $Fe_2O_3/ZrO_2$ was prepared by aerial oxidation method. The reactivity experiments were performed in a thermogravimetric analyzer (TGA) with different reacting gas concentrations and temperatures. The obtained activation energy of reduction by methane, oxidation by water and oxidation by air are 219 kJ/mol, 238 and 20 respectively.

• 한국응용과학기술학회지
• /
• 제23권3호
• /
• pp.223-229
• /
• 2006

Methanol and formaldehyde were produced directly by the partial oxidation of methane over mixed oxide catalysts. The catalysts were composed of Mo and Bi with late-transition metals, such as Mn, Fe, and Co. The reaction was carried out at $450^{\circ}C$, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by $O_2-TPD$ and BET apparatus. Among the catalysts used, the catalyst composed of 1:1:2.5 molar ratio of Mo:Bi:Mn showed the best methane conversion and methanol selectivity. The change in ratio of methane to oxygen affected at the conversion and selectivity, and the most proper ratio was 10:1.5. Methane conversion, methanol and formaldehyde selectivities increased with the surface areas of the catalysts. From the $O_2-TPD$ result, it was found that the oxygen species responsible for this reaction might be the lattice oxygen species desorbed at high temperature around $800^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• 제26권10호
• /
• pp.1591-1596
• /
• 2005

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.278-283
• /
• 2000

The activity of catalysts obtained by self-propagating high temperature synthesis in reaction of partial methane oxidation at atmospheric pressure was investigated. Basing on the compared results of X-ray analysis and gas chromatography analysis of reaction products, the dependence of compounds formation on the phase concentrations in the studied catalyst samples was found.

• 한국미생물·생명공학회지
• /
• 제37권4호
• /
• pp.293-305
• /
• 2009

메탄은 온실효과가 이산화탄소 보다 20배 이상인 대표적인 non-$CO_2$ 온실가스이다. 매립지는 주요 인위적 메탄 발생원으로, 매립지의 메탄 발생량은 연간 35~73 Tg(tera gram)으로 추정된다. 바이오커버(개방형 시스템)과 바이오필터(폐쇄형 시스템)을 이용하는 생물학적 방법은 메탄을 회수하여 자원화하기에는 메탄 농도가 너무 낮거나 가스 포집정이 설치되어 있지 않는 노후화된 매립지나 소규모 매립지로부터 메탄 배출을 저감할 수 있는 유용한 방법이다. 메탄을 유일탄소원과 에너지원으로 활용하는 메탄산화세균은 이러한 생물학적 방법에 있어 메탄을 산화시켜 제거하는데 매우 중요한 역할을 담당한다. 토양, compost, 지렁이 분변토 등과 같은 다양한 충전재를 이용하여 실험실 규모의 바이오커버/바이오필터의 메탄산화효율에 관한 많은 연구가 진행되었다. 이 중에서 compost는 가장 많이 이용되고 있는 충전재이고, compost를 이용한 바이오커버/바이오필터의 메탄산화속도는 50에서 $700\;g-CH_4\;m^{-2}\;d^{-1}$로 보고되고 있다. 또한, 실제 매립지에 파일럿 규모의 바이오커버/바이오필터를 설치하여 메탄 배출 저감 효과에 관한 연구도 진행되고 있다. 매립지의 메탄 배출 저감은 탄소배출권 거래와 연관될 수 있으므로, 바이오커버/바이오필터에 의한 메탄 저감량을 정확하게 평가하는 것이 매우 중요하다. 그러므로, 매립지 현장에 설치된 바이오커버/바이오필터의 성능을 평가하는 방법은 표준화되어야 하며, 메탄 저감량을 정확하게 정량화할 수 있는 방법 개발이 필요하다.