• Bulletin of the Korean Chemical Society
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• 제23권8호
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• pp.1149-1153
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• 2002

CH4/CO2 dry reforming was carried out to make syn gas on the Ni/Al2O3 catalysts calcined at different temperatures. The Ni/Al2O3 (850 $^{\circ}C)$ catalyst gave good activity and stability w hereas the Ni/Al2O3 $(450^{\circ}C)$ catalyst showed lower activity and stability. The NiO/Al2O3 catalyst calcined at $850^{\circ}C$ for 16 h (Ni/Al2O3 $(850^{\circ}C))$ formed the spinel structure of nickel aluminate, which was confirmed by TPR. The carbon formation rate on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was very low till 20 h, and then steeply increased with reaction time without decreasing the activity for CH4 reforming. The Ni/Al2O3 $(450^{\circ}C)$ catalyst showed high carbon formation rate at the initial reaction time and then, the rate nearly stopped with continuous decreasing the activity for CH4 reforming. Even though the amount of carbon deposition on the Ni/Al2O3 $(850^{\circ}C)$ catalyst was higher than that on the Ni/Al2O3 $(450^{\circ}C)$ catalyst, the activity for CH4ing was also high, which could be attributed to the different type of the carbon formed on the catalyst surface.

• 한국연소학회지
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• 제13권4호
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• pp.47-53
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• 2008

The reaction mechanism of methane dry reforming has been investigated using an arc-jet reactor. The effects of input power, $CO_2/CH_4$ and added $O_2$ were investigated by product analysis, including CO, $H_2$, $C_{2}H_{Y}$ and $C_{3}H_{Y}$ as well as $CH_4$ and $CO_2$. In the process, input electrical power activated the reactions between $CH_4$ and $CO_2$ significantly. The increased feed ratio of the $CO_2$ to $CH_4$ in the dry reforming does not affect to the $CH_4$ conversion. but we could observe increase in CO selectivity together with decreasing $H_2$ generation. Added oxygen can also increase not only CO selectivity but also $CH_4$ conversion. However, hydrogen selectivity was decreased significantly due to a increased $H_{2}O$ formation.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.153-156
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• 2009

Low temperature methane steam reforming to produce $H_2$ for fuel cells has been calculated thermodynamically considering both heat loss of the reformer and unreacted $H_2$ in fuel cell stack. According to the thermodynamic equilibrium analysis, it is possible to operate methane steam reforming at low temperatures. A scheme for the low temperature methane steam reforming to produce $H_2$ for fuel cells by burning both unconverted $CH_4$ and $H_2$ to supply the heat for steam methane reforming has been proposed. The calculated value of the heat balance temperature is strongly dependent upon the amount of unreacted $H_2$ and heat loss of the reformer. If unreacted $H_2$ increases, less methane is required because unreacted $H_2$ can be burned to supply the heat. As a consequence, it is suitable to increase the reaction temperature for getting higher $CH_4$ conversion and more $H_2$ for fuel cell stack. If heat loss increases from the reformer, it is necessary to supply more heat for the endothermic methane steam reforming reaction from burning unconverted $CH_4$, resulting in decreasing the reforming temperature. Experimentally, it has been confirmed that low temperature methane steam reforming is possible with stable activity.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.554-561
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• 2016

Depending on the Bio-gas sources, main component gases of $CH_4$ and $CO_2$ are shown to be variously present in amounts. For the anaerobic digester, The concentration of $CH_4$ and $CO_2$ in the gases are 60~70 and 30~35 vol%. For the landfill gas, $CH_4$ and $CO_2$ are 40~60 and 40~60 vol%. For the food wastes, $CH_4$ and $CO_2$ are 60~80 and 20~40 vol%, respectively. In this study, maximum conversion rates of $CO_2$ were obtained from the variety of concentrations of $CH_4$ and $CO_2$ by the catalysts of reforming reactions. Moreover, in order to get maximum producing amount of synthetic gas, experimental studies were performed to optimize the reaction variables. On the basis of $CH_4$, 243 ml, R [$CH_4/(O2+CO_2)$] value were varied from 0.8 to 1.35, in the study of $CH_4$ and $CO_2$ reforming reactions. It was shown that the optimal results were obtained for 1.35 of R value. And also, at $850^{\circ}C$ and 1 atm, the production rate of synthetic gas was 90% and the conversion rates of $CH_4$ and $CO_2$ were higher than 99% and 90%, respectively.

• Korean Chemical Engineering Research
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• 제45권6호
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• pp.663-668
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• 2007

$Ni/CeO_2-ZrO_2$ 촉매를 이용하여 수소 제조를 위한 메탄의 자열개질반응 특성을 조사하였다. 메탄의 자열개질반응에서 촉매의 활성과 안정성을 향상시키기 위해 알루미나가 코팅된 금속 모노리스를 사용하였으며, 금속모노리스 촉매체는 높은 반응온도에서 분말형태의 촉매에 비해 높은 메탄 전환율을 나타내었다. 자열개질반응에 있어서 $H_2O/CH_4/O_2$의 비는 전환율에 영향을 미치는 중요한 변수임을 알 수 있었다. $H_2O/CH_4$ 비가 증가함에 따라 수소 수율은 증가되고, 또한 $O_2/CH_4$ 비가 증가함에 따라 메탄 전환율은 증가하지만 수소 수율은 감소하였다. $Ni/CeO_2-ZrO_2$ 촉매에 0.5 wt%의 귀금속 촉매인 Ru 첨가로 인해 낮은 반응온도에서 촉매 활성이 향상되었다.

• Bulletin of the Korean Chemical Society
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• 제22권12호
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• pp.1323-1327
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• 2001

The catalyst Ni/MgO (Ni : 15 wt%) has been applied to methane reforming reactions, such as steam reforming of methane (SRM), partial oxidation of methane (POM), and oxy-steam reforming of methane (OSRM). It showed high activity and good stability in all the reforming reactions. Especially, it exhibited stable catalytic performance even in stoichiometric SRM (H2O/CH4 = 1). From TPR and H2 pulse chemisorption results, a strong interaction between NiO and MgO results in a high dispersion of Ni crystallite. Pulse reaction results revealed that both CH4 and O2 are activated on the surface of metallic Ni over the catalyst, and then surface carbon species react with adsorbed oxygen to produce CO.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.1-10
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• 2018

The amount of biogas increases as the amount of organic waste increases. Recently, biogas from organic waste have been made much efforts to utilize as a energy. In particular, the concentration of $CH_4$ and $CO_2$ generated from sewage sludge and livestock manure treatment are 60-70% and 30-35%, and $CH_4$ and $CO_2$ generated from food wastes are 60-80% and 20-40%. In case of landfill gas, $CH_4$ and $CO_2$ have a concentration of 40-60% and 40-60% respectively. Therefore, in order to use the biogas more widely, it is necessary to convert the biogas to methanol, LNG or DME. In this study, experiments were conducted to produce hydrogen and carbon monoxide through various biogas reforming reactions on $Ni/Ce-ZrO_2/Al2O3$ catalysts. The experiment of synthetic gas synthesis was carried out on a wide concentrations of methane and carbon dioxide, which were the major constituents of biogas from various organic wastes. The effect of $(O_2+CO_2)/CH_4$ (=R') on the yields of hydrogen and carbon monoxide, the conversion rate of methane and carbon dioxide was investigated. Also simulation for syngas synthesis on the $CO_2$ reforming of $CH_4$ was computed by employing total Gibbs free energy minimization method using PRO/II simulator, and compared with the experimental results on wet and dry reforming reaction of biogas.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.802-807
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• 2012

본 연구에서는 메탄으로부터 합성가스를 만드는 자열 개질(Autothermal reforming)반응 특성을 Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO 금속모노리스 촉매체와 전기 발열식 촉매를 사용하여 조사하였다. 자체 가동 형 반응기는 자열 개질 반응기에 $700^{\circ}C$ 반응물을 공급하는데 걸리는 start-up 시간이 2분 이내였다. 반응물의 $O_2/CH_4$와 $H_2O/CH_4$ 비가 메탄의 전환율과 반응기의 온도 분포에 미치는 영향은 매우 크다. 반응기의 온도는 $H_2O/CH_4$ 비가 감소할수록 흡열반응에서 발열반응으로 전환되어 증가한다. 또한 $H_2O/CH_4$ 비가 증가함에 따라 수성가스화 전이반응에 의하여 생성물 중에 $CO_2$양이 증가한다. $GHSV=10,000\;h^{-1}$, 반응물 조성($H_2O/CH_4=0.6$과 $O_2/CH_4=0.5$)의 자열 개질반응에서, 97%의 메탄의 전환율을 얻었으며, 반응기의 온도는 $600^{\circ}C$로 유지되었다. 이 반응조건에서 170 cc 금속모노리스 촉매체를 충진한 반응기에서 자열개질 반응으로 생성된 최대 합성가스의 유량은 $0.94\;Nm^3/h$ 이었다.

• Korean Chemical Engineering Research
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• 제46권5호
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• pp.1002-1007
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• 2008

이 논문의 목적은 PEMFC 작동을 위한 플라즈마 개질 시스템의 최적 조건을 연구한 것이다. 플라즈마 개질 반응기는 니켈 촉매 반응기와 동시에 사용하여 수소 생성을 증대하였다. 또한 수성가스 전환 반응기 및 선택적 산화 반응기는 연료전지의 촉매 피독에 영향을 주는 일산화탄소의 농도를 10 ppm 이하로 줄이기 위하여 제작되었다. 플라즈마 개질기에서 최대 수소생산 조건은 S/C 비 3.2, 메탄 2.0 L/min, 촉매반응기 온도는 $700{\pm}5^{\circ}C$ 그리고 입력전력 900 W이다. 이때의 합성가스의 농도는 $H_2$ 70.2%, CO 7.5%, $CO_2$ 16.2%, $CH_4$ 1.8% 이다. 수소 수율, 수소 선택도 그리고 메탄 전환율는 각각 56.8%, 38.1%, 92.2%이다. 에너지 효율과 에너지 요구량은 37.0%, 183.6 kJ/mol 이다. 추가적으로 $CO_2/CH_4$ 비 실험을 진행하였다. 또한 수성가스 전환 반응기는 플라즈마 개질 반응기의 최적조건으로 실험을 진행하였으며, 출구 농도는 $H_2$ 68.0%, CO 337 ppm, $CO_2$ 24.0%, $CH_4$ 2.2%, $C_2H_4$ 0.4%, $C_2H_6$ 4.1% 이다. 이때의 선택적 산화 반응기의 실험결과는 $H_2$ 51.9%, CO 0%, $CO_2$ 17.3%를 나타냈다.

• Bulletin of the Korean Chemical Society
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• 제23권5호
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• pp.669-673
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• 2002

Ni catalyst (Ni: 15 wt%) supported on precalcined SiO2 has been investigated in reforming reactions of methane to synthesis gas. The catalyst exhibited fairly good activity and stability in partial oxidation of methane (POM), whereas it deactivated in steam reforming of methane (SRM). Pulse reaction results of CH4, O2, and CH4/O2 revealed that Ni/SiO2 has high capability to dissociate methane. The results also revealed that both CH4 and O2 are activated on the surface of metallic Ni, and then surface carbon species react with adsorbed oxygen to produce CO and CO2 depending on the bond strength of the oxygen species on the catalyst surface.