• Clean Technology
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• v.29 no.4
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• pp.327-332
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• 2023

This study investigated synthesis gas production via steam reforming of biogas. Ni-Al₂O₃ and Ni-CeO₂ catalysts were synthesized using the co-precipitation method, with controlled precipitation agent injection rates. Catalytic performances were tested at various temperatures, with a gas composition ratio of CH₄:CO₂:H₂O = 1:0.67:3 and a gas hourly space velocity (GHSV) of 647,000 mL h^-1 gcat^-1. The rate of precipitation agent injection influenced the characteristics of the catalysts depending on the type of support used. As the temperature increased, both the CO₂ reforming of methane and the reverse water gas shift reactions occurred. The Ni-Al₂O₃ catalyst, synthesized with a single injection of the precipitation agent, exhibited the best catalytic activity under conditions with sufficient steam supply among the prepared catalysts, due to its high Ni dispersion.

• Korean Chemical Engineering Research
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• v.54 no.4
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• pp.560-567
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• 2016

In this study, we characterized steam reforming reactions and surface of $Ni/Al_2O_3$ catalysts. Ni-Mo based catalysts were prepared by loading Mo as the co-catalyst and reaction activities of the Ni-Mo based catalysts were compared with those of Ni-based catalysts. Through the $H_2$-TPR and XPS analysis it was confirmed that this characteristic efficiency. $O_2$-TPO analysis was performed to examine the deposition characteristics, bonding structures and evaporation characteristics of carbon deposited on the surface of catalysts after long run experiments were performed for steam reforming reactions. As the results, it was found that durability was improved in Ni-Mo based catalysts inhibiting formation of graphitic carbon species which reduced reaction activities of the catalysts by strongly interacting with Ni in the steam reforming reaction.

• 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%.

• Environmental Engineering Research
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• v.20 no.4
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• pp.329-335
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• 2015

The effects of ion-doping on $TiO_2$ nanotubes were investigated to obtain the optimal catalyst for the effective decomposition of Rhodamine B (RB) through UV photocatalytic oxidation process. Changing the calcination temperature, which changed the weight fractions of the anatase phase, the average crystallite sizes, the BET surface area, and the energy band gap of the catalyst, affected the photocatalytic activity of the catalyst. The ionic radius, valence state, and configuration of the dopant also affected the photocatalytic activity. The photocatalytic activities of the catalysts on RB removal increased when $Ag^+$, $Al^{3+}$ and $Zn^{2+}$ were doped into the $TiO_2$ nanotubes, whereas such activities decreased as a result of $Mn^{2+}$ or $Ni^{2+}$ doping. In the presence of $Zn^{2+}$-doped $TiO_2$ nanotubes calcined at $550^{\circ}C$, the removal efficiency of RB within 50 min was 98.7%.

• Journal of Environmental Science International
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• v.28 no.1
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• pp.65-73
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• 2019

The catalytic activity of Ni-0.2%YSZ (Yttria-Stabilized Zirconia) with different promoters was evaluated for $CO_2$ methanation. The catalysts were weighed for mixing and they were dried at $110^{\circ}C$ for molding into disks. The concentration of $CO_2$ and $CH_4$ for conducting of $CO_2$ methanation were analyzed by gas chromatography and the physical characteristics of the disk-type catalyst formed were analyzed by X-ray diffraction, scanning electron microscope and energy dispersive x-ray spectrometer. The addition of $CeO_2$ as a promoter for Ni-0.2%YSZ (denoted as Ni-5%Ce-0.2%YSZ) resulted in the highest $CO_2$ methanation. It also showed catalytic activity at a low temperature($200^{\circ}C$). Following this, $ZrO_2$, $SiO_2$, $Al_2O_3$ and $TiO_2$ were added to Ni-5%Ce-0.2%YSZ to compare the $CO_2$ methanation, and the highest efficiency was found for. Ni-1%Ti-5%Ce-0.2%YSZ Then, the concentration of Ti was increased to 10% and the catalytic activity was estimated using seven different types of commercial $TiO_2$. In conclusion, ST-01 $TiO_2$ showed the highest efficiency for $CO_2$ methanation.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3205-3208
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• 2014

Catalytic gasification of cellulose was carried out in a U-type fixed reactor with Ni loaded MSU-F catalyst (Ni/MSU-F) and Ni loaded ${\gamma}-Al_2O_3$ (Ni/${\gamma}-Al_2O_3$). The characteristics of the catalysts were analyzed by using X-ray diffraction, $H_2$-temperature programmed reduction, and Brunauer-Emmett-Teller analyses. The operation conditions of catalytic gasification reactions were $750^{\circ}$ and 0.2 equivalence ratio. Air was used as gasification agent. Catalytic gasification characteristics, such as gas yield and gas composition ($H_2$, CO, $CO_2$, $C_1-C_4$), were measured and calculated. The gas yield of Ni/MSU-F was much higher than that of Ni/${\gamma}-Al_2O_3$. Especially high amount of hydrogen was produced by Ni/MSU-F.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.619-625
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• 2023

In order to solve problems caused by the heat load of hypersonic aircraft, this study examined the optimization of the Si/Al ratio of the catalyst and nickel ion exchange to improve the performance of the hydrocarbon decomposition reaction (endothermic reaction). It was confirmed that the catalysts prepared through Si/Al ratio optimization and nickel ion exchange showed about 10% improvement in heat absorption performance compared to thermal cracking at 4 MPa and 550 ℃. FT-IR and NH₃-TPD analyses were found to identify factors affecting activity changes, and it was observed that the Si/Al ratio of the HZSM-5 catalyst was closely correlated with acid site development and catalytic activity. In addition, TGA and O₂-TPO analyses were conducted to observe the carbon deposition inhibition properties of the nickel-added catalyst.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.1
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• pp.52-61
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• 1989

The hydrodenitrogenation of quinoline dissolved in n-heptane was studied over sulfided Ni-Mo/$\gamma-Al_2O_3$ catalyst at the range of the temperature between 553 K and 673 and the total pressure between $20 \times 10^5$ Pa and $60 \times 10^5$ Pa in a fixed bed flow reactor. Quinoline conversion was very high at relatively low temperature and total pressure, and decreased with quinoline partial pressure. The thermodynamic equilibrium between quinoline and Py-THQ existed in wide ranges of experimental conditions and shifted in favor of quinoline at higher temperature. At the range of the temperature betwwen 553 K and 673 K and at the total pressure $60 \times 10^5$ Pa, the quinoline reaction rate was 1st order with respect to the concentr4ation of quinoline and its apparent activation energy was 7.15 Kcal/mole.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.256-259
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• 2005

본 연구에서는 기존 니켈 활성성분만의 알루미나담지 촉매에 비해 고온에서의 수소를 사용한 환원 전처리 과정을 거치지 않고도 높은 반응활성을 나타내며, 반응 중 탄소침적에 대한 촉매 저항성에서도 우수한 결과를 나타낸 루테늄-니켈 촉매에 대해보고 하고자 한다. 메탄 수증기 개질 반응을 통해, 루테늄을 최종적으로 담지한 알루미나 담지니켈계 촉매는 별도의 전처리과정 없이 $650^{\circ}C$에서부터 높은 반응성을 보였으며, 루테늄과 니켈을 동시에 담지한 경우보다 더 우수한 활성을 나타내었다. Ru의 담지량을 달리한 실험에서는$RU(0.5)/Ni(20)/Al_2O_3$ 촉매가 가장 높은 활성을 보였다. $H_2-TPR$ 분석 결과, $Ru(0.5)/Ni(20)/A1_2O_3$촉매의 경우 세 가지 환원 피크가 나타났으며, $Ni(20)/A1_2O_3$촉매와 비교해 볼 때, 저온(<$130^{\circ}C)$에서 환원가능한 $RUO_2$의 존재를 확인할 수 있었다. 담지된 RU은 분산도가 높아, XRD분석 결과에서 Ru이나 $RuO_2$의 특성 피크가 존재하지 않았다. 또한 $650^{\circ}C$에서 10시간 개질반응 후 얻어진 촉매에 대해 $O_2-TGA$를 분석한 결과, $Ni(20)/Al_2O_3$촉매는 $-7.2wt\%$ 정도의 큰 무게 감소를 보였으며, 이는 촉매 표면에 생성된 carbon tube에 의한 것임을 SEM 분석을 통해 알 수 있었다 이에 반해, $Ru(0.5)/Ni(20)/Al_2O_$ 촉매는 $O_2-TGA$시 $0.3wt\%$ 정도 무게 증가에 그쳤으며, SEM 분석상 carbon tube의 생성이 크게 억제되었음을 알 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.535-548
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• 2023

The intermittent nature of renewable energy is a challenge to overcome for safety and stable performance in water electrolysis systems linked to renewable energy. Oxygen removal using the catalyst is suitable for maintaining the oxygen concentration in hydrogen below the explosive level (4%) even in intermittent power supply. Metals such as Pd, Pt, and Ni are expected to be effective materials due to their hydrogen affinity. The oxygen removal performance was compared under high hydrogen concentration conditions by loading on γ-Al₂O₃ with high reactivity and large surface area. The characteristics of the catalyst before and after the reaction were analyzed through X-ray diffraction, transmission electron microscope, H₂-temperature programmed reduction, X-ray photoelectron spectroscope, etc. The Pd catalyst that showed the best performance was able to lower 2% oxygen to less than 5 ppm. Changes in catalyst characteristics after the reaction indicate that oxygen vacancies are related to oxygen removal performance and catalyst deactivation.