• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.412-418
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• 2010

Steam reforming of n-hexadecane, a major component of diesel over Ni-based hydrotalcite-like catalyst was carried out at $900^{\circ}C$ at atmospheric pressure with space velocity of $10,000h^{-1}$ and feed molar ratio of steam/carbon=3.0. Ni-based hydrotalcite catalyst was prepared by a solid phase crystallization (spc) method and characterized by $N_2$-physisorption, CO chemisorption, TPR., XRD, and TEM techniques. It was found that spc Ni/MgAl catalyst showed higher catalytic stability and inhibition of carbon formation than Ni/$\gamma-Al_2O_3$ catalyst under the tested conditions. The results suggest that the modified spc-Ni/MgAl catalyst after optimization may be applied for the SR reaction of diesel.

• 한국표면공학회지
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• 제46권4호
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• pp.175-180
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• 2013

Carbon nanofilaments (CNFs) could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under thermal chemical vapor deposition system. Ni powders were used as the catalyst for the formation of the CNFs. During the initial deposition stage, the initiation of the CNFs on the Ni catalyst was investigated. The geometries of the as-grown CNFs on Ni catalyst were strongly dependent on the size and/or the shape of Ni catalyst. Small size catalyst (<150 nm in diameter) gives rise to the unidirectional growth of the CNFs. On the other hand, large size catalyst (150~500 nm), the bidirectional growth of the CNFs could be observed. Particularly, the well faceted parallelogram-shaped Ni catalyst could give rise to the bidirectional growth of the CNFs having the symmetrically opposite direction. Eventually, these bidirectional growths of CNFs were understood to form the well-developed carbon microcoils (CMCs). Based on these results, the optimal shape and the size of the Ni catalyst to form the CMCs were discussed.

• 한국수소및신에너지학회논문집
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• 제35권1호
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• pp.27-33
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• 2024

In this study, we researched Ni-based bead catalysts for the catalytic thermal decomposition of light hydrocarbons. A Ni-based bead-type catalyst was prepared, and catalytic thermal decomposition performance of light hydrocarbons was evaluated. The 30Ni/Al₂O₃ catalyst exhibited the most superior performance, with the presence of both fibrous and carbon black forms on the catalyst surface. Catalytic performance was evaluated for particles sized between 150-250 and 500 ㎛, with excellent catalytic thermal decomposition properties in the 150-250 ㎛ range. After the reaction, carbon removal through collision between catalysts in the fluidized bed was observed. It was confirmed that as the particle size increases, the amount of carbon removed increases.

• 청정기술
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• 제5권2호
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• pp.63-68
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• 1999

The activities of Ni(20wt%)/$La_2O_3$, Ni(20wt%)/${\gamma}-Al_2O_3$, and Ni(20wt%)/$SiO_2$ catalyst for $CO_2$ reforming of $CH_4$ were investigated in a fixed bed flow reactor under atmospheric condition. Catalyst characterization using XRD, TEM, SEM, BET analysis were also conducted. The catalytic activity of Ni(20wt%)/$La_2O_3$ catalyst has relatively superior to that of Ni(20wt%)/${\gamma}-Al_2O_3$ and Ni(20wt%)/$SiO_2$ catalyst. The good activity of Ni(20wt%)/$La_2O_3$ catalyst seems to depend on reduced $Ni^{\circ}$ phases of NiO($\rightarrow$ Ni + O), $LaNiO_3$($\rightarrow$ $Ni+La_2O_3$), Ni crystalline phases, and decoration of Ni phases by lanthanum species is also an important factor. Ni(20wt%)/${\gamma}-Al_2O_3$ and Ni(20wt%)/$SiO_2$ catalyst due to surface acidity resulted in the deposition of wisker type and encapsulate carbon on the surface of catalyst, but Ni(20wt%)/$La_2O_3$ catalyst did not show carbon on the surface of catalyst up to 8.5hr reaction.

• 공업화학
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• 제32권6호
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• pp.627-631
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• 2021

휘발성유기화합물을 제거하기 위한 기존 촉매 시스템의 문제를 해결하고자 유도가열 촉매 시스템에 대한 연구를 수행하였다. 본 연구에서는 3종류의 Ni계 상용촉매를 적용하였으며, 촉매 부피, 조성, 열처리 분위기, 코일 내 위치를 포함한 유도가열 반응 특성을 조사하였다. 촉매의 조성 및 부피는 유도가열 시스템에 의한 발열 및 톨루엔 산화 성능에 영향을 미쳤다. 특히 철이 첨가된 촉매는 99% 이상의 Ni로 구성된 촉매에 비해 높은 발열을 나타내었으나 낮은 톨루엔 산화 성능을 나타내었다. 또한 Ni계 촉매의 열처리에 있어 공기 분위기는 촉매의 성능을 급격히 저하시킨다. 유도가열 시스템에서 촉매는 코일 내 중심에 위치하는 것이 최적 조건으로 나타났다. 연구를 통해 도출한 최적의 조건에서 촉매를 7회 반복 실험하였으며, 유사한 성능을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제21권6호
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• pp.493-499
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• 2010

Steam reforming (SR) of glycerol, a main by-product of manufacturing process of bio-diesel, for the production of hydrogen was investigated over the Ni-based catalysts. The Ni-based catalysts were prepared by an impregnation method, and characterized by $N_2$ physisorption, CO chemisorption, XRD and TEM techniques. It was found that the Ni/${\gamma}-Al_2O_3$ catalyst showed higher conversion and catalytic stability for the carbon formation than the other catalysts in the steam reforming of glycerol under the tested conditions. The results suggest that the steam reforming of glycerol over modified Ni/${\gamma}-Al_2O_3$ catalyst minimized carbon formation can be applied in hydrogen station for fuel-cell powered vehicles and fuel processor for stationary and portable fuel cells.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.249-256
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• 2011

In this study, the Ni-based catalysts for the production of synthetic natural gas were prepared by various preparation methods such as the co-precipitation, precipitation, impregnation and physical mixing methods. The ranges of the reaction conditions were the temperatures of 250~$350^{\circ}C$, $H_2$/CO mole ratio of 3.0, the pressures of 1 atm and the space velocity of 20000 $ml/g_{-cat{\cdot}}{\cdot}h$. It was found that the catalyst prepared by precipitation method had higher CO conversion than the catalyst prepared by co-precipitation method. While the catalyst prepared by precipitation method had the formation of NiO structure, the catalyst prepared by co-precipitation method had the formation of $NiAl_2O_4$ structure. It was confirmed that Ni-based catalyst prepared by the physical mixing method had the lowest CO conversion because it was deactivated by the production of $Ni_3C$ during the methanation. As a result, it was shown clearly that Ni-based catalysts prepared by impregnation method expressed the highest catalytic activity in CO methanation.

• 신재생에너지
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• 제4권4호
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• pp.80-87
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• 2008

Steam reforming of LPG was investigated over spc-Ni/MgAl catalyst in a temperature range of $600{\sim}850^{\circ}C$, feed molar ratio of $H_2O/C=1.0{\sim}3.0$, space velocity of $10,000{\sim}90,000h^{-1}$ and at atmospheric pressure. spc-Ni/MgAl catalyst was prepared by a co-precipitation method, whereas Ni/MgO and $Ni/Al_2O_3$ catalysts were prepared by an incipient wetness method. The characteristics of catalysts were analyzed by N2 Physisorption, CO chemisorption, XRD, TOF-SIMS, SEM and TEM techniques. The Ni/MgO and $Ni/Al_2O_3$ catalysts were deactivated by the formation of carbon. However, the spc-Ni/MgAl catalyst showed higher conversion and $H_2$ selectivity than the other catalysts, even though carbon was formed on the surface of the catalyst during the reaction under the tested reaction conditions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.247-250
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• 2008

Biomass gasification is a promising technology for producing a fuel gas which is useful for power generation systems. In biomass gasification processes, tar formation often causes some problems such as pipeline plugging. Thus, proper tar treatment is necessary. So far, nickel (Ni)-based catalysts have been intensively studied for the catalytic tar removal. However, the deactivation of Ni-based catalysts takes place because of coke deposition and sintering of Ni metal particles. To overcome these problems, we have been using ruthenium (Ru)-based catalyst for tar removal. It is reported by Okada et al., that a Ru/$Al_2O_3$ catalyst is very effective for preventing the carbon deposition during the steam reforming of hydrocarbons. Also, this catalyst is more active than the Ni-based catalyst at a low steam to carbon ratio (S/C). Benzene was used for the tar model compound because it is the main constituent of biomass tar and also because it represents a stable aromatic structure apparent in tar formed in biomass gasification processes. The steam reforming process transforms hydrocarbons into gaseous mixtures constituted of carbon dioxide ($CO_2$), carbon monoxide (CO), methane ($CH_4$) and hydrogen ($H_2$).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.267-267
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• 2012

$TiO_2$-Ni inverse catalysts were prepared using atomic layer deposition (ALD) process and catalytic $CO_2$ reforming of methane (CRM) reaction over catalysts (either bare Ni or $TiO_2$ coated-Ni particles) were performed using a continuous flow reactor at $800^{\circ}C$. $TiO_2$-Ni inverse catalyst showed higher catalytic reactivity at initial stage of CRM reactions at $800^{\circ}C$ comparing to bare Ni catalysts. Moreover, catalytic activity of $TiO_2$/Ni catalyst was kept high during 13 hrs of the CRM reactions at $800^{\circ}C$, whereas deactivation of bare Ni surface was started within 1hr under same conditions. The results of surface analysis using SEM, XPS, and Raman showed that deposition of graphitic carbon was effectively suppressed in a presence of $TiO_2$ nanoparticles on Ni surface, thereby improving catalytic reactivity and stability of $TiO_2$/Ni catalytic systems. We suggest that utilizing decoration effect of metal catalyst with oxide nanoaprticles is of great potential to develop metal-based catalysts with high stability and reactivity.