• Korean Chemical Engineering Research
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• 제46권6호
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• pp.1113-1118
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• 2008

$CuFe_2O_4$와 $Fe_3O_4$의 탄소 침적 및 환원 특성을 $900^{\circ}C$에서 TGA, XRD, SEM, TEM 등의 분석 및 반응 후 가스조성분석을 통하여 연구하였다. XRD 분석결과 환원된 $Fe_3O_4$는 Fe(iron)와 graphite(C) 그리고 $Fe_3C$으로 구성되어 있는 것으로 나타났다. 반면에, 환원된 $CuFe_2O_4$에서는 graphite나 $Fe_3C$가 나타나지 않았다. SEM을 이용하여 표면 구조를 관찰한 결과 환원된 $Fe_3O_4$의 표면이 탄소로 뒤덮여 있는 것을 확인할 수 있었다. 이와 달리 $CuFe_2O_4$에서는 $CH_4$ 전환율 및 환원속도가 높았고, 환원반응 후 탄소량 추정결과 $Fe_3O_4$에서보다 훨씬 낮게 나타났다. TEM 분석결과 $Fe_3O_4$ 입자로부터 탄소가 판상구조의 형태로 성장한 것을 확인할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.89-92
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• 2007

Partail oxidation(POX) of n-butane was investigated in this research by employing ceria-promoted Ni/calcium hydroxyapatite catalysts ($Ce_xNi_{2.5}Ca_{10}(OH)_2(PO_4)_6$ ; x = $0.1{\sim}0.3$) which had recently been reported to exhibit good catalytic performance in POX of methane and propane. The experiments were carried out with changing ceria content, $O_2/n-C_4H_{10}$ ratio and temperature. As the $O_2/n-C_4H_{10}$ feed ratio increased up to 2.75, n-$C_4H_{10}$ conversion and $H_2$ yield increased and the selectivity of methane and other hydrocarbons decreased. But with $O_2/n-C_4H_{10}$ = 3.0, $n-C_4H_{10}$ conversion and $H_2$ yield decreased. This is considered due to that too much oxygen may inhibit the reduction of Ni or induce the oxidation of Ni, which results in poor catalytic activity. The optimum $O_2/n-C_4H_{10}$ ratio lay between 2.50 and 2.75. $Ce_{0.1}Ni_{2.5}Ca_{10}(OH)_2(PO_4)_6$ showed the highest $n-C_4H_{10}$ conversion and $H-2$ yield on the whole. In durability tests, higher hydrogen yield and better catalyst stability were obtained with the $O_2/n-C_4H_{10}$ ratio of 2.75 than with the ratio of 2.5.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.346-352
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• 2012

The properties of methane oxidation were studied in this research over transition metal containing $CeO_2$ (TM/$CeO_2$, TM=Ni, Co, Cu, Fe) with TM content of 5 wt. % at atmospheric pressure. The characteristics of catalysts were investigated by various characterization techniques, including XRD, GC, SEM and EPMA analyses. The catalytic tests were carried out in a fixed Rmix ratio of 1.5 ($CH_4/O_2$) in a fixed-bed reactor operating isothermally at atmospheric pressure. Only the Ni/$CeO_2$ catalysts showed syngas production above $400^{\circ}C$ via typical partial oxidation reaction whereas other catalysts induced complete oxidation resulting in the production of $CO_2$ and $H_2O$ in whole reaction temperature range. From the quantitative analysis on carbon deposition after catalytic tests, Cu/$CeO_2$ was found to show the highest resistance on carbon deposition. Therefore Cu can be proposed as an efficient catalyst element which can be combined with a conventional Ni-based SOFC anode to enhance the carbon tolerance.

• 한국응용과학기술학회지
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• 제21권3호
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• pp.225-230
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• 2004

Synthesis gas is a high valued compound as a basic chemicals at various chemical processes. Synthesis gas is mainly produced commercially by a steam reforming process. However, the process is highly endothermic so that the process is very energy-consuming process. Thus, this study was carried out to produce synthesis gas by the partial oxidation of methane to decrease the energy cost. The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst in a fluidized bed reactor. With the fluidized bed reactor, $CH_4$ conversion was 91%, and Hz and CO selectivities were both 98% at 850$^{\circ}C$ and total flow rate of 100 mL/min. These values were higher than those of fixed bed reactor. From this result, we found that with the use of the fluidized bed reactor it was possible to avoid the disadvantage of fixed bed reactor (explosion) and increase the productivity of synthesis gas.

• 한국응용과학기술학회지
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• 제20권4호
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• pp.289-295
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• 2003

Synthesis gas is produced commercially by a steam reforming process. However, the process is highly endothermic and energy intensive. Thus, this study was conducted to produce synthesis gas by the partial oxidation of methane to cut down the energy cost. Supported Ni catalysts were prepared by the impregnation method. To examine the activity of the catalysts, a differential fixed bed reactor was used, and the reaction was carried out at $750{\sim}850^{\circ}C$ and 1 atm. The fresh and used catalysts were characterized by XRD, XPS, TGA and AAS. The highest catalytic activity was obtained with the 13wt% Ni/MgO catalyst, with which methane conversion was 81%, and $H_2$ and CO selectivities were 94% and 93%, respectively. 13wt% Ni/MgO catalyst showed the best $MgNiO_2$ solid solution state, which can explain the highest catalytic activity of the 13wt% Ni/MgO catalyst.

• Korean Chemical Engineering Research
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• 제51권3호
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• pp.319-324
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• 2013

합성가스를 생산하기 위한 메탄의 부분산화반응 특성을 $Ni/CeO_2-ZrO_2$, $Ni-Ru/CeO_2-ZrO_2$와 $Ni-Pd/CeO_2-ZrO_2$ 촉매체를 이용하여 조사하였다. 메탄의 부분 산화 개질 반응에서 촉매의 높은 활성과 안정성을 위하여 허니컴 구조의 금속모노리스 촉매 체를 적용하였다. 촉매분석은 XRD와 FE-SEM을 사용하였으며, 제조된 촉매들의 합성가스 제조 특성은 반응물 비(O/C), GHSV와 온도를 변화시키면서 연구하였다. 개질 실험에서 사용된 촉매 중에서 $Ni-Pd/CeO_2-ZrO_2$ 촉매 체가 가장 높은 활성을 보여 주었으며, $900^{\circ}C$, GHSV=10,000 $h^{-1}$과 O/C=0.55에서 99%의 메탄 전환율을 얻었다. O/C 비가 증가함에 따라 수소 yield는 증가되고, 반면에 CO yield는 거의 일정하게 유지됨을 확인할 수 있었다. 또한 GHSV가 증가할수록 메탄의 전환율은 감소하였으며, 높은 메탄의 전환율을 얻을 수 있는 GHSV의 범위는 10,000 $h^{-1}$ 이하임을 알 수 있었다.

• 공업화학
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• 제32권4호
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• pp.478-482
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• 2021

고정층 상압 유통식 반응기를 사용하여 Ln(1)-Ni(5)/SBA-15 (Ln = Dy, Eu, Pr, Tb) 촉매상에서 메탄의 부분 산화 반응을 수행하여 수소의 수율을 조사하였다. X-ray photoelectron spectroscopy (XPS) 분석으로 Ni(5)/SBA-15 촉매에 1 wt%의 Eu를 첨가함으로써 Eu(1)-Ni(5)/SBA-15의 O1s와 Si2p의 핵심 전자 수준의 화학적 이동이 있었으며, O1s, Ni2p_3/2, Si2p의 원자의 비가 1.284, 1.298, 1.058로 증가하였다. 촉매 표면상에 O^-, O^2-의 산소와 Eu³⁺, Ni⁰, Ni²⁺, Si⁴⁺의 이온이 존재함을 알 수 있었다. Eu(1)-Ni(5)/SBA-15 촉매상에서 수소의 수율은 57.2%이었으며, Ln(1)-Ni(5)/SBA-15 (Ln = Dy, Pr, Tb)보다 우수한 수소 수율을 보여주었고 25 h의 반응에서 안정된 촉매 활성을 유지하였다. Eu를 Ni(5)/SBA-15에 1wt%를 첨가함으로서 금속과 담체 간에 강한 상호 작용에 의한 SMSI 효과로 산소 빈자리를 만들고 촉매 표면상에 Ni⁰, N²⁺의 나노입자의 분산을 증가시켜 촉매 활성을 유지시켰다.

• 에너지공학
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• 제20권3호
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• pp.252-258
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• 2011

Nickel fiber mat was investigated as a potential structured catalyst for steam reforming of biogas in the temperature range of $600-700^{\circ}C$. The activity of as-received catalyst was very low owing to the smooth surface of fibers. Pretreatment of the catalyst by oxidation followed by reduction under methane partial oxidation condition significantly improved the catalytic activity, although degradation of the activity was found during the reaction due to oxidation and sintering. This deactivation was retarded by supplying additional hydrogen in the inlet gases or by coating $CeO_2$ over the catalyst surfaces.

• 공업화학
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• 제28권6호
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• pp.720-725
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• 2017

메탄의 부분 산화반응으로부터 합성가스를 제조하기 위해 M(10)-Ni(5)/SBA-15(M=Ce, Nd, Sm)를 제조하였다. 촉매는 BET, TEM, XPS의 기기를 사용하여 특성화하였다. M(10)-Ni(5)/SBA-15(M=Ce, Nd, Sm)의 BET 비표면적, 평균 기공 크기는 각각 538.8, 504.3, $447.3m^2/g$과 6.4, 6.8, 7.1 nm이었다. SBA-15 담체의 TEM 이미지는 중기공성 육방정계 구조를 보여주었고, Ce(10)-Ni(5)/SBA-15 촉매는 Ni와 Ce의 금속 입자가 SBA-15 담체의 구속효과에 의해서 담체 표면상에 균일하게 분포하고 있었다. XPS 분석으로 촉매 표면상에 격자산소($O^{2-}$, $O^-$)와 $Ce^{4+}$과 $Ce^{3+}$의 두개의 산화상태가 존재함을 알 수 있었다. 촉매상에서 메탄의 부분 산화 반응으로부터 합성가스의 수율은 1 atm, 973 K, $CH_4/O_2=2$, $GHSV=1.08{\times}10^5mL/g_{cat.}{\cdot}h$에서 52.9% $H_2$와 21.7% CO이었으며, 75 h의 반응에서도 이 값을 일정하게 유지하였다. M(10)-Ni(5)/SBA-15(M=Ce, Nd, Sm)촉매는 합성가스 수율이 같은 경향을 보여주었다. 이러한 결과는 조촉매인 Ce, Nd, Sm의 Redox 반응이 촉매의 수율과 안정성을 향상시킨다는 것을 보여주었다.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1998년도 추계학술발표회 논문집
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• pp.271-276
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• 1998