• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1265-1272
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• 2007

A solid acid catalyst, NiSO4/CeO2-ZrO2 was prepared simply by promoting ZrO2 with CeO2 and supporting nickel sulfate on CeO2-ZrO2. The support of NiSO4 on ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperatures because of the interaction between NiSO4 and ZrO2. The surface area of 10-NiSO4/1-CeO2-ZrO2 promoted with CeO2 and calcined at 600 oC was very high (83 m2/g) compared to that of unpromoted 10-NiSO4/ZrO2 (45 m2/g). This high surface area of 10-NiSO4/1-CeO2-ZrO2 was due to the promoting effect of CeO2 which makes zirconia a stable tetragonal phase as confirmed by XRD. The role of CeO2 was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity of the sample, and high thermal stability of the surface sulfate species. 10-NiSO4/1- CeO2-ZrO2 containing 1 mol% CeO2 and 10 wt% NiSO4, and calcined at 600 oC exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation.

• Bulletin of the Korean Chemical Society
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• 제27권12호
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• pp.1989-1996
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• 2006

The $NiSO_4/CeO_2-ZrO_2 $catalysts containing different nickel sulfate and $CeO_2$ contents were prepared by the impregnation method, where support, $CeO_2-ZrO_2$was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and cerium nitrate solution followed by adding an aqueous ammonia solution. No diffraction line of nickel sulfate was observed up to 20 wt %, indicating good dispersion of nickel sulfate on the surface of $CeO_2-ZrO_2$. The addition of nickel sulfate (or $CeO_2$) to $ZrO_2$ shifted the phase transition of $ZrO_2$ from amorphous to tetragonal to higher temperatures because of the interaction between nickel sulfate (or $CeO_2$) and $ZrO_2$. A catalyst (10-$NiSO_4/1-CeO_2-ZrO_2$) containing 10 wt % $NiSO_4$ and 1 mole % $CeO_2$, and calcined at $600{^{\circ}C}$ exhibited a maximum catalytic activity for ethylene dimerization. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The role of $CeO_2$was to form a thermally stable solid solution with zirconia and consequently to give high surface area, thermal stability and acidity of the sample.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.470-472
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• 2010

• 한국전기전자재료학회논문지
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• 제14권2호
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• pp.152-157
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• 2001

For the fabrication of YBa$_2$Cu$_3$O$_{x}$ thick film using diffusion process between $Y_3$BaCuO$_{5}$ and BaO+CuO, each material was selected as substrate and doping material. In this paper, we investigated the characteristic of YBa$_2$Cu$_3$O$_{x}$ thick film due to both addition of CeO$_2$into substrate and initial particle size of doping material. Through X-ray diffraction patterns and SEM photographs, the variation of composition and thickness of the formed phase was observed. It was from the experiment obtained that the addition of CeO$_2$into $Y_2$BaCuO$_{5}$ substrate and the initial particle size of doping material play important part in promoting the reaction between substrate and doping material.aterial.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.145-145
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• 2000

M-CeO2 (M : noble metal) catalysts have been widely studied as three-way catalysts and methanol synthesis catalysts. Ceria is thought to play a number of roles in these catalysts. The Ce(IV)/Ce(III) redox pair may store/release gases under oxidizing/reducing conditions, extending the operational window. Additionally, metal-ceria interactions lead to several effects, including the dispersion of the active components and promoting the activation of molecules such as CO or NO. Pd is a promising component to current TWC formulations and behaves particularly well when compared with Pt and Rh-based catalysts for low-temperature oxidation of Co and hydrocarbon. However the effect of Pd-ceria interactions on the physicochemical properties of Pd and the redox properties of Ce is not elucidated yet. In order to know exactly about the metal-ceria interactions, the model study are expecting to give a better environment, resulting in the wide use of the surface science tools. The substrate was Si(100) wafer, on which Ta metal was sputtered as a thickness of 100nm. The CeO2 thin film of 30nm was deposited by using the magnetron sputtering. Spin coating and magnetron sputtering methods were used to make the Pd thin film layer. The prepared sample was investigated by in-situ XPS, AES, SEM and AFM analysis.

• 청정기술
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• 제21권3호
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• pp.153-163
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• 2015

Fe/제올라이트 촉매의 저온에서의 NO의 암모니아 선택적 촉매환원반응 활성에 미치는 반응가스 중의 수분과 SO₂의 영향을 조사하였다. Fe/제올라이트 촉매에 조촉매로 Mn, Zr과 Ce를 첨가한 Fe/제올라이트 촉매로 수분과 SO₂가 포함된 저온에서의 NO의 암모니아 선택적 촉매환원반응에서 조촉매 첨가효과를 조사하였다. 조촉매는 이온교환법으로 철을 담지시킨 Fe/제올라이트 촉매에 건식 함침법으로 첨가하였다. 제올라이트는 디젤엔진에서의 SCR기술의 적용을 위하여 NH₄-BEA와 NH₄-ZSM-5을 사용하였다. 촉매의 특성은 BET, XRD, SEM/EDS와 TEM/EDS를 사용하여 조사하였다. 반응가스 중에 5% H₂O와 100 ppm SO₂이 존재하는 경우 Fe/BEA 촉매의 NO 전환율은 200 ℃에서 77%에서 47%로 감소하였다. MnFe/BEA 촉매는 수분과 SO₂가 존재하는 경우에 200 ℃에서 53% 이상의 NO 전환율을 나타내며 Fe/BEA 촉매보다 우수한 반응활성을 보였다. Mn은 Fe 성분의 분산도를 증가시키고 Fe의 소중합체 형성을 방지하는 효과를 나타내었다. 첨가제는 Mn이 Zr과 Ce보다 우수한 특성을 나타내었다. 250 ℃ 이하의 온도에서 Fe/BEA 촉매가 Fe/ZSM-5 촉매보다 우수한 반응특성을 나타내었다.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.633-638
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• 2011

Mn이 치환된 헥사알루미네이트 촉매인 $LaMnAl_{11}O_{19}$, $BaMnAl_{11}O_{19}$, $SrMnAl_{11}O_{19}$을 $(NH_4)_2CO_3$ 공침법을 이용하여, $1,200^{\circ}C$ 5시간 소성을 통해 제조하였다. X-선 회절, 질소흡착을 통해 촉매의 결정구조와 비표면적을 분석한 결과, 결정 격자 내 거울면에 La이 존재하는 $LaMnAl_{11}O_{19}$이 $BaMnAl_{11}O_{19}$과 $SrMnAl_{11}O_{19}$보다 우수한 헥사알루미네이트 결정 구조를 가지는 동시에 13 $m^2/g$의 높은 비표면적을 가지고 있었다. 또한 SEM 분석을 통해 $LaMnAl_{11}O_{19}$이 특유의 판상구조가 잘 발달함을 확인하였다. 메탄 연소 활성은 다음과 같은 차례로 증가하였고: $LaMnAl_{11}O_{19}$ > $SrMnAl_{11}O_{19}$ > $BaMnAl_{11}O_{19}$. 메탄 연소 활성은 비표면적에 의존하였다. $LaMnAl_{11}O_{19}$에 60 wt%의 $CeO_2$를 첨가하고 $700^{\circ}C$의 저온에서 소성한 경우 $700^{\circ}C$의 저온에서 100% 전환율에 도달함으로써 ceria 첨가에 의한 메탄 연소 개선 효과를 확인할 수 있었으며, 이 촉매가 저온 및 중온 영역의 메탄 연소 촉매로 활용될 수 있음을 확인하였다. 그러나, 이 촉매의 경우 $1,200^{\circ}C$의 고온에서 5시간 소성한 후에는 ceria입자 크기의 증가로 인해 메탄의 연소 활성 개선 효과를 잃게됨으로 고온용 연소 촉매로서의 사용은 한계가 있음을 확인하였다.