• Clean Technology
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• v.19 no.1
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• pp.65-72
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• 2013

In this study, we investigated the activity of Pd and Cu co-incorporated on mesoporous silica support such as MCM-41 and SBA-15 for catalytic nitrate reduction in water. In pure hydrogen flow, nitrate concentration was gradually decreased with the reaction time, but nitrogen selectivity was too low due to very high pH of reaction medium after the reaction. In order to acquire high nitrogen selectivity, we utilized carbon dioxide as a pH buffer, which resulted in higher nitrogen selectivity (about 40%). For the above reaction conditions, Pd-Cu/MCM-41 showed better performance than Pd-Cu/SBA-15. The physicochemical properties of both catalysts were investigated to figure out the relationship between the characteristics of the catalysts and the catalytic activity on the catalytic nitrate reduction by $N_2$ adsoprtion-desorption, X-ray diffraction (XRD), $H_2$-temperature programmed reduction, X-ray photoelectron spectroscopy (XPS) techniques.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.328-332
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• 2010

In this study, porous ZnO sphere and Cu-ZnO composite were synthesized by coprecipitation method in diethylene glycol solvent. The physicochemical properties of as-prepared composite materials were characterized by SEM, XRD, $N_2$-sorption and $H_2$-TPR. A series of porous Cu-ZnO with different Cu contents (0, 6.6, 21.3, 36.4, 54.6, 77.8 wt%) was investigated for CO oxidation activity in a fixed bed reactor system. With increasing Cu content in Cu-ZnO the surface area and micropore volume of Cu-ZnO are decreased and Cu (36.4 wt%)-ZnO shows higher activity for CO oxidation compared to the others.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.49-57
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• 2005

[ $MO/Al_2O_3-ZrO_2$ ](M=Ni and Cu) mixed metal oxides were prepared using sol-gel method in order to investigate the applicability to the 2-step thermo-chemical water splitting process and their redox behaviors were studied by temperature programmed reaction(TPR) from room temperature to 900$^{\circ}C$ under 5% $H_2$/Ar for the reduction and $H_2O$/Ar for the oxidation, respectively. From the results, peaks of the reduction and the oxidation on temperature were shifted with the change of crystalline phases due to the addition of $Al_2O_3$ and $ZrO_2$. The intensities of the peaks were also increased with the increase of contents of NiO or CuO that could be considered as active species. In addition, based on the observation of SEM images before and after the redox test, it seemed that $Al_2O_3-ZrO_2$ added prevented high temperature sintering of active metal components such as Ni (or Cu) on the surface and played a role of dispersing the active species homogeneously in solid solution of mixed oxides.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.228.1-228.1
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• 2010

선택적 CO 산화반응(PrOx)을 위한 Ru이 고분산 담지된 $Ru/{\alpha}-Al_2O_3$ 촉매를 증착-침전법(deposition-precipitation)으로 제조하였다. 용액의 pH와 aging 시간에 따른 Ru 입자의 크기 변화와 분산도의 영향을 살펴보았으며 함침법(impregnation)으로 비교 촉매를 제조하였다. 촉매의 특성분석은 BET, TPR, CO-Chemisorption분석을 수행하여 촉매의 비표면적, 환원특성, 분산도를 알 수 있었다. 특성분석결과, 증착-침전법으로 제조한 $Ru/{\alpha}-Al_2O_3$ 촉매가 함침법으로 제조한 촉매에 비해 분산도가 높았으며, pH별 촉매 제조에서는 pH6.5로 제조한 촉매가 22.06%로 가장 높은 분산도를 보였다. 또한, 담체의 비표면적 영향에 따른 Ru 입자의 분산도를 살펴보기 위해 ${\gamma}-Al_2O_3$와 ${\alpha}-Al_2O_3$ 담체를 적용한 결과, 비표면적이 작은 ${\alpha}-Al_2O_3$ 담체 표면에서 Ru 분산도가 ${\gamma}-Al_2O_3$ 담체에 비해 높았다. 이는 기공이 발달하여 비표면적이 넓은 ${\gamma}-Al_2O_3$ 담체는 소량의 Ru을 고분산 담지 시 담체 표면보다는 기공 내에 담지 되는 양이 많아 실제 반응 시 반응에 참여하는 표면 활성 금속양이 적음을 알 수 있다. 특히, 선택적 산화반응과 같이 표면에서 빠른 반응이 일어나는 경우, 기공 내부의 활성금속이 반응에 참여하기 어려워 반응 활성이 낮음을 PrOx 반응실험을 통해 확인할 수 있었다. PrOx test 조건은 GHSV 250000~60000, 온도는 80~200도, 람다값은 2~4로 성능 비교하여 실험 하였다. PrOx의 성능평가 결과 담체를 ${\alpha}-Al_2O_3$를 사용하여 deposition-precipitation방법으로 제조한 pH6.5 촉매에서 $100{\sim}160^{\circ}C$에서 90%의 가장 높은 CO conversion을 가지고 18%의 선택도를 가졌다.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2365-2378
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• 2018

We investigated the correlation between vanadium surface density and VOx structure species in the selective catalytic reduction of NOx by $NH_3$. The properties of the $VOx/TiO_2$ catalysts were investigated using physicochemical measurements, including BET, XRD, Raman spectroscopy, FE-TEM, UV-visible DRS, $NH_3-TPD$, $H_2-TPR$, $O_2-On/Off$. Catalysts were prepared using the wet impregnation method by supporting 1.0-3.0 wt% vanadium on $TiO_2$ thermally treated at various calcination temperatures. Through the above analysis, we found that VOx surface density was $3.4VOx/nm^2$, and the optimal V loading amounts were 2.0-2.5 wt% and the specific surface area was $65-80m^2/g$. In addition, it was confirmed that the optimal VOx surface density and formation of vanadium structure species correlated with the reaction activity depending on the V loading amounts and the specific surface area size.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.527-527
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• 2009

1세대 바이오디젤인 fatty acid methyl ester(FAME)의 문제점을 극복하기 위하여 많은 연구가 진행 중 이다. 소위 차세대 바이오디젤은 triglyceride의 산소 화합물을 제거하여 정유 공정을 통해 생산된 디젤과 동일한 특성을 지닌 탄화수소로 전환시킨 오일이다. 이를 위하여 수소를 첨가하여 산소를 제거 시키는 Hydrodeoxygenation(HDO) 반응이 필요하다. 고온($300-400^{\circ}C$), 고압(50-100 bar)의 혹독한 조건에서 높은 수율과 안정성을 보이는 촉매 개발이 필요하다. 이를 위하여 반응물중의 산소를 효과적으로 제거하기 위하여 산소 전달능이 뛰어난 $CeO_2$ 담체에 열안정성을 높이는 $ZrO_2$를 조합한 $Ce-ZrO_2$ 담체를 선정하였으며 수소첨가 탈산소 반응에 활성을 나타낼 것으로 예상되는 니켈을 활성성분으로 선정하였다. 본 연구에서는 15%Ni-$Ce_{(1-x)}Zr_{(x)}O_2$ ($0{\leq}x{\leq}1$)촉매를 공침법(co-precipitation)으로 제조하였으며 $500^{\circ}C$에서 소성하였다. 촉매 특성분석은 XRD, BET, H2-TPR을 이용하였다.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.1
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• pp.10-17
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• 2008

This study has been focused on the partial oxidation(POX) of n-octane over Rh-containing catalysts supported on alumina. The catalysts for this reaction were prepared by incipient wetness(IW) and co-gel(CG) methods, followed by the calcination at $900{\circ}C$ or $1,200{\circ}C$. When applied to the POX of n-octane carried out at $600{\circ}C$ with C/O=3 and GHSV=3,450/h, the catalyst prepared by the CG method and calcined at $1,200{\circ}C$ showed the best activity, yielding 42% syngas($H_2$+CO) with the $H_2$/CO ratio of $2{\sim}2.4$. To enhance the activity and stability of catalysts, bimetallic catalysts were synthesized by the CG method. As a result, the performance of Rh-Ni/$Al_2O_3$ catalyst was superior to that of Rh/$Al_2O_3$ catalyst in terms of the catalyst stability, due to the retarding effect on the Rh-to-$Rh_2O_3$ transition by the addition of Ni. This result was confirmed by XRD, TEM, and TPR characterizations.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.715-719
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• 2011

The $La_{0.7}Sr_{0.3}Cr_{1-x}Ni_{x}O_{3}$(LSCN-x) perovskites were prepared by citric acid and EDTA using a sol-gel method. The LSCN-x was characterized by BET, XRD, SEM, $H_2$-TPR, EA and TEM. The catalytic performance of LSCN-x catalysts in steam reforming of propane in the temperature range 600~$800^{\circ}C$ was investigated. Propane conversion and hydrogen yield increased with an increase in the amount of added Ni up to x=0.5 in the B-site, denoted as LSCN-0.5, under S/C=1 and S/C=1.7 reaction conditions. The LSCN-0.5 catalyst exhibited the best performance under Ni-substitution of which propane conversion and hydrogen yield was 100%, 95.9% at $800^{\circ}C$ in the S/C=1.7 condition, respectively. The morphology of carbon deposited on the catalysts after reaction exhibited filamentous carbon and amount of carbon deposited on the catalysts after reaction increased with an increase in the amount of added Ni.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.555-561
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• 2011

The objective of this study is the development of carbon recycle technology which converts $CO_2$ captured from flue gas to CO or carbon and reuse in industrial fields. Since $CO_2$ is very stable and difficult to decompose, metal oxide was used as an activation agent for the decomposition of $CO_2$ at low temperature. Metal oxides which convert $CO_2$ to CO or carbon at $500^{\circ}C$ were prepared using Zn-ferrite by the solid state reaction and hydrothermal synthesis. The behaviors of $CO_2$ decomposition were studied using temperature programmed reduction/oxidation (TPR/TPO) and thermogravimetric analyzer (TGA). Zn-ferrite containing 5 wt% ZnO showed the largest reduction and oxidation. Reduction by $H_2$ was 26.53 wt%, oxidation by $CO_2$ was 25.73 wt% and 96.98% of adsorbed $CO_2$ was decomposed to $CO_2$ and carbon with excellent oxidation-reduction behaviors.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.616-624
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• 2011

Hydrogen storage and release of Fe/Zr/Mo mixed oxide mediums were investigated by hydrogen reduction and water splitting oxidation($Fe_3O_4+4H_2{\rightleftharpoons}3Fe+4H_2O$). As the results of TPR/O, Mo was an additive to enhance the reactivity of water splitting oxidation as well as the stability of the medium. On the other hand, it seemed that $ZrO_2$ additive provided the passway for the diffusion of gaseous chemicals on the medium in repeated redox cycles. Among the Fe/Zr/Mo mediums, a FeZrMo-7 medium (Fe/Zr/Mo=80/13/7mol%) exhibited the best performance with good durability during five repeated redox cycles. The amount of hydrogen evolved on the medium was maintained at ca. 10.7mmol-$H_2$/g-medium corresponding to the hydrogen storage amount of ca. 2.2wt%.