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  • Title/Summary/Keyword: ZrO_2$

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Experimental Study of Hydrogen and Syngas Production over Ni/Ce-ZrO2/Al2O3 Catalysts with Additives (Ni/Ce-ZrO2/Al2O3 촉매의 첨가제에 따른 수소 및 합성가스 생성에 대한 실험적 연구)

  • Cho, Wonjun;Yu, Hyejin;Mo, Yonggi;Ahn, Whaseung
    • Journal of Hydrogen and New Energy
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    • v.25 no.2
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    • pp.105-113
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    • 2014
  • Performance tests on Ni/CeZrO2/Al2O3 catalysts with additives (MgO, La2O3) were investigated in the combined reforming processes (SCR, ATR, TRM) in order to produce hydrogen and carbon monoxide (it is called "syngas".). The catalyst characterization was conducted using the BET surface analyzer, X-ray diffraction (XRD), SEM, TPR and TGA. The combined reforming process was developed to adjust the syngas ratio depending on the synthetic fuel (methanol, DME and GTL) manufacturing processes. Ni-based catalysts supported on alumina has been generally recommended as a combined reforming reaction catalyst. It was found that both free NiO and complexed NiO species were responsible for the catalytic activity in the combined reforming of methane conversion, and the CeZrO2 binary support employed had improved the oxygen storage capacity and thermal stability. The additives, MgO and La2O3, also seemed to play an important role to prevent the formation of the carbon deposition over the catalysts. The experimental results were compared with the equilibrium data using a commercial simulation tool (PRO/II).

Effect of the Additives on Direct Dimethyl Carbonate Synthesis using Methanol and Carbon Dioxide over Ce0.8Zr0.2O2 Catalyst (Ce0.8Zr0.2O2 촉매 상에서 메탄올과 이산화탄소를 이용한 디메틸카보네이트 직접 합성에 대한 첨가제의 영향)

  • Han, Gi Bo;Park, No-Kuk;Yoon, Suk Hoon;Lee, Tae Jin
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.554-559
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    • 2007
  • In order to improve the reactivity for the direct synthesis of dimethyl carbonate (DMC) using methanol and carbon dioxide, the various additives were used in the DMC synthesis using Ce0.8Zr0.2O2 catalyst, and then effect of the additives was investigated. The various additives were molecular sieves 3A and the compounds having the various functional groups such as sulfate, carbonate, nitrate and phosphate. As a result, the compound such as K2SO4 and Na2SO4 having sulfate group were the most effective additive among the various additives. When K2SO4 was used as an additive in the direct synthesis of DMC, the amount of DMC was about 0.91 mmol, which was the highest mount of DMC among using only-Ce0.8Zr0.2O2 catalyst and the various additives.

Properties of the β-SiC+39vol.%ZrB2 Composites with Al2O3+Y2O3 additives (Al2O3+Y2O3를 첨가한 β-SiC+39vol.%ZrB2 복합체의 특성)

  • Shin, Yong-Deok;Ju, Jin-Young;Jin, Hong-Bum;Park, Gi-Yub;Yea, Dong-Hun
    • Proceedings of the KIEE Conference
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    • 1999.07d
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    • pp.1913-1915
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    • 1999
  • The βSiC+ZrB2 ceramic composites were hot-press sintered and annealed by adding 1, 2, 3wt% Al2O3+Y2O3(6 : 4wt%) powder as a liquid forming additives at 1950C for 4h. In this microstructures, no reactions were observed between β-SiC and ZrB2, and the relative density is over 90.79% of the theoretical density and the porosity decreased with increasing Al2O3+Y2O3 contents. Phase analysis of the composites by XRD revealed of α-SiC(6H, 4H), ZrB2, Al2O3 and β-SiC(15R). Flexural strength showed the highest of 315.46MPa for composites added with 3wt% Al2O3+Y2O3 additives at room temperature. Owing to crack deflection and crack bridging of fracture toughness mechanism, the fracture toughness showed the highest of 5.5328MPam1/2 for composites added with 2wt% Al2O3+Y2O3 additives at room temperature.

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Characterization of the Oxide Layer Formed on the Cu-Zr Based Metallic Glass during Continuous Heating

  • Lim, Ka-Ram;Kim, Won-Tae;Kim, Do-Hyang
    • Applied Microscopy
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    • v.42 no.3
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    • pp.174-178
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    • 2012
  • In the present study, the oxidation behavior of Cu50Zr50 and Cu46Zr46Al8 metallic glasses has been investigated using transmission electron microscopy with a particular attention on the oxidation behavior in the supercooled liquid state. Identification of the oxidation product after continuous heating treatment shows that in Cu50Zr50 metallic glass, ZrO2 with the monoclinic structure forms on the supercooled liquid as well as on the crystallized matrix. On the contrary, in Cu46Zr46Al8 metallic glass, ZrO2 with the tetragonal structure forms on the supercooled liquid, but that with the monoclinic structure forms on the crystallized matrix. The result indicates that the Cu50Zr50 metallic glass exhibits far better oxidation resistance in the supercooled liquid state than the Cu46Zr46Al8 metallic glass.

Optical Properties of TiO2/M/Ag/M/TiO2 Films with Different Diffusion Barrier Layers (확산방지막에 따른 TiO2/M/Ag/M/TiO2 투명 열절연 박막의 광학적 성질)

  • 이경준;이진구;박주동;김진현;김영환;오태성
    • Journal of the Korean Vacuum Society
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    • v.5 no.2
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    • pp.147-155
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    • 1996
  • Optical properties of TiO2/M/Ag/M/TiO2 films have been changed with the diffusion barrier metal M. Optimum opticla properties of TiO2/M/Ag/M/TiO2 as the transparent heat mirror film, could be obtained with Ti among diffusion barrier metals of Ti, Cu, Zr and Al. TiO2/M/Ag/M/TiO2 film, which was fabricated by sputtering of 18 nm-thick TiO2 and Ag, and 4nm-thick Ti, showed maximum transimittance of 89% at visible wavelength and infrared reflectance of 97% at wavelength of 3000 nm. Optical properties of this film was not degraded by Xenon-sunshine weather test for 240 hours. For specimens with barrier layers of Cu, Zr, and Al, degradation of optical properties by weather test was increased in a sequence of films with Cu, Zr, and Al barrier layers.

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Support Effects of Containing Catalysts on Methanol Dehydrogenation

  • Jung, Kwang-Deog;Joo, Oh-Shim
    • Bulletin of the Korean Chemical Society
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    • v.23 no.8
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    • pp.1135-1138
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    • 2002
  • CuO/ZnO, CuO/SiO,sub>2, and CuO/ZrO2 catalysts were prepared for investigating the support effects on methanol dehydrogenation. It was found that the conversion of methanol was proportional to the copper surface area on Cu/ZnO cat alysts and was independent on that on Cu/ZrO2 and Cu/SiO2. The highest copper surface area was obtained with the Cu/ZrO2 (9/1). The unusual deactivation of the Cu/ZnO, which showed the highest selectivity among the catalysts tested, was observed. Pulse reaction with methanol indicated that the lattice oxygen in ZnO could be removed by forming CO2 in the catalytic reaction, supporting that the ZnO reduction was responsible for the severe deactivation of the Cu/ZnO.

Synergistic Effect of Sulfonated Poly(Ether Ether Ketone)/Strontium Zirconate Perovskite Nanofiber-Based Novel Electrospun Composite Membranes for Fuel Cell Applications (연료전지용 술폰화된 폴리(이써 이써 케톤)/스트론튬 지르코네이트 페로브스카이트 나노섬유 기반 신규 전기방사 복합막의 시너지 효과)

  • SELVAKUMAR, KANAKARAJ;KIM, AE RHAN;YOO, DONG JIN
    • Journal of Hydrogen and New Energy
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    • v.33 no.2
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    • pp.164-175
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    • 2022
  • In this work, sulfonated poly (ether ether ketone) (SPEEK) composite membranes including strontium zirconate (SrZrO3) were fabricated by the electrospinning method. Fourier-transform infrared spectroscopic analysis and X-ray diffraction analysis were used to identify the chemical structure and the crystallinity of SrZrO3 and electrospun composite membranes. The thermal stability of the pure SPEEK and SPEEK/SrZrO3 electrospun composite membranes were investigated by using thermogravimetric analysis. The physicochemical properties and proton conductivity were enhanced with the addition of different weight ratio of SrZrO3 nanofiller (2, 4 and 6 wt%) in SPEEK polymer. The optimized SPEEK/SrZrO3-4 electrospun membrane containing 4 wt% of SrZrO3 showed a high proton conductivity compared to other electrospun SPEEK/SrZrO3 composite membranes. The results indicate that electrospun composite membranes incorporating these perovskite nanofillers should be explored as potential candidates for use in proton exchange membrane fuel cells.

A Synthesis and Characteristics for Zirconia Powders by Coprecipitation Method ; III) The Properties and Sinterabilities of ZrO2-Y2O3-Bi2O3 (공침법에 의한 지르코니아분말의 합성 및 특성 III) ZrO2-Y2O3-Bi2O3의 특성 및 소결성)

  • 윤종석;이동인;오영제;이희수
    • Journal of the Korean Ceramic Society
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    • v.26 no.5
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    • pp.655-660
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    • 1989
  • The physical properties and sinterabilities of ZrO2-Y2O3-Bi2O3 ternary system powder prepared by coprecipitation were investigated. The crystallization temperatures of ternary system were increased and the specific surface areas were decreased with increasing Bi2O3 amount as sintering agents both PSZ and FSZ. Especially, the partially stabilized zirconia showed monoclinic phase. The sinterability was increased with the amount of Bi2O3 added which caused liquid phase sintering.

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Preparation and Characterization of Chromium Oxide Supported on Zirconia

  • Sohn Jong Rack;Ryu, Sam Gon;Park Man Young;Pae Yeong Il
    • Bulletin of the Korean Chemical Society
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    • v.13 no.6
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    • pp.605-612
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    • 1992
  • Chromium oxide/zirconia catalysts were prepared by dry impregnation of powdered Zr(OH)4 with (NH4)2CrO4aqueous solution. The characterization of prepared catalysts was performed using FTIR, XPS, XRD and DTA methods, and by the measurement of surface area. The addition of chromium oxide to zirconia shifted the transitions of ZrO2 from amorphous to tetragonal phase and from tetragonal to monoclinic phase to higher temperature due to the strong interaction between chromium oxide and zirconia, and the specific surface area of catalysts increased in proportion to the chromium oxide content. Since the ZrO2 stabilizes supported chromium oxide, chromium oxide was well dispersed on the surface of zirconia, and α-Cr2O3 was observed only at the calcination temperature above 1173 K. Upon the addition of only small amount of chromium oxide (1 wt% Cr) to ZrO2, both the acidity and acid strength of catalyst increased remarkably, showing the presence of two kinds of acid sites on the surface of CrOx/ZrO4-Bronsted and Lewis.

Synthesis of Dimethyl Carbonate from Methanol and Supercritical Carbon Dioxide over K2CO3/ZrO2 Catalysts (메탄올과 초임계 이산화탄소로부터 K2CO3/ZrO2 촉매를 이용한 디메틸카보네이트 (Dimethyl Carbonate) 합성)

  • Hong, Seung Tae;Park, Hyung Sang;Lim, Jong Sung;Yoo, Ki-Pung
    • Korean Chemical Engineering Research
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    • v.46 no.3
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    • pp.550-554
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    • 2008
  • The synthesis of dimethyl carbonate (DMC) from methanol and supercritical carbon dioxide over K2CO3/ZrO2 catalysts have been studied. The catalysts were prepared by impregnating ZrO2 with an aqueous K2CO3 solution. The optimum calcination temperature to disperse K species on the ZrO2 surface was found to be 673 K. Monoclinic ZrO2 was not active, as itself, for the DMC production. However, when the K2CO3 was impregnated on the ZrO2, the catalytic performance was improved. Besides the catalyst, CH3I was used as a promoter. The CH3I promoter as well as the K2CO3/ZrO2 catalyst was found to take an important role to improve the production of DMC. The optimum quantities for the catalyst and the promoter were estimated. The effect of the catalyst and the promoter for the DMC synthesis from methanol and supercritical carbon dioxide was investigated and the reaction mechanism was proposed.