• Title, Summary, Keyword: alumina ceramic bead

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Preparation of High-capacity Ceramic Catalytic Support from Gibbsite (깁사이트를 이용한 고기능 세라믹 촉매담체의 제조)

  • Park, Byung-Ki;Suh, Jeong-Kwon;Lee, Jung-Min;Suhr, Dong-Soo
    • Journal of the Korean Ceramic Society
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    • v.39 no.3
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    • pp.245-251
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    • 2002
  • We prepared γ-alumina beads using the amorphous alumina, obtained by fast calcination of gibbsite, and its were immersed in aqueous solution of the mixture of 21.87% nitric acid and 28.57% acetic acid. The beads thus were hydrothermaly treated at 200$^{\circ}$C for 3h, and were investigated changes of crystal, pore characteristics, $N_2$ adsorption and desorption isotherms, mechanical strengths and thermal resistance. Acicular platelet crystals of 0.1∼0.3${\mu}$m were transformed into acicular boehmite crystals of 1∼2${\mu}$m having the same crystal structure. Through this changes, we found that reversible phase transformation due to hydrothermal reaction took placed between boehmite and ${\gamma}$-alumina. In comparison to the ${\gamma}$-alumina bead before hydrothermal treatment, $N_2$ adsorption capacity was increased from 450㎖/g to 670㎖/g, and pore volume between 100${\AA}$ and 1000${\AA}$ was increased form 0.15㎖/g to 0.77㎖g, and mechanical strength was increased form 1.4MPa to 2.2MPa. Also, it showed the remarkable thermal resistance which sustained ${\theta}$-alumina crystal structure and pores between 100${\AA}$ and 1000${\AA}$ at 1000$^{\circ}$C in 40vol% steam.

De-NOx Characteristics for Cu-ZSM5/Alumina Beads Catalyst Filter in Urea-SCR System (Urea-SCR 시스템에서의 Cu-ZSM5/알루미나 비드 촉매필터의 De-NOx 특성)

  • Jang, Young-Sang;Shin, Young-Seop;Lee, Byoung-Jun;Park, Jai-Koo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.5
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    • pp.60-67
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    • 2008
  • The catalytic filter of Cu-ZSM5/alumina beads was considered to reduce NOx in the urea SCR system. Catalytic support of porous alumina beads with mean pore size $130{\mu}m$ and porosity $75{\sim}83%$ were prepared using foaming and gel-casting method. The Cu-ZSM5 catalysts were coated on the supporting alumina beads using $Cu(NO_3)_2$ by ion exchange method. After a washcoating process was applied to coat 10w% Cu-ZSM5 on porous alumina bead, coating layer was estimated $20{\mu}m$ in thickness. The characterization and the feasibility as a catalytic supports were investigated. And the NOx conversion test in Cu-ZSM5/Alumina Beads filter system was conducted by using Urea as reductants under laboratory test. The NOx conversion was increased as size and porosity of beads and observed more than 95% excellent NOx conversion above $300^{\circ}C$.

Experiments on Welding of Ceramics by Use of High Power Laser (고출력 레이저를 이용한 세라믹 재료의 용접 실험)

  • 변철웅
    • Journal of Welding and Joining
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    • v.12 no.2
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    • pp.39-48
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    • 1994
  • In comparison to the conventional brazing, laser welding of ceramics has advantages of direct bonding without filler material, which causes the thermal stress due to the differences of thermal expansion coefficients. In pulse-mode, laser welding of dispersion ceramic having high thermal resistance is possible at relatively low preheating temperature of $1300^{\circ}C$ In CW-mode, alumina can be welded at high preheating temperature $1500^{\circ}C$ under the condition of low feed rate of 500 mm/min, respectively. Further studies on developing mechanism of pores in the bead during laser welding of ceramics is required.

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Alcoholic Fermentation of Traditional Kanjang by Semi-pilot Scale Bioreactor Systems (Semi-pilot plant 규모 bioreactor를 이용한 재래식 간장의 알코올발효)

  • Kwon, Kwang-Il;Lee, Jong-Gu;Choi, Jong-Dong;Chung, Hyun-Chae;Ryu, Mun-Kyun;Im, Moo-Hyeog;Kim, Ki-Ju;Choi, Yong-Hoon;Kim, Young-Ji;Choi, Cheong;Choi, Kwang-Soo
    • Korean Journal of Food Science and Technology
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    • v.35 no.1
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    • pp.103-110
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    • 2003
  • Stable production of fermented kanjang containing 1.8% (v/v) ethanol was obtained within four days using traditional kanjang containing 4% added glucose in packed-bed bioreactor systems filled with immobilized Zygosaccharomyces rouxii and Candida versatilis on porous alumina ceramic bead carrier at $28{\pm}0.5^{\circ}C$ and aeration rate of 0.05 vvm. Specific rates of alcohol production for Z. rouxii and C. versatilis were 0.0033 and 0.0031/day, respectively, and those of glucose consumption were both -0.0087/day in the batch type of alcoholic fermentation. In semi-continuous alcoholic fermentation at a dilution rate of 0.25/day, specific rates of alcohol production for Z. rouxii and C. versatilis were 0.0045 and 0.0029/day, and those of glucose consumption were -0.01 and -0.008/day, respectively, using identical bioreactor system. Similar specific rates of alcohol production were observed both in the batch or semi-continuous process and in the continuous one at the dilution rate of 0.25/day. Sensory characteristics of all alcoholic-fermented kanjang by Z. rouxii, C. versatilis, and a mixture of both yeasts (2:1, w/w) were shown to be significantly superior to those of home-made kanjang as revealed through organoleptic evaluation tests (p<0.05).