• Title, Summary, Keyword: 은 담지 알루미나

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Partial Oxidation of Methane in Palladium-silver Alloy Membrane Reactor (팔라듐-은 막반응기를 이용한 메탄의 부분산화반응)

  • Choi, Tae-Ho;Kim, Kwang-Je;Moon, Sang-Jin;Suh, Jung-Chul;Baek, Young-Soon
    • Applied Chemistry for Engineering
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    • v.16 no.5
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    • pp.641-647
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    • 2005
  • The partial oxidation of methane is one of important processes for hydrogen production. As a membrane reactor, palladium-silver (Pd-Ag) alloy membrane prepared by electroless plating technique was employed for partial oxidation of methane. The experimental variables were reaction temperature, $O_2/CH_4$ mole ratio, $CH_4$ feed rate, and $N_2$ sweep gas flow rate. The methane conversions increased with the reaction temperatures in the range of 350 to $730^{\circ}C$. The highest methane conversion and CO selectivity were obtained at the condition of $O_2/CH_4$ mole ratio of 0.5 and $730^{\circ}C$ using commercially available nickel/alumina catalyst. The Pd-Ag membrane reactor showed higher methane conversions, 10~40% higher, compared to those in a traditional reactor.

Simultaneous Application of Platinum-Supported Alumina Catalyst and Ozone Oxidant for Low-temperature Oxidation of Soot (백금담지 알루미나 촉매와 오존 산화제 동시 적용에 의한 탄소 입자상 물질의 저온 산화반응)

  • Lee, Jin Soo;Lee, Dae-Won
    • Korean Chemical Engineering Research
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    • v.56 no.5
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    • pp.752-760
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    • 2018
  • The lowering of temperature for combustion of diesel particulate matters (or diesel soot) is one of the important tasks in automotive industry that is searching for a way to meet up "high-fuel efficiency, low-emission" standard. In this study, it was discussed how the use of ozone over platinum-based catalyst promotes a low-temperature soot oxidation occurred at $150^{\circ}C$. The use of platinum catalyst did not increase oxidation rate largely but was very effective in improving the selectivity of carbon dioxide. The pre-oxidation of NO into $NO_2$ using ozone was rather crucial in improving the oxidation rate of soot at $150^{\circ}C$.

Kinetics of Hydrogen Rich Ethanol as Reductant for HC-SCR over $Al_2O_3$ Supported Ag Catalyst (Ag/$Al_2O_3$ 촉매하의 HC-SCR에서 수소 풍부 에탄올의 반응 특성)

  • Lee, Ju-Heon;Park, Jeong-Whan;Kim, Seong-Soo;Yoo, Seung-Joon;Kim, Jin-Gul
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.6
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    • pp.519-525
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    • 2010
  • Ethanol was used as reductant to remove $NO_x$ over Ag/$Al_2O_3$ catalyst via SCR from stationary emission source. Among the tested hydrocarbon reductants, ethanol showed highest de-$NO_x$ performance over the Ag/$Al_2O_3$ catalyst. De-$NO_x$ efficiency of about 83% was obtained in the condition of GHSV 20,000 $hr^{-1}$, $NO_x$ 200 ppm, CO 200 ppm, $O_2$ 13%, $H_2O$ 5% and mole ratio of ethanol/$NO_x$ = 2 between temperature of $300^{\circ}C$ and $400^{\circ}C$. While $SO_2$ presence in the $NO_x$ exhaust suppressed the catalytic activity, catalyst with acid (0.7% $H_2SO_4$) treatment of catalyst showed higher catalytic activity, where In-Situ DRIFT showed S presence over catalyst surface was increased after acid treatment of catalyst. From in-situ DRIFT and SCR results, it was concluded that sulfur presence over the surface of Ag/$Al_2O_3$ catalyst was the dominant factor to control the de-$NO_x$ reaction yield via HC-SCR from the exhausted gas including $SO_2$.

Ammonia Conversion in the Presence of Precious Metal Catalysts (귀금속촉매하에서 암모니아의 전환반응)

  • Jang, Hyun Tae;Park, YoonKook;Ko, Yong Sig
    • Korean Chemical Engineering Research
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    • v.46 no.4
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    • pp.806-812
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    • 2008
  • The ammonia decomposition reaction has been of increasing interest as a means of treating ammonia in flue gas in the presence of precious metal catalyst. Various catalysts, $Pt-Rh/Al_2O_3$, $Pt-Rh/TiO_2$, $Pt-Rh/ZrO_2$, $Pt-Pd/Al_2O_3$, $Pd-Rh/Al_2O_3$, $Pd-Rh/TiO_2$, $Pd-Rh/ZrO_2$, $Pt-Pd-Rh/Al_2O_3$, $Pd/Ga-Al_2O_3$, $Rh/Ga-Al_2O_3$, and Ru/Ga-$Al_2O_3$, were synthesized by using excess wet impregnation method. Using a homemade 1/4" reactor at $10,000{\sim}50,000hr^{-1}$ of space velocity in the presence of precious metal catalyst ammonia decomposition reactions were carried out to investigate the catalyst activity. The inlet ammonia concentration was maintained at 2,000 ppm, with an air balance. Both $T_{50}$ and $T_{90}$, defined as the temperatures where 50% and 90% of ammonia, respectively, are converted, decreased significantly when alumina-supported catalysts were applied. In terms of catalytic performance on the ammonia conversion in the presence of hydrogen sulfide, $Pt-Rh/Al_2O_3$ catalyst showed no effect on the poisoning caused by hydrogen sulfide. These results indicate that platinum-rhodium bimetallic catalyst is a useful catalyst for ammonia decomposition.