• Title/Summary/Keyword: Pt/Alumina catalyst

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Effect of Bimetallic Pt-Rh and Trimetallic Pt-Pd-Rh Catalysts for Low Temperature Catalytic Combustion of Methane

  • Bhagiyalakshmi, Margandan;Anuradha, Ramani;Park, Sang-Do;Park, Tae-Sung;Cha, Wang-Seog;Jang, Hyun-Tae
    • Bulletin of the Korean Chemical Society
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    • v.31 no.1
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    • pp.120-124
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    • 2010
  • Monometallic, bimetallic and trimetallic particles consisting of different weight compositions of Pt-Pd-Rh over pure alumina wash coats have been synthesized and their catalytic performance on methane conversion was studied from 150 to $600^{\circ}C$. Different catalyst formulations with variable Pt, Pd and Rh contents for bimetallic and trimetallic systems were tried and $Pt_{(1.5)}Rh_{(0.3)}/Al_2O_3$ and $Pt_{(1.0)}Pd_{(1.0)}Rh_{(0.3)}/Al_2O_3$ shows low $T_{50}$ and $T_{90}$ temperatures. Bimetallic and trimetallic particle synergism acts as three way catalysts and therefore, all the catalysts show 100% methane conversion. The effect of supports such as $ZrO_2$ and $TiO_2$ on methane combustion was investigated; from $T_{50}$ and $T_{90}$ results both $Al_2O_3$ and $ZrO_2$ are suitable supports for low temperature methane combustion.

Catalytic Oxidation of 1.2-Dichloroethane on Precious Metal Catalysts (귀금속 촉매를 이용한 1.2-Dichloroethane의 산화분해에 관한 연구)

  • Lee, Hae-Wan;Kim, Young-Chai;Moon, Sei-Ki
    • Applied Chemistry for Engineering
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    • v.9 no.4
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    • pp.497-503
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    • 1998
  • The catalytic oxidation of 1.2-dichloroethane was investigated over precious metal supported on alumina using a fixed bed microreactor. Among the catalysts tested, the conversion of 1.2-dichloroethane decreased in the following order : Ru > Pt > Pd $${\sim_=}$$ Rh and Pt was found to be the most active catalyst for the complete oxidation of 1.2-dichloroethane to $CO_2$. Major products containing carbon were vinyl chloride and $Co_2$ at temperature ranging from 200 to $400^{\circ}C$. The presence of vinyl chloride in products suggests that the first step in the oxidation of 1.2-dichloroethane is dehydrochlorination and the second is oxidation of vinyl chloride to $CO_2$. To investigate the effect of HCl on the activity of the complete oxidation, some experiments were conducted by adding HCl to the feed. The presence of HCl increased the conversion of 1.2-dichloroethane below $300^{\circ}C$ owing to the increase of surface acidity, but it didn't affect the conversion above $300^{\circ}C$. The reversible adsorption of HCl onto catalyst surface inhibited the complete oxidation to $CO_2$.

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Morphological change of Pt/MoO3/SiO2 for the Synthesis of i-Butylene from n-Butene (N-Butene으로부터 i-Butylene 합성을 위한 Pt/MoO3/SiO2 촉매의 표면 구조 변화)

  • Kim, Jin Gul
    • Applied Chemistry for Engineering
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    • v.7 no.5
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    • pp.861-868
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    • 1996
  • Skeletal isomerization reaction known as exothermic reaction shows possible maximum yield of i-butene from n-butene at $110^{\circ}C$ over $Pt/MoO_3/SiO_2$. Compared with conventional catalyst such as silica, zeolite, alumina etc., $Pt/MoO_3/SiO_2$ demonstrates higher yield while by-products except 2-butene do not form. Faster H spillover rate over $Pt/MoO_3/SiO_2$ is demonstrated via isothermal reduction experiment at $110^{\circ}C$ compared to the rate over $Pt/MoO_3/Al_2O_3$. Overall isomerization rates are proportional to higher spillover rates from Pt onto $MoO_3$ surface. The skeletal isomerization reaction is composed of two elementary steps. First, carbonium ion formation over Pt crystallites by H spillover. Second, carbenium ion formation over $MoO_3$ followed by formation of i-butene. Moreover, it is suggested that H spillover step from Pt surface onto $MoO_3$ is assumed to be the rate determining step and control the overall isomerization rate.

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The Response time of the Hydrogen Peroxide Monopropellant Thruster as Different Catalysts (서로 다른 촉매를 사용하는 과산화수소 추력기의 응답 속도)

  • An, Sung-Yong;Kwon, Se-Jin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.371-374
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    • 2008
  • The performance of several catalysts to decompose the high test peroxide (HTP) was described in this paper. Manganese oxide, Platinum and Iridium were coated on the gamma alumina. The response time of various catalysts was measured with a 50 Newton class thruster. Ir/$Al_2O_3$ that showed the fastest response time at the thruster, failed the reaction when continuous mode test was carried out with the thruster. Pt/$Al_2O_3$ and MnO_2/Al_2O_3$ can be substitutes to decompose the HTP. In addition, for larger thruster, MnO_2/Al_2O_3$ can be a good catalyst because its cost is below 5 % of Pt/$Al_2O_3$.

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Decomposition of Acetonitrile by Planar Type Dielectric Barrier Discharge Reactor (평판형 유전체 장벽 방전 반응기에서 Acetonitrile의 분해 특성)

  • 송영훈;김관태;류삼곤;이해완
    • Journal of the Korea Institute of Military Science and Technology
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    • v.5 no.3
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    • pp.105-112
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    • 2002
  • A combined process of non-thermal plasma and catalytic techniques has been investigated to treat toxic gas compounds in air. The treated gas in the present study is $CH_3$CN that has been known to be a simulant of toxic chemical agent. A planar type dielectric barrier discharge(DBD) reactor has been used to generate non-thermal plasma that produces various chemically active species, O, N, OH, $O_3$, ion, electrons, etc. Several different types of adsorbents and catalysts, which are MS 5A, MS 13X, Pt/alumina, are packed into the plasma reactor, and have been tested to save power consumption and to treat by-products. Various aspects of the present techniques, which are decomposition efficiencies along with the power consumption, by-product analysis, reaction pathways modified by the adsorbents and catalysts, have been discussed in the present study.

Decomposition of Acetonitrile Using a Planar Type Dielectric Barrier Discharge Reactor Packed with Adsorption and Catalyst Materials (평판형 유전체 장벽 방전 반응기에서 충진물질에 따른 아세토나이트릴의 분해 특성)

  • 김관태;송영훈;김석준
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.2
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    • pp.157-165
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    • 2003
  • A combined process of non-thermal plasma and catalytic technique has been investigated to treat $CH_3$CN gas in the atmosphere. A planar type dielectric barrier discharge (DBD) reactor has been used to generate the non-thermal plasma that produces various chemically active species, such as O, N, OH, $O_3$, ion, electrons, etc. Several different types of the beads. which are Molecular Sieve (MS) 5A, MS 13X, Pt/alumina beads, are packed into the DBD reactor, and have been tested to characterize the effects of adsorption and catalytic process on treating the $CH_3$CN gas in the DBD reactor. The test results showed that the operating power consumption and the amounts of the by-products of the non-thermal plasma process can be reduced by the assistance of the adsorption and catalytic process.

Catalytic Incineration Kinetics of Gaseous MEK and Toluene (MEK와 톨루엔의 촉매연소 속도특성)

  • 이재동
    • Journal of environmental and Sanitary engineering
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    • v.14 no.2
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    • pp.113-119
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    • 1999
  • In this study, the incineration of MEK and toluene was studied on a Pt supported alumina catalyst at temperature range from 200 to $350^{\circ}C$. An approach based on the Mars-van Krevelen rate model was used to explain the results. The object of this study was to study the kinetic behavior of the platinum catalyst for deep oxidation. The conversions of MEK and toluene were increased as the inlet concentration was decreased and the reaction temperature was increased. The maximum deep conversion of MEK and toluene were 91.81% and 55.69% at $350^{\circ}C$, respectively. The ${\kappa}_3$ constant increases with temperature faster than the ${\kappa}_1$ constant, that is, the surface concentration of ($VOCs{\cdots}O$) is higher than that of (O) at higher temperature according to the Mars-van Krevelen mechanism. Also the activation energy of toluene was larger than MEK for toluene is aromatic compound which have stronger bonding energy.Therefore, the catalytic incineration kinetics of MEK and toluene with Mars-van Krevelen mechanism could be used as the basic data for industrial processes.

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The Response Characteristics of the Hydrogen Peroxide Monopropellant Thruster as Active Materials (활성물질에 따른 과산화수소 추력기의 응답 특성)

  • An, Sung-Yong;Kwon, Se-Jin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.12 no.5
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    • pp.26-34
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    • 2008
  • The performance of several catalysts to decompose the high test peroxide (HTP) was described in this paper. Manganese oxide, Platinum and Iridium were coated on the gamma alumina. The catalyst activity as active materials was measured at the flask reactor. The response time of various catalysts was also measured with a 50 Newton class thruster. $Ir/Al_2O_3$ that showed the best activity in the flask reactor and response time at the thruster, failed the reaction when continuous mode test was carried out with the thruster. $Pt/Al_2O_3$ and $MnO_2/Al_2O_3$ can be substitutes to decompose the HTP. In addition, for larger thruster, $MnO_2/Al_2O_3$ can be a good catalyst because its cost is below 5 % of $Pt/Al_2O_3$.

The Characteristics of HI Decomposition using Pt/Al2O3 Catalyst Heat Treated in Air and Hydrogen Atmosphere (공기 및 수소 분위기에서 열처리 된 Pt/Al2O3 촉매의 HI분해반응 특성)

  • Park, Eun Jung;Ko, Yun Ki;Park, Chu Sik;Kim, Chang Hee;Kang, Kyoung Soo;Cho, Won Chul;Jeong, Seong Uk;Bae, Ki Kwang;Kim, Young Ho
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.3
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    • pp.219-226
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    • 2014
  • In HI decomposition, $Pt/Al_2O_3$ has been studied by several researchers. However, after HI decomposition, it could be seen that metal dispersion of $Pt/Al_2O_3$ was greatly decreased. This reason was expected of platinum loss and sintering, which platinum was aggregated. Also, this decrease of metal dispersion caused catalytic deactivation. This study was conducted to find the condition to minimize platinum sintering and loss. In particular, heat treatment atmosphere and temperature were examined to improve the activity of HI decomposition reaction. First of all, although $Pt/Al_2O_3$ treated in hydrogen atmosphere had low platinum dispersion between 13 and 18%, it was shown to suitable platinum form that played an important role in improving HI decomposition reaction. Oxygen in the air atmosphere made $Pt/Al_2O_3$ have high platinum dispersion even 61.52% at $500^{\circ}C$. Therefore, in order to get high platinum dispersion and suitable platinum form in HI decomposition reaction, air heat treatment at $500^{\circ}C$ was needed to add before hydrogen heat treatment. In case of 5A3H, it had 51.13% platinum dispersion and improved HI decomposition reaction activity. Also, after HI decomposition reaction it had considerable platinum dispersion of 23.89%.

The Catalytic Reduction of Carbon Dioxide by Butane over Nickel loaded Catalysts (니켈담지촉매상에서 부탄에 의한 이산화탄소의 환원반응)

  • Yoon, Cho-Hee;Kim, Geon-Joong
    • Applied Chemistry for Engineering
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    • v.8 no.3
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    • pp.543-549
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    • 1997
  • The direct reaction of carbon dioxide($CO_2$) with butane($C_4H_{10}$) to obtain synthesis gas and hydrocarbon compounds have been studied on nickel loaded catalysts. In the reaction of $CO_2$ with $C_4H_{10}$, Ni loaded catalysts showed similar activity with Pt catalyst and Coke deposition on the catalyst was severe by dehydrogenation of butane. The main products were carbon monoxide and hydrogen, when alumina and Y type zeolite were used as a support. Instead, a great deal of aromatic hydrocarbons were obtained on the Ni loaded ZSM-5 catalyst. The conversion of $CO_2$ increased with the increasing molar ratio of $CO_2$/$C_4H_{10}$ on Ni/ZSM-5, Ni/NaY and Ni/alumina catalyst, but the conversion decreased again from the ratio of 2. The value of $CO_2$ conversion was the highest at the 5wt% of Ni loading on ZSM-5 catalyst. A part of cokes deposited on the catalysts diminished when only $CO_2$ gas or water steam flowed into the reactor. The coke deposited on the catalysts was very reactive and it may be an important intermediate for the carbon dioxide reforming reaction.

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