• Title/Summary/Keyword: Catalyst oxidation

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Catalytic Oxidation of Ammonia over Metal Supported on Alumina at Low Temperature (금속담지 활성알루미나 촉매의 암모니아 저온연소반응)

  • Lim, Yun-Hui;Lee, Ji-Yeol;Park, Byung-Hyun
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.3
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    • pp.371-379
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    • 2013
  • In order to improve the selective oxidation reaction of gaseous ammonia at a low temperature, various types of metal-impregnated activated alumina were prepared, and also physical and chemical properties of the conversion of ammonia were determined. Both types of metal (Cu, Ag) impregnated activated alumina show high conversion rate of ammonia at high temperature (over $300^{\circ}C$). However, at lower temperature ($200^{\circ}C$), Ag-impregnated catalyst shows the highest conversion rate (93%). In addition, the effects of lattice oxygen of the developed catalyst was studied. Ce-impregnated catalyst showed higher conversion rate than commercial alumina, but also showed lower conversion rate than Ag-impregnated sample. Moreover, 5 vol.% of Ag activation under hydrogen shows the highest conversion rate result. Finally, through high conversion at low temperature, it was considered that the production of NO and $NO_2$, toxic by-products, were effectively inhibited.

Benzyl Alcohol Oxidation over H5PMo10V2O40 Catalyst Chemically Immobilized on Sulfur-containing Mesoporous Carbon (황이 포함된 중형기공성 탄소에 화학적으로 고정화된 H5PMo10V2O40 촉매 상에서 Benzyl Alcohol 산화반응)

  • Gim, Min Yeong;Kang, Tae Hun;Choi, Jung Ho;Song, In Kyu
    • Korean Chemical Engineering Research
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    • v.54 no.3
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    • pp.419-424
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    • 2016
  • $H_5PMo_{10}V_2O_{40}$ ($PMo_{10}V_2$) catalyst chemically immobilized on sulfur-containing mesoporous carbon (S-MC) was prepared, and it was applied to the benzyl alcohol oxidation reaction. S-MC was synthesized by a templating method using SBA-15 and p-toluenesulfonic acid as a templating agent and a carbon precursor, respectively. S-MC was then modified to have a positive charge, and thus, to provide sites for the immobilization of $PMo_{10}V_2$. By taking advantage of the overall negative charge of $[PMo_{10}V_2O4_{40}]^{5-}$, $PMo_{10}V_2$ catalyst was immobilized on the S-MC support as a charge matching component. It was revealed that $PMo_{10}V_2$ species were finely and molecularly dispersed on the S-MC via chemical immobilization. In the vapor-phase oxidation of benzyl alcohol, $PMo_{10}V_2$/S-MC catalyst showed higher conversion of benzyl alcohol and higher yield for benzaldehyde and benzoic acid than unsupported $PMo_{10}V_2$ catalyst. The enhanced catalytic performance of $PMo_{10}V_2$/S-MC was due to fine dispersion of $PMo_{10}V_2$ species on the S-MC via chemical immobilization.

Decomposition of Sulfamethoxazole by Catalytic Wet Peroxide Oxidation (촉매습식과산화(CWPO)를 이용한 설파메톡사졸의 분해)

  • Kim, Dul Sun;Lee, Dong-Keun;Kim, Jin Sol
    • Clean Technology
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    • v.24 no.4
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    • pp.293-300
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    • 2018
  • Sulfamethoxazole (SMX) is sulfaamide-based synthetic antibiotics, which are widely prescribed pharmaceutical compound to treat bacterial infections in both human and animals. Most of them are not completely decomposed as refractory substances. The environmental impact of pharmaceuticals as emerging contaminants has generated severe concerns. In this study, catalytic wet peroxide oxidation (CWPO) of SMX was carried out with $Cu/Al_2O_3$ catalyst and investigated the optimum reaction conditions of temperature, dosage of catalyst and concentration of $H_2O_2$ to completely decompose the SMX. It was observed that SMX was completely decomposed within 20 min using 0.79 mM $H_2O_2$ and 6 g $Cu/Al_2O_3$ catalyst at 1 atm and $40^{\circ}C$, but SMX was not fully mineralized and converted to intermediates as hydroylated-SMX, sulfanilic acid, 4-aminobenzenesulfinic acid and nitrobenzene. After that these are completely mineralized through organic acid. We proposed the decomposition reaction path ways of SMX by analyzing the behavior of these intermediates. To investigate the durability of heterogeneous catalyst, decomposition of SMX was observed by continuously recycling catalysts. When the heterogeneous catalyst of 10 wt% $Cu/Al_2O_3$ was continuously reused 5 times, decomposition of SMX was a little lowered, but the activity of catalyst was overall very stable.

Preparation of Pd/TiO2 Catalyst Using Room Temperature Ionic Liquids for Aerobic Benzyl Alcohol Oxidation (상온 이온성액체를 이용한 호기성 벤질 알코올 산화반응용 Pd/TiO2 촉매 제조)

  • Cho, Tae Jun;Yoo, Kye Sang
    • Applied Chemistry for Engineering
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    • v.26 no.3
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    • pp.351-355
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    • 2015
  • $Pd/TiO_2$ catalysts for aerobic benzyl alcohol oxidation were synthesized and eight different room temperature ionic liquids were used to control the palladium properties as active sites. $Pd/TiO_2$ particles were also calcined at 300, 400 and $500^{\circ}C$ to obtain an optimum catalyst. As the calcination temperature increased, the surface area and pore volume of catalyst decreased, but negligible changes were observed for the pore size of catalyst. However, the structural properties of catalyst varied with respect to the type of ionic liquids. Under identical reaction conditions, different catalytic activities were obtained depending upon the calcination temperature and type of ionic liquids. Mostly, the catalyst calcined at $400^{\circ}C$ showed higher catalytic activity than those at other temperatures. However, the catalyst prepared with 1-octyl-3-methylimidazolium hexafluorophosphate and 1-octyl-3-methylimidazolium trifluoromethanesulfonate showed good catalytic performance after calcination at $300^{\circ}C$. Among the catalyst, $Pd/TiO_2$ prepared with 1-octyl-3-methylimidazolium tetrafluoroborate and calcined at $400^{\circ}C$ showed the highest catalytic activity.

Production of Dry Oxidant through Catalytic H2O2 Decomposition over Mn-based Catalysts for NO Oxidation (NO 산화를 위한 Mn계 촉매상 과산화수소 분해를 이용한 건식산화제 생성)

  • Jang, Jung Hee;Choi, Hee Young;Han, Gi Bo
    • Clean Technology
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    • v.21 no.2
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    • pp.130-139
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    • 2015
  • The NO oxidation process has been applied to improve a removal efficiency of NO included in exhaust gas. In this study, to produce a dry oxidant for the NO oxidation process, the catalytic H2O2 decomposition method was proposed. A variety of the heterogeneous solid-acidic Mn-based catalysts were prepared for the catalytic H2O2 decomposition and the effect of their physico-chemical properties on the catalytic H2O2 decomposition were investigated. The results of this study showed that the acidic sites of the Mn-based catalysts has an influence on the catalytic H2O2 decomposition. The Mn-based catalyst having the abundant acidic sites within the wide temperature range in NH3-TPD shows the best performance for the catalytic H2O2 decomposition. Therefore, the NO oxidation efficiency, using the dry oxidant produced by the H2O2 decomposition over the Mn-based catalyst having the abundant acidic properties under the wide temperature range, was higher than the others. As a remarkable result, the best performances in the catalytic H2O2 decomposition and NO oxidation was shown when the Mn-based Fe2O3 support catalyst containing K component was used for the catalytic H2O2 decomposition.

Improvement of $\lambda$--window Range of the Three-Way Catalyst for Natural Gas Vehicles (천연가스 자동차용 삼원촉매의 $\lambda$-윈도우 영역 개선)

  • 최병철;정필수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.1
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    • pp.92-100
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    • 2000
  • The model gas reaction tests were carried out to investigate the purification characteristics of methane on the exclusive catalyst for NGV. The experiment was conducted with the factors which affect the conversion efficiency of methane, such as Redox ratio, coexistence components of CO, MO, $H_2$O, precious metals and additives. The catalyst loaded with larger amount of pd and with additive La showed lower light-off temperature. In the presence of CO and NO, the conversion efficiency of methane was varied according to the kind of additive loaded. The conversion efficiency of methane was dropped for the catalyst loaded with La under lean air-fuel ratio, while it increased for the one loaded with Ti+Zr for the same condition. It was shown that the water vapor inhibited methane from oxidation by its poisoning on the surface of catalyst.

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Complete Oxidation of Volatile Organic Compounds(BTX) over the Supported Transition Metal Catalysts (전이금속 담지 촉매상에서 휘발성유기화합물(BTX)의 완전산화)

  • Kim, Sang-Chai;Seo, Seong-Gyu;Yu, Eui-Yeon
    • Clean Technology
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    • v.6 no.1
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    • pp.17-25
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    • 2000
  • Catalytic oxidation of volatile organic compounds(benzene, toluene, xylene) over transition metals/ALO-6 catalysts was investigated in a fixed bed flow reactor system at atmospheric pressure. The orders of catalytic activities for the complete oxidation of toluene were Cu>Mn>Fe>V>Mo>Co>Ni>Zn for 15% transition metals/ALO-6 catalyst system. Increasing the calcination temperature resulted in decreasing the specific surface areas of catalyst, subsequently the catalytic activity. The loading of Cu on ALO-6 had a great effect on the catalytic activity and 5% Cu/ALO-6 catalyst showed higher catalytic activity, which may be contributed to the uniformly distributed active sites. Benzene, toluene and xylene were completely oxidized to carbon dioxide over 5% Cu/ALO-6 catalyst at over $380^{\circ}C$ and 4.5 g-cat.hr./g-mole. The orders of the kinds of reactants for catalytic activity over 5% Cu/ALO-6 were toluene>xylene>benzene. As the concentration of reactant increased, the catalytic activity decreased due to self-poison of reactant.

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Partial Oxidation of n-Octane over Rh-Containing Alumina-Supported Catalysts (알루미나에 담지된 Rh 함유 촉매의 n-옥탄 부분산화반응)

  • Lee, Shin-Hwa;Suh, Young-Woong;Suh, Dong-Jin;Park, Tae-Jin;Lee, Kwan-Young
    • 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.

The Effect of SO2 in Flue Gas on the SCR Activity of V/TiO2 (배가스 중 SO2가 V/TiO2 SCR활성에 미치는 영향)

  • Hong, Sung-Chang
    • Applied Chemistry for Engineering
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    • v.17 no.5
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    • pp.490-497
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    • 2006
  • $V_{2}O_{5}$/$TiO_{2}$ catalyst can be deactivated by ammonium salts formed by $SO_{2}$ oxidation and unreacted ammonium in presence of $SO_{2}$ in flue gas. The deactivation of catalyst by $SO_{2}$ depends on the $SO_{2}$ oxidation to $SO_{3}$. The oxidation of $SO_{2}$ is weakly affected by oxygen concentration, and strongly by the amount of vanadium loaded onto titania supports. Because unreacted ammonia is one of elements to form the ammonium salts, it is important to control the mole ratio of $NH_{3}/NOx$ in SCR. Thus the experiments about $NH_{3}/NOx$ were carried out. The reason of low activity of catalyst deactivated by ammonium salts is the change of pore volume. And TPD (Temperature Programmed Decomposition) was performed to find the decomposition of ammonium bisulfate on deactivated catalyst.