• Title/Summary/Keyword: selective catalytic oxidation

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Investigation of Elemental Mercury Oxidation on Commercial SCR Catalysts in Flue Gas of Fossil Fired Power Plant (상용 SCR 촉매상에서 화력발전소 배기가스 중 원소수은의 산화반응연구)

  • Lee, Seung-Min;Lee, Jung-Bin
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.3
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    • pp.245-252
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    • 2010
  • For the purpose of evaluating to remove elemental mercury using SCR (Selective Catalytic Reduction) catalysts, the result of the concentration variation of elemental mercury in lab experiment and field measurement was compared. The effect of the elemental mercury oxidation on commercial catalysts was studied in simulated gas. Three species of SCR catalyst, $V_2O_5-TiO_2$ type, were selected. The elemental mercury reduced 30% without HCl gas in SCR operating condition. But the width of reduction increased 60% at 20 ppm HCl gas. According to the result of field measurement, reduction rate of elemental mercury at SCR outlet showed 60%. The total mercury concentration decreased about 20%. The results were similar to the lab test. The results of chemical analysis of test sample showed increase of mercury concentration but surface change was not observed.

Reaction Mechanism and Support Effect for the Gas-Phase Oxidation of o-Xylene (자일렌의 기상 산화반응에서의 반응 메카니즘과 담체영향)

  • Lee, Gun-Dae;Lee, Ho-In
    • Applied Chemistry for Engineering
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    • v.2 no.2
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    • pp.155-164
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    • 1991
  • The reaction mechanism and the effects of the oxidation state of vanadium oxide and of support on catalytic activity for the oxidation of o-xylene were investigated. The oxidation of o-xylene simultaneously proceeded through the consecutive and parallel mechanisms. The high valence of vanadium favored selective oxidation to phthalic anhydride, while the low valence caused complete oxidation of phthalic anhydride to CO and $CO_2$. Crystalline $V_2O_5$ showed better selectivity for partial oxidation rather than amorphous one.

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Characterization of Low Temperature Selective Catalytic Reduction over Ti Added Mn-Cu Metal Oxides (Ti가 첨가된 Mn-Cu 혼합산화물을 이용한 저온 SCR 반응 특성)

  • Lee, Hyun Hee;Park, Kwang Hee;Cha, Wang Seog
    • Applied Chemistry for Engineering
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    • v.24 no.6
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    • pp.599-604
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    • 2013
  • In this study, Ti added Mn-Cu mixed oxide catalysts were prepared by a co-precipitation method and used for the low temperature (< $200^{\circ}C$) selective catalytic reduction (SCR) of NOx with $NH_3$. Physicochemical properties of these catalysts were characterized by BET, XRD, XPS, and TPD. Mn-Cu mixed oxide catalysts were found to be amorphous with a large surface and they showed high SCR activity. Experimental results showed that the addition of $TiO_2$ to Mn-Cu oxide enhanced the SCR activity and $N_2$ selectivity. Ti addition led to the chemically adsorbed oxygen species that promoted the oxidation of NO to $NO_2$ and increased the number of $NH_3$ adsorbed-sites such as $Mn^{3+}$.

The Application of Dump Combustor for Evaluation of After-Treatment System (후처리장치 성능 평가를 위한 Dump Combustor의 활용)

  • Nam, Youn-Woo;Lee, Won-Nam;Oh, Kwang-Chul;Lee, Chun-Beom
    • Journal of the Korean Society of Combustion
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    • v.12 no.3
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    • pp.16-23
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    • 2007
  • Employing an after-treatment system has almost become a mandatory requirement for Diesel vehicles, which results from a reinforced exhaust regulations as the number of vehicles powered by a Diesel engine increases. The Diesel Particulate Filter (DPF) system is considered as one of the most efficient method to reduce particulate matter (PM); however, the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas composition and flow rate of exhaust gas are important parameters in DPF evaluation processes, especially during a regeneration process. Engine dynamometer and segment tester are generally used in DPF evaluation so far. These test methods, however, could not completely evaluate the effect of various parameters on real DPF, such as oxygen concentration, amount of soot and exhaust gas temperatures. The evaluation of DPF systems using a dump combustor has been verified experimentally and this dump combustor system is likely to be appropriate for the DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) assessments test, too.

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Simple and Selective Flow Injection Catalytic Determination of Ruthenium with Spectrophotometric Detection (분광광도 검출법으로 간단하고 선택적인 흐름주입촉매법에의한 루테늄 정량)

  • Rezaei, Behzad;Majidi, Najmeh
    • Journal of the Korean Chemical Society
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    • v.51 no.2
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    • pp.147-153
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    • 2007
  • A simple, selective and highly sensitive flow injection catalytic method was presented for determination of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate in pH=1.0. The reaction rate is controlled specrophotometricaly by monitoring the dye absorbance at 555 nm. The optimized conditions make it possible to determine ruthenium in the ranges of 0.1-10.0 ng/mL (r2=0.9982) and 10.0-50.0 ng/mL (r2=0.9934) with a detection limit of 0.04 ng/mL and a sample rate of 30±5 samples/h. Relative standard deviation for the results of five replicate measurements does not exceed 1.44%. The proposed method has been successfully applied for quantitation of ultra trace amounts of ruthenium in some environmental and biological samples.

Characteristics of Mercury Oxidation by an SCR Catalyst with Gas Composition (가스조성에 따른 선택적 환원촉매의 수은 산화 특성)

  • Lee, Sang-Sup;Kim, Kwang-Yul;Oh, Kwang-Joong;Jeon, Jun-Min;Kim, Do-Jeung;Kim, Ju-Yeong
    • Particle and aerosol research
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    • v.8 no.4
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    • pp.125-132
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    • 2012
  • Mercury oxidation in an SCR(selective catalytic reduction) catalyst was tested in this study with the conditions simulating the SCR system in full-scale coal-fired flue gas. A commercially available SCR catalyst was located in a temperature-controlled reactor system, and simulated gas was injected into the reactor. Mercury oxidation efficiency was determined from the difference between inlet and outlet elemental mercury concentrations. A control experiment was carried out with the gas composition of 12% $CO_{2}$, 5% $H_{2}O$, 5% $O_{2}$, 500 ppm $SO_{2}$, 400 ppm NO, 400 ppm $NH_{3}$, 5 ppm HCl, and 20 ${\mu}g/m^{3}$ Hg. Additional tests were conducted with different gas composition from the control condition to investigate the effect of gas composition on mercury oxidation in the SCR catalyst.

The Effect of Calcination/reduction Condition Over Ru/TiO2 on the NH3-SCO Reaction Activity (소성/환원 조건이 Ru/TiO2의 NH3-SCO 반응활성에 미치는 영향)

  • Shin, Jung Hun;Hong, Sung Chang
    • Applied Chemistry for Engineering
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    • v.31 no.1
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    • pp.108-114
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    • 2020
  • In this study, NH3-selective catalytic oxidation (SCO) efficiencies according to calcination/reduction conditions were compared when preparing various Ru[1]/TiO2 catalysts. The Ru[1]/TiO2 red catalyst had better NH3 conversion and NH3 to N2 conversion than those of Ru[1]/TiO2 cal. Physico-chemical properties of Ru[1]/TiO2 catalysts were confirmed by Brunauer Emmett Teller (BET), X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (H2-TPR) analyses, and the properties were shown to affect the dispersion and surface adsorption oxygen species (Oβ) ratio of the active metal.

A Novel Al-Bridged Trinuclear Iron(II) Bis(imino)pyridyl Complex with Catalytic Ethylene Polymerization Behavior

  • Long, Zerong;Li, Zhongquan;Ma, Ning;Wu, Biao
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2537-2543
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    • 2011
  • A self-assembled Al-bridged diiminopyridine-based ligand (3) was synthesized and characterized by FT-IR, ESI-MS and NMR spectroscopy. Electron spectral titrations were performed to confirm the formation of a novel trinuclear bis(imino)pyridyl iron(II) complex (4) upon addition of $FeCl_2$ into Al-bridged ligand 3 in methanol solution. Simultaneously, a typical bis(imino)pyridine-iron(II) complex (2) was synthesized and fully characterized. The X-ray crystal study of the iron(II) complex 2 disclosed a five-coordinate, distorted square-pyramidal structure with the tridentate N^N^N ligand and chlorides. The optimal molecular structure of 4 was obtained by means of molecular mechanics, which showed that each iron atom in the complex 4 is surrounded by two chlorides, a tridentate N^N^N ligand and one oxygen atom, supporting considerations about the possibility of six-coordinate geometry from MMAO or the ethylene access. A comparison of 4 with the reference 2 revealed a remarkable decrease of the catalytic activity and MMAO consumption (activity up to $0.41{\times}10^3\;kg\;{mol_{Fe}}^{-1}h^{-1}bar^{-1}$, Al/Fe = 650 for 4 and $7.02{\times}10^3\;kg\;{mol_{Fe}}^{-1}h^{-1}bar^{-1}$, Al/Fe = 1600 for 2).

The Effect of Calcination Temperature of RuTi Catalysts on the Reaction Activity of NH3-SCO (RuTi 촉매의 소성온도가 NH3-SCO 반응활성에 미치는 영향)

  • Shin, Jung Hun;Hong, Sung Chang
    • Applied Chemistry for Engineering
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    • v.31 no.2
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    • pp.200-207
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    • 2020
  • In this study, the effect of calcination temperature on the production of RuTi catalyst in NH3-SCO (selective catalytic oxidation) was investigated. The RuTi catalyst was prepared using the wet impregnation method, and calcined at 400~600 ℃ for 4 h in air condition. The catalysts were named RuTi x00 where x00 means the calcination temperature. According to XRD (X-Ray diffraction), TEM (transmission electron microscope), H2-TPR (H2-temperature programmed reduction) analyses, RuTi x00 catalysts displayed that the dispersion of active metal decreased via increasing the calcination temperature. The catalysts with low dispersion showed a decrease in the surface adsorption oxygen species (Oβ) and NH3 adsorption amount via XPS, and NH3-TPD analyses. Therefore, the RuTi 400 catalyst was well dispersed in the active metal on TiO2 surface, and also, the NH3 removal efficiency was excellent.