• 제목/요약/키워드: Metal oxide addition

검색결과 299건 처리시간 0.037초

폐 산업용 금속산화물계 촉매를 이용한 휘발성유기화합물의 제거 (Decomposition of Volatile Organic Compounds Using Regenerated Metal Oxide Catalysts)

  • 남승원;심왕근;김상채
    • 한국대기환경학회지
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    • 제22권4호
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    • pp.431-439
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    • 2006
  • Catalytic oxidation of benzene, toluene and xylene (BTX) using regenerated metal oxide catalysts (ZnO-CuO, NiO, $Fe_2O_3$, ZnO, CrO) were investigated in a fixed bed flow reactor to evaluate their feasibility for the purpose of removing volatile organic compounds (VOCs). Four kinds of pre-treatment methods such as gas (air and hydrogen), acid aqueous solution, alkali aqueous solution and cleaning agent were used to find out the optimal regeneration conditions. The physico-chemical properties of the used and regenerated catalysts were characterized by BET and TPR (Temperature Programmed Reduction). The used catalysts showed high conversion ratio and the catalytic ability of toluene oxidation was in the order of ZnO-CuO>$Fe_2O_3$>NiO>ZnO>CrO. We found that the acid aqueous pre-treatment (0.1 N HNO$_3$) was the best way to enhance the catalytic activity of $Fe_2O_3$. In addition, air and hydrogen gas treatment were optimal for NiO and ZnO-CuO catalysts, respectively. Furthermore, the decomposition of BTX depends on the type of a catalyst and a gas molecule.

Analysis Method of Volatile Sulfur Compounds Utilizing Separation Column and Metal Oxide Semiconductor Gas Sensor

  • Han-Soo Kim;Inho Kim;Eun Duck Park;Sang-Do Han
    • 센서학회지
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    • 제33권3호
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    • pp.125-133
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    • 2024
  • Gas chromatography (GC) separation technology and metal oxide semiconductor (MOS) gas sensors have been integrated for the effective analysis of volatile sulfur compounds (VSCs) such as H2S, CH3SH, (CH3)2S, and (CH3)2S2. The separation and detection characteristics of the GC/MOS system using diluted standard gases were investigated for the qualitative and quantitative analysis of VSCs. The typical concentrations of the standard gases were 0.1, 0.5, 1.0, 5.0, and 10.0 ppm. The GC/MOS system successfully separated H2S, CH3SH, (CH3)2S, and (CH3)2S2 using a celite-filled column. The reproducibility of the retention time measurements was at a 3% relative standard deviation level, and the correlation coefficient (R2) for the VSC concentration was greater than 0.99. In addition, the chromatograms of single and mixed gases were almost identical.

Change of Optical Properties in Zinc Oxide-Based Glasses including Metal Oxides for Transparent Dielectric

  • Seo, Byung-Hwa;Kim, Hyung-Sun;Suh, Dong-Hack
    • 한국재료학회지
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    • 제19권10호
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    • pp.533-537
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    • 2009
  • This paper presents a new method for the improvement of color temperature without the change of the driving scheme using transparent dielectric layers with various metal oxides (CeO$_2$, Co$_3$O$_4$, CuO, Fe$_2$O$_3$, MnO$_2$, NiO) in plasma display panels (PDP). In this study, we fabricated ZnO-B$_2$O$_3$-SiO$_2$-Al$_2$O$_3$ glasse with various metal oxides and examined the optical properties of these glasses. As the metal oxides were added to the glasses, the visible transmittances of the dielectric layers decreased and the transmittances in special wavelength regions were reduced at different rates. The change of the transmittance in each wavelength range induced the variation of the visible emission spectra and the change of the color temperature in the PDP. The addition of Co$_3$O$_4$ and CuO slightly decreased the intensity of the blue light, but the intensities of the green and the red light were significantly decreased. Therefore, the color temperature can be improved from 6087K to 7378K and 7057K, respectively.

VUV 이오나이저용 Ca-Sr-Ba계 산화물 캐소드에 낮은 일함수를 갖는 금속산화물 첨가의 영향 (Effects on Addition of Metal Oxides with Low Workfunctions on the Ca-Sr-Ba Oxide Cathodes for VUV Ionizers)

  • 박승규;이종혁;김란희;정주형;한완규;이수현;전성우;김대준;김도윤;이광섭
    • 한국재료학회지
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    • 제29권4호
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    • pp.241-251
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    • 2019
  • There are several manufacturing techniques for developing thermionic cathodes for vacuum ultraviolet(VUV) ionizers. The triple alkaline earth metal emitters(Ca-Sr-Ba) are formulated as efficient and reliable thermo-electron sources with a great many different compositions for the ionizing devices. We prepare two basic suspensions with different compositions: calcium, strontium and barium. After evaluating the electron-emitting performance for europium, gadolinium, and yttrium-based cathodes mixed with these suspensions, we selected the yttrium for its better performance. Next, another transition metal indium and a lanthanide metal neodymium salt is introduced to two base emitters. These final composite metal emitters are coated on the tungsten filament and then activated to the oxide cathodes by an intentionally programmed calcination process under an ultra-high vacuum(${\sim}10^{-6}torr$). The performance of electron emission of the cathodes is characterized by their anode currents with respect to the addition of each element, In and Nd, and their concentration of cathodes. Compared to both the base cathodes, the electron emission performance of the cathodes containing indium and neodymium decreases. The anode current of the Nd cathode is more markedly degraded than that with In.

Synthesis of New pH-Sensitive Poly(ethylene oxide-b-maleic acid) from Modification of Poly(ethylene oxide-b-N-phenylmaleimide)

  • Go, Da-Hyeon;Jeon, Hee-Jeong;Kim, Tae-Hwan;Kim, Geun-Seok;Choi, Jin-Hee;Lee, Jae-Yeol;Kim, Jung-Ahn;Yoo, Hyun-Oh;Bae, You-Han
    • Macromolecular Research
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    • 제16권7호
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    • pp.659-662
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    • 2008
  • A new and useful poly(ethylene oxide)-based pH-sensitive block copolymer is introduced. Poly(ethylene oxide-b-N-phenylmaleimide) was first synthesized by anionic polymerization of N-phenylmaleimide (N-PMI) using mixed alkali metal polymeric alkoxide by sequential monomer addition method in the mixture of benzene/THF/DMSO (10/5/3, v/v/v) at room temperature. Reductive deimidation of the resulting block copolymer was performed using hydrazine monohydrate leading to the formation of the corresponding pH-sensitive poly(ethylene oxide-b-maleic acid).

$CaO-TiO_2-P_2O_5$계 다공질 결정화 유리의 물성에 미치는 알카리 금속 산화물의 첨가효과 (Addition Effects of Alkali Metal Oxide on Some Properties of Porous Glass-Ceramics in the $CaO-TiO_2-P_2O_5$ System)

  • 장순규;최세영
    • 한국세라믹학회지
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    • 제31권11호
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    • pp.1337-1345
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    • 1994
  • Glasses in the system of 45CaO-25TiO2-30P2O5 containing 1 mole% of M2O(M=Li, Na, K) were melted and crystallized. And their crystal phases were Ca3(PO4)2, CaTi4(PO4)6, and TiO2. Porous glass-ceramics with skeleton of two crystal phase CaTi4(PO4)6 and TiO2 were prepared by selective leaching of Ca3(PO4)2 with 0.1 N-HCl. Glass transition temperature(Tg) and crystallization temperature(Tc) were decreased by addition of 1 mole% alkali metal oxide. Pore size of porous glass-ceramics was increased with increasing heat treatment temperature and its dependence on heat treatment temperature was decreased with addition of Na2O and K2O. It was found that porous glass-ceramics of parent glass and containing 1mole% M2O(M=Li, Na, K) composition had maximum specific surface area, porosity and maximum of crystallzed phase by heat treatment at 80$0^{\circ}C$, 76$0^{\circ}C$, 78$0^{\circ}C$, 80$0^{\circ}C$ respectively.

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층상 혼합금속산화물 촉매에 의한 $N_2O$ 분해에서 Ceria 첨가 및 CO 환원제의 영향 (Effects of Ceria and CO Reductant on $N_2O$ Decomposition over the Layered Mixed Oxide Catalysts)

  • 양기선;장길상
    • 청정기술
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    • 제16권4호
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    • pp.284-291
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    • 2010
  • 온실가스로 알려진 $N_2O$의 촉매 분해는 최소한 670 K 이상의 온도가 요구되는 난해한 공정으로 알려져 있다. 본 연구는 CO 환원제와 더불어 473 K의 저온에서도 $N_2O$를 전량 분해될 정도로 높은 활성을 나타내는 혼합금속산화물(mixed metal oxide: MMO) 촉매에 Ce을 첨가함으로서 나타나는 $N_2O$ 분해활성에의 영향을 검토하기 위하여 수행되었다. MMO 촉매는 Co 및 Al 외에 Rh과 Pd을 사용하고, 여기에 Ce을 미량 첨가하여 공침전법으로 제조하였으며, 결과적으로 Ce 함량이 증가함에 따라 촉매 표면적은 감소하고 $N_2O$의 직접분해 활성이 감소하는 현상이 나타났다. 그러나 CO 환원제의 분위기 하에서는 이러한 활성 감소를 상쇄하고도 남을 정도의 높은 $N_2O$ 분해활성을 나타냈으며 Ce 첨가비율에 따른 활성저하도 줄일 수 있어서 MMO 촉매의 물리적 안정성 증대를 위해 Ce을 첨가할 경우 CO 환원제에 의한 $N_2O$ 환원 반응계의 활성 안정성도 유지될 수 있는 것으로 확인되었다.

Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

  • Yoon, Sung-Eun;Ahn, Jae-Yeong;Park, Jong-Sung
    • 한국세라믹학회지
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    • 제52권5호
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    • pp.350-355
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    • 2015
  • To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

스퍼터링으로 증착한 바나듐 텅스텐 산화물 박막의 전기화학적 거동 (Electrochemical Behavior of Vanadium Trungsten Oxide Thin Films Deposited by Sputtering)

  • 박영신;이병일;주승기
    • 한국표면공학회지
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    • 제30권2호
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    • pp.121-127
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    • 1997
  • Vanadium tungsten oxide thin films were formed by RF magnetron sputtering and the effects of tungsten addition on the crystallinity and on the electrochemical behavior were investigated. X-ray analysis revealed that amorphized films could be obtained by tungase addition. In order to investigate the electrochemical behavior of the vanadium tungsten oxide films, electrochemical insertion and extraction of lithium were out in 1m $LiCIO_4$-PC-DME electrolyte using litium metal as a counter electrode. When the tungsten was added to the $V_2O_5$ films, cycling reversibility was considerably improved. Electrochemical test showed the cell capacity of about $70\mu\;Ah/\textrm{cm}^2-\mu\textrm{m}$ when the amount of additive tungseten reached 30 atomic percent. No appreciable degradation of the cell capacity could be observed after hundred cycles of insertion and extration od Li.

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Catalyst-aided Regeneration of Amine Solvents for Efficient CO2 Capture Process

  • Bhatti, Umair H.;Sultan, Haider;Cho, Jin Soo;Nam, Sungchan;Park, Sung Youl;Baek, Il Hyun
    • 에너지공학
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    • 제28권4호
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    • pp.8-12
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    • 2019
  • Thermal amine scrubbing is the most advanced CO2 capture technique but its largescale application is hindered due to the large heat requirement during solvent regeneration step. The addition of a solid metal oxide catalysts can optimize the CO2 desorption rate and thus minimize the energy consumption. Herein, we evaluate the solvent regeneration performance of Monoethanolamine (MEA) and Diethanolamine (DEA) solvents without and with two metal oxide catalysts (TiO2 and V2O5) within a temperature range of 40-86℃. The solvent regeneration performance was evaluated in terms of CO2 desorption rate and overall amount of CO2 desorbed during the experiments. Both catalysts improved the solvent regeneration performance by desorbing greater amounts of CO2 with higher CO2 desorption rates at low temperature. Improvements of 86% and 50% in the CO2 desorption rate were made by the catalysts for MEA and DEA solvents, respectively. The total amount of the desorbed CO2 also improved by 17% and 13% from MEA and DEA solvents, respectively. The metal oxide catalyst-aided regeneration of amine solutions can be a new approach to minimize the heat requirement during solvent regeneration and thus can remove a primary shortfall of this technology.