• Title/Summary/Keyword: $V/TiO_2$

Search Result 1,447, Processing Time 0.025 seconds

Preparation of $WO_3/TiO_2$ and $V_2O_5/TiO_2$ powders and their catalytic performances in the SCR of $NO_x$ ($WO_3/TiO_2$$V_2O_5/TiO_2$ 분말의 합성 및 $NO_x$ 제거 SCR특성)

  • Lee, Tae-Suk;Lee, In-Gyu;Lee, Byeong-Woo;Shin, Dong-Woo
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.16 no.5
    • /
    • pp.216-221
    • /
    • 2006
  • An investigation of the influence of $WO_3$ and $V_2O_5$ catalysts on the microstructure, phase formation and selective catalytic reduction (SCR) efficiency of the synthesized SCR powders has been carried out. A commercial anatase-$TiO_2$ was used as the catalysts support. For $WO_3(10wt%)/TiO_2$, the W loading to the $TiO_2$ support led to the lower in anatase to rutile transition temperature from $1200^{\circ}C$ of $TiO_2$ support to ${\sim}900^{\circ}C$. The transition temperature was also lowered to below $650^{\circ}C$ in the $V_2O_5$(5 and 10 wt%) added composition. The $WO_3(10wt%)/TiO_2$ SCR powder obtained at $450^{\circ}C$ showed near 100% of $NO_x$ conversion efficiency at $350{\sim}400^{\circ}C$ and for the powder prepared at $650^{\circ}C$ the same efficiency was achieved in wider temperature range $300{\sim}400^{\circ}C$. The highest $NO_x$ conversion efficiency of 100% was obtained in the $V_2O_5(5wt%)/TiO_2$ SCR composition calcined at $650^{\circ}C$ in the relatively wider temperature range $250{\sim}350^{\circ}C$, while the catalytic efficiency considerably decreased for the $V_2O_5(10wt%)/TiO_2$. The lowered conversion efficiency of $NO_x$ observed in the $V_2O_5(10wt%)/TiO_2$ composition calcined at $650^{\circ}C$ was considered to be correlated with the lowered surface area resulting from the increased crystallite growth by highly reactive vanadium loading.

Synthesis of SnO2-TiO2-V2O5 System Yellow Pigment (SnO2-TiO2-V2O5계의 노랑안료 합성)

  • Joo, In-Don;Hwang, Dong-Ha;Lee, Hyun-Soo;Park, Joo-Seok;Lee, Byung-Ha
    • Journal of the Korean Ceramic Society
    • /
    • v.46 no.6
    • /
    • pp.639-642
    • /
    • 2009
  • The research was performed to find out the optimum firing condition for the $SnO_2-TiO_2-V_2O_5$ system yellow pigment. The pigment based on $SnO_2-V_2O_5$ system showed very intense yellow color and it was used widely in ceramics industry. Synthesized pigment, with partial substitutions of $SnO_2\;by\;TiO_2$, was fired at $1300{^{\circ}C}$ soaking 1h and it showed bright yellow color. $SnO_2-TiO_2-V_2O_5$ system was very more intensive changes in yellow color by colorimetric value $b^*$ than $SnO_2-V_2O_5$ system. Synthesized yellow pigments were characterized by X-ray diffraction (XRD), FT-IR, and UV-vis spectroscopy. The best composition for yellow pigment was 93:7:0.5(mole%) for $SnO_2-V_2O_5-TiO_2$. The measurement of CIE $L^*a^*b^*$ of pigment was $L^*(78.82),\;a^*(-4.88)\;and\;b^*$(59.25).

Microwave Dielectric Properties of $0.95MgTiO_3-0.05SrTiO_3$ Ceramics with $V_2O_5$ ($V_2O_5$ 첨가에 따른 $0.95MgTiO_3-0.05SrTiO_3$ 세라믹스의 마이크로파 유전특성)

  • Nam, Gyu-Bin;Kim, Kang;Park, In-Gil;Ryu, Ki-Won;Lee, Young-Hie
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2002.05c
    • /
    • pp.112-116
    • /
    • 2002
  • The $0.95MgTiO_3-0.05SrTiO_3$ ceramics with $V_2O_5$(10wt%) were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperatue by XRD. According to the X-ray diffraction pattern of the $0.95MgTiO_3-0.05SrTiO_3$ ceramics with $V_2O_5$(10wt%), the ilmenite $MgTiO_3$ and perovskite $SrTiO_3$ structures were coexisted and secondary phase $MgTi_2O_5$ were appeared. In the case of $0.95MgTiO_3-0.05SrTiO_3$ ceramics with $V_2O_5$(10wt%), dielectric constant, quality factor and temperature coefficient of resonant frequency were 15.84~18.28, 12627~23138GHz, -21.414~1.568$ppm/^{\circ}C$, respectively.

  • PDF

Effect of Nb, V and Cr on the High Temperature Oxidation of Ti-(42, 44)% Al Alloys (Ti-(42, 44)%Al 합금의 고온내산화성에 미치는 Nb, V 및 Cr의 영향)

  • Lee, Yeong-Chan;Kim, Mi-Hyeon;Kim, Seong-Hun;Lee, Won-Uk;Baek, Jong-Hyeon;Lee, Dong-Bok
    • Korean Journal of Materials Research
    • /
    • v.9 no.10
    • /
    • pp.1025-1031
    • /
    • 1999
  • Alloys of TiAl with six different compositions. i. e., Ti-(42, 44)Al-2Nb-4V. Ti-(42, 44)Al-4Nb-2V and Ti -(42, 44)Al-4Nb-2Cr, were manufactured by arc-melting. and their oxidation behavior was studied. Both isothermal and cyclic oxidation tests were performed at 700, 800 and $900^{\circ}C$ in air for 50hr. The oxidation resistance increased in the order of Ti-(42, 44)Al-2Nb-4V, Ti-(42, 44)Al-4Nb-ZV and Ti-(42, 44)Al-4Nb-2Cr. It was found that V was a deleterious element, while Cr was a beneficial element in terms of oxidation resistance. During oxidation, a simultaneous interdiffusion was observed. All the constituent elements in the base alloys diffused outward. whereas oxygen from the atmosphere diffused inward, to form triple oxide layers composed of an outermost $\textrm{TiO}_2$ layer. upper ($\textrm{TiO}_2+\textrm{Al}_2\textrm{O}_3$) mixed layer, and lower $\textrm{TiO}_2$-rich layer.

  • PDF

Studies on the Preparation for the Simultaneous Removal of NO and $SO_2$ from Stationary Sources I.Surface properties and reactivity of $V_2O_5-MoO_3/TiO_2$ catalysts (고정원에서 배출되는 $NO_x/SO_x$의 동시제거를 위한 SCR 촉매의 제조법에 관한 연구: I. $V_2O_5-MoO_3/TiO_2$ 촉매들의 표면특성과 반응성)

  • 구미화;정석진
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.8 no.1
    • /
    • pp.58-67
    • /
    • 1992
  • For removing $NO_x$ and $SO_x$ from the flue gases emitted from stationary sources, $V_2O_5-MoO_3/TiO_2$ catalysts were prepared by the conventional impregnation method (aqueous solution) and a sort of surface fixation method(nonaqueous solution) as reported excellent reproducibility catalysts. And these catalysts observed their catalytic activities as well as their surface properties. V-Mo-O oxide, prepared from nonaqueous solution of $VOCl_3$ and $Mo(CO)_6$ and aqeous solution method, was supported as amorphous state by XRD and SEM measurements. The infrared spectra of fresh and used catalysts showed that in used catalysts, V=O bands decreased and new bands of vanadium oxysulfate bands were very sensitive. So the catalysts prepared from nonaqueous solution may bring about the high activity. Results from catalytic activity measurements at 350$^\circ$C, in the presence of $SO_2, NO$ conversion was more increased than in absence of $SO_2$. As the $MoO_3$ was added to $V_2O_5/TiO_2 system, SO_2$ conversion increased. It found that from the results, $V_2O-5-MoO_3/TiO_2$ catalysts prepared from an nonaqueous solution may bring about the high activity for both the reaction of NO and $SO_2$ removal.

  • PDF

In situ FT-IR Study of 1,2-dichlorobenzene Decomposition over VOx/Mesoporous Titania by Prepared Spray Pyrolysis (분무 열분해법을 이용해 제조된 VOx/Mesoporous Titania 상에서 1,2-dichlorobenzene의 분해반응에 대한 in situ FT-IR 연구)

  • Jeon, Jong-Ki;Jung, Kyeong Youl;Park, Young-Kwon
    • Applied Chemistry for Engineering
    • /
    • v.22 no.5
    • /
    • pp.582-585
    • /
    • 2011
  • In this study, surface-adsorbed species of 1,2-dichlorobenzene (1,2-DCB) on mesoporous $V_2O_5/TiO_2$ catalysts synthesized by spray pyrolysis were investigated through the adsorption/desorption performed using in situ FT-IR cell. Also, the comparison of adsorbed species with $TiO_2$ and $V_2O_5/TiO_2$ synthesized by the incipient wetness was carried out.

Photodegradation of Volatile Organic Compound (VOC) Through Pure TiO2 and V-Doped TiO2 Coated Glasses

  • Moon, Jiyeon;Kim, Seonmin
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2014.02a
    • /
    • pp.425.2-425.2
    • /
    • 2014
  • $TiO_2$ possesses great photocatalytic properties but absorbs only UV light owing to high band gap energy (Eg = 3.2 eV). By narrowing the band gap through doping a metal ion, the photocatalytic activity can be enhanced in condition of the light of a higher than 365 nm wavelength. Main purpose for this study is to evaluate the activities of metal doped $TiO_2$ for degrading the volatile organic compounds (VOCs); p-xylene is chosen in the VOC removal test. Vanadium is selected in this study because an ionic radius of vanadium is almost the same as titanium ion and vanadium can be easily doped into $TiO_2$. V-doped $TiO_2$ was synthesized by sol-gel methods and compared with pure $TiO_2$. Pure TiO2 powder and V-doped $TiO_2$ powder were coated on glasses by spray coating method. UV-Visible spectrophotometer was used for the measurement of the band gap changes. VOC concentration degradation level was tested with using various UV light sources in an enclosed chamber. Catalytic activities of prepared samples were evaluated based on the experimental results and compared with coated pure $TiO_2$ sample.

  • PDF

Electrochemical Properties of Ti/IrO2/SnO2-Sb-Ni Electrode for Water Treatment (수처리용 Ti/IrO2/SnO2-Sb-Ni 전극의 전기화학적 특성평가)

  • Yang, So Young
    • Journal of Environmental Science International
    • /
    • v.29 no.10
    • /
    • pp.943-949
    • /
    • 2020
  • In this work, we prepared a heterojunction anode with a surface layer of SnO2-Sb-Ni (SSN) on a Ti/IrO2 electrode by thermal decomposition to improve the electrochemical activity of the Ti/IrO2 electrode. The Ti/IrO2-SSN electrode showed significantly improved electrochemical activity compared with Ti/IrO2. For the 0.1 M NaCl and 0.1 M Na2SO4 electrolytes, the onset potential of the Ti/IrO2-SSN electrode shifted in the positive direction by 0.1 VSCE and 0.4 VSCE, respectively. In 2.0-2.5 V voltages, the concentration in Ti/IrO2-SSN was 2.59-214.6 mg/L Cl2, and Ti/IrO2 was 0.55-49.21 mg/L Cl2. Moreover, the generation of the reactive chlorine species and degradation of Eosin-Y increased by 3.79-7.60 times and 1.06-2.15 times compared with that of Ti/IrO2. Among these voltages, the generation of the reactive chlorine species and degradation of Eosin-Y were the most improved at 2.25 V. Accordingly, in the Ti/IrO2-SSN electrode, it can be assumed that the competitive reaction between chlorine ion oxidation and water oxidation is minimized at an applied voltage of 2.25V.

V2O5WO3/TiO2 Catalyst Prepared on Nanodispersed TiO2 for NH3-SCR: Relationship between D ispersed Particle Size of TiO2 and Maximum Decomposition Temperature of NOx (NH3-SCR용 나노분산 TiO2 담체상에 제조된 V2O5WO3/TiO2 촉매: TiO2 분산입도와 NOx 최대 분해온도와의 상관성)

  • Min Chae, Seo;Se-Min, Ban;Jae Gu, Heo;Yong Sik, Chu;Kyung-Seok, Moon;Dae-Sung, Kim
    • Korean Journal of Materials Research
    • /
    • v.32 no.11
    • /
    • pp.496-507
    • /
    • 2022
  • For the selective catalytic reduction of NOx with ammonia (NH3-SCR), a V2O5WO3/TiO2 (VW/nTi) catalyst was prepared using V2O5 and WO3 on a nanodispersed TiO2 (nTi) support by simple impregnation process. The nTi support was dispersed for 0~3 hrs under controlled bead-milling in ethanol. The average particle size (D50) of nTi was reduced from 582 nm to 93 nm depending on the milling time. The NOx activity of these catalysts with maximum temperature shift was influenced by the dispersion of the TiO2. For the V0.5W2/nTi-0h catalyst, prepared with 582 nm nTi-0h before milling, the decomposition temperature with over 94 % NOx conversion had a narrow temperature window, within the range of 365-391 ℃. Similarly, the V0.5W2/nTi-2h catalyst, prepared with 107 nm nTi-2h bead-milled for 2hrs, showed a broad temperature window in the range of 358~450 ℃. However, the V0.5W2/Ti catalyst (D50 = 2.4 ㎛, aqueous, without milling) was observed at 325-385 ℃. Our results could pave the way for the production of effective NOx decomposition catalysts with a higher temperature range. This approach is also better at facilitating the dispersion on the support material. NH3-TPD, H2-TPR, FT-IR, and XPS were used to investigate the role of nTi in the DeNOx catalyst.

Effect of V$_2$O$_5$ Addition on Microwave Dielectric Properties of (Zr$_{0.8}$,Sn$_{0.2}$)TiO$_4$ (V$_2$O$_5$의 첨가가 (Zr$_{0.8}$,Sn$_{0.2}$)TiO$_4$의 마이크로파 유전특성에 미치는 영향)

  • 이경호
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.8 no.1
    • /
    • pp.27-32
    • /
    • 2001
  • The effect of $V_2O_5$, a donor-type dopant on the degradation of quality factor of ($Zr_{0.8}, Sn_{0.2})TiO_4$was compared with Ta$_2$O$_{5}$ doped ($Zr_{0.8}, Sn_{0.2})TiO_4$ in terms of microstructure, electrical conductivity, and oxidation state of the dopant. It is well known that the addition of the donor type species such as $Ta_2O_5,Nb_2O_5, Sb_2O_5, WO_{3}$, increases the quality factor of ($Zr_{0.8}, Sn_{0.2})TiO_4$due to decrease the oxygen vacancy concentration. Unlike other dopants, however, the addition of $V_2O_5$ decreased the quality factor. The degradation of quality factor of ($Zr_{0.8}, Sn_{0.2})TiO_4$was resulted from the formation of grain boundary phase and $V_2O_5$rich fiber shaped secondary phase, and the increasing the oxygen vacancy concentration due to unstability of oxidation state of vanadium ions in ($Zr_{0.8}, Sn_{0.2})TiO_4$ceramic.c.

  • PDF