• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.271-275
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• 2019

Anodic $TiO_2$ nanotubes were simultaneously grown and doped with $RuO_2$ by single-step anodization in a negatively-charged $RuO_4{^-}$ precursor. Subsequently, a high positive voltage was imposed on the nanotubes in an $F^-$-based electrolyte (a process referred to as potential shock), which led to the formation of a through-hole $RuO_2$-doped $TiO_2$ nanotube membrane without significant loss of the $RuO_2$ catalyst. XPS results confirmed that the doped Ru metal was converted into $RuO_2$ as the potential shock voltage increased. Further increases in the potential shock voltage led to the formation of $RuO_x/Ru$ in the $TiO_2$ nanotubes. All of our results clearly showed that a through-hole catalyst-doped $TiO_2$ nanotube membrane can be produced by a sequence consisting of single-step anodization and the potential shock process.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.793-801
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• 1996

The effect of catalysts which was catalyzed by acid($HNO_3$) and base ($NH_4OH$) or not on the surface microst-ructures and consequent dielectric characteristics of the $PbTiO_3$ thin films prepared by sol-gel method were investigated. The result indicated that bse catalyst promoted the phase transformation of perovskite phase while acid catalyst was found to produce most uniform surface microstructure and improved dielectric properties However degradation of properties due to secondary phase formation and non-uniform microstructure at high annealing temperature (>75$0^{\circ}C$) by rapid diffusion of lead was unavoidable in any case as long as $Si_{(100)}$ \ $SiO_2$ \Pt substrate used.

• Clean Technology
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• v.17 no.4
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• pp.370-378
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• 2011

Catalytic activity of $V_2O_5-WO_3/TiO_2$-based SCR catalyst was examined for the oxidation of gas-phase elemental mercury to oxidized mercury. Mercury species was not detected on the commercial SCR catalyst after the oxidation reaction of elemental mercury, regadless of the presence of HCl acting as oxidant and the reaction conditions. This suggests that elemental mercury oxidation by HCl could occur via a Eley-Rideal mechanism with gas phase or weakly-bound mercury on the surface of $V_2O_5-WO_3/TiO_2$ SCR catalyst. The activity for mercury oxidation was significantly increased with the increase of $V_2O_5$ loading, which indicates that $V_2O_5$ is the active site. However, turnover frequency for mercury oxidation was decreased with the increase of $V_2O_5$ loading, indicating the activity for mercury oxidation was strongly dependent on the surface structure of vanadia species. The activity for oxidation of elemental mercury under SCR condition was much less than that under oxidation condition at the same HCl concentration and reaction temperature.

• Journal of Environmental Science International
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• v.12 no.10
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• pp.1071-1077
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• 2003

The aim of this study is, firstly, to find out what kinds of inorganic species are produced in the photocatalytic oxidation of ammonium-nitrogen containing water and, secondly, to seek the influence of anion for the photocatalytic oxidation of ammonium contained compounds. The photoenergy above 3 eV(λ <415 nm) was effectively absorbed by TiO$_2$ and TiO$_2$/polymer was used to be oxidized NH$_4$-N in wastewater to NO$_3$-N. Existing the anion as Cl$\^$-/, the rate of photocatalytic oxidation decreased regardless of other condition. This result showed that the chloride ions reduced the rate of oxidation by scavenging oxidizing radical species as OH$\^$-/ and OCl$\^$-/. Some of the added ion might have blocked the active sites of the catalyst surface, thus deactivated the catalyst.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.376-381
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• 2008

The deactivation of $V/TiO_2$ catalyst used in SCR (Selective Catalytic Reduction) using ammonia as a reductant to remove the nitrogen oxides (NOx) in the exhaust gas from fired power plant has been studied. The activity and surface area of the catalyst (Used-cat) which was exposed to the exhaust gas for long period have considerably decreased. The characterizations of these SCR catalysts were performed by XRD, FT-IR, FE-SEM, and IC/ICP. The crystal structure of $TiO_2$ both fresh and used catalyst has not been changed. However, $(NH_4)HSO_4$ deposited on the used catalyst surface verified from FT-IR, FE-SEM, and IC/ICP analysis. Moreover, the durability of $SO_2$ was increased by diminishing sulfate ($SO_4^{-2}$)f form.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.451-463
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• 2004

The performance of disk-type catalytic filters impregnated by TiO$_2$ or TiO$_2$-3Al$_2$O$_3$ㆍ 2SiO$_2$ supports and V$_2$O$_{5}$ catalyst was evaluated for selective catalytic reduction (SCR) of NO with ammonia as a reductant. XRD, FT -IR, BET and SEM were used to characterize the catalytic filters prepared in this work. Optimal V$_2$O$_{5}$ loading and reaction temperature for V$_2$O$_{5}$/TiO$_2$ catalytic filters were 3-6 wt.% and 350-40$0^{\circ}C$ at GHSV 14,300 $hr^{-1}$ in the presence of oxygen, respectively. With increasing the V$_2$O$_{5}$ loading from 0.5 to 6 wt%, NO conversion increased from 24 to 96% at 40$0^{\circ}C$ and 14.300$hr^{-1}$, and maintained at 80% over in the V$_2$O$_{5}$ loading range of 3-6 wt.% and then dropped at V$_2$O$_{5}$ loading of 7wt.% over. In comparing V$_2$O$_{5}$/ TiO$_2$ and V$_2$O$_{5}$/ TiO$_2$-3Al$_2$O$_3$ㆍ2SiO$_2$ catalytic fillers, which have same 3wt.% V$_2$O$_{5}$ loading, the V$_2$O$_{5}$/ TiO$_2$-3A1$_2$O$_3$ㆍ2SiO$_2$ catalytic filter showed higher activity than V$_2$O$_{5}$/ TiO$_2$ catalytic filter, but higher differential pressure drops owing to its low air permeability. low air permeability.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.54-60
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• 2008

Deactivation of SCR catalyst applied in Orimusion fuel power plant was investigated to develope the technique for the regeneration of deactivated SCR catalyst and optimize the operation of SCR facility. The characterization study of the catalysts was carried out using XRD, ICP-AES, SEM and EDS. The NO$_X$ removal activity and SO$_2$ oxidation activity of the catalysts were measured. The NO$_X$ conversion of the deactivated catalyst was 5$\sim$10% lower than that of the fresh catalyst and the value of SO$_2$conversion to SO$_3$ over the deactivated catalyst was about 0.59% higher than that of the fresh catalyst. Vanadium(V), Magnesium(Mg) and Sulfur(S) were largely accumulated in the deactivated catalyst. The accumulation of Vanadium(V) and Sulfur(S) is due to the components of the Orimulsion fuel and the accumulation of Magnesium(Mg) is due to MgO that is injected in the boiler to prevent the oxidation of SO$_2$ to SO$_3$. The diffraction line of the TiO$_2$ of the deactivated catalyst was identified as the crystalline peaks of anatase as the fresh catalyst.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2870-2874
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• 2011

Soil pollution around railroad has been occurred mainly by diesel and lubricant oil, which is difficult to treat due to high carbon number. In this study, we investigated the feasibility of inorganic-inorganic nanohybrid photo-catalyst for the remediation of diesel-contaminated railroad soil. Generally, the $TiO_2$ nanoparticle easily removes organic pollutants due to photo and natural clay of layer structure. Also, montmorillonite (MMT) have an excellent absorption property with organic component. So, we prepared $TiO_2$ pillared MMT nanohybrid photo-catalyst as a chemical oxidant through the integration of theses advantage. As a result, the removal efficiency of diesel was more than 45% at a laboratory-scale test with diesel concentration and the amount of $TiO_2$-MMT. In future, we will improve the removal efficiency of diesel to optimize experimental parameters and apply the field soil The remediation method using photo-catalyst can be used to clean up the railroad soil polluted with high concentration instead of common methods such as soil washing, bioremediation, etc..

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.4
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• pp.431-438
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• 2005

In order to apply the photocatalytic decomposition of aromatic VOCs, adsorbent prepared from MSWI fly ash was coated by $TiO_2$ solution to endow with photo-catalytic function. The effects of coating number, existence of light source and the type of $TiO_2$ solution used for coating were examined. Adsorbent coated with amorphous $TiO_2$ solution showed higher adsorptivity than adsorbent coated with crystal $TiO_2$ solution. Without light source, breakthrough curve of photo -catalyst absorbent for VOCs removal was similar to that of absorbent made from MSWI fly ash. On the other hand, breakthrough time was enlarged with light source and total removal efficiency of benzene and toluene was also increased. It can be explained as photo-decomposition effect of $TiO_2$ photo-catalyst. Total removal efficiency of benzene and toluene was increased according to the increase of coating number with light source. It was due to the effect of adsorption and photo reaction of photo-catalytic adsorbent. But total removal efficiency of benzene was lower than that of toluene. Because benzene was removed more effectively than toluene by adsorption, but photo - decomposition effect oi toluene was more high than benzene.

• Journal of the Korean Ceramic Society
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• v.45 no.1
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• pp.43-47
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• 2008

The photocatalyst of $TiO_2$ coated on a fly ash composites (TCF) was prepared from precipitant dropping method to remove the acetaldehyde by photocatalytic reaction. The TCF were characterized by crystal aize, crystal structure and specific surface area. The photodegradation of acetaldehyde has been investigated using a UV-illuminated fixed photocatalytic reactor with TCF catalyst and P-25 catalyst in gas phase. The effect of photodegradation reaction conditions, such as initial concentration of acetaldehyde, concentration of oxidant in mixed gas and the light intensity on the photodegradation of acetaldehyde were investigated. P-25 catalyst showed the highest photodegradation of acetaldehyde and anatase $TiO_2$ coated TCF showed higher decomposition rate than rutile coated TCF. The photodegradation rate of acetaldehyde increased with the decrease of flow rate, initial concentration of acetaldehyde ($C_i$) and water vapor, however, it was increased with the increas of UV light intensity. The optimum conditions were weight of TCF=10 g, flow rate=50 ml/min $C_i$=100 ppm, concentration of oxygen=20%, concentration of water vapor=100 ppm.