• Environmental Engineering Research
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• v.10 no.1
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• pp.31-37
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• 2005

The selective catalytic experiments using both sulfated/sulfur-free titania and V2O5/TiO2 catalysts have been conducted for NO reduction by NH3 in a packed-bed, down-flow reactor. The sulfated and vanadia loaded titania exhibited higher activity for NO removal than the sulfur-free catalysts, where > 90% NO removal was achieved over the sulfated V2O5/TiO2 catalyst between 280∼500 C. The surface structure of vanadia species on the catalyst surface played a critical role in the high performance of catalysts in which the existence of monomeric/polymeric vanadate is revealed by Raman spectra studies. Water vapor and SO2 were added to the reacting system for the catalyst deactivation tests. At higher temperatures (T ≥ 350 C), little deactivation was observed over the sulfated V2O5/TiO2 catalysts, showing good durability against SO2 and water vapor, which is compared with deactivation at lower temperatures.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.576-580
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• 2017

In the present paper, the thermal deactivation characteristics of plate-type commercial $V_2O_5-WO_3/TiO_2$ SCR catalyst were investigated. For this purpose, the plate-type catalyst was calcined at different temperatures ranging from $500^{\circ}C$ to $800^{\circ}C$ for 3 hours. Structural and morphological changes were characterized byXRD, specific surface area, porosity, SEM-EDS and also NOx conversion with ammonia according to the calcine temperature. The NOx conversion decreased with increasing calcine temperature, especially when the catalysts were calcined at temperatures above $700^{\circ}C$. This is because the crystal phase of $TiO_2$ changed from anatase to rutile, and the $TiO_2$ grain growth and $CaWO_4$ crystal phase were formed, which reduced the specific surface area and pore volume. In addition, $V_2O_5$, which is a catalytically active material, was sublimated or vaporized over $700^{\circ}C$, and a metal mesh used as a support of the catalyst occurred intergranular corrosion and oxidation due to the formation of Cr carbide.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.101-107
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• 1999

$TiO_2$ and $xTiO_2-ySiO_2$ system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area was measured. Considering the efficiency of the ethanol decomposition using the catalyst, the conclusion was made as follows: 1) By means of X-ray analysis of $TiO_2$ powder that is obtained from water and Titanium alkoxide with various molar ratios, it is shown that structure of crystallization is a dominating structure and, on the other hand, the crystallization of rutile also partly exists. The specific surface area is at its maximum value at R=6, which is the molar ratio of water vs. alkoxide, whereas its value goes down as the molar ratio increases. In the reaction of using $TiO_2$ catalyst, the ethanol is decomposed into the extent of 15 ~30% in an hour and three hours are necessitated for 70% decomposition. 2) $TiO_2/SiO_2$ powder is developed from Titanium and Silicon alkoxide by a hetero-condensation process. The increase of SiO$_2$ contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. In the decomposition reaction of the ethanol, the decomposition efficiency represents 25~60% in an hour. It is, however, examined that the efficiency inactively increases corresponding to the duration of reaction time. It is shown that more than 90% of ethanol is decomposed when reaction time is about three hours and the efficiency illustrates the maximum value for 60-$TiO_2/4O-SiO_2$ catalyst.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.28.2-28.2
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• 2011

The selective catalytic reduction (SCR) of NOx by $NH_3$ is well known as one of the most convenient, efficient, and economical method to prevent NOx emission in flue gas from stationary sources. The degradation of the reactivity is the obstacle for its real application, since high concentrations of sulfur dioxide and thermal factor would deactivate the catalyst. It is necessary to develop high stability of catalysts for low-temperature SCR. Among the transition metal oxides, $WO_3$ is known to exhibit high SCR activity and good thermal stability. The $MnOx-WO_3-TiO_2$ catalysts prepared by sol-gel method with various $WO_3$ contents were investigated for low-temperature SCR. These catalysts were observed in terms of micro-structure and spectroscopy analyses. The $WO_3$ catalyst as a promoter is used to enhance the thermal stability of catalyst since it increases the phase transition temperature of $TiO_2$ support. It was found that the addition of tungsten oxides not only maintained the temperature window of NO conversion but also increased the acid sites of catalyst.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.284-284
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• 2012

In this study, $V_2O_5/TiO_2$ catalyst was measured reactivity of ethanol when vanadia ratio was increasing. First, $V_2O_5/TiO_2$ catalyst was prepared to the increasing vanadia ($VO_x$) ratio as 0.2, 1, 10 wt%. And we were used X-ray diffraction (XRD), then not appear markedly peak to pure vanadia about XRD analysis. So we were decided vanadia that was evenly dispersed on $TiO_2$. Result about temperature-programmed reduction (TPR) analysis was obtained 3 reactions that was dehydrogenationfrom obtained to acetaldehyde, dehydration from obtained to ethylene, condensation from obtained to diethyl ether. If vanadia ratio was increasing in $V_2O_5/TiO_2$, reactions temperature of ethanol was known lower. And condensation into diethyl ether is quenched away with increasing vanadia loading. In addition, competition between reductive dehydration and oxidative dehydrogenation occurs, while the selectivity toward dehydrogenation is favored with increasing vanadia loading.

• Korean Journal of Materials Research
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• v.17 no.10
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• pp.548-554
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• 2007

[ $BaTiO_3$ ] thick film by an interfacial polymerization method was prepared at the liquid/liquid interface between benzyl alcohol saturated solution with the basic catalyst [diethyl amine ($NHEt_2$) or triethylamine ($NEt_3$)], and the water dissolved with $TiO_2$ and $Ba(CH_3COO)_2$. The film thickness increased gradually with an increase in diethyl amine($NHEt_2$) or triethylamine($NEt_3$) volume and the reaction time. The homogeneity of $BaTiO_3$ thick film after sintered at $600^{\circ}C$ was confirmed by EPMA analysis, which showed that both of Ba and Ti element were homogeneously distributed on the surface as well as in the perpendicular direction of the film. The thickness of $BaTiO_3$ film obtained by this process was $8.75\;{\mu}m$.

• Journal of Electrochemical Science and Technology
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• v.5 no.2
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• pp.45-48
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• 2014

$TiO_2$ nanoparticles (NPs) with a diameter of 100 nm were synthesized by a simple hydrothermal route at $220^{\circ}C$ and then processed for a possible alternate cathode catalyst material in the lithium-oxygen batteries. It was found that when $TiO_2$ nanoparticles were utilized as cathodes, substantial improvements in the discharge capacity, cycle ability, rate capability and low overpotential were observed. This can be attributed to its high catalytic activity and large surface area.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.859-869
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• 2005

The commercial $V_2O_5-WO_3/TiO_2$ catalysts which had been exposed to the off gas from incinerator for a long time were regenerated by physical and chemical treatment. The catalytic properties and NOx conversion reactivity of those catalysts were examined by analysis equipment and NOx conversion experiment. The characterization of the catalysts were performed by XRD(x-ray diffractometer), BET, POROSIMETER, EDX(energy dispersive x-ray spectrometer), ICP(inductively coupled plasma), TGA(thermogravimetric analyzer) and SEM (scanning electron microscopy). NOx conversion experiment were performed with simulated off gas of the incinerator and $NH_3$ was used as a reductant of SCR reaction. Among the regeneration treatment methods which were applied to regenerate the aged catalysts in this study, it showed that the heat treatment method had excellent regeneration effect on the catalytic performance for NOx conversion. The catalytic performance of the regenerated catalysts with heat treatment method were recovered over than 95% of that of fresh catalyst. For the regenerated catalysts with the acid solution(pH 5) and the alkali solution(pH 12), the catalytic performance were recovered over than 90% of that of fresh catalyst. From the characterization results of the regenerated catalysts, the specific surface area was recovered in the range of $85{\sim}95%$ of that of fresh catalyst. S and Ca element, which are well known as the deactivation materials for the SCR catalysts, accumulated on the aged catalyst surface were removed up to maximum 99%. Among the P, Cr, Zn and Pb elements accumulated on the aged catalyst surface, P, Cr and Zn element were removed up to 95%. But the Pb element were removed in the range of $10{\sim}30%$ of that of fresh catalyst.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.494-498
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• 2013

In this study, selective catalytic oxidation (SCO) of $NH_3$ using $Ce/TiO_2$ catalyst was examined to control the slipped NH3 from various pollutants. It was found that the catalytic activity increased with increasing the Ce loadings till reaching 10 wt% Ce loading. However, when Ce loaded over 10 wt%, the activity of catalysts rather decreased than that of catalysts, below 10 wt% Ce. Therefore, the composition of $Ce/TiO_2$ catalyst optimized in this study can be applied to industrial fields.

• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.516-523
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• 2021

A study using selective catalytic reduction (SCR) was conducted in conjunction with ammonia as a reducing agent for controlling nitrogen oxides, a typical secondary inducer of fine dust in the atmosphere. For NH₃-SCR experiments, a commercial catalyst of V/W/TiO₂ only and also V/W-Sb/TiO₂ catalyst with Sb were used, and phosphorous durability was confirmed. As a result of NH₃-SCR experiments, it was confirmed that the addition of Sb to V/W/TiO₂ had durability against phosphorous. In addition, the physical and chemical properties were comparatively analyzed through BET, XPS, H₂-TPR, NH₃-TPD, and FT-IR analysis. From the anaylsis results, when Sb was added to V/W/TiO₂ catalyst, P was also added resulting in the formation of SbPO₄ and the generation of VOPO₄ was suppressed. The phosphorous durability was confirmed by maintaining the redox characteristics of the catalyst before P was added.