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 °C. 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 °C. However, the V0.5W2/Ti catalyst (D50 = 2.4 μm, aqueous, without milling) was observed at 325-385 °C. 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.

We designed new compositions for lead free and low temperature sealing glass frit of ZnO-V2O5-P2O5 system, which can be used for PDP (Plasma Display Panel) or other electronic devices. The ZnO-V2O5-P2O5 system can be used as a sealing material at temperatures even lower than 430˚C. This system, however, showed lower bonding strength with glass substrate compared to commercialized Pb based sealing materials. So, we added TiO2 as a promoter for bonding strength. We examined the effect of TiO2 addition on sealing behaviors of ZnO-V2O5-P2O5 glasses with the data for flow button, wetting angle, temporary & permanent residual stress of glass substrate, EPMA analysis of interface between sealing materials and glass substrate, and bonding strength. As a result, sealing characteristics of ZnO-V2O5-P2O5 system glasses were improved with TiO2 addition, but showed a maximum value at 5 mol% TiO2 addition. The reason for improved bonding characteristics was considered to be the chemical interaction between glass substrate and sealing glass, and structural densification of sealing glass itself.

V2O5-TiO2 catalysts were prepared by various methods. V2O5-TiO2 were prepared by sol-gel method with different drying conditions (aerogel and xerogel), and V2O5 supported on TiO2 obtained by sol-gel method with precipitation-deposition method and impregnation method. The performance of the V2O5-TiO2 catalysts was investigated for the selective oxidation of hydrogen sulfide in the stream containing both ammonia and excess water. All the catalysts showed good dispersion of vanadium and they had high H2S conversion with no or little production of sulfur dioxide. The V2O5-TiO2 aerogel catalyst prepared by sol-gel method with drying under super critical condition had the highest surface area which led to better catalytic activity compared to those by other synthesis methods.

질소산화물 등의 배출규제 강화로 인한 사용처의 확대로 SCR(선택적 촉매 환원) 촉매 수요가 증가하고 있으며, 이에 따라 폐촉매 발생량도 증가할 것으로 예상된다. 폐촉매는 지정폐기물로 분류되어 처리시에 비용이 발생하여, 물리적으로 재생하여 재사용 하거나 유가금속을 회수하는 방법으로 재활용하고 있다. 그러나 재생의 횟수가 제한적이고, 유가금속 회수는 비용이 고가이며 촉매의 85~90%를 차지하는 TiO2가 폐기된다는 문제점이 있다. 따라서, 본 연구에서는 SCR 촉매를 경제적이며 지속적으로 사용하기 위해 피독된 SCR 촉매 내 피독물질만 화학적으로 수세 및 정제하고 유가금속/TiO2의 함량을 높이는 최적의 세정 용매를 도출하는 촉매 재활성을 위한 기초연구를 수행하였다. 비교대상 촉매인 Poisoned 촉매를 5가지 세정용매로 화학적 처리결과, acetic acid 용매가 V2O5 1.19 wt%의 높은 함량과 57.6%의 높은 피독물질 제거효율을 나타내며 다른 산 처리 용매에 비해 촉매 재생성이 높은 것으로 분석되었다. 세정 용매의 농도와 세정 시간에 따른 V2O5 함량과 피독물질 제거효율에 미치는 영향을 알아보기 위해 각각 변수를 두어 실험을 진행하였다. 본 연구를 통해 0.1 N acetic acid로 처리한 촉매가 가장 높은 NOX전환율을 나타냈으며, 유가금속/TiO2 함량 또한 높게 나타나 본 연구 목표에 가장 적합한 세정용매로 판단되었다.

Catalytic activities of V2O5/TiO2 catalyst were investigated under reaction conditions such as reaction temperature, catalyst size, inlet concentration and space velocity. A 1,2-dichlorobenzene(1,2-DCB) concentrations were measured in front and after of the heated V2O5/TiO2 catalyst bed, and conversion efficiency of 1,2-DCB was determined from it's concentration difference. The conversion of 1,2-DCB using a pellet type catalyst in the bench-scale reactor was lower than that with the powder type used in the micro flow-scale reactor. However, when the pellet size was halved, the conversion was similar to that with the powder type catalyst. The highest conversion was shown with an inlet concentration of 100 ppmv, but when the concentration was higher or lower than 100 ppmv, the conversion was found to decrease. Complete conversion was obtained when the GHSV was maintained at below 10,000 h-1, even at the relatively low temperature of 250°C. Water vapor inhibited the conversion of 1,2-DCB, which was suspected to be due to the competitive adsorption between the reactant and water for active sites.

This study examined the catalytic destruction of 1,2-dichlorobenzene on V2O5/TiO2 nanoparticles. The V2O5/TiO2 nanoparticles were synthesized by the thermal decomposition of vanadium oxytripropoxide and titanium. The effects of the synthesis conditions, such as the synthesis temperature and precursor heating temperature, were investigated. The specific surface areas of V2O5/TiO2 nanoparticles increased with increasing synthesis temperature and decreasing precursor heating temperature. In addition, the removal efficiency of 1,2-dichlorobenzene was promoted by a decrease in heating temperature. However, the removal efficiency of 1, 2-dichlorobenzene was decreased by an anatase to rutile phase transformation at temperatures 1,300℃.

V2O5/TiO2 catalyst impregnated ceramic candle filters are in principle, capable of performing shallow-bed dust filtration plus a catalytic reaction, promoted by a catalytic deposited in their inner structure. Pilot-scale V2O5/TiO2 catalyst impregnated ceramic candle filters were prepared, characterized and tested for their activity towards the SCR reaction. The effect on NO conversion of operating temperature, gas hourly space velocity, amount of deposited catalyst, pressure drops and long-term experiment (life of catalytic filter) was determined. The following effects of V2O5/TiO2 catalyst impregnated ceramic candle filters in SCR reaction are observed: (1) It increases the activity and widens the temperature window for SCR. (2) When the content of V2O5 catalyst increases further from 3 to 9wt.%, activity of NO increases. (3) NO conversion at first increases with temperature and then decreases at high temperatures (above 400℃ over), possibly due to the occurrence of the ammonia oxidation reaction.

A (5 wt.%)Mn-(1 wt.%)V2O5/TiO2 catalyst were prepared by co-precipitation method and used for low-temperature selective catalytic reduction (SCR) of NOx with ammonia in the presence of oxygen. The properties of the catalysts were studied by X-ray diffraction (XRD), temperature programmed reduction (TPR) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS). The experimental results showed that (5 wt.%)Mn-(1 wt.%)V2O5/TiO2 catalyst yielded 81% NO conversion at temperature as low as 150℃ and a space velocity of 2,400 h-1. Crystalline phase of Mn2O3 was present at ≥15% Mn on V2O5/TiO2. XRD confirmed the presence of manganese oxide (Mn2O3) at 2θ=32.978°(222). The XRD patterns presented of (5 wt.%)Mn-(1 wt.%)V2O5/TiO2 did not show intense or sharp peaks for manganese oxides and vanadia oxides. The TPR profiles of (5 wt.%)Mn-(1 wt.%)V2O5/TiO2 catalyst showed main reduction peak of a maximum at 595℃.

V2O5/TiO2 catalysts promoted with Mn were prepared and tested for selective catalytic reduction of NOx in NH3. The effects of promoter content, degree of catalyst loading were investigated for NOx activity while changing temperatures, mole ratio, space velocity and O2 concentration. Among the various V2O5 catalysts having different metal loadings, V2O5(1 wt.%) catalyst showed the highest activity(98%) under wide temperature range of 200-250℃. When the V2O5 catalyst was further modified with 5 wt.% Mn as a promoter, the highest activity(90-47%) was obtained over the low temperature windows of 100-200℃. From Mn-V2O5/TiO2, it was found that by addition of 5 wt.% Mn on V2O5/TiO2 catalyst, reduction activity of catalyst was improved, which resulted in the increase of catalytic activity and NOx reduction. According to the results, NOx removal decreased for 10%, but the reaction temperature down to 100℃.