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Tailored synthesis of graphene supports for high performance low temperature SCR catalysts
예보라,김홍대,정보라 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Selective Catalytic Reduction technology is a typical technique used to remove Nitrogen oxides (NOx), which is a major source of industrial particulate matter (PM). Recently, as the application of SCR catalysts are expanded, the needs for the low temperature SCR catalyst which have high NOx removal efficiency at low temperature region ( 250 ℃) increased. In this study, various types of graphene supports were applied to improve the dispersion properties of active materials in order to synthesize SCR catalysts with high NOx removal characteristics. Since the catalytic reaction is surface reaction, graphene supports having higher dispersion characteristics are applied such as rGO, GO, porous graphene and surface treated graphene with N containing functional groups to enhance the catalytic acidity. As results, N-doped graphene added catalysts have high NOx removal characteristic of 90% at 200 ℃ based on its high thermal stability, dispersion characteristics and surface area properties.
Highly dispersed nanocatalyst using modified support for NH<sub>3</sub>-SCR reaction
예보라,정보라,김진우,정승재,김홍대 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
These days, there are several issues such as expanding the operating temperature range and demanding higher NO<sub>x</sub> removal efficiency for SCR catalysts. In order to increase the NO<sub>x</sub> removal efficiency, it is most important to increase the catalytic reaction site through improvement of specific surface area and to disperse the catalytically active particles on the overall catalyst. When the active materials have low dispersibility, there is a problem that the activity is lowered through catalyst aggregation and crystallization as the content of catalytic materials increases. Here, we conducted a study of nano-dispersing active particles through using the modified graphene support or surface treated TiO<sub>2</sub>. By adding these support, active materials could be evenly dispersed on the catalyst surface which has abundant anchoring sites with improved specific surface area. And as results, these developed catalyst exhibit high catalytic activity in the wide temperature window.
Bora Jeong(정보라),Myeung-jin Lee(이명진),Bora Ye(예보라),Seung-Yeop Chun(전승엽),Taewook Kim(김태욱),Hong-Dae Kim(김홍대) 한국에너지기후변화학회 2021 한국에너지기후변화학회 학술대회 Vol.2021 No.5
Regulation of air pollution (e.g., EURO 6, TIER 3) has been strengthened in many jurisdictions due to the occurrence of problems such as particulate matter (PM). At present, selective catalytic reduction (SCR) is the most effective method to control NOX emissions. Industrial V2O5-WO3/TiO2 catalysts (usually containing 0.5–3wt% V2O5 and 5–10wt% WO3) exhibit high de-NOX efficiency, and excellent resistance to sulfur (SO2) and H2O. Nevertheless, they also have several disadvantages such as high and narrow effective temperature range(300–400°C), and a tendency to oxidize SO2 to SO3. Therefore, SCR catalysts with high de-NOX efficiency at lower operating temperatures are required in order to obtain economic benefits and reduced energy consumption. Typically, silica has a good candidate to improve catalytic properties such as led to generation acid site, specific surface area, thermal stability. In this reason, enhanced the SCR catalyst property by using colloidal silica and glass fiber. The aim of this work, we confirmed the effect of silica on the chemi-physical properties and de-NO<sub>X</sub> efficiency of vanadium based catalyst. These synthesized catalysts were analyzed by BET, TPD, FT-IR and catalytic performances using fixed-bed reactor in the range of 200-450°C.
BaO가 담지된 V2O5-WO3/TiO2 SCR 촉매의 질소산화물 흡, 탈착 특성 및 제거 효율
김진우,예보라,이민우,정보라,이덕현,이희수,김홍대 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.4
Recently, directly emitted NOx upon start-up has been spotlighted as a significant emissions problem. BaO loaded V2O5-WO3/TiO2 Selective Catalytic Reduction (SCR) catalysts were synthesized with various contents of barium which was a representative NOx adsorbent and their NOx adsorption, desorption, and removal efficiency were shown. The phase of BaO was changed to a BaO or BaCO3 phase, which is capable of NOx adsorption when loaded on the TiO2 support. The more BaO contents were increased, the higher the intensity of Ba2+, the NOx adsorption site, measured by FT-IR. Also, NOx storage capacities of the BaO loaded catalysts, which contained 5 wt% and 10 wt% of BaO, were calculated to be 12.59 μmol/g and 20.21 μmol/g at 200 °C respectively. The improvement in NOx storage capacity was explained by the increase in BaO content. And then the BaO loaded catalyst desorbed NOx in the temperature range of 345 to 360 °C, which was the catalyst operating temperature. The NOx removal efficiency increased by reducing BaO content, and the catalyst loaded with 3 wt% of BaO showed 98% NOx removal efficiency at 350 °C. The adsorbed NOx at 200 °C was desorbed at 300~400 °C and then removed by the SCR reaction. The synthesized NOx trap functional SCR catalyst can be applied to reduce the NOx generated at the time of equipment start-up at low temperatures.
김진우,예보라,김태욱,이희수,김홍대 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
선택적 촉매 환원법 (Selective Catalytic Reduction; SCR)은 인체 및 환경에 유해한 NOx를 제거하는 배연탈질 기술로 강화되는 대기환경 규제 대응을 위해 대표적으로 활용되는 기술이다. 고정원에서 주로 상용화 되어있는 V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2</sub> (VW/Ti) 계 SCR 촉매는 300-400°C의 제한된 영역에서 90% 이상의 높은 NOx 저감 효율을 나타내지만, 장비의 시동운전과 같은 저온 구동 (Start up) 환경에서 발생한 NOx는 촉메에 의해 제거되지 못하고 대기 중으로 그대로 배출되어 문제가 되고 있다. 본 연구에서는 활성온도 이하에서 NOx를 흡착하였다가 활성온도에서 NOx를 탈착과 동시에 제거하는 SCR 촉매를 설계하였다. SCR 촉매인 VW/Ti 촉매의 NOx 흡착 성능을 개선하기 위해 대표적인 NOx 흡착제인 Barium과 반응에 필요한 산소를 활성물질에 공급하는 조촉매인 Ceria를 함침법을 이용하여 담지하였다. 분석 결과 기존 촉매 대비 저온에서 높은 NOx 흡착 성능을 나타내는 것을 확인하였고 촉매 활성온도 영역인 300-350°C에서 탈착거동을 확인하였다. 또한, 탈질평가를 통해 약 90%의 탈질효율을 확인하여 담지 후에도 활성저하가 없는 것을 확인하였다.
2LO-17 V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>-TiO<sub>2</sub> 분산 RGO 적용 SCR 촉매의 향상된 NOx 저감효율
이민우,예보라,이희수,김홍대 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
현재 대표적인 NOx 저감기술인 V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2</sub>계 SCR 촉매는 주성분으로 바나듐(V)과 텅스텐(W)이 사용된다. 이 두 물질은 희금속으로 지속적인 수요의 증가로 가격상승의 문제, 또한 환경 및 인체에 악영향을 미치는 중금속으로 사용량 절감이 필요하다. 이에, 본 연구에서는 높은 비표면적의 특성을 가지는 RGO를 촉매의 담지체로 사용하여 V, W의 함량을 줄임에도 고효율의 NOx 저감 촉매를 제조하였다. 고정층반응기를 통해 제조된 촉매의 탈질성능 분석 결과, standard 촉매와 동일한 함량의 촉매성분으로 제조한 RGO 첨가 촉매의 효율이 최고 89%로 약 1.2배 향상된 결과를 확인하였고, 표면반응을 하는 촉매의 활성에 중요한 역할을 하는 비표면적 또한 약 1.5배 높은 것을 확인하였다. 또한, TEM을 이용한 형상 분석으로 표면에서의 활성물질의 분산을 확인하였으며, 구조, 성분, 산점 등의 분석을 통해 standard 촉매에 비해 RGO 첨가 촉매의 높은 효율 및 향상된 촉매특성을 확인하였다.