N₂O 분해반응용 Co₃O₄ 기반 촉매의 K첨가 효과

황라현,박지혜,백정훈,임효빈,이광복,Hwang, Ra Hyun,Park, Ji Hye,Baek, Jeong Hun,Im, Hyo Been,Yi, Kwang Bok 한국청정기술학회 2018 청정기술 Vol.24 No.1

$N_2O$ 촉매 분해 반응을 위한 $Co_3O_4$ 촉매는 공침법을 이용하여 제조하였으며, 조촉매로서 Ce 및 Zr의 양을 (Ce 또는 Zr)/Co = 0.05의 몰비로 고정하여 제조하였다. 또한 K가 촉매에 미치는 영향을 조사하기 위해 1 wt%의 $K_2CO_3$를 함침하여 촉매를 제조하였다. 제조된 촉매의 특성은 BET, SEM, XRD, $H_2-TPR$, XPS를 통해 분석하였다. $Co_3O_4$ 촉매는 스피넬 결정상을 나타냈으며, 조촉매의 첨가는 입자 크기와 결정 크기를 감소시켜 비표면적을 증가시키는 것으로 나타났다. K의 도핑은 촉매 활성 물질인 Co의 활성 종인 $Co^{2+}$의 농도를 증가시켜 촉매 활성을 향상시키는 것으로 확인되었다. $N_2O$ 분해 반응 테스트는 $GHSV=45,000h^{-1}$, $250{\sim}375^{\circ}C$에서 수행되었으며 $Co_3O_4$ 촉매에 조촉매를 첨가하였을 때도 반응성이 증가하였지만, K를 함침하면 활성이 더욱 크게 증가하는 것으로 나타났다. K의 도핑이 활성 종인 $Co^{2+}$의 농도를 증가시키며, 환원온도를 낮춰 주어 활성에 큰 영향을 주는 것으로 확인하였다. $Co_3O_4$ catalysts for $N_2O$ decomposition were prepared by co-precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. Also, 1 wt% $K_2CO_3$ was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. The prepared catalysts were characterized with SEM, BET, XRD, XPS and $H_2-TPR$. The $Co_3O_4$ catalyst exhibited a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was confirmed that the doping of K improves the catalytic activity by increasing the concentration of $Co^{2+}$ in the catalyst which is an active site for catalytic reaction. The catalytic activity tests were carried out at a GHSV of $45,000h^{-1}$ and a temperature range of $250{\sim}375^{\circ}C$. The K-impregnated $Co_3O_4$ catalyst showed much higher activity than $Co_3O_4$ catalysts with promoter only. It is found that the K-impregnation increased the concentration of $Co^{2+}$ more than the added of promoter did, and lowered the reduction temperature to a great extent.

N₂O 분해반응용 Co₃O₄ 기반 촉매의 K첨가 효과

황라현(Ra Hyun Hwang),박지혜(Ji Hye Park),백정훈(Jeong Hun Baek),임효빈(Hyo Been Im),이광복(Kwang Bok Yi) 한국청정기술학회 2018 청정기술 Vol.24 No.1

N₂O 촉매 분해 반응을 위한 Co₃O₄ 촉매는 공침법을 이용하여 제조하였으며, 조촉매로서 Ce 및 Zr의 양을 (Ce 또는 Zr)/Co = 0.05의 몰비로 고정하여 제조하였다. 또한 K가 촉매에 미치는 영향을 조사하기 위해 1 wt%의 K₂CO₃를 함침하여 촉매를 제조하였다. 제조된 촉매의 특성은 BET, SEM, XRD, H₂-TPR, XPS를 통해 분석하였다. Co₃O₄ 촉매는 스피넬 결정상을 나타냈으며, 조촉매의 첨가는 입자 크기와 결정 크기를 감소시켜 비표면적을 증가시키는 것으로 나타났다. K의 도핑은 촉매 활성물질인 Co의 활성 종인 Co<SUP>2+</SUP>의 농도를 증가시켜 촉매 활성을 향상시키는 것으로 확인되었다. N₂O 분해 반응 테스트는 GHSV = 45,000 h-1, 250 ~ 375 ℃에서 수행되었으며 Co₃O₄ 촉매에 조촉매를 첨가하였을 때도 반응성이 증가하였지만, K를 함침하면 활성이 더욱 크게 증가하는 것으로 나타났다. K의 도핑이 활성 종인 Co<SUP>2+</SUP>의 농도를 증가시키며, 환원온도를 낮춰주어 활성에 큰 영향을 주는 것으로 확인하였다. Co₃O₄ catalysts for N₂O decomposition were prepared by co-precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. Also, 1 wt% K₂CO₃ was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. The prepared catalysts were characterized with SEM, BET, XRD, XPS and H₂-TPR. The Co₃O₄ catalyst exhibited a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was confirmed that the doping of K improves the catalytic activity by increasing the concentration of Co<SUP>2+</SUP> in the catalyst which is an active site for catalytic reaction. The catalytic activity tests were carried out at a GHSV of 45,000 h-1 and a temperature range of 250 ~ 375 ℃. The K-impregnated Co₃O₄ catalyst showed much higher activity than Co₃O₄ catalysts with promoter only. It is found that the K-impregnation increased the concentration of Co<SUP>2+</SUP> more than the added of promoter did, and lowered the reduction temperature to a great extent.

Effects of metal loading on activated carbon on its adsorption and desorption characteristics

박지혜,황라현,윤형철,이광복 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.74 No.-

Metal loaded activated carbons (AC) were synthesized for an application in NH3 enrichment throughrepeated adsorption and desorption. The metal loaded activated carbons possesses higher NH3adsorption capacity than the raw AC at room temperature. Mg loaded AC (AC–Mg) showed about 10 times(6.34 mg NH3/g) higher adsorption capacity than raw AC and its adsorption capacity was maintained evenin repeated breakthrough tests. Metal loading on activated carbon increased the concentration of surfaceoxygen, which provides relatively weak adsorption sites for NH3 so that the adsorbed NH3 can be releasedrelatively easier compared to the case of raw AC.

매체순환연소를 위한 Ni계열 산소전달입자의 반응 특성 및 반응 모델

박지혜,황라현,백점인,류호정,이광복,PARK, JI HYE,HWANG, RA HYUN,BAEK, JEOM-IN,RYU, HO-JUNG,YI, KWANG BOK 한국수소및신에너지학회 2018 한국수소 및 신에너지학회논문집 Vol.29 No.1

Reaction characteristics and kinetics of a oxygen carrier (OCN717-R1SU) for chemical looping combustion (CLC) have been investigated using TGA by changing gas concentration (10-30 vol.% $CH_4$) and reaction temperature ($825-900^{\circ}C$). Reaction rate of OCN717-R1SU increased as temperature increased and it was found that reaction is delayed at the initial reaction regime. Johnson-Mehl-Avrami (JMA) model was adopted to explain the reaction phenomenon. The activation energy (E) determined by JMA model in reduction reaction of OCN717-R1SU is $151.7{\pm}2.03kJ/mol$ and pre-exponential factor and JMA exponent were also obtained. The parameters calculated in this study will be applied in design of the reactor and operation conditions for CLC process.

Mg 첨가에 따른 수성가스전이반응용 Cu/ZnO/Al2O3 촉매의 활성 연구

박지혜,백정훈,황라현,이광복 한국청정기술학회 2017 청정기술 Vol.25 No.4

To investigate the effect of magnesium oxide addition, Cu/ZnO/MgO/Al2O3 (CZMA) catalysts were prepared using co-precipitation method with fixed molar ratio of Cu/Zn/Mg/Al as 45/45/5/5 mol% for low-temperature water gas shift reaction. Synthesized catalysts were characterized by using BET, N2O chemisorption, XRD, H2-TPR and NH3-TPD analysis. The catalytic activity tests were carried out at a GHSV of 28,000 h-1 and a temperature range of 200 ~ 320 ℃. At the same condition, magnesium oxide added catalyst (CZMA 400) showed that the lowest reduction temperature and stable presence of Cu+, that is active species and abundant weak acid site. Also magnesium oxide added catalysts (CZMA) showed higher catalytic activity at temperature range above 240 ℃ than the catalyst without magnesium oxide (CZA). Consequently, CZMA 400 catalyst is considered to be excellent catalyst showing CO conversion of 77.59% without deactivation for about 75 hours at 240 ℃, GHSV 28,000 h-1. 저온 수성가스전이반응에서 Cu/ZnO/MgO/Al2O3 (CZMA) 촉매의 마그네슘의 영향을 조사하기 위하여 Cu/Zn/Mg/Al의 비율을 45/45/5/5 mol%로 공침법을 사용하여 제조하였다. 제조된 촉매들은 BET, N2O 화학흡착, XRD, H2-TPR and NH3-TPD를사용하여 분석되었다. 촉매 활성 테스트는 GHSV 28,000 h-1와 온도 범위 200 ~ 320 ℃에서 수행되었다. 동일한 조건에서 마그네슘이 첨가된 촉매(CZMA 400)는 가장 낮은 환원 온도를 나타내며 활성종인 Cu+가 안정적으로 존재하고 또한 많은 약산점을 보유하였다. 또한 마그네슘이 첨가된 촉매(CZMA)는 마그네슘이 첨가되지 않은 촉매(CZA)와 비교하였을 때 240 이상의 높은 온도에서 촉매 활성이 증가하였다. CZMA 400 촉매는 최적의 촉매로서 240 ℃, GHSV 28,000 h-1에서 75 h 동안 활성의 저하없이 평균 CO 전환율 77.59%를 나타내었다.

수성가스전이반응(Water Gas Shift Reaction)을 위한 Ce 첨가에 따른 Cu/Mn 촉매의 활성 연구

박지혜,임효빈,황라현,백정훈,구기영,이광복 한국수소및신에너지학회 2017 한국수소 및 신에너지학회논문집 Vol.28 No.1

Cu/Mn/Ce catalysts for water gas shift (WGS) reaction were synthesized by urea-nitrate combustion method with the fixed molar ratio of Cu/Mn as 1:4 and 1:1 with the doping concentration of Ce from 0.3 to 0.8 mol%. The prepared catalysts were characterized with SEM, BET, XRD, XPS, H2-TPR, CO2 TPD, N2O chemisorption analysis. The catalytic activity tests were carried out at a GHSV of 28,000 h-1 and a temperature range of 200 to 400°C. The Cu/Mn(CM) catalysts formed Cu-Mn mixed oxide of spinel structure (Cu1.5Mn1.5O4) and manganese oxides (MnOx). However, when a small amount of Ce was doped, the growth of Cu1.5Mn1.5O4 was inhibited and the degree of Cu dispersion were increased. Also, the doping of Ce on the CM catalyst reduced the reduction temperature and the base site to induce the active site of the catalyst to be exposed on the catalyst surface. From the XPS analysis, it was confirmed that maintaining the oxidation state of Cu appropriately was a main factor in the WGS reaction. Consequently, Ce as support and dopant in the water gas shift reaction catalysts exhibited the enhanced catalytic activities on CM catalysts. We found that proper amount of Ce by preparing catalysts with different Cu/Mn ratios.

Mg 첨가에 따른 수성가스전이반응용 Cu/ZnO/Al₂O₃ 촉매의 활성 연구

박지혜,백정훈,황라현,이광복,Park, Ji Hye,Baek, Jeong Hun,Hwang, Ra Hyun,Yi, Kwang Bok 한국청정기술학회 2017 청정기술 Vol.23 No.4

저온 수성가스전이반응에서 $Cu/ZnO/MgO/Al_2O_3$ (CZMA) 촉매의 마그네슘의 영향을 조사하기 위하여 Cu/Zn/Mg/Al의 비율을 45/45/5/5 mol%로 공침법을 사용하여 제조하였다. 제조된 촉매들은 BET, $N_2O$ 화학흡착, XRD, $H_2-TPR$ and $NH_3-TPD$를 사용하여 분석되었다. 촉매 활성 테스트는 GHSV $28,000h^{-1}$와 온도 범위 $200{\sim}320^{\circ}C$에서 수행되었다. 동일한 조건에서 마그네슘이 첨가된 촉매(CZMA 400)는 가장 낮은 환원 온도를 나타내며 활성종인 $Cu^+$가 안정적으로 존재하고 또한 많은 약산점을 보유하였다. 또한 마그네슘이 첨가된 촉매(CZMA)는 마그네슘이 첨가되지 않은 촉매(CZA)와 비교하였을 때 240 이상의 높은 온도에서 촉매 활성이 증가하였다. CZMA 400 촉매는 최적의 촉매로서 $240^{\circ}C$, GHSV $28,000h^{-1}$에서 75 h 동안 활성의 저하없이 평균 CO 전환율 77.59%를 나타내었다. To investigate the effect of magnesium oxide addition, $Cu/ZnO/MgO/Al_2O_3$ (CZMA) catalysts were prepared using co-precipitation method with fixed molar ratio of Cu/Zn/Mg/Al as 45/45/5/5 mol% for low-temperature water gas shift reaction. Synthesized catalysts were characterized by using BET, $N_2O$ chemisorption, XRD, $H_2-TPR$ and $NH_3-TPD$ analysis. The catalytic activity tests were carried out at a GHSV of $28,000h^{-1}$ and a temperature range of $200{\sim}320^{\circ}C$. At the same condition, magnesium oxide added catalyst (CZMA 400) showed that the lowest reduction temperature and stable presence of $Cu^+$, that is active species and abundant weak acid site. Also magnesium oxide added catalysts (CZMA) showed higher catalytic activity at temperature range above $240^{\circ}C$ than the catalyst without magnesium oxide (CZA). Consequently, CZMA 400 catalyst is considered to be excellent catalyst showing CO conversion of 77.59% without deactivation for about 75 hours at $240^{\circ}C$, GHSV $28,000h^{-1}$.

Effects of steam introduction on deactivation of Fe-BEA catalyst in NH3-SCR of N2O and NO

백정훈,이수민,박지혜,정정민,황라현,고창현,전상구,최태훈,이광복 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.48 No.-

The effects of water vapor on the catalytic activity of a Fe-BEA catalyst in the NH3-SCR reaction for N2Oand NO were investigated using diffusive reflectance infrared Fourier transform spectroscopy (DRIFTS)tests and SCC-DFTB calculation. It was found that water vapor only decreased the N2O conversion rate anddid not affect the conversion rates of NO. The DRIFTS analysis revealed that the presence of waterincreased the adsorption strength of nitrous oxide (N2O) on the catalyst surface. On the other hand, nitricoxide (NO) conversion route was only altered from NO2-SCR to standard selective catalytic reduction(SCR) upon injection of water vapor. It was confirmed that the water vapor not only inhibited thedesorption of N2O during the reduction step but also induced stronger adsorption of N2O during the NH3-SCR reaction. A computational chemical model that includes hydroxyl zeolite, N2O, and NO supported theexperimental result showing binding force between the hydroxyl zeolite and N2O is much higher thanthat between hydroxyl zeolite and NO. It is believed that the stronger adsorption induced by water vaporcaused delayed dissociation of N2O thereby not allowing for catalytic conversion.

Effect of acid treatment of Fe-BEA zeolite on catalytic N2O conversion

정정민,박지혜,백정훈,황라현,전상구,이광복 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1

The effect of acid treatment on the physical and chemical characteristics of BEA zeolite, as well as the catalytic activity of the Fe-BEA catalyst for N2O reduction under NH3-selective catalytic reduction (NH3-SCR) conditions, was examined. The acid treatment caused dealumination of BEA and enrichment of the silanol groups on vacant Tsites and the Brønsted acid sites. As the acid treatment time increased, the silanol groups and the weak acid sites in BEA also increased. Because the weak acid sites behave as anchoring sites for Fe ions, the catalytic activity also increased as the treatment time increased. However, extended exposure of BEA to acid decreased the catalytic activity of the Fe-BEA catalyst somewhat, and decreased the silanol groups and weak acid sites. The catalytic activity and the amount of weak acid sites were well correlated with the BEA acid treatment time.

NH₃-SCR 반응에서 스팀 처리된 zeolite BEA 촉매의 영향

박지혜(Ji Hye Park),조광희(Gwang Hee Cho),황라현(Ra Hyun Hwang),백정훈(Jeong Hun Baek),이광복(Kwang Bok Yi) 한국청정기술학회 2020 청정기술 Vol.26 No.2

아산화질소(N₂O)는 6대 온실가스 중 하나로 이산화탄소(CO₂)의 310배에 해당하는 지구온난화지수(global warming potential, GWP)를 나타내어 N₂O를 저감하는 것은 필수적이다. 선택적 촉매환원법(selective catalytic reduction, SCR)은 대기 오염 물질의 하나인 NOx의 제거를 위해 암모니아를 환원제로 사용하여 무해한 N₂ 및 H₂O로 전환하는 기술로 높은 탈질효율을 나타낸다. 본 연구에서는NH₃-SCR반응에서 스팀 처리된 Fe-BEA촉매가 활성에 미치는 영향을 조사하기 위하여 Fe-BEA 촉매는 Fe를 이온교환하기 전, 고정층 반응기로 100℃에서 2h 동안 스팀 처리 되었다. 제조된 촉매의 NH₃-SCR반응 테스트는 고정층 반응기로 WHSV = 180 h<SUP>-1</SUP>, 370 ~400℃에서 수행되었다. 100℃ 에서 스팀 처리된 Fe-BEA(100) 촉매가 370 ~ 390℃에서 Fe-BEA촉매보다 다소 높은 활성을 나타내었다. NH₃-SCR 활성에 영향을 주는 원인을 파악하기 위하여 제조된 촉매는 BET, ICP, NH₃-TPD, H₂-TPR, <SUP>27</SUP>Al MAS NMR을 통하여 특성분석 되었다. H₂-TPR결과를 통해 Fe-BEA(100) 촉매가 Fe-BEA 촉매 보다 isolated Fe<SUP>3+</SUP>의 환원이 더 많이 일어난 것을 확인하였으며, 스팀 처리는 활성종인 isolated Fe<SUP>3+</SUP>의 양을 늘려주어 활성이 증가한 것으로 판단된다. Nitrous oxide (N₂O) is one of the six greenhouse gases, and it is essential to reduce N₂O by showing a global warming potential (GWP) equivalent to 310 times that of carbon dioxide (CO₂). Selective catalytic reduction (SCR) is a technology that converts ammonia into harmless N₂ and H₂O by using ammonia as a reducing agent to remove NOx, one of the air pollutants; the process also produces high denitrification efficiency. In this study, the Fe-BEA catalyst was steam-treated at 100°C for 2h before Fe ion exchange in the fixed bed reactor in order to investigate the effect of the steam-treated Fe-BEA catalyst on the NH₃-SCR reaction. NH₃-SCR reaction test of synthesized catalysts was performed at WHSV = 180 h<SUP>-1</SUP>, 370 to 400°C in the fixed bed reactor. The Fe-BEA(100) catalyst steam-treated at 100 °C showed a somewhat higher activity than the Fe-BEA catalyst at 370 to 390 °C. The catalysts were characterized by BET, ICP, NH₃-TPD,H₂-TPR, and <SUP>27</SUP>Al MAS NMR in order to determine the cause affecting NH₃-SCR activity. The H₂-TPR result confirmed that the Fe-BEA(100) catalyst had a higher reduction of isolated Fe<SUP>3+</SUP> than the Fe-BEA catalyst, and that the steam treatment increased the amount of isolated Fe<SUP>3+</SUP> as an active species, thus increasing the activity.