• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.319-319
• /
• 2011

Hydrolysis of sodium borohydride provides a safe and clean approach to hydrogen generation. Having the proper catalytic support for controlling this reaction is therefore a valuable technology. Here we demonstrate the capability of hydroxyapatite as a novel catalytic support material for hydrogen generation. Aside from being inexpensive and durable, we reveal that Ru ion exchange on the HAP surface provides a highly active support for sodium borohydride hydrolysis, exemplifying a high total turnover number of nearly 24,000 mol $H_2$/ mol Ru. Moreover, we observe that the RuHAP support exhibits a high catalytic lifetime of approximately one month upon repeated exposure to $NaBH_4$ solutions. In addition to examining surface area effects, we also identified the role of complex surface morphology in enhancing hydrolysis by the catalytic transition metal covered surface. Particularly, we found that a polycrystalline RuHAP catalytic support exhibits shorter induction times for the initial bubble formation as well as increased hydrogen generation rates as compared to a single crystal supports. The independent factor of a complex surface morphology is believed to provide enhanced sites for gas release during the initial stages of the reaction. By demonstrating the ability to shorten induction time and enhance catalytic activity through changes in surface morphology and Ru content, we find it feasible to further explore this catalyst support in the construction of a practical hydrogen generator.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 추계학술발표대회
• /
• pp.28.2-28.2
• /
• 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.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.286-286
• /
• 2010

The lack of homogeneously sized single-walled carbon nanotubes (SWNTs) hinders their many applications because properties of SWNTs, in particular electrical conduction, are highly dependent on the diameter and chirality. Therefore, the preferential growth of SWNTs with predetermined diameters is an ultimate objective for applications of SWNTs-based nanoelectronics. It has been previously emphasized that a catalyst size is the one crucial factor to determine the CNTs diameter in chemical vapor deposition (CVD) process, giving rise to several attempts to obtain size-controllable catalyst by diverse methods, such as solid supported catalyst, metal-containing molecular nanoclusters, and nanostructured catalytic layer. In this work, diameter-controlled CNTs were synthesized using a nanostructured catalytic layer consisting of Fe/Al2O3/Si substrate. The CNTs diameter was controlled by structural modification of Al2O3 supporting layer, because Al2O3 supporting layer can affect agglomeration phenomenon induced by heat-driven surface diffusion of Fe catalytic nanoparticles at growth temperature.

• 한국막학회:학술대회논문집
• /
• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
• /
• pp.43-47
• /
• 1999

Pd-ceramic composite membranes and catalytic membrane reactors(CMR) have been studied for hydrogen purification and recovery in th fusion reactor fuel cycle. The development of techniques for coating microporous ceramic tubes with Pd and Pd/Ag layers is described: composite membranes have been produced by electroless deposition (Pd/Ag film of 10-20${\mu}{\textrm}{m}$) and rolling of thin metal sheet (Pd and Pd/ Ag membranes of 50-70 ${\mu}{\textrm}{m}$). Experimental results on electroless membranes showed that the metallic film presented some defects and the membranes had not complete hydrogen selectivity . Then the catalytic membrane reactors with electroless membranes can be applied for some industrial processes that do not require a complete separation of the hydrogen (i.e. in the dehydrogenation of hydrocarbons). The rolled thin Pd/Ag membranes separated the hydrogen from the other gas with a complete selectivity and exhibited a slightly larger (about a factor 1.7) mass transfer resistance with respect to the electroless membranes. Experimental tests confirmed the good performances in terms of durability.

• 환경위생공학
• /
• 제18권2호
• /
• pp.27-33
• /
• 2003

This survey was performed to investigate the NOx emission factors at 3 Municipal Solid Waste Incinerators(MSWI) and 5 Power generation boilers in Seoul. The NOx concentrations were measured before and after control systems. The results were as follows. 1) The NOx reduction efficiencies of Selective Catalytic Reduction (SCR) using ammonia as reducing agent ranged from 53.7% to 89.9%. The NOx reduction efficiencies of SCR using methanol as reducing agent, Non- Selective Catalytic Reduction (NSCR) using ethanol as reducing agent and low-NOx burner were 20.8%, 29.1% and 24.7%, respectively. 2) The NOx emission factors at A-1, A-2 and A-3 facilities of MSWI were 0.786, 0.127 and 0.594 kg Nox/ton fuel, respectively. The factors of A-1 and A-3 facilities were higher than the average value of Korea. 3) The NOx emission factors at B-1, B-2, B-3, B-4 and B-5 facilities of Power generation boiler were 2.109, 0.726, 4.106, 8.378 and 5.168 kg Nox/ton fuel, respectively. The factors of B-4 and B-5 facilities were higher than the average value of Korea.

• Biomolecules & Therapeutics
• /
• 제25권4호
• /
• pp.427-433
• /
• 2017

Previously, we demonstrated that galangin (3,5,7-trihydroxyflavone) protects human keratinocytes against ultraviolet B (UVB)-induced oxidative damage. In this study, we investigated the effect of galangin on induction of antioxidant enzymes involved in synthesis of reduced glutathione (GSH), and investigated the associated upstream signaling cascades. By activating nuclear factor-erythroid 2-related factor (Nrf2), galangin treatment significantly increased expression of glutamate-cysteine ligase catalytic subunit (GCLC) and glutathione synthetase (GSS). This activation of Nrf2 depended on extracellular signal-regulated kinases (ERKs) and protein kinase B (AKT) signaling. Inhibition of GSH in galangin-treated cells attenuated the protective effect of galangin against the deleterious effects of UVB. Our results reveal that galangin protects human keratinocytes by activating ERK/AKT-Nrf2, leading to elevated expression of GSH-synthesizing enzymes.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
• /
• pp.61-63
• /
• 2015

In the low pressure selective catalytic reduction (LP SCR) system, the uniformity of both ammonia concentration and exhaust gas flow at the SCR catalyst layer are important design factor for the efficient SCR-deNOx performance. According to the shape of the guide vane and static mixer, numerical simulations were conducted to analyze flow patterns and finally to find out the appropriate alternative for uniform flow at the front of catalyst in the real scale LP SCR reactor. The variations of gas velocity and ammonia concentration were quantitatively evaluated. Based on the present results, the shape was devised to satisfy the design criteria.

• Korean Chemical Engineering Research
• /
• 제44권2호
• /
• pp.193-199
• /
• 2006

${\gamma}-Al_2O_3$에 담지한 Cu-Mn 산화물 촉매에서 톨루엔 완전산화 반응을 $160{\sim}280^{\circ}C$의 온도 범위에서 고정층 반응기로 조사하였다. BET, SEM, TPR, TPO, XPS 및 XRD를 이용하여 촉매 특성분석을 하였다. 톨루엔의 완전산화 반응은 $280^{\circ}C$ 이하에서 이루어졌으며, 적절한 Cu-Mn 담지량은 15.0 wt％Cu-10.0 wt％Mn인 것으로 나타났다. TPR/TPO 및 XPS 분석 결과, 15 Cu-10 Mn 촉매의 산화환원 봉우리가 낮은 온도로 이동하였으며 결합에너지가 높은 값으로 이동하였다. XRD 결과, 고분산된 Mn 산화물과 CuO 보다 $Cu_{1.5}Mn_{1.5}O_4$의 촉매활성 인자로서의 역할이 더욱 우수한 것으로 추측되며, 촉매의 활성은 촉매의 산화환원 능력과 촉매의 높은 산화 상태에 기인하는 것으로 사료된다.

• 공업화학
• /
• 제33권5호
• /
• pp.482-487
• /
• 2022

본 연구에서는 V/TiO₂ 촉매를 사용하여 황화수소 상온 제거 특성을 평가하기 위해 촉매 활성 실험 및 특성 분석을 수행하였다. 최적 바나듐 함량은 10 wt%였고, 상대습도 60~80% 조건에서 60분 이상의 내구성을 보였다. BET 및 raman 분석을 통해, 표면에 노출된 바나듐의 구조가 V/TiO₂ 촉매 활성의 지배적인 요인인 것으로 나타났다. 또한 SEM, EDS 그리고 XRD 분석은 촉매 표면에 생성물인 황이 축적될 수 있음을 보였으며, 결과적으로 촉매의 내구성이 감소되었다. 따라서 촉매 산화와 재생 공정의 연계가 필요할 것으로 판단된다.

• BMB Reports
• /
• 제33권3호
• /
• pp.213-220
• /
• 2000

A fulminant hepatitis is associated with massive liver cell necrosis and a high mortality rate. But survivors regenerate a normal liver and do not have chronic liver disease. This clinical course suggests that the acutely injured livers release a factor that allows a recovery from chronic hepatitis or cirrhosis. The objective of this study was to isolate and characterize an anti-fibrotic factor from acutely damaged rat livers. The liver cell necrosis was prepared from rat by warm ischemical perfusion and the perfusates were assessed against the growth inhibition of fat-storing cells (FSC). A liver-derived growth inhibitory factor (LDGIF) was purified from ischemically damaged rat livers by chromatographies on Sephacryl S-300, CM Sepharose, hydroxyapatite, and Superose 12. The LDGIF was isolated with an overall purification of 194-fold and 40% recovery. Although LDGIF was identified as the rat liver arginase by Nterminal sequence analysis, LDGIF exists as a monomer and the purified native arginase has a trimer form. Furthermore, LDGIF has a lower enzyme activity on the hydrolysis of L-arginine and a higher inhibitory effect on proliferation of FSC than the normal rat liver arginase. The catalytic activity of LDGIF is ascribed to the monomeric characteristics of the LDGIF. Therefore, the inhibitory action of LDGIF might not be due to the arginine depletion by the catalytic activity of arginase. In conclusion, the presence of the LDGIF could interpret the clinical course that serious fibrosis is not found in the liver of patients recovering from severe hepatic necrosis due to fulminant hepatitis, suggesting that this LDGIF may provide a novel target for the prevention and treatment of hepatic fibrosis.