• Bulletin of the Korean Chemical Society
• /
• 제30권2호
• /
• pp.441-444
• /
• 2009

The formation and structure of self-assembled monolayers (SAMs) by the adsorption of acetyl-protected octylthioacetate (OTA) on Au(111) in a catalytic tetrabutylammonium cyanide (TBACN) solution were examined by means of scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Molecular-scale STM imaging revealed that OTA molecules on Au(111) in a pure solvent form disordered SAMs, whereas they form well-ordered SAMs showing a c(4 × 2) structure in a catalytic TBACN solution. XPS and CV measurements also revealed that OTA SAMs on Au(111) formed in a TBACN solution have a stronger chemisorbed peak in the S 2p region at 162 eV and a higher blocking effect compared to OTA SAMs formed in a pure solvent. In this study, we clearly demonstrate that TBACN can be used as an effective deprotecting reagent for obtaining well-ordered SAMs of thioacetyl-protected molecules on gold.

• 한국세라믹학회지
• /
• 제52권3호
• /
• pp.209-214
• /
• 2015

Silicon nitride films were deposited at $100^{\circ}C$ by using the catalytic chemical vapor deposition technique. The source gas mixing ratio, $R_N=[NH_3]/[SiH_4]$, was varied from 10 to 30, and the hydrogen dilution ratio, $R_H=[H_2]/[SiH_4]$, was varied from 20 to 100. The breakdown field strength reached a maximum value at $R_N=20$ and $R_H=20$, whereas the resistivity decreased in the same sample. The relative permittivity had a positive correlation with the breakdown field strength. The capacitance-voltage threshold curve showed an asymmetric hysteresis loop, which became more squared as $R_H$ increased. The width of the hysteresis window showed a negative correlation with the slope of the transition region, implying that the combined effect of $R_N$ and $R_H$ overides the interface defects while creating charge storage sites in the bulk region.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1628-1630
• /
• 2000

Vertically aligned multiwalled carbon nanotubes are grown on silicon oxide substrate at 950$^{\circ}C$ by thermal chemical vapor deposition using $C_{2}H_2$. Three catalytic metals such as iron(Fe), cobalt (Co), and nickel(Ni) are used as catalyst, we found that the growth rate of carbon nanotubes for three catalyst particles are in an order of Fe > Ni > Co. All carbon nanotubes are revealed to have bamboo structure with no encapsulated catalytic particles, the diameter of carbon nanotubes depend on the catalyst, the tip and the compartment sheets of bamboo structure also depend on the shape of catalytic particles.

• Korean Chemical Engineering Research
• /
• 제44권6호
• /
• pp.563-571
• /
• 2006

스테인리스 스틸 메쉬 표면을 환원 전처리하여 그 표면상에 직접 탄소나노튜브 또는 탄소나노섬유와 같은 VGCF (vapor grown carbon fiber) 나노물질을 합성 성장시켰다. 수소 가스를 이용하여 스테인리스 스틸 메쉬를 환원 처리함으로써, 금속 표면상에 bi-modal 분포의 작은 촉매입자와 큰 촉매입자들이 함께 생성되었다. 환원된 스테인리스 스틸 메쉬로부터 VGCF의 합성 시, 수소 가스가 공급되지 않은 경우는 작은 촉매입자로부터 탄소나노튜브들이 주로 성장되었으나, 특정 량의 수소 가스가 공급될 경우 큰 촉매입자로부터 탄소나노섬유들이 주로 성장되었다.

• 한국재료학회지
• /
• 제19권6호
• /
• pp.319-324
• /
• 2009

The deposition behavior and structural and magnetic properties of electroless Co-B and Co-Fe-B deposits, as well as the amorphous ribbon substrates, were investigated. These Co-based alloy deposits exhibited characteristic polycrystalline structures and surface morphology and magnetic properties that were dependent on the type of amorphous substrates. The catalytic activity sequence of the amorphous ribbon electrodes for anodic oxidation of DMAB was estimated from the current density-potential curve in the anodic partial electrolytic bath that did not contain the metal ions. Both the deposition rate and potential in the initial region were obtained in order of the catalytic activity, depending on the alloy compositions of the substrates. The deposition rate linearly varied against the deposition time. The initial deposition potential may have also determined the structural and magnetic properties of the deposit based on the thickness of ${\mu}m$ order. Furthermore, a basic study of the electroless deposition processes on an amorphous ribbon substrate has been carried out in connection with the structural and magnetic properties of the deposits.

• International Journal of Advanced Culture Technology
• /
• 제10권3호
• /
• pp.295-306
• /
• 2022

The NOx removal performance of the SCR process depends on various factors such as catalytic factors (catalyst composition, shape, space velocity, etc.), temperature and flow rate distribution of the exhaust gas. Among them, the uniformity of the flow flowing into the catalyst bed plays the most important role. In this study, the flow characteristics in the SCR reactor in the design stage were simulated using a three-dimensional numerical analysis technique to confirm the uniformity of the airflow. Due to the limitation of the installation space, the shape of the inlet duct was compared with the two types of inlet duct shape because there were many curved sections of the inlet duct and the duct size margin was not large. The effect of inlet duct shape, guide vane or mixer installation, and venturi shape change on SCR reactor internal flow, airflow uniformity, and space utilization rate of ammonia concentration were studied. It was found that the uniformity of the airflow reaching the catalyst layer was greatly improved when an inlet duct with a shape that could suppress drift was applied and guide vanes were installed in the curved part of the inlet duct to properly distribute the process gas. In addition, the space utilization rate was greatly improved when the duct at the rear of the nozzle was applied as a venturi type rather than a mixer for uniform distribution of ammonia gas.

• 대한화학회지
• /
• 제51권2호
• /
• pp.147-153
• /
• 2007

간단하고 선택적인 흐름주입촉매법으로 pH 1.0에서 고황산염(periodate)에 의한 pyronin B의 산화의 촉매 효과를 근간으로 루테늄 정량에 대해 논하였다. 반응속도는 555 nm에서의 흡수를 분광광도법으로 조절하였다. 루테늄 정량의 최적화된 조건으로 검출한계는 0.04 ng/mL로 측정범위로 0.1-10.0 ng/mL(r2=0.9982)와 10.0-50.0 ng/mL (r2=0.9934), 그리고 시료속도는 30±5 samples/h를 얻었다. 5번 측정의 상대표준편차는 1.44%를 넘지 않았다. 제안된 본 방법은 성공적으로 환경 및 생물학적 시료 중에서 루테늄의 초미량 정량에 성공적으로 적용되었다.

• 공업화학
• /
• 제2권1호
• /
• pp.77-85
• /
• 1991

염산 및 불산으로 모더나이트를 처리하여 실리카/알루미나 비가 다른 일련의 시료를 만들었다. 이러한 시료에 대하여 암모니아 TPD와 피리딘 흡착으로 IR을 이용하여 산성도를 측정하고 o-xylene 반응의 활성과 이성화반응에 대한 선택성을 측정하였다. 그 결과 염산처리 시료는 실리카/알루미나 비가 증가할수록 구조알루미늄이 추출되어 산량이 감소하였으며 실리카/알루미나 비가 22인 시료가 다른 시료들보다 활성이 좋았다. 불산처리 시료는 불산처리 시 불소가 구조 중 규소원자와 결합하였으며 처리시간이 증가함에 따라 결합된 불소는 증가하였다. 이 경우의 활성은 염산처리와는 달리 알루미늄의 추출과 함께 모더나이트의 수산기가 불소로 치환되어 이로 인하여 산점이 줄어 활성이 감소하나 불산은 규소도 추출하므로 표면을 파고들어 새로운 면이 노출되어 산점이 형성되고 이 산점은 증가된 결합불소의 영향을 받아 강해지면서 활성이 다소 증가하였다.

• 한국분말재료학회지
• /
• 제21권1호
• /
• pp.28-33
• /
• 2014

This paper describes the surface modification effect of a Ti substrate for improved dispersibility of the catalytic metal. Etching of a pure titanium substrate was conducted in 50% $H_2SO_4$, $50^{\circ}C$ for 1 h-12 h to observe the surface roughness as a function of the etching time. At 1 h, the grain boundaries were obvious and the crystal grains were distinguishable. The grain surface showed micro-porosities owing to the formation of micro-pits less than $1{\mu}m$ in diameter. The depths of the grain boundary and micro-pits appear to increase with etching time. After synthesizing the catalytic metal and growing the carbon nano tube (CNT) on Ti substrate with varying surface roughness, the distribution trends of the catalytic metal and grown CNT on Ti substrate are discussed from a micro-structural perspective.

• 대한환경공학회지
• /
• 제39권7호
• /
• pp.412-417
• /
• 2017

촉매오존화 공정에 의한 메틸오렌지 제거특성과 그에 미치는 운전변수의 영향에 관한 회분식 실험과 동력학적 연구를 수행하였다. 활성탄은 오존의 자가분해를 촉진시켜 $OH{\cdot}$를 발생시키므로 메틸오렌지 분해속도를 증가시키는 것으로 나타났다. 활성탄의 투입량이 증가함에 따라 메틸오렌지 분해반응의 속도상수가 증가하는 것으로 나타났다. 가스상 오존농도 증가는 수용액으로의 물질전달을 증가시켜 메틸오렌지 분해반응의 속도를 증가시키는 것으로 나타났다. 메틸오렌지 제거반응은 실험된 5~12 범위에서, TOC 제거는 7 이상의 pH에서 큰 영향을 미치지 않는 것으로 나타났다. 이러한 결과는 촉매오존화공정이 효과적인 염료처리 기술로서 고려될 수 있음을 보여준다.