• Applied Chemistry
• /
• v.15 no.1
• /
• pp.81-84
• /
• 2011

Platinum catalyst activity and stability is excellent in terms of fuel cells as a catalyst here. Although it is widely used, to compensate for the high price issue non-precious fuel cell catalysts are being developed. In this study, Co/PANi/CNT composite and non-precious as a catalyst for oxygen reduction was applied. Polyaniline on the interaction between cobalt and the oxygen reduction reaction and the structural characteristics observed in the impact and heat treatment was carried out according to the improved catalytic performance. Potential range is oxygen reduction reaction 0.55 V to 0.78 V(vs. NHE) after pyrolysis. Through this study, Co /PANi/CNT composites as a potential catalyst for fuel cells were non-precious.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.113-116
• /
• 2007

Performance of a steam reformer can be improved by using a coaxial cylindrical reactor, because the design can enhance the heat transfer for the steam reforming reaction, which is the one of main rate-determining steps of overall reactions. The objective of this study is to investigate the coaxial cylindrical reactor numerically. Pseudo-homogeneous model and one medium approach are incorporated for the chemical reactions, and models are validated with experimental results. The catalyst of the coaxial cylindrical reactor is 67% for one of the cylindrical reactor, but fuel conversion of the coaxial cylindrical reactor is increased by 10%. Heat flux profiles are investigated by modified Nusselt number and heat flux which is transported from the product gas to the catalyst bed affecting performance of the steam reformer.

• Journal of Surface Science and Engineering
• /
• v.47 no.6
• /
• pp.275-281
• /
• 2014

An ultrasound-assisted Sn-Ag-Pd activation method for electroless copper plating was presented in this study. With this activation process, it was shown that the fine catalyst particles were homogeneously distributed with high density on the entire specimen. In addition, it was observed that incubation period occurred during the electroless plating step was decreased owing to the absorption of Ag which holds high catalytic activity. Resulting from the refinement and high densification of catalyst, the defect-free gap-fill was achieved within the 20x nm trench.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.8
• /
• pp.859-869
• /
• 2005

The commercial $V_2O_5-WO_3/TiO_2$ catalysts which had been exposed to the off gas from incinerator for a long time were regenerated by physical and chemical treatment. The catalytic properties and NOx conversion reactivity of those catalysts were examined by analysis equipment and NOx conversion experiment. The characterization of the catalysts were performed by XRD(x-ray diffractometer), BET, POROSIMETER, EDX(energy dispersive x-ray spectrometer), ICP(inductively coupled plasma), TGA(thermogravimetric analyzer) and SEM (scanning electron microscopy). NOx conversion experiment were performed with simulated off gas of the incinerator and $NH_3$ was used as a reductant of SCR reaction. Among the regeneration treatment methods which were applied to regenerate the aged catalysts in this study, it showed that the heat treatment method had excellent regeneration effect on the catalytic performance for NOx conversion. The catalytic performance of the regenerated catalysts with heat treatment method were recovered over than 95% of that of fresh catalyst. For the regenerated catalysts with the acid solution(pH 5) and the alkali solution(pH 12), the catalytic performance were recovered over than 90% of that of fresh catalyst. From the characterization results of the regenerated catalysts, the specific surface area was recovered in the range of $85{\sim}95%$ of that of fresh catalyst. S and Ca element, which are well known as the deactivation materials for the SCR catalysts, accumulated on the aged catalyst surface were removed up to maximum 99%. Among the P, Cr, Zn and Pb elements accumulated on the aged catalyst surface, P, Cr and Zn element were removed up to 95%. But the Pb element were removed in the range of $10{\sim}30%$ of that of fresh catalyst.

• Applied Chemistry for Engineering
• /
• v.34 no.6
• /
• pp.619-625
• /
• 2023

In order to solve problems caused by the heat load of hypersonic aircraft, this study examined the optimization of the Si/Al ratio of the catalyst and nickel ion exchange to improve the performance of the hydrocarbon decomposition reaction (endothermic reaction). It was confirmed that the catalysts prepared through Si/Al ratio optimization and nickel ion exchange showed about 10% improvement in heat absorption performance compared to thermal cracking at 4 MPa and 550 ℃. FT-IR and NH₃-TPD analyses were found to identify factors affecting activity changes, and it was observed that the Si/Al ratio of the HZSM-5 catalyst was closely correlated with acid site development and catalytic activity. In addition, TGA and O₂-TPO analyses were conducted to observe the carbon deposition inhibition properties of the nickel-added catalyst.

• Journal of Korean Society for Atmospheric Environment
• /
• v.1 no.1
• /
• pp.43-51
• /
• 1985

This study is concerned with the oxidation of carbon monoxide on platinum and platinum-palladium catalysts. Catalysts were made by the impregnation method and flow reactor was used in the catalytic reaction. As for the mixed gases, carbon monoxide concentration varied from 1 to 4% and that of oxygen from 1 to 4%. $N_2$ was used as carrier gas and GHSV varied from 24, 000 $h^{-1} to 60, h^{-1}$. The temperature range was from 200 to $600^\circ$C. It was also taken into consideration that the heat and mass transfer resistance of our catalysts was negligible in the study. Experimental results showed that platinum-palladium catalyst was about 1.5-3.9% superior to platinum catalyst in conversion yield. When we used platinum-palladium catalyst, we observed that carbon monoxide oxidation was found to be 1 st order with respect to carbon monoxide concentration. Activation energy of the catalyst was 23.5 kcal/mol.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.3
• /
• pp.15-26
• /
• 1997

In this study, the theoretical investigation of the electrically heated catalyst(EHC) for vehicle application has been carried out using the thermal equivalence of EHC system and the data of vehicle tests to meet ultra low emission vehicle(ULEV) standard. To improve the efficiency of EHC system, it is necessary to understand relation between the power, the operating time and the conversion efficiency of EHC system. The relation was found with thermal equivalence of EHC system which considers the power supply to EHC, heat loss, chemical exothermic energy generated by oxidation reaction and net energy coming in via the exhaust gas. From this relation, the limits of needful power and operating time to meet the ULEV standard can be suggested, when the conversion efficiency of catalyst was known.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.2
• /
• pp.205-212
• /
• 1998

Experiments were conducted to investigate the temperature profile and the emissions conversion efficiency of catalytic converters for natural gas vehicles. Two types of the catalyst structure and several transient engine operating conditions were used. The dual-bed catalyst effectively reduced the emissions in a transient period due to the low heat capacity of the front bed. The lanthanoid additives were effective in improving catalyst durability. When the natural gas fueled engine were operated outside of a very narrow window of excess air ratio (from 0.993 to 1.004), the HC and NOx conversion efficiency dropped off. The drop-off were especially fast on the lean side of the window.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.4
• /
• pp.425-430
• /
• 2012

In this study, a preconverter of an MCFC for an emergency electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). A commercial code is used to simulate a porous catalyst with a user subroutine to model three dominant chemical reactions-steam reforming, water-gas shift, and direct steam reforming. To achieve a fuel conversion rate of 10% in the preconverter, the required external heat flux is supplied from the outer wall of the preconverter. The calculated results show that the temperature distribution and chemical reaction are extremely nonuniform near the wall of the preconverter. These phenomena can be explained by the low heat conductivity of the porous catalyst and the endothermic reforming reaction. The calculated results indicate that the use of a compact-size preconverter makes the chemical reaction more uniform and provides many advantages for catalyst maintenance.

• 한국연소학회:학술대회논문집
• /
• 2006.10a
• /
• pp.235-241
• /
• 2006

Catalytic combustion is one of the suitable methods for micro power source due to high energy density and no flame quenching. Catalyst loading in the micro structured combustion chamber is one of the most important issues in the development of micro catalytic combustors. In this research, to coat catalyst on the chamber wall, two methods were investigated. First, $Al_2O_3$ was selected as a support of Pt and $Pt/Al_2O_3$ was synthesized through the alumina sol-gel procedure. To improve the coating thickness and adhesion between catalyst and substrate, heat resistant and water solvable organic-inorganic hybrid binder was used. Porous silicon was also investigated as a catalyst support for platinum. Through the parametric studies of current density and etching time, fabrication process of $1{\sim}2{\mu}m$ of diameter and about $25{\mu}m$ depth pores was confirmed. Coated substrates were test in the micro channel combustor which was fabricated by the wet etching and machining of SUS 304. Using $Pt/Al_2O_3$ coated substrate and Pt coated porous silicon substrate, conversion rate of fuel was over 95% for $H_2$/Air premixed gas.