Dal-Ryung Park

The Effect of Sn Addition on a Pt ∕ C Electrocatalyst Synthesized by Borohydride Reduction and Hydrothermal Treatment for a Low-Temperature Fuel Cell

A 3PtlSn/C catalyst was readily synthesized by borohydride reduction and hydrothermal treatment for the anode electrode of a low-temperature fuel cell. The physical and electrochemical characterization of the 3PtlSn/C catalyst was performed by transmission electron microscopy (TEM), X-ray diffraction, H 2 adsorption-desorption, methanol oxidation, and CO stripping. In the TEM image, the PtSn nanoparticles were uniformly well-dispersed on the carbon support with an average particle size of around 2.4 nm. The 3PtlSn/C catalyst showed higher activity than commercial catalysts, and its onset potential for methanol oxidation was lower, possibly due to the electronic interaction between Pt and Sn and the increase of Pt lattice parameter.

Thermodynamic design data and performance evaluation of the water + lithium bromide + lithium iodide + lithium nitrate + lithium chloride system for absorption chiller

Abstract Duhring (P–T–X) and enthalpy-concentration (H–X–T) diagrams of the H2O + LiBr + LiNO3 + LiI + LiCl (mole ratio of LiBr : LiNO3 : LiI : LiCl = 5 : 1 : 1 : 2) system were constructed by using the experimental data sets. Thermodynamic design data for a double-effect series-flow absorption chiller were calculated at various operating conditions [ 2≤Te≤14°C, 30≤Ta≤50°C, 30≤Tc≤50°C, T gh COP =0 ≤T gh ≤T gh (crystallization limit)] by a computer simulation. The proposed working fluid was found to be applicable to cycle operation of air-cooled absorption chiller with no crystallization problem at higher absorber temperature.

Photocatalytic oxidation of ethylene to CO2 and H2O on ultrafine powdered TiO2 photocatalysts: Effect of the presence of O2 and H2O and the addition of Pt

The complete photocatalytic oxidation of C2H4 with O2 into CO2 and H2O has been achieved on ultrafine powdered TiO2 photocatalysts and the addition of H2O was found to enhance the reaction. The photocatalytic reaction has been studied by IR, ESR, and analysis of the reaction products. UV irradiation of the photocatalysts at 275 K led to the photocatalytic oxidation of C2H4 with O2 into CO2, CO, and H2O. The large surface area of the photocatalyst is one of the most important factors in achieving a high efficiency in the photocatalytic oxidation of C2H4. The photoformed OH species as well as O2− and O3− anion radicals play a significant role as a key active species in the complete photocatalytic oxidation of C2H4 with O2 into CO2 and H2O. Interestingly, small amount of Pt addition to the TiO2 photocatalyst increased the amount of selective formation of CO2 which was the oxidation product of C2H4 and O2.

Solubilities, Vapor Pressures, and Heat Capacities of the Water + Lithium Bromide + Lithium Nitrate + Lithium Iodide + Lithium Chloride System

The optimum mole ratio of lithium salts in the H2O + LiBr + LiNO3 + LiI + LiCl system was experimentally determined to be LiBr : LiNO3 : LiI : LiCl = 5 : 1 : 1 : 2. The solubilities were measured at temperatures from 252.02 to 336.75 K. Regression equations on the solubility data were obtained with a least-squares method. Average absolute deviations of the calculated values from the experimental data were 0.15% at temperatures <285.18 K and 0.05% at temperatures ≥285.18 K. The vapor pressures were measured at concentrations ranging from 50.0 to 70.0 mass% and at temperatures from 330.13 to 434.88 K. The experimental data were correlated with an Antoine-type equation, and the average absolute deviation of the calculated values from the experimental data was 2.25%. The heat capacities were measured at concentrations from 50.0 to 65.0 mass% and temperatures from 298.15 to 328.15 K. The average absolute deviation of the values calculated by the regression equation from the experimental data was 0.24%.

The conversion of natural gas to higher hydrocarbons using a microwave plasma and catalysts

Methane, the major constituent of natural gas, had been converted to higher hydrocarbons by a microwave plasma. The yield of C2+ products increased from 29.2% to 42.2% with increasing the plasma power and decreasing the flow rate of methane. When the catalysts were used in the plasma reactor, the selectivities of ethylene and acetylene increased while the yield of C2+ remained constant. Among the various catalysts used, the Fe catalyst showed the highest ethylene selectivity of 30%. When we introduced the actual natural gas, more C2+ products were obtained (46%). This is due to the ethane and propane in the natural gas. When an electric field inductance for evolving the high plasma was applied, a high yield in C2+ products of 63.7% was obtained for the Pd-Ni bimetal catalyst.

H2/CO2 separation characteristics of γ-Al2O3 membrane by aging stage in sol-gel process

Abstractγ-AlO(OH) sol solution was prepared by aluminum isopropoxide as an initial material. γ-Al2O3 membrane on the α-Al2O3 support was continuously made through coating and thermal treatment from the α-AlO(OH) sol. Previous work [Yoo et al., 1997] has shown that the aging stage in the sol preparation process mainly affects the characterization of γ-Al2O3 particles as well as γ-AlO(OH) sol. Based on this fact, the γ-Al2O3 membrane was prepared with two aging conditions in the present study. The separation characteristics experiment of the H2/CO2 mixture was performed on these membranes. As a result of the study, the mechanism of gas transport on the two membranes was proved as Knudsen diffusion. The ideal separation factor was reached at the value of the calculated Knudsen separation factor; however, permeability increased and selectivity decreased selectivity according to the aging.