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Repair of Pd-based composite membrane by polishing treatment
Ryi, S.K.,Park, J.S.,Hwang, K.R.,Lee, C.B.,Lee, S.W. Pergamon Press ; Elsevier Science Ltd 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.21
In this study, polishing treatment was introduced to repair Pd-based composite membrane. Some pinholes remained after sputtering with palladium followed by heat-treatment at 723 K for 2 h. The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced polishing treatment after the palladium sputtering. Scanning election microscopy (SEM) analysis and helium leak tests confirmed the effectiveness of the polishing treatment in removing the pinholes. The helium leaks were drastically decreased by the polishing treatment. Hydrogen permeation and helium leak tests showed that the polishing treatment increased the hydrogen perm-selectivity from 52 to >40,000 with a hydrogen permeation flux of 1.8 x 10<SUP>-1</SUP> mol m<SUP>-2</SUP> s<SUP>-1</SUP> at a pressure difference of 100 kPa and temperature of 673 K. The advantage of our membrane fabrication procedures lies in its simplicity. Our coating and polishing method offers the promise of highly reproducible Pd-based composite membrane.
Ryi, J.,Choi, J. S. Springer Science + Business Media 2017 Science China. Technological sciences Vol.60 No.2
<P>This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the wind tunnel test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 kW wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a wind tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with wind tunnel test data at the 2D airfoil and model rotor condition.</P>
Novel non-alloy Ru/Pd composite membrane fabricated by electroless plating for hydrogen separation
Ryi, Shin-Kun,Li, Anwu,Lim, C. Jim,Grace, John R. Elsevier 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.15
<P><B>Abstract</B></P> <P>This study presents a new non-alloy Ru/Pd composite membrane fabricated by electroless plating for hydrogen separation. It shows that palladium and ruthenium can be deposited on an aluminum-oxide-modified porous Hastalloy by using our new EDTA-free plating bath at room temperature and 358 K, respectively. A 6.8 μm thick non-alloy Ru/Pd membrane film could be plated and helium leak test confirmed that the membrane was free of defects. Hydrogen permeation test showed that the membrane had a hydrogen permeation flux of 4.5 × 10<SUP>−1</SUP> mol m<SUP>−2</SUP> s<SUP>−1</SUP> at a temperature of 773 K and a pressure difference of 100 kPa. The hydrogen permeability normalized value with thickness of the membrane was 1.4 times higher than our pure Pd membrane having similar structure. The EDX profiles of the front and back side membrane, cross-sectional EDX line scanning and XRD profile show that there was no alloying progress between the palladium and ruthenium layer after hydrogen permeation test at 773 K.</P>
Ryi, Shin-Kun,Xu, Nong,Li, Anwu,Lim, C. Jim,Grace, John R. Elsevier 2010 International journal of hydrogen energy Vol.35 No.6
<P><B>Abstract</B></P><P>This study demonstrates palladium membranes can be electrolessly plated on aluminum oxide-modified porous Hastelloy with hydrazine using an EDTA-free bath. The plating bath temperature affected the membrane surface morphology, with the palladium grain size increasing with increasing temperature. A 7.5μm thick membrane plating was obtained at room temperature. Helium leak testing confirmed that the membrane was free of defects. Hydrogen permeation test showed that the membrane had a hydrogen permeation flux of 3.3×10<SUP>−1</SUP>molm<SUP>−2</SUP>s<SUP>−1</SUP> at a temperature of 823K and at a pressure difference of 100kPa. There was no measurable interdiffusion between the membrane film and the porous Hastalloy substrate at 823K. This room temperature membrane plating method provides several advantages such as very high selectivity, stability, favorable energy efficiency and simplicity.</P>
Ryi, S.K.,Lee, S.W.,Park, J.W.,Oh, D.K.,Park, J.S.,Kim, S.S. Elsevier Science Publishers 2014 CATALYSIS TODAY - Vol.236 No.1
In this study, test on the combined steam and dry reforming of methane were carried out over a catalytic nickel membrane within a very short residence time of 120ms under different process conditions (CO<SUB>2</SUB>/H<SUB>2</SUB>O feed ratio and temperature). The effect of the molar ratio of CO<SUB>2</SUB>/H<SUB>2</SUB>O in the reactants on the H<SUB>2</SUB>/CO ratio in the products was investigated at 923-1023K. In the reaction of the combined steam and dry reforming of methane, CH<SUB>4</SUB> conversion was strongly influenced by the CO<SUB>2</SUB>/H<SUB>2</SUB>O feed ratio and decreased with the increase in the CO<SUB>2</SUB>/H<SUB>2</SUB>O feed ratio at 923K, while the influence of the CO<SUB>2</SUB>/H<SUB>2</SUB>O feed ratio on CH<SUB>4</SUB> conversion was not significant at temperatures ≥973K. Unlikely CH<SUB>4</SUB> conversion, the conversion of CO<SUB>2</SUB> increased with the increase in the CO<SUB>2</SUB>/H<SUB>2</SUB>O feed ratio over the temperature range of 923-1023K. The conversion of CH<SUB>4</SUB> and that of CO<SUB>2</SUB> both increased with increasing temperature because the corresponding reactions are endothermic and remained nearly constant at temperatures ≥973K. The H<SUB>2</SUB>/CO molar ratio could be adjusted by the CO<SUB>2</SUB>/H<SUB>2</SUB>O feed ratio for downstream applications. No carbon deposition on the catalytic nickel membrane was observed after the combined steam and dry reforming of methane tests under all process conditions.
Ryi, S.K.,Ahn, H.S.,Park, J.S.,Kim, D.W. Pergamon Press ; Elsevier Science Ltd 2014 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.39 No.9
In this study, the hydrogen permeation behavior of a Pd<SUB>93</SUB>-Cu<SUB>7</SUB> alloy membrane deposited on ceria-modified porous nickel support (PNS) was evaluated. PNS, which has an average pore size of 600 nm, was modified by alumina sol. Alumina sol was prepared using precursors that had a mean particle size of 300 nm. Alumina-modified PNS was further treated with ceria sol modification to produce a smoother surface morphology and narrow surface pores. A 7 μm thick Pd<SUB>93</SUB>-Cu<SUB>7</SUB> alloy membrane was made on an alumina-modified PNS and a ceria-finished membrane was fabricated by magnetron sputtering followed by Cu-reflow at 700 <SUP>o</SUP>C for 2 h. SEM analysis showed that the membrane deposited on a ceria-finished PNS contained more clear grain boundaries than the membrane deposited on the alumina-modified PNS. The membrane was mounted in a stainless steel permeation cell with a gold-plated stainless steel O-ring. Permeation tests were then conducted using pure hydrogen and helium at temperatures ranging from 673 to 773 K and feed side pressures ranging from 100 to 400 kPa. These tests showed that the membrane had a hydrogen permeation flux of 2.8 x 10<SUP>-1</SUP> mol m<SUP>-2</SUP> s<SUP>-1</SUP> with H<SUB>2</SUB>/He selectivity of >50,000 at a temperature of 773 K and pressure difference of 400 kPa.