• Journal of Surface Science and Engineering
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• v.49 no.3
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• pp.265-273
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• 2016

The effects of surface modification by nitric acid on the pre-treatment of electroless copper plating were investigated. Copper was electroless-plated on the nitric acid treated graphite activated by a two-step pre-treatment process (sensitization + activation). The chemical state and relative quantities of the various surface species were determined by X-ray photoelectron spectroscopy (XPS) after nitric acid modification or pre-treatment. The acid treatment increased the surface roughness of the graphite due to deep and fine pores and introduced the oxygen-containing functional groups (-COOH and O-C=O) on the surface of graphite. In the pre-treatment step, the high roughness and many functional groups on the nitric acid treated graphite promoted the adsorption of Sn and Pd ions, leading to the uniform adsorption of catalyst ($Pd^0$) for Cu deposition. In the early stage of electroless plating, a lot of tiny copper particles were formed on the whole surface of acid treated graphite and then homogeneous copper film with low variation in thickness was formed after 30 min.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.412-415
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• 2013

Palladium on carbon powder was prepared using 1-hexyl-3-methylimidazolium tetrafluoroborate, one of room temperature ionic liquids. The synthesized particles were tested as a hexafluoropropylene hydrogenation catalyst. Moreover, the hydrogenation was performed under various reaction conditions to develop an optimum reaction process. The catalyst prepared by more than 3 wt% of palladium and the unity mole ratio of ionic liquid to palladium precursor showed higher catalytic activity. For reaction conditions, the complete hexafluoropropylene (HFP) conversion was achieved at these conditions; the volume flow ratio of hydrogen to HFP was higher than 1.25 and $GHSV_{HFP}$ was lower than 50000 mL/g-h.

• Resources Recycling
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• v.13 no.5
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• pp.28-36
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• 2004

The extraction of platinum group metals such as Pt, Pd and Rh from spent automobile catalyst has been investigated by leaching in HCl solutions using $HNO_3$ or NaOCl as a oxidant. The effect of type and amount of oxidant, reaction time and pulp density on the extraction of platinum group metals was examined. Platinum group metals were recovered by the cementation method using aluminum as a reducing agent. The extraction ratio was higher when NaOCl was used as a oxidant. The optimum leaching conditions were obtained to be: HCl 8 M, the amount of NaOCl 1.4 mole, leaching temperature $90^{\circ}C$, leaching time 180 minutes, pulp density 400g/L. Under the optimum conditions, the extraction of Pt, Pd and Rh were 96.1%, 93.6% and 77.3%, respectively. With the addition of 2.0g of aluminum which corresponds to 28 equivalent the reduction were 98% for Pt. 98.8% for Pd and 65.3% for Rh, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.405-412
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• 2012

In the MCFC power generation system, the combustor supplies a high temperature mixture of gases to the cathode and heat to the reformer by using the off-gas from the anode; the off-gas includes high concentrations of $H_2O$ and $CO_2$. Since a combustor needs to be operated in a very lean condition and avoid local heating, a catalytic combustor is usually adopted. Catalytic combustion is also generally accepted as one of the environmentally preferred alternatives for generation of heat and power from fossil fuels because of its complete combustion and low emissions of pollutants such as CO, UHC, and $NO_x$. In this study, experiments were conducted on catalytic combustion behavior in the presence of Pd-based catalysts for the BOP (Balance Of Plant) of 5 kW MCFC (Molten Carbonate Fuel Cell) power generation systems. Extensive investigations were carried out on the catalyst performance with the gaseous $CH_4$ fuel by changing such various parameters as $H_2$ addition, inlet temperature, excess air ratio, space velocity, catalyst type, and start-up schedule of the pilot system adopted in the BOP.

• Resources Recycling
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• v.20 no.4
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• pp.36-45
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• 2011

The recovery of platinum group metals (PGMs) from the leach solution of spent auto-catalyst and the wash solution of the leach residue was investigated in the laboratory scale experiments by the cementation process using metal powders as the reductant. In this study, the effect of Al, Mg and Zn powders on the cementation process was particularly examined. Aluminum powder was selected as the most suitable reductant for the cementation of PGMs. At the cementation time of 10 minute under the aluminium stoichimetric amount of 19.3 and the reaction temperature of $50{\sim}60^{\circ}C$, the recovery of platinum group metals from the leach solution of the spent auto-catalyst was found to be 99.3%, 99.4%, 90.2% for Pt, Pd and Rh, respectively. Under the same conditions with the aluminium stoichimetric amount of 45, the recovery of platinum group metals from the wash solution of the leach residue of spent catalyst was observed to be 97%, 97% and 90% for Pt, Pd and Rh, respectively. In addition, it was possible to upgrade the platinum group metals in the precipitates obtained from the cementation process by about 10% through the removal of metal impurities by the nitric acid leaching at ambient temperature.

• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.295-301
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• 1994

The Ru(Ⅲ), Ni(Ⅱ), Cu(Ⅱ), and Pd(Ⅱ) complexes of N$_4$-polydentate ligands(meso-Me$_6$-[14]-ane, rac-Me$_6$-[14]-ane, and cyclam) have been prepared and their catalytic activity and selectivity in the oxidation of olefins in the presence of oxidant such as NaOCl, H$_2$O$_2$, t-BuOOH, and PhIO studied. The oxidations of cyclohexene, 1-hexene, cyclooctene, 1-octene, and styrene as substrates have been investigated gas chromatographically. The Ru(Ⅲ)-N$_4$ complexes showed high selectivity for epoxide in the catalyzed oxidation of olefins with NaOCl. The catalytic activities of Ru(Ⅲ)-N$_4$ complexes were discussed in terms of the flexibility of N$_4$-polydentate ligands, the Ru(Ⅲ)-Cl bond interaction and the steric effect of oxidants. The oxidation of 1-octene using PhIO as oxidant was carried out to verify. The Pd(Ⅱ) complex turned out to be more active catalyst than the Ni(Ⅱ) complexes.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.432-439
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• 2018

Metal catalysts such as Fe, Co, Mn, and Pd supported on the activated carbon (AC) were prepared to improve functional groups for the chemical adsorption and catalytic ozonation. Following ascending orders of the phenol decomposition rate, dissolved ozone decomposition ratio and TOC (total organic carbon) removal from experimental results of advanced oxidation process (AOP) were observed: Fe-AC < AC < Co-AC < Mn-AC < Pd-AC. BET analysis results showed that the physical properties of the metal impregnated activated carbon had no effect on the catalytic ozonation, and the catalytic effect was dependent on the kind of impregnated metal. The ratio of the formed concentration of OH radical to that of ozone (RCT) was measured by using the decomposition outcome of p-chlorobenzoic acid, a probe compound that reacts rapidly with OH radical but slowly with ozone. The measured values of RCT were $5.48{\times}10^{-9}$ and $1.47{\times}10^{-8}$ for the ozone alone and activated carbon processes, respectively, and $2.13{\times}10^{-9}$, $1.51{\times}10^{-8}$, $4.77{\times}10^{-8}$, and $5.58{\times}10^{-8}$ for Fe-AC, Co-AC, Mn-AC, and Pd-AC processes, respectively.

• Resources Recycling
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• v.20 no.2
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• pp.74-81
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• 2011

The dry method and wet method are currently used for the recovery of platinum group metals (Pt, Rh, Pd) contained in spent automobile catalysts. The study herein aims to identify the melting condition and optimum collector metal in accordance with a comparison of each concentration change in melting waste catalysts, using Fe and Cu in a basic experiment to recover waste catalysts through application of the dry melting method. As a summarized result of the experiment herein, it was determined to be more advantageous to use Fe as a parent material rather than Cu from the aspect of recollection rate, and the concentration change rate of platinum group metals within slag was greatly enhanced at $1,600^{\circ}C$ melting condition rather than at $1,500^{\circ}C$ in terms of melting processing temperature. The mean concentration of platinum group metals - Rh, Pd and Pt - within slag after a melting process at $1,600^{\circ}C$ were 6.21 ppm, 5.98 ppm and 6.97 ppm. The Rh and Pd were 50.58% and 55.31% respectively greater than the concentration change rate of platinum group metals in slag at a melting temperature of $1,500^{\circ}C$. However, since the initial concentration of Pt within the waste catalysts was 12.9 ppm, is relatively low, it was difficult to compare concentration change rates after the melting process.

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.161-164
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• 1979

The effect of acidity and the metal surface area of the Pd loaded zeolite catalysts; prepared from $Ca^{2+}-,\;La^{3+}-,\;NH_4^+-$exchanged Y and dealuminated HY was studied for the reaction of n-butane. The amount of strong acid site determined by the temperature programmed desorption of ammonia increased in the order NaY < CaY < LaY. Total amount of acid site decreased with increasing degree of dealumination, but the portion of strong acid site increased with increasing $SiO_2/Al_2O_3$ ratio. The effective metal surface area determined by the CO adsorption technique was large for those zeolite catalysts having strong acidity. It was found that conversion of n-butane was strongly dependent on the acidity and the effective metal surface area of the catalysts. The fact that the conversion of n-butane was proportional to the effective metal surface area suggests that the dehydrogenation by metallic component is the primary step in the reaction of n-butane.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.23-29
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• 1996

Thick film type gas sensors with parallel Pt heaters were fabricated by screen printing process and investigated sensitivities for methane gas. The TR7905 was selected as Pt paste for heater by characterization the properties of TCRs and thick film microstructures. The average resistance of parallel Pt heaters was $1.8{\Omega}$, and the best TCR obtained was $3685\;ppm/^{\circ}C$. On the top of the Pt heaters, a sensing layer added with Pt and Pd as catalyst paste was screen printed and heat treated. The sensitivity of the sensor was 4.3mV/1000ppm for methane. The power consumption of the sensors was 2.12watts.