• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.806-812
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• 2008

The ammonia decomposition reaction has been of increasing interest as a means of treating ammonia in flue gas in the presence of precious metal catalyst. Various catalysts, $Pt-Rh/Al_2O_3$, $Pt-Rh/TiO_2$, $Pt-Rh/ZrO_2$, $Pt-Pd/Al_2O_3$, $Pd-Rh/Al_2O_3$, $Pd-Rh/TiO_2$, $Pd-Rh/ZrO_2$, $Pt-Pd-Rh/Al_2O_3$, $Pd/Ga-Al_2O_3$, $Rh/Ga-Al_2O_3$, and Ru/Ga-$Al_2O_3$, were synthesized by using excess wet impregnation method. Using a homemade 1/4" reactor at $10,000{\sim}50,000hr^{-1}$ of space velocity in the presence of precious metal catalyst ammonia decomposition reactions were carried out to investigate the catalyst activity. The inlet ammonia concentration was maintained at 2,000 ppm, with an air balance. Both $T_{50}$ and $T_{90}$, defined as the temperatures where 50% and 90% of ammonia, respectively, are converted, decreased significantly when alumina-supported catalysts were applied. In terms of catalytic performance on the ammonia conversion in the presence of hydrogen sulfide, $Pt-Rh/Al_2O_3$ catalyst showed no effect on the poisoning caused by hydrogen sulfide. These results indicate that platinum-rhodium bimetallic catalyst is a useful catalyst for ammonia decomposition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.34-38
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• 1999

$PbTiO_3$(PT)thin films were prepared by simultaneous of $TiO_2$ and PbO on Si(100) substrate using metaloganic chemical vapor deposition (MOCVD). Titanium tetra-isopropoxide (TTIP) and $Pb(TMHD)_2$were used as source materials. As evaporation temperature and flow rate of TTIP were examined the crystal structure of PT thin films using XRD with setting deposition temperature, flow rate of Pb, and total flow rate of $520^{\circ}C$, 30 sccm, and 750 sccm, respectively. PT thin films could be deposited under 48~$50^{\circ}C$ and 18~22sccm of evaporation temperature and flow rate of TTIP, respectively. It was found that lead, oxygen, and silicon diffused at the iaterface between the film and the substrate.

• Clean Technology
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• v.11 no.3
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• pp.123-128
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• 2005

Among various metal oxides semiconductors, $TiO_2$ is the most studied semiconductor for environmental clean-up applications due to its unique ability in photocatalyzing various organic contaminants, its chemical inertness, and nontoxicity. $TiO_2$, however, has a few drawbacks to be solved such as reactivity mainly working under ultraviolet irradiation (${\lambda}$ < 387 nm) and electron - hole recombination on $TiO_2$. In this study, to extend the absorption range of $TiO_2$ into the visible range and enhance electron - hole separation, we synthesized platinum (Pt) deposited $C-TiO_2$. The presence of Pt as an electron sink has been known to snhance the separation of photogenerated electron-hole pairs and induce the thermal decomposition. The characterization of as-synthesized $Pt-C-TiO_2$ was performed by Transmission Electron Microscopic (TEM), the Brunuer-Emmett-Teller (BET) method, X-ray Diffractometer (XRD), UV-vis spectrometer (UV-DRS), and X-ray Photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photodegradation experiment of an azo dye (Acid Red 44; $C_{10}H_7N=NC_{10}H_3(SO_3Na)_2OH$)was carried out by using an Xe arc lamp (300 W, Oriel). A 420 nm cut-off filter was used for visible light irradiation. From the results, Pt-deposited $C-TiO_2$ showed a far superior phothdegradation activity to Degussa P25, the commercial product under the irradiation of visible light and enhanced photocatalytic activity of visible-working $C-TiO_2$. This is a useful result into the application for the purification system of dye wastewater using visible energy of sun light.

• Clean Technology
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• v.22 no.1
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• pp.16-28
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• 2016

Textile industry is considered as one of the most polluting sectors in terms of effluent composition and volume of discharge. It is well known that the effluents from textile dying industry contain not only chromatic substances but also large amounts of organic compounds and insolubles. The azo dyes generate huge amount of pollutions among many types of pigments. In general, the electrochemical treatments, separating colors and organic materials by oxidation and reduction on electrode surfaces, are regarded as simpler and faster processes for removal of pollutants compared to other wastewater treatments. In this paper the electrochemical degradation characteristics of dye wastewater containing CI Direct Blue 15 were analyzed. The experiments were performed with various anode materials, such as RuO₂/Ti, PtO₂/Ti, IrO₂/Ti and graphite, with stainless steel for cathode. The optimal anode material was located by changing operating conditions like electrolyte concentration, current density, reaction temperature and initial pH. The degradation efficiency of dye wastewater increased in proportion to the electrolyte concentration and the current density for all anode materials, while the temperature effect was dependent on the kind. The performance orders of anode materials were RuO₂/Ti > PtO₂/Ti > IrO₂/Ti > graphite in acid condition and RuO₂/Ti > IrO₂/Ti > PtO₂/Ti > graphite in neutral and basic conditions. As a result, RuO₂/Ti demonstrated the best performance as an anode material for the electrochemical treatment of dye wastewater.

• Journal of the Korean Ceramic Society
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• v.25 no.5
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• pp.523-531
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• 1988

The dielectric and piezoelectric properties with compositions in Pb(Ni1/3Nb2/3)O3-PbTiO3-PbZrO3-(PNN-PT-PZ)solid solution ceramics were investigated. In this study, the compsition ranges were 30 PNN 45mole%, 20 PT 50mole% and 50 PZ5mole%. As PT fraction were increased the grain size was increased and the fired density was decreased, but the changes of PNN fraction had no effect on the grain size. The Curie temperature was increased when PT and PNN fraction were increased. The displacement was increased but had a great hysteresis loss when PT fraction was increased. In morphotropic phase boundary, the maximum piezoelectric and electromechanical coupling factor were indicated. Morphotropic phase boundary(MPB) was 34 PT 36mole% in chang of compositions.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.130-130
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• 1997

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.58-58
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• 1997

• Journal of the Korean institute of surface engineering
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• v.48 no.2
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• pp.38-42
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• 2015

Atomic layer deposition (ALD) is essential for the fabrication of nanoscale electronic devices because it has excellent conformality, atomic scale thickness control, and large area uniformity. Metal thin films are one of the important material components for electronic devices as a conductor. As the size of electronic devices shrinks, the thickness of metal thin films is decreased down to few nanometers, and the metal films become non-continuous due to inherent island growth of metal below a critical thickness. So, fabrication of continuous metal thin films by ALD is fundamentally and practically important. Since ALD films are grown through self-saturated reactions between precursors on surface, initial growth characteristics significantly depend on the surface properties and the selection of precursors. In this work, we investigated ALD Pt on $TiO_2$ substrate by using trimethyl-methyl-cyclopentadienyl-Platinum ($MeCpPtMe_3$) precursor and $O_3$ reactant. By using $O_3$ instead of $O_2$, initial nucleation rate of ALD Pt was increased on $TiO_2$ surface, resulting in formation of continuous thin Pt films. Morphologies of ALD Pt on $TiO_2$ were characterized by using Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). Crystallinity of ALD Pt on $TiO_2$ correlated with its growth characteristics was analyzed by X-Ray Diffraction (XRD).

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.82.2-82
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• 2003

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.100-105
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• 1998

This paper describes the preparation of Pt-and $TiO_2$-doped $Nb_2O_5$ thin film by Ion-Beam-Enhanced Deposition. Platinum and titanium doping, and Nb2O5 deposition were carried out in situ. The dependence of oxygen sensing properties on the amounts of Pt and Ti dopant in the $Nb_2O_5$ film was investigated. There were the highist sensitivity, the lowest temperature coefficient and the shortest responce time at doping of 5 mol% $TiO_2$ and 0.3 mol%Pt