• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.128.2-128.2
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• 2013

Crucially, effective catalysts must be capable of efficiently catalyzing the protonation of adsorbed CO to adsorbed CHO or COH. One of the strategies is alloying with metals with higher oxygen affinity and Au-Zn alloy is one of the best candidates. At first, we made Au-Zn alloy using vacuum evaporating method. Zn was deposited on the Au(211) surface and the amount was estimated by X-ray photoelectron spectroscopy (XPS) using the relative sensitivity of Au 4f and Zn 3d. We investigated CO adsorption on a clean Au(211) and Au-Zn alloy using temperature-programmed desorption (TPD) and XPS. From the TPD results, we can conclude that the presence of the particular step sites at the Au(211) surface imparts stronger CO bonding and Zn atoms are sitting on the step sites at the Au(211) when Zn is deposited. The XPS results show the oxygen atoms of CO bond Zn atoms on Au-Zn surface. It should be an evidence that alloying Zn atoms that has high oxygen affinity into an electrocatalyst may allow CHO* to bind to the surface through both the carbon and oxygen atoms.

• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.25-34
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• 2021

This study develops a new device system for measuring a slope of object with non-adhesive, non-contact and non-face-to-face, namely Inclinometer Slope Laser Measuring (ISLM), that is applicable in the field. This system includes cradle, laser, camera, and computer and the filming and is performed after laser projection at programmed intervals. After measuring the amount of displacement converted to numerical values, these values can then be transferred to the office using the selected data transmission method. The obtained results from the test carried out to verify the reliability of the ISLM system indicated that the ISLM system can measure with accurately level of 0.1mm/Pixel at 1m distance and when increasing the camera resolution, the precision might increase proportionally. Therefore, the proposed measure system may widely apply on-site for various constructions, especially, in the case of object with very high surface temperature where exhibits difficulty to directly measure the adjacent structures. However, due to the sensitive reaction to the illuminance, this method can be applied with caution at times of large changes in illuminance, such as at dawn and at dusk.

• Journal of Environmental Science International
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• v.31 no.10
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• pp.833-844
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• 2022

A zeolite material with a Si/Al molar ratio of 1.2 was synthesized by changing the NaOH/CFA ratio of coal fly ash (CFA) via a fusion/hydrothermal reaction in the HD thermal power plant. The change in the crystal structure of the zeolite was confirmed using XRD and SEM, and the ammonia adsorption capacities of the synthesized zeolitic materials and a commercial zeolite (Na-A zeolite) were analyzed via an ammonia temperature-programmed desorption (NH₃-TPD) process. The SEM and XRD results revealed out the zeolitic materials from the coal fly ash maintained a hexagonal Linde-type crystal structure similar to that of Na-A zeolite, but the crystallinity of the synthesized zeolitic material was reduced due to impurities. The NH₃ adsorption capacity, determined from the NH₃-TPD analysis of was 1.122 mmol/g of the synthesized zeolitic material, which was lower than the NH₃ adsorption capacity of the Na-A zeolite.

• Advances in Energy Research
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• v.8 no.4
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• pp.223-231
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• 2022

An ex-situ gravitational fixed bed pyrolysis reactor was used over Al₂O₃ supported Ni₂P based catalyst with various Ni/P molar ratios (0.5-2.0) and constant nickel loading of 5.37 mmol/g Al₂O₃ to determine the hydrodeoxygenation of rubberwood sawdust (RWS) at atmospheric pressure. The 3D catalysts formed were characterized structurally as well as acidic properties were determined by hydrogen-temperature programmed reduction (TPR). The Ni₂P phase formed completely on Al₂O₃ for 1.5 Ni/P ratio, although lesser crystallite sizes of Ni₂P were seen at Ni/P ratios less than 1.5. Additionally, it was shown that when nickel loading level increased, acidity increased and specific surface area dropped, probably because nickel phosphate is not easily converted to Ni₂P. When Ni/P ratio was 1.5, Ni₂P phase fully formed on Al₂O₃. The catalytic activity was explained in terms of impacts of reaction temperature and Ni/P molar ratio. At relatively high temperature of 450℃, the high-value deoxygenated produce was predominantly composed of n-alkanes. Based on the findings, it was suggested that hydrogenolysis, hydrodeoxygenation, dehydration, decarbonylation, and hydrogenation are all part of mechanism underlying hydrotreatment of RWS. In conclusion, the synthesized Ni₂P/ Al₂O₃ catalyst was capable of deoxygenating RWS with ease at atmospheric pressure, primarily resulting in long chained (C₉-C₂₄) hydrocarbons and acetic acid.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.196-196
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• 2011

Molecular $N_2O$ has bee known to react over oxygen vacancy on a reduced rutile $TiO_2$(110)-1${\times}$1 surface to desorb as molecular $N_2$ leaving oxygen atom behind. In the present study, we investigated the reaction of $N_2O$ on rutile $TiO_2$(110) using temperature-programmed desorption (TPD). Our results indicate that $N_2O$ does not react over the oxygen vacancy under a typical UHV experimental condition. On a rutile $TiO_2$(110)-1${\times}$1 with a well-defined oxygen vacancy concentration of 5% ($2.6{\times}10^{13}/cm^2$), $N_2O$ desorption features show a monolayer peak maximum at 135 K followed by a small peak maximum at 170 K. When the oxygen vacancy is blocked with $H_2O$, the $N_2O$ peak at 170 K disappears completely, indicating that the peak is due to molecular $N_2O$ interacting with oxygen vacancy. The integrated amount of desorbed $N_2O$ plotted against the amount of adsorbed $N_2O$ however shows a straight line with no offset indicating no loss of $N_2O$ during our cycles of TPD measurements. In addition, our $N_2O$ uptake measurements at 70~100 K showed no $N_2$ (as a reaction product) desorption except contaminant $N_2$. Also, $H_2O$ TPD taken after $N_2O$ scattering up to 350 K indicates no change in the vacancy-related $H_2O$ desorption peak at 500 K showing no change in the oxygen vacancy concentration after the interaction with $N_2O$.

• Journal of Hydrogen and New Energy
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• v.18 no.2
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• pp.140-150
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• 2007

Thermochemical 2-step methane reforming, involving the reduction of metal oxide with methane to produce syngas and the oxidation of the reduced metal oxide with water to produce pure hydrogen, was investigated on ferrite-based metal oxide mediums. The mediums, CoFZ, CuFZ, or MnFZ, were composed of the mixture of M(M=Co, Cu or Mn)-substituted ferrite as an active component and $ZrO_2$ as a binder, respectively. The WZ medium, composed of the mixture of $WO_3$ and $ZrO_2$, was also prepared to compare. With an addition of $ZrO_2$, the surface area of the mediums was slightly increased and the sintering of active components was greatly suppressed during the reduction. The higher reactivity of the reduced mediums for water splitting was confirmed by the temperature programmed reaction. From the results of the thermochemical 2-step methane reforming, the reactivity of $CH_4$ reduction and water splitting with ferrite-based metal oxide mediums was relatively higher than that with WZ, and the order of reactivity of the mediums was MnFZ>CoFZ>CuFZ>WZ.

• Journal of Hydrogen and New Energy
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• v.19 no.5
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• pp.394-402
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• 2008

The Effects of Cu or Ni additives co-added with Ce/Zr mixed oxides to Fe-based oxide mediums were investigated for the purpose of the replacement of Rh, a precious metal additive, in terms of hydrogen storage(reduction by hydrogen) and release(water splitting). From the results of temperature programmed reduction(TPR), initial reduction rate of iron oxide in the mediums was greatly increased with the addition of Cu, similar to that of Rh. For isothermal redox reaction of 10 cycles, the total amounts of hydrogen evolved in water splitting steps for the mediums added with Cu or Ni were highly maintained at ca. 7 mmol/g-material, even though the oxidation rates were slightly lower than that for the medium added with Rh. This result suggests that the replacement of Rh to Cu or Ni is possible as a co-additive for Fe-based oxide mediums.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3387-3390
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• 2013

Catalytic gasification of mandarin waste residue was carried out using direct and indirect catalyst-contact methods for the first time. In the indirect method, non-catalytic reaction in a reactor was followed by catalytic upgrading of vapor product in another reactor. Two different catalysts, $Ni/{\gamma}-Al_2O_3$ and $Ni/CeO_2-ZrO_2$, were employed. $CeO_2-ZrO_2$ support was prepared using hydrothermal synthesis in supercritical water. The catalysts were characterized by $H_2$-temperature programmed reduction and Brunauer-Emmett-Teller analyses. Under the condition of equivalent ratio (ER) = 0, the indirect catalyst-contact method led to a higher gas yield than the direct method. Under ER = 0.2, the yield of biogas obtained over $Ni/CeO_2-ZrO_2$ was higher than that obtained over $Ni/{\gamma}-Al_2O_3$. Also, the coke formation of $Ni/CeO_2-ZrO_2$ was lower than that of $Ni/{\gamma}-Al_2O_3$. Such results were attributed to the higher reducibility and better lattice oxygen mobility of $Ni/CeO_2-ZrO_2$, which were advantageous for partial oxidation reaction.

• Clean Technology
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• v.21 no.4
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• pp.248-256
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• 2015

MnO₂ was prepared by a hydrothermal process method in the range of 120-200 ℃ and 0.5-5 h, calcined at 300 ℃ after induction of precipitation using KMnO₄ and MnCl₂･4H₂O, and its catalytic activity was compared for CO oxidation. The catalysts were characterized using by X-ray diffraction, N₂-sorption, scanning electron microscopy, and temperature programmed reduction of H₂ or CO. The crystalline structure of pure α-MnO₂ or hybrid α/β-MnO₂ was controlled by the preparation conditions. The pure α-MnO₂ showed better catalytic activity and thermal stability than hybrid α/β-MnO₂. Especially, α-MnO₂ prepared at 150 ℃ for 1 h has the highest specific surface area 214 m² g^-1, reducibility and labile lattice oxygen species analyzed by H₂, CO-TPR, respectively. It also showed the best CO oxidation activity in both conditions of temperature programmed and isothermal reaction. The results came from the physicochemical properties of catalysts like the crystalline structure, specific surface area, reducibility and lattice oxygen species, and which are correlated with catalytic performance.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.435-441
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• 2012

The direct conversion of cellulose into polyols in $H_2$ was examined over Pt catalysts supported on various zeolites, viz., mordenite, Y, ferrierite, and ${\beta}$. For comparison, Pt catalysts supported on ${\gamma}-Al_2O_3$, $SiO_2-Al_2O_3$, and $SiO_2$ were also tested. The physical properties of the catalysts were probed with $N_2$ physisorption. The surface acidity was measured with temperature programmed desorption of ammonia ($NH_3$-TPD). The Pt content was quantified with inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The Pt dispersion was determined with CO chemisorptions and transmission electron microscopy (TEM). The conversion of cellulose appeared to be mainly dependent on the reaction temperature and reaction time because it depends on the concentration of $H^+$ ions reversibly formed in hot water. Pt/H-mordenite (20) showed the highest yield to polyols among the tested catalysts. Pt/H-zeolite was superior to Pt/Na-zeolite for this reaction. The polyol yield was dependent on the surface acid density and the external surface area.