• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.543-549
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• 1997

The direct reaction of carbon dioxide($CO_2$) with butane($C_4H_{10}$) to obtain synthesis gas and hydrocarbon compounds have been studied on nickel loaded catalysts. In the reaction of $CO_2$ with $C_4H_{10}$, Ni loaded catalysts showed similar activity with Pt catalyst and Coke deposition on the catalyst was severe by dehydrogenation of butane. The main products were carbon monoxide and hydrogen, when alumina and Y type zeolite were used as a support. Instead, a great deal of aromatic hydrocarbons were obtained on the Ni loaded ZSM-5 catalyst. The conversion of $CO_2$ increased with the increasing molar ratio of $CO_2$/$C_4H_{10}$ on Ni/ZSM-5, Ni/NaY and Ni/alumina catalyst, but the conversion decreased again from the ratio of 2. The value of $CO_2$ conversion was the highest at the 5wt% of Ni loading on ZSM-5 catalyst. A part of cokes deposited on the catalysts diminished when only $CO_2$ gas or water steam flowed into the reactor. The coke deposited on the catalysts was very reactive and it may be an important intermediate for the carbon dioxide reforming reaction.

• 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.

• Journal of the Korean Electrochemical Society
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• v.11 no.2
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• pp.109-114
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• 2008

Though ethanol can theoretically generate 12 electrons during oxidation to carbon dioxide, the complete oxidation of ethanol is hard to achieve due to the strong bond between the two carbons in its molecular structure. Therefore, development of high activity catalyst for ethanol oxidation is necessary for the commercialization of direct ethanol fuel cell. In this study, some binary and ternary electrocatalysts of PtSn/C and PtSnAu/C have been synthesized and characterized. The catalysts were fabricated with modified polyol method with the amounts of 20 wt%, where the Pt : Sn ratios in the PtSn/C were 1 : 0, 4 : 1, 3 : 1, 2 : 1, 1.5 : 1, 1 : 1, 1 : 1.5 and Pt:Sn:Au ratios in the PtSnAu/C were 5 : 5 : 0, 5 : 4 : 1, 5 : 3 : 2, 5 : 2 : 3. From the XRD and TEM analysis results, the catalysts were found to have face centered cubic structure with particle size of around $1.9{\sim}2.4\;nm$. The activity in the ethanol oxidation was examined with cyclic voltammetry and the results indicated that PtSn(1.5 : 1)/C and PtSnAu(5 : 2 : 3)/C had the highest activity in each catalyst system. Further tests with single cell were performed with those catalysts. It was found that PtSn/C(1.5 : 1) exhibited the best performance while the long term stability of PtSnAu/C(5 : 2 : 3) is better than PtSn/C(1.5 : 1).

• Clean Technology
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• v.25 no.4
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• pp.296-301
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• 2019

This study was conducted to investigate the characteristics of CO oxidation by NO poisoning in Pt/TiO₂ catalyst prepared by wet impregnation method and calcined at 400 ℃. In order to confirm the NO poisoning effect of the Pt/TiO₂ catalyst, the change of reaction activity was observed when NO was injected during the CO+O₂ reaction where it was ascertained that the CO conversion rate rapidly decreased below 200 ℃. Also, CO conversion was not observed below 125 ℃. Recovery of initial CO conversion was not verified even if NO injection was blocked at 125 ℃. Accordingly, various analyses were performed according to NO injection. First, as a result of the TPD analysis, it was confirmed that NO pre-adsorption in catalyst inhibited CO adsorption and conversion desorption from adsorbed CO to CO₂. When NO was pre-adsorbed, it was confirmed through H₂-TPR analysis that the oxygen mobility of the catalyst was reduced. In addition, it was validated through FT-IR analysis that the redox cycle (Pt²⁺→Pt⁰→Pt²⁺) of the catalyst was inhibited. Therefore, the presence of NO in the Pt/TiO₂ catalyst was considered to be a poisoning factor in the CO oxidation reaction, and it was determined that the oxygen mobility of the catalyst is required to prevent NO poisoning.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.79-86
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• 2010

Effects of operating parameters such as applied voltage, solution conductivity, ferrous ion concentration, electrode material on phenol degradation by pulsed corona discharges were investigated in laboratory scale experiments. The increase of applied voltage enhanced the phenol degradation by generating more energetic electrons. The solution conductivity inversely affected phenol removal rate in the tested ranges because the increase of conductivity decreased the electric field strength through the liquid phase. The addition of ferrous sulfate promoted the phenol degradation through the OH radical production by the Fentonlike reactions between ferrous ion and hydrogen peroxide generated by pulsed corona discharges. Catechol and hydroquinone were detected as primary intermediates of phenol degradation and the decrease of pH and the increase of conductivity were observed probably due to the generation of organic acids. Almost all of the initial phenol was disappeared and 29% of total organic corbon (TOC) was removed in the condition of 0.5 mM of ferrous sulfate after approximately 230 kJ of discharge energy transferred to the reactor.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.2
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• pp.82-88
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• 2017

MET (Microbial Electrochemical Technology), such as MFC (Microbial Fuel Cell) and MEC (Microbial Electrolysis Cell), is a promising technology for producing sustainable biogas from an anaerobic digester (AD). At current stage, however, the most likely limiting factors, large internal resistances, should be overcome for successful scale up of this technology. Various researchers reported that application of electrode materials containing high current density, increase of ion strength and conductivity, configuration of electrode are good methods for minimizing internal resistances. Recently, stainless steel is receiving great attention because of not only high performance and durability but also low cost. Therefore, in this study, we evaluate electrochemical characteristics and biogas production rate using various electrode materials and configuration (graphite carbon coated with catalysts ($GC-C_M$) or not (GC), stainless steel mesh (SUS-M) and plate (SUS-P)). As the results, current densities of $GC-C_M$, GC, SUS-P, SUS-M were 2.03, 1.36, 1.04, $1.13A/m^2$, respectively. Methane yields of $GC-C_M$, GC, SUS-P, SUS-M were 0.27, 0.14, 0.19, 0.21 $L-CH_4/g-COD_{rem}$., respectively. Stainless steel shows high current density and methane yield, which are similar as graphite carbon coated with catalysts.

• Clean Technology
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• v.28 no.4
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• pp.331-338
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• 2022

The objective of this study is to prepare bead-type and pellet-type Pt (1 wt%)/Kieselguhr catalysts as hydrogenation catalysts for the polycyclic aromatic hydrocarbons (PAHs) included in pyrolysis fuel oil (PFO). The optimal reaction temperature to maximize the yield of saturated cyclic hydrocarbons during the PFO-cut hydrogenation reaction in a trickle bed reactor was determined to be 250 ℃. A hydrogen/PFO-cut flow rate ratio of 1800 was found to maximize 1-ring saturated cyclic compounds. The yield of saturated cyclic compound increased as the space velocity (LHSV) of PFO-cut decreased. The difference in hydrogenation reaction performance between the pellet catalyst and the bead catalyst was negligible. However, the catalyst impregnated by Pt after molding the Kieselguhr support (AI catalyst) showed higher hydrogenation activity than the catalyst molded after Pt impregnation on the Kieselguhr powder (BI catalyst), which was a common phenomenon in both the pellet catalysts and bead catalysts. This may be due to a higher number of active sites over the AI catalyst compared to the BI catalyst. It was confirmed that the pellet catalyst prepared by the AI method had the best reaction activity of the prepared catalysts in this study. The majority of the PFO-cut hydrogenation products were cyclic hydrocarbons ranging from C₈ to C₁₅, and C₁₁ cyclic hydrocarbons had the highest distribution. It was confirmed that both a cracking reaction and hydrogenation occurred, which shifted the carbon number distribution towards light hydrocarbons.

• Korean journal of applied entomology
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• v.14 no.3 s.24
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• pp.111-131
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• 1975

The study has been carried out to investigate the occurrence, damage, characteristics of the pathogen, environmental conditions affecting the disease outbreak, varietal resistance, forecasting, and chemical control of bacterial leaf blight of rice in Korea since 1964. Bacterial leaf blight of rice became a major disease in Korea since 1960. A correlation was found between the annual increase of epidemics and increase of cultivation area of susceptible varieties, Jinheung, Keumnampung etc. Areal damage within the country showed that the more was at southern province, Jeonnam, Gyeongnam and western coast, and at flooded rice paddy. Yield reduction directly related with the amount of infection on upper leaves at heading stage. Fifty per cent of reduction resulted when the lesion area was more than 60 per cent. Less than 20 per cent of lesion area, however, was not affected so much on yield loss One hundred and six isolates collected from all over the country were classified as 8 strains by using 4 different bacteriophages in 1973. It was, however, only two in 1965. There were some specificities on varietal distributions among the strains such as that the Jinheung attacked mainly by strain A, B, C and I, those attack Kimmaze were A, B, H and I. Most strains were found from Tongil except D and E, whereas Akibare was only variety that attacked by strain E. Low temperature, high humidity, heavy rainfall and insutficient daylight favored the disease epidemics. Especially, typhoon and flooding at heading stage were critical factors. The earlier transplanting the more disease was resulted, and more nitrogen fertilizer application accerelated the diseased development in general. The resistance to the disease varied by growing stage of the sane plants. All of recommended varieties in Korea were susceptible to the disease except Norm No. 6 and Sirogane which moderately resistant. The pathogen, Xanthomonas oryzae, was detectable from extract of healthy seedlings that were grown in the field with an heavy infection previous year. The more bacteriophage in irigation water resulted the more disease outbreak, and the existence of more than 50 bacteriophages in 1ml. of irrigation water were necessary to initiate the disease out break. The curves representing occurrence of bacteriophages and disease outbreak were similar with 15 days interval. The survey of bacteriophage occurrence can be utilized in forecasting of the disease two weeks ahead of disease outbreak. Three applications of chemicals, Phenazin and Sangkel, in weekly intervals at the early satage of out-break depressed the symptom development, and increased yield by 20per cent. Proper period for the chemical application was just before the number of bacteriophage reaches 50 in 1ml. of irrigation water.