The silver nanofluids were synthesized by the pulsed wire evaporation (PWE) method in a liquid-gas mixture. The size and microstructure of nanoparticles in the deionized water were investigated by a particle size analyzer (PSA), transmission electron microscope (TEM), and scanning electron microscope (SEM). Also, the synthesized nanofluids were investigated in order to assess the stability of dispersion of nanofluid by the zetapotential analyzer and dispersion stability analyzer. The results showed that the spherical silver nanoparticle formed in the deionized water and mean particle size was about 50 nm. Also, when explosion times were in the range of 20~200 times, the absolute value of zeta potential was less than -27 mV and the dispersion stability characteristic of low concentration silver nanofluid was better than the high concentration silver nanofluid by turbiscan.

Bulk amorphous materials have been intensively studied to apply for various advanced industry fields due to their high mechanical, chemical and electrical properties. These materials have been produced by several techniques such as mechanical alloying, melt spinning and gas atomization, etc. Among them, the atomization is the most potential technique for commercialization due to high cooling rate during solidification of the melt and mass productivity. However, the amorphous powders still have some limitations because of their low ductility and toughness. Therefore, intensive efforts have to be carried out to increase the ductility and toughness. In this study, the Ni-based amorphous powder was produced by the gas atomization process. And in order to increase the ductile toughness, ductile Cu phase was coated on the Ni amorphous powder by spray drying process. The characteristics of the as-synthesis powders have been examined and briefly mentioned. The master alloy with Ni57Zr20Ti16Si2Sn3 was prepared by vacum induction melting furnace with graphite crucible and mold. The atomization was conducted at 1450oC under the vacuum of 10-2 torr. The gas pressure during atomization was varied from 35 to 50 bars. After making the Ni amorphous powders, the spray drying was processed to produce the Cu -coated Ni amorphous composite powder. The amorphous powder and Cu nitrate solution were mixed together with a small amount of binder and then it was sprayed at temperature of 130oC and rotating speed of 15,000 R.P.M..

The effects of reaction temperature and precursor concentration on the microstructure and magnetic properties of nanoparticles synthesized as final products of iron acetylacetonate in chemical vapor condensation (CVC) were investigated. Pure phase was obtained at temperature above and crystallite size of nanoparticles decreased with lowering precursor concentration. Also, the coercivity decreases with decreasing crystallite size of nanopowder. The lowest coercivity was 7.8 Oe, which was obtained from the nanopowder sample synthesized at precursor concentration of 0.3M. Then, the crystallite size of nanoparticles was 8.8 nm.

Synthesis gas is a high valued compound as a basic chemicals at various chemical processes. Synthesis gas is mainly produced commercially by a steam reforming process. However, the process is highly endothermic so that the process is very energy-consuming process. Thus, this study was carried out to produce synthesis gas by the partial oxidation of methane to decrease the energy cost. The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst in a fluidized bed reactor. With the fluidized bed reactor, CH4 conversion was 91%, and Hz and CO selectivities were both 98% at 850℃ and total flow rate of 100 mL/min. These values were higher than those of fixed bed reactor. From this result, we found that with the use of the fluidized bed reactor it was possible to avoid the disadvantage of fixed bed reactor (explosion) and increase the productivity of synthesis gas.

The effect of La promoter on the carbon deposition and catalytic activity in the synthesis gas production with supported Ni catalysts was investigated. Active component was Ni and support was CeO2 and the promoter used was La. The reaction was carried out in a fixed bed reactor at 1 atm and 650~800℃. The catalysts were prepared by two methods, the impregnation method and urea method. The catalysts prepared by the urea method showed 10 times higher surface area than those of prepared by the impregnation method. By the introduction of La promoter in the catalyst system, carbon deposition was remarkably reduced from 16% to 2%. It appears that the promoter facilitates the formation of a stable fluoride-type phase, which reduces the carbon deposition. The best catalytic activity and CO and H2 selectivities were obtained with 2.5wt% Ni/Ce(La)Ox catalyst at 750℃, giving 90% methane conversion, 93 and.80% of CO and H2 selectivities, respectively.

The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst. Reaction temperatures were changed from 600 to 850℃, and reactants flow rates were changed from 100 to 200 mL/mim. There were no significant changes in the methane conversion observed in the range of temperatures used. It is possibly stemmed from the nearly total exhaustion of oxygen introduced. The selectiveties of hydrogen and carbon monoxide did not largely depend on the reaction temperature. The selectivities of hydrogen and carbon monoxide were 96 and 90%, respectively. Carbon deposition observed was the smallest at 750℃ and the largest at 850℃. It is found that the proper reaction temperature is 750℃. The best reactant flow rate was 150 ml/min.

Synthesis gas is produced commercially by a steam reforming process. However, the process is highly endothermic and energy intensive. Thus, this study was conducted to produce synthesis gas by the partial oxidation of methane to cut down the energy cost. Supported Ni catalysts were prepared by the impregnation method. To examine the activity of the catalysts, a differential fixed bed reactor was used, and the reaction was carried out at 750~850℃ and 1 atm. The fresh and used catalysts were characterized by XRD, XPS, TGA and AAS. The highest catalytic activity was obtained with the 13wt% Ni/MgO catalyst, with which methane conversion was 81%, and H2 and CO selectivities were 94% and 93%, respectively. 13wt% Ni/MgO catalyst showed the best MgNiO2 solid solution state, which can explain the highest catalytic activity of the 13wt% Ni/MgO catalyst.

Synthesis gas is commercially produced by a steam reforming process. However, the process is highly endothermic and energy-consuming. Thus, this study was conducted to produce synthesis gas by the partial oxidation of methane to decrease the energy cost. Supported Ni catalysts were prepared by the impregnation method. To examine the activity of the catalysts, a differential fixed bed reactor was used, and the reaction was carried out at 750~850℃ and 1 atm. The fresh and used catalysts were characterized by XRD, XPS, TGA and AAS. The highest catalytic activity was obtained with the 13wt% Ni/MgO catalyst, with which methane conversion was 81%, and H2 and CO selectivities were 94% and 93%, respectively. 13wt% Ni/MgO catalyst showed the best MgNiO2 solid solution state, which can explain the highest catalytic activity of the 13wt% Ni/MgO catalyst.

본 연구에서는 고밀도 플라즈마를 형성하는 planar magnetron RF 플라즈마 CVD를 이용하여 DLC(diamond-like carbon) 박막을 합성하였다. 이 방법을 이용하여 DLC 박막을 합성한다면 고밀도 플라즈마 때문에 종래의 플라즈마 CVD(RF-PECVD)법보다 증착속도가 더욱더 향상될 것이라는 것에 착안하였다. 이를 위해 magnetron에 의한 고밀도 플라즈마가 존재할 때도 역시 DLC박막형성에 미치는 RF 전력과 반응가스 압력이 중요한 반응변수인가에 대해 조사하였고, 일정한 자기장의 세기에서 RF전력과 DC self-bias 전압과의 관계를 조사하였다. 또한 RF전력변화에 따른 박막의 증착속도와 밀도를 측정하였다. 본 연구에 의해 얻어진 박막의 증착속도는 magnetron에 의한 이온화율이 매우 높아 기존의 RF-PECVD 법보다 매우 빠르며, DLC박막의 구조와 물질특성을 알아보기 위해 FTIR(fourier transform infrared)및 Raman 분광분석을 행한 결과 전형적인 양질의 고경질 다이아몬드상 탄소박막임을 알 수 있었다.

본 연구에서는 폐자원 합성가스를 이용한 고온전이반응용 Ce가 첨가된 Cu/γ-Al2O3 촉매의 물리 화학적 특성을 비교 분석하였다. 합성방법에 따른 촉매의 특성을 비교하기 위해 활성물질의 담지 순서를 변경하여 Ce/Cu/γ-Al2O3, Ce-Cu/γ-Al2O3, Cu/Ce/γ-Al2O3, Cu/γ-Al2O3 촉매를 제조하였다. 제조된 촉매 중 Ce/Cu/γ-Al2O3 촉매가 가장 높은 활성도 및 안전성을 나타냈다. 제조된 촉매의 물리-화학적 특성은 XRD, H2-TPR, XPS, Raman, Photoluminescence 등으로 분석하였다. 그리고 CO 전환율에서도 CeO2로 첨가된 모든 Cu/γ-Al2O3 촉매는 Cu/γ-Al2O3보다 높은 CO 전환율을 보였다. 이 연구결과는 CeO2의 첨가가 고온전이반응에서 Cu/γ-Al2O3 촉매의 성능을 향상 시킨 것을 나타낸다. 또한, Ce/Cu/γ-Al2O3 촉매의 높은 촉매 활성은 주로 고농도 산소저장능 및 환원된 Cu종과 관련이 있음을 알 수 있었다.

Waste gasification can generate hydrocarbon gases that may be utilized for the synthesis of chemicals or liquid fuels, or for fuel cell power generation, if extensive, deep syngas cleaning is initially conducted. Conventional gas cleaning technology for such applications is expensive and may limit the feasibility of wet technology. Conventional cold gas cleanup (scrubbing by solvents) technique needs the temperature of raw waste gasification gas ranging from 900 to 1600℃ reduced to room temperature. Then, the cleaned - up syngas needs to be reheated. Obviously, the process is energetically inefficient. It is the objective of this study to economically meet the most stringent cleanup requirements without reheating syngas for these applications. We investigated the temperature and pressure effect in breakthrough performance of various sorbents for desulfurization and de-chlorination. Based on the results obtained during the desulfurization (Fe₂O₃, Fe₃O₄, ZnO) and the dechlorination (Na₂CO₃, NaHCO₃, Na₂O) screening tests, ZnO and Na₂O were selected as preferred optimum sorbents. H₂S breakthrough time corresponds to an effective capacity of approximately 11 g Cl/100 g of material. Also, HCl, breakthrough time corresponds to an effective capacity of approximately 5 g Cl/100 g of material. ZnO and Na₂O at high temperature of around 550℃ display high sorption performance and removal efficiency for waste syngas along with H₂S and HCl. Although there is an issue of CO₂ recovery in warm gas clean-up technology for desulfurization, we have obtained an interesting new alternative warm gas clean-up system with heat budget merit.

Magnetite (Fe3O4) has been prepared directly to avoid the reduction process prior to the H2 production from the high temperature water gas shift reaction of the simulated waste derived synthesis gas. Citric acid has been employed as a complexing agent for the direct synthesis of magnetite. Notably, without the reduction process, the catalyst prepared at the citric acid molar ratio of 1.0 showed 80% CO conversion at 350℃ at a gas hourly space velocity of 40,057 h-1.

This study was designed to synthesize mesoporous carbon, porous carbonic material and to characterize its surface in an attempt to adsorption methane gas(CH4). Synthesis of mesoporous carbon was carried out under two steps ; 1. forming a RF-silica complex with a mold using CTMABr, a surfactant, and TEOS, raw material of silica, and 2. eliminating silica through carbonization and HF treatment. The mesoporous carbon was synthesized under various conditions of synthesis time and calcination. Eight different types of mesoporous carbon, which were designated as MC1, MC2, MC3, MC4, MCT1, MCT2, MCT3, and MCT4, were prepared depending upon preparation conditions. The analysis of mesoporous carbon characteristics showed that the calcination of silica stabilized the mixed structure of silica and carbonic complex, and made the particle uniform. The results also showed that hydrothermal synthesis time did not have a strong influence on the size of pore. The bigger specific surface area was obtained as the hydrothermal synthesis time was extended. However, the specific surface area was getting smaller again after a certain period of time. In adsorption experiments, CH4 was used as adsorbate. For the case of CH4, MCT3 showed the highest adsorption efficiency.

This work presents an experimental study of the influence of lifting velocity on cake formation during filtration. For design of hot gas cleanup system using ceramic filter reactor, the most important consideration is coating conditions of sorbent in filter surface (for example : lifting velocity, coating weight of sorbent, pulsing interval and removal effect for dechlorination and desulfurization). We studied the optimum operation condition as paticle size and lifting velocity using a ceramic filter reactor at 550oC. Based on the results obtained during cold and hot test, optimum lifting velocity in a ceramic filter reactor was selected 0.68 m/s. Also, the removal behaviour of the ceramic filter during filtration was studied using differential pressure. Optimum removal efficiency for dechlorination and desulfurization accomplished at differential pressure condition over 74 mmH2O.