• 한국수소및신에너지학회논문집
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• 제13권1호
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• pp.42-51
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• 2002

Methane can be converted directly to hydrogen by pyrolysis. The reaction is highly endothemic and heat must be supplied at high temperatures. Gibbs free energy minimization calculations have been carried out for the methane pyrolysis to determine equilibrium products. The calculation parameters are the temperature, the initial H/C ratio, the pressure and Gibbs energies of each substance. Methane, ethylene, acetylene, benzene, naphthalene, and hydrogen are the main products. Excluding hydrogen, it is observed that ethylene and aromatics(benzene+naphthalene) are predominant products below 1400K, whereas acetylene is significantly formed above 1400K. Hydrogen dilution increases the selectivities for ethylene and acetylene and decreases the selectivity for aromatics. Increasing the pressure also decreases the decomposition of methane.

• 공업화학
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• 제29권4호
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• pp.474-478
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• 2018

Thermal decomposition of waste Achyranthes Root (WAR) emitted from its decoction process was investigated using a TG analyzer and a fixed-bed reactor. The WAR had the larger C and fixed carbon content than fresh AR (FAR) due to the extraction of hemicelluloses from FAR during decoction process. Thermogravimetric (TG) analysis results also revealed the elimination of hemicellulose by its decoction. Relatively high contents of the cellulose and lignin made high contents of their typical pyrolyzates, such as acids, ketones, furans, and phenols, in the pyrolysis of WAR using the fixed-bed reactor. The increase of pyrolysis temperature from 400 to $500^{\circ}C$ increased yields of oil and gas due to the more effective cracking efficiency of WAR at a higher temperature. The chemical composition of product oil was also changed by applying the higher pyrolysis temperature, which increased the selectivity to furans and phenols.

• 한국세라믹학회지
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• 제41권11호
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• pp.793-796
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• 2004

Process Parameters were studied in synthesis of LiCoO$_2$ Powder by ultrasonic spray Pyrolysis. Concentration of the mixed solution influenced the size, shape, and yield of the synthesized powder. The yield was affected primarily by the height of the solution, and then by the flow rate of a carrier gas. The temperature of the reactor governed the crystallinity and morphology of the powder. LiCoO$_2$ powders were synthesized as a layered high temperature phase above 800$^{\circ}C$. The synthesized powders were sphere and secondary Particles consisted of primary particles of 55-70 nm. The secondary Particles became bigger from 0.28 to 1.43 $\mu\textrm{m}$ as the concentration of the solution was increased from 0.05 to 2.0 M. The 2.0 M solution provided the highest production rate.

• 한국표면공학회지
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• 제50권2호
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• pp.114-118
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• 2017

Bismuth telluride ($Bi_2Te_3$) and its alloys are well-known thermoelectric materials for ambient temperature applications. In this study, the dissolved Bi-Te precursor solution was used to synthesis metallic $Bi_2Te_3$ powder via ultrasonic spray pyrolysis and reduction process. The droplets of the Bi-Te precursor solution were decomposed to Bi-Te oxide powders by ultrasonic spray pyrolysis. The spherical $Bi_2Te_3$ powders were synthesized by reduction reaction in atmosphere of hydrogen gas at the temperature above $375^{\circ}C$ for 6h. The reduced $Bi_2Te_3$ powders have a mean particle size of $1.5{\mu}m$. The crystal structure of the powder was evaluated by X-Ray diffraction(XRD), and the microstructure with size and shape powders was observed by fieldemission scanning electron microscope(FE-SEM) and transmission electron microscope(TEM).

• Environmental Engineering Research
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• 제17권3호
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• pp.157-165
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• 2012

This experimental study was performed to obtain thermal energy from the combustion of synthetic gas, produced by the pyrolysis of insulating oil containing polychlorinated biphenyls (PCBs) in a high temperature and high pressure reactor. The average synthetic gas generated was $59.67Am^3/hr$ via the steady state gasification of insulating oil waste (20 kg/hr) with average concentrations (standard deviation) of $CO_2$, CO, and $H_2$ in the synthetic gas of $38.63{\pm}3.11%$, $35.18{\pm}1.93%$, and $28.42{\pm}1.68%$, respectively. The concentrations of the PCBs in the transformer insulating oil and synthetic gas after its gasification, and the concentrations of the dioxins that could be produced from the incomplete degradation of PCBs were measured. It was revealed that the PCBs in the insulating oil were composed of the series from tetrachlorobiphenyl to octachlorobiphenyl. However, only the #49, #44, #52, and #47/75/48 congeners were detected from the synthetic gas after gasification of the insulating oil and in the flue gas from the combustor. In conclusion, the experimental conditions suggested in this study were very useful for the appropriate treatment of insulating oil containing PCBs. Also, fuel gas containing CO and $H_2$ can be obtained from the pyrolysis of insulating oil containing PCBs.

• 센서학회지
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• 제5권3호
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• pp.41-48
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• 1996

SOx 가스를 고감도로 감지할 수 있는 SAW 가스 센서를 개발하였다. 이는 SAW device 위에 SOx 가스에 감응하는 재료를 박막으로 증착함으로써 고감도의 마이크로 센서형으로 한 것이다. SOx 감응 재료로서 CdS를 선정하였으며, 이를 SAW device 위에 박막화하기 위해 초음파 분무 노즐을 이용한 분무 열분해의 박막 증착공정을 응용하였다. 초음파 분무 노즐을 통하여 생성된 균일하고 미세한 입자들은 기판위에서 안정한 열분해 환경을 조성함으로써 센서 감응막을 위한 넓은 표면적의 박막을 증착 시켰는데 기판의 온도는 $300^{\circ}C$ 내외에서 최소 50 nm수준의 결정립의 박막을 얻었다. 이렇게 하여 얻은 SAW 가스 센서는 $SO_{2}$ 가스에 감응하였으며 재현성도 보였다. 다른 가스의 존재하에서 $SO_{2}$ 가스에 대한 선택성에 관하여는 계속적인 연구가 필요하다.

• 한국세라믹학회지
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• 제53권2호
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• pp.134-138
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• 2016

Porous $Co_3O_4$ spheres with bimodal pore distribution (size: 2-3 nm and ~ 30 nm) were prepared by ultrasonic spray pyrolysis of aqueous droplets containing Co-acetate and polyethylene glycol (PEG), while dense $Co_3O_4$ secondary particles with monomodal pore distribution (size: 2-3 nm) were prepared from the spray solution without PEG. The formation of mesopores (~ 30 nm) was attributed to the decomposition of PEG. The responses of a porous $Co_3O_4$ sensor to various indoor air pollutants such as 5 ppm $C_2H_5OH$, xylene, toluene, benzene, and HCHO at $200^{\circ}C$ were found to be significantly higher than those of a commercial sensor using $Co_3O_4$ and dense $Co_3O_4$ secondary particles. Enhanced gas response of porous $Co_3O_4$ sensor was attributed to high surface area and the effective diffusion of analyte gas through mesopores (~ 30 nm). Highly sensitive porous $Co_3O_4$ sensor can be used to monitor various indoor air pollutants.

• 한국분무공학회지
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• 제20권3호
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• pp.162-167
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• 2015

Recently, there has been rising interest in applying urea-SCR systems to large marine diesel engines because the International Maritime Organization (IMO) has decided to enforce NOx reduction regulations. Generally, in the case of urea-SCR of the marine diesel engine, a type of twin fluid atomizer has been using for injection of the urea solution. This study conducted to investigate an effect of the atomization of external-mixing twin fluid nozzle on the conversion efficiency of reductant. The lab-scaled experiment device was installed to mimic the urea-SCR system of the marine diesel engine for this study. In a low temperature inflow gas condition which is similar with the exhaust temperature of large marine diesel engine, this study found that the conversion efficiency of reductant of when relative big size urea solution droplets are injected into exhaust gas stream can be larger than that of when small size urea solution droplets are injected. According to results of this study, the reason was associated with decrease of reaction rate constant caused from temperature drop of inflow gas by assist air of twin fluid atomizer.

• Journal of the Korean Wood Science and Technology
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• 제14권3호
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• pp.43-46
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• 1986

A stainless steel autoclave reactor, which is the property of Pacific Northwest Laboratories(PNL) and located in PNL, was acted for pyrolysis and gasification of sawdust, ricestraw, and ricehusk. The initial reaction temperature of this reactor was 300$^{\circ}C$, and up to 500$^{\circ}C$ to complete pyrolysis and gasification reaction. The maximum exerted pressure on this reactor was 800 psig. In order to examine the effect of catalyst on reaction temperature, $K_2CO_3$, and nickel/alkali carbonate catalyst mixture were also used. The experimental results obtained with this reactor indicated that good yields of methane-rich gas(exceeding 40% methane) can be produced. The product gas mixtures were also identified to be CO. $CO_2$, $C_2H_4$, and $CH_3CHO$ etc. by Gas Chromatography and Mass Spectrometer.

• Transactions on Electrical and Electronic Materials
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• 제13권3호
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• pp.111-115
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• 2012

Spray pyrolysis method was applied for the preparation of indium oxide ($In_2O_3$) thin films, by varying the substrate temperature range from 400-$600^{\circ}C$. All the samples were characterized at room temperature by using X-Ray diffraction, Scanning electron microscopy, Atomic Force Microscopy, Hall Effect and UV-Visible spectrophotometry. The optimal substrate temperature required for obtaining films of high crystallographic quality was $575^{\circ}C$. By comparing optical transmittance and electrical conductivity it was observed that the best figure of merit for these films was achieved for the same temperature and electrical resistivity was in the order of ${\rho}=1.47{\times}10^{-1}[{\Omega}cm]$. Gas sensing measurements of the films in ethanol showed enhancement with surface roughness and sheet resistance.