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이산화탄소에서 메탄올로의 전환을 위한 CuO-ZnO/TCP 촉매의 최적 반응조건에 관한 연구
안원주 ( Won-ju Ahn ),이환규 ( Hwan-gyu Lee ),이영호 ( Young-ho Lee ),손석환 ( Seok-hwan Son ),정운조 ( Woon-jo Jeong ),정민철 ( Min-chul Chung ),박권필 ( Kwon-pil Park ),안호근 ( Ho-geun Ahn ) 한국환경기술학회 2014 한국환경기술학회지 Vol.15 No.3
이산화탄소의 온실효과는 세계에서 가장 심각한 문제점 중의 하나로 인식되어 왔다. 메탄올은 화학산업에서 기초적인 중간생성물 중의 하나이며, 또한 연료 첨가제 및 청정 연소 연료로서 사용되어지고 있다. 본 연구에서는 메탄올로의 이산화탄소의 전환 방법을 촉매 화학적 방법을 이용하여 조사하였다. 티타늄 칩 플레이트는 촉매 지지체로서 사용되었다. CuO-ZnO/TCP 촉매는 Wash-coat방법을 이용하여 제조하였다. 제조된 촉매는 SEM과 XRD을 이용하여 담지상태를 조사하였다. 메탄올로의 이산화탄소 수소화에 대한 촉매의 활성은 다양한 반응온도, 반응압력 및 담지 횟수 등을 바꿔가며 유통식 반응기를 이용하여 조사하였다. SEM 이미지와 XRD 패턴으로부터 CuO와 ZnO촉매성분은 Titanium Chip Plate의 표면에 균일하게 잘 담지되어 있음을 알았다. CuO와 ZnO계 담지촉매를 제조하는데 있어서, 전구체 수용액 25.7%(w/v)를 이용한 3회 담지가 가장 높은 효율을 보였으며, 1회 담지를 위한 전구체의 농도는 51.4%(w/v)가 적절하였다. 이산화탄소의 수소화의 활성은 반응온도 210℃에서 최대이고, 반응온도가 250℃ 이상으로 증가하면 역수성 가스 전환반응으로 전환하기 때문에 감소하는 경향을 보였다. 메탄올의 선택도는 반응압력 20atm에서 가장 높게 나타내었으며, 20atm 이상에서는 감소하는 경향을 나타내었다. 결과적으로, 210℃의 CuO-ZnO/TCP 촉매상에서 이산화탄소의 전화율은 27.2%이었고, 최대수율은 13.8%임을 알았다. The greenhouse effect of carbon dioxide has been recognized as one of the most serious problems in the world. Methyl alcohol is one of the basic intermediates in the chemical industry and is also being used as a fuel additive and as a clean burning fuel. In this study, conversion of carbon dioxide to methyl alcohol was investigated using catalytic chemical methods. Titanium chip plate(TCP) was used as a catalyst support. Titanium chip plate(TCP) supported CuO-ZnO catalysts were prepared by wash-coat method. The prepared catalysts were characterized by using SEM and XRD. The catalytic activity for carbon dioxide hydrogenation to methyl alcohol was investigated using a flow-type reactor under various reaction temperatures, reaction pressures and the numbers of impregnation. SEM images and XRD patterns showed that CuO and ZnO was uniformly supported on TCP. In the preparation of CuO-ZnO/TCP catalyst, the appropriate number of impregnation by the precursor solution of 25.7%(w/v) and 51.4%(w/v) concentration were 3 times and a time, respectively. The optimum reaction temperature in the hydrogenation was 210℃, and the selectivity to methyl alcohol was maximum at reaction pressure of 20atm. As the results. CO<sub>2</sub> conversion and yield to methyl alcohol were 27.2% and 13.8% over CuO-ZnO/TCP catalyst at 210℃.
Bias Stress Instability of Double-Gate a-IGZO TFTs on Polyimide Substrate
조원주,안민주 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.6
In this study, flexible double-gate thin-film transistor (TFT)-based amorphous indium-galliumzinc- oxide (a-IGZO) was fabricated on a polyimide substrate. Double-gate operation with connected front and back gates was compared with a single-gate operation. As a result, the double-gate a- IGZO TFT exhibited enhanced electrical characteristics as well as improved long-term reliability. Under positive- and negative-bias temperature stress, the threshold voltage shift of the double-gate operation was much smaller than that of the single-gate operation.
High-Performance a-IGZO Thin-Film Transistor with Conductive Indium-Tin-Oxide Buried Layer
안민주,조원주 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.7
In this study, we fabricated top-contact top-gate (TCTG) structure of amorphous indium-galliumzinc oxide (a-IGZO) thin-film transistors (TFTs) with a thin buried conductive indium-tin oxide (ITO) layer. The electrical performance of a-IGZO TFTs was improved by inserting an ITO buried layer under the IGZO channel. Also, the effect of the buried layer’s length on the electrical characteristics of a-IGZO TFTs was investigated. The electrical performance of the transistors improved with increasing the buried layer’s length: a large on/off current ratio of 1.1×107, a high field-effect mobility of 35.6 cm2/Vs, a small subthreshold slope of 116.1 mV/dec, and a low interface trap density of 4.2×1011 cm−2eV−1 were obtained. The buried layer a-IGZO TFTs exhibited enhanced transistor performance and excellent stability against the gate bias stress.