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Multiwall Nanotube에 담지된 몰리브데늄 카바이드 촉매의 수소화 반응과 전기화학적 산화반응 특성

Title
Multiwall Nanotube에 담지된 몰리브데늄 카바이드 촉매의 수소화 반응과 전기화학적 산화반응 특성
Other Titles
Hydrogenation and Electrochemical Oxidation Reaction Properties of Multiwall Nanotube Supported Molybdenum Carbide Catalyst
Author
서민호
Alternative Author(s)
Seo, Min-Ho
Advisor(s)
박융호
Issue Date
2007-02
Publisher
한양대학교
Degree
Master
Abstract
본 연구에서는 고가의 귀금속을 사용해야하는 연료전지 촉매의 가격을 낮추는 방안으로 전이금속 탄화물 촉매인 몰리브데늄 카바이드를 사용하였다. 기존의 낮은 활성을 극복하는 방안으로 우선 담지량을 증가시키고 다른 여러 촉매 제조의 공정변수를 변화시켜 보다 높은 활성을 가지는 촉매를 제조하는 방법에 대한 연구를 수행하였다. 지지체의 산 처리, 전구체의 양 증가, 전구체의 종류변화, 탄화공정 온도조건에 의하여 제조된 촉매는 Biphenyl의 촉매수소화반응과 메탄올의 전기화학적 산화반응을 통해 촉매활성을 확인하였고 ICP-AES, XRD, TEM을 통하여 촉매특성을 분석하였다. 지지체의 산 처리 시간과 산의 농도에 비례하여 촉매의 입자크기는 감소하였으나, 담지된 촉매양은 산 처리 시간과 산의 농도에 비례하지 않았다. 촉매수소화반응활성은 담지량에 영향을 받았으나 입자의 크기에 따라 달라졌으며 전기화학적 반응은 담지량의 증가에 따라 높아졌다. 전구체의 양을 증가시킬수록 담지량은 증가하였고 이에 따라 전기화학적 산화반응의 활성은 높아졌다. 하지만 수소화 반응에서는 담지량이 낮음에도 입자의 크기가 작은 촉매가 높은 활성을 보이는 경우도 있었다. 전구체의 종류에 따라 담지량이 차이가 났고 몰리브데늄 아세토아세테이트를 사용한 촉매가 암모니움 몰리브데이트 전구체를 사용한 촉매보다 전반적으로 담지율과 활성이 높았다. 수소화 반응에서는 암모니움 몰리브데이트 전구체를 사용한 촉매가 담지율이 낮았음에도 불구하고 작은 입자크기로 인하여 유사한 촉매 활성을 보였다. 다양한 탄화공정을 통해 촉매를 제조했을 때 탄화 온도가 높을수록 높은 활성을 보였다.
One of major factors limiting the practical development of fuel cell is high cost of catalyst. As an inexpensive material, molybdenum carbide has catalytic activity at electrochemical oxidation reaction of methanol, hydrogen and formic acid. But the previous studies over the catalytic activity were very rare and bulk-sized molybdenum carbide were mainly prepared and tested as a catalyst. In this research nano-sized molybdenum carbide supported on MWNT catalysts were prepared and various methods have been adopted to verify their catalytic performance. The preparation condition of catalysts, such as, the acid treatment of support, the amount and the type of metal precursor and carburization temperature were varied and the prepared catalysts were applied for the hydrogenation and electrochemical oxidation reactions. Biphenyl and methanol were used for catalytic hydrogenation and electrochemical oxidation respectively. And ICP-AES, XRD, TEM were used for the catalyst characterization. The size of catalyst metal was decreased as the concentration of acid treatment time of support increased while metal content was not proportional to acid treatment. The activity of catalytic hydrogenation was highered with the increase of catalyst metal size and that of electrochemical oxidation was also highered with the increase of metal content. When the amount of metal precursor was increased, the impregnated metal content was increased proportionally and which induced the higher activity in electrochemical oxidation of methanol. On the concentrary, the activity was highered in hydrogenation in spite of the application of catalyst with lower metal content and smaller size distribution. Metal content was influenced by the type of precursors and catalyst prepared from molybdenum acetoacetate resulted in the larger impregnation of metal and th higher electrochemical activity comparing with the catalyst prepared from ammonium molybdate. In the biphenyl hydrogenation, catalyst prepared from ammonium molybdate shows better activity than the catalyst prepared from ammonium acetoacetate despite the lower metal content. The temperature increased in carburization induced the catalytic activity to be higher.
URI
https://repository.hanyang.ac.kr/handle/20.500.11754/150045http://hanyang.dcollection.net/common/orgView/200000405468
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > DEPARTMENT OF FINE CHEMICAL ENGINEERING(정밀화학공학과) > Theses (Master)
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