이중기능 촉매를 위한 금속 나노입자의 합성 및 촉매반응 적용에 대한 연구

학위논문(석사) - 한국과학기술원 : 화학과, 2007.2, [ v, 32 p. ]Most commercial heterogeneous catalysts employ bifunctional components of active nanoparticles and high surface area supports because of the ease of product separation and catalyst recycling. The size, shape, surface structure, and dispersity of the active nanoparticles in catalysts strongly affect the common reactions. Being small in size increases the nanoparticle surface tension and makes surface atoms very active. Herein, we have synthesized uniform and small nanoparticles of Co, Ni, $Mo/MoO_x$, $MoO_3$ and $MoS_2$ and then incorporated them into MCF (mesocellular siliceous foam) structures by sonication making bifunctional catalysts. In particular, polycrystalline $Mo/MoO_x$ nanoflakes were synthesized by thermal decomposition of $Mo(CO)_6$, and easily transformed to small $MoO_3$ and $MoS_2$ nanoparticles by either oxygen bubbling or sulfur addition, respectively. To the best of our knowledge, there were no generic synthetic schemes for Ku $MoO_3$ and $MoS_2$ nanostructures as colloidal forms. It is anticipated that the colloidal forms of smaller and regular molybdenum oxides and sulfides would exhibit better catalytic performances compared to the bulk catalysts due to their large surface area and high activity. We have also applied cobalt and nickel bifunctional catalysts in Pauson-Khand and desulfurization reactions, respectively.한국과학기술원 : 화학과

촉매 반응을 위한 금속 및 산화금속 혼성 나노구조체의 합성 및 형상 조절에 관한 연구

학위논문(박사) - 한국과학기술원 : 화학과, 2010.08, [ xx, 242 p. ]Transition metal nanoparticles are of considerable interest as heterogeneous catalysts in numerous industrial processes. Recently, mesoporous silica materials have attracted much attention as excellent supports of bifunctional catalysts with high surface area. Bifunctional structures combining active metal particles and metal oxide supports are known to be the most effective form of heterogeneous catalysts owing to their high stability and multiple functionalities. Rational design of the bifunctional catalyst structures using nanosynthetic technology can improve reaction performances including activity, selectivity, thermal stability, and recyclability. In chapter I, we introduce unique features of the metal nanoparticles as good heterogeneous catalysts and the importance of controlling nanostructures for catalytic reactions. In chapter 2, we report gram scale synthesis of uniform $Cu_2O$ nanocubes and their subsequent transformation to polycrystalline CuO hollow nanostructures. These CuO nanostructures are used as lithium ion battery anode materials and are applied to organic catalytic reactions as good heterogeneous catalysts. In chapter 3, we introduce various metal@silica yolk-shell nanoreactor frameworks which consist of metal cores inside hollow silica shells for various gas- and solution-phase catalytic reactions. In chapter 4, we report hybridization of bifunctional elements by solution-phase chemical reactions. The final nanostructures are successfully employed as active nanocatalysts for organic catalytic reactions with excellent activity and recyclability.한국과학기술원 : 화학과

CATALYST FOR CARBON-CARBON COUPLING REACTIONS USING TRANSITION-METAL SILICA NANOPARTICLES

본 발명은 전이금속 나노입자가 기공을 가지는 실리카 껍질로 둘러싸여 있고 실리카 껍질과 금속 나노입자사이에는 빈 공간이 존재하는, 전이금속-실리카 요크-쉘 나노입자를 촉매로 이용하여 다양한 탄소-탄소 짝지음 반응에 이용함으로써 상기 짝지음 반응에 높은 활성을 가지며, 또한 촉매의 재사용을 용이하게 할 수 있다.상기 전이금속-실리카 요크-쉘 나노입자 촉매는 (a) 금속 이온 선구물질과 특정 계면활성제를 유기용매 하에서 고온으로 가열하는 단계; (b) 상기 (a)단계의 혼합액을 고온에서 계속 반응시켜 금속 이온 전구체를 환원시킴과 동시에 계면활성제로 그 표면을 보호시킴으로써 안정한 금속 나노 입자를 형성하는 단계; (c) 상기 (b)단계에서 합성된 금속 나노입자를 분리 및 정제하는 단계; (d) 상기 (c)단계에서 정제된 금속 나노입자를 졸-겔 과정(sol-gel route)을 통해 실리카로 코팅하여 쉘을 형성시키는 단계; (e) 상기 (d)단계에서 형성된 금속-실리카 코어-쉘 나노입자의 실리카 층에 열적 반응, 또는 화학적 반응과 열적반응의 순차적 수행을 통해 기공을 형성시키는 단계;를 통해 제조될 수 있다.본 발명에 따른 촉매는 탄소-탄소 짝지음 반응을 촉진시켜 이로 인한 다양한 화합물의 효율적인 생성을 가능케 한다