Zeolites with multi-level pore hierarchy: synthesis, characterization of diffusion property and catalytic investigation = 다단계 위계다공성 제올라이트: 합성, 확산특성 분석, 촉매특성 연구

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Zeolites are a family of crystalline aluminosilicates whose structure is composed of a regular array of uniform micropores of a molecular dimension (micropores are defined as pores with diameters of less than 2 nm). Zeolite is hydrothermally synthesized using a micropore-generating agent (i.e., microporogen) such as metal cations (e.g., Na+, K+) or quaternary ammonium compounds. This material has been widely used in industry as a solid acid catalyst. However, due to the sole presence of small micropores, it has serious diffusion limitations in various applications, especially in catalytic applications. To resolve this problem, introducing larger pores (diameter > 2 nm) in hierarchical order has been suggested. The hierarchical structure of mesopores and micropores can be generated using a mixture of two different porogens, typical ammonium-type micro-porogen and organosilane surfactants which are self-assembled into micelles which act as meso-porogen. Even where zeolite crystal was obtained with a very large particle size (~ 10μm), the organosilane surfactant could generate uniform mesopores throughout the crystal. In addition, a hierarchical pore structure can be generated using a multi-ammonium surfactant which can generate both micropores and mesopores simultaneously. With this method, if the zeolite can be synthesized while retaining its initial morphology, a higher-level pore hierarchy containing an additional larger pore (i.e., larger mesopore or macropore) could be generated where a macroporous (diameter > 50 nm) solid zeolite precursor or a gel-type precursor which contained a larger mesopore (diameter ~ 30 nm) is typically used. Hierarchical pore structures have been generated from the beginning of the zeolite-crystal growth phase using an organosilane surfactant or a multi-ammonium surfactant, which was investigated in detail via a structural investigation using electron microscopy and x-ray diffraction analysis. In addition, the effect of the hierar...
Advisors
Ryoo, Ryongresearcher유룡
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
2013
Identifier
514007/325007  / 020097085
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 화학과, 2013.2, [ xiii, 101 p. ]

Keywords

129Xe NMR; mechanism study of hierarchical pore generation; multi-level pore hierarchy; hierarchical-pore structure; zeolite; methanol-to-gasoline conversion; 제올라이트; 위계적 나노다공구조; 다단계 위계적 나노다공구조; 위계적 나노다공구조 형성 메커니즘 분석; 129Xe NMR; 메탄올-가솔린 전환 촉매 반응; 탄화수소 분해 촉매 반응; catalytic cracking of hydrocarbons

URI
http://hdl.handle.net/10203/180276
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=514007&flag=dissertation
Appears in Collection
CH-Theses_Ph.D.(박사논문)
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