Pore Structures of Metal-Organic Frameworks by Small-Angle and Wide-Angle X-ray Scattering

• Main Authors: Wei-cheng Lin, 林韋承
• Other Authors: Ya-sen Sun
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/38189998051289456547

博士 === 國立中央大學 === 化學工程與材料工程學系 === 103 === In this investigation, small-angle and wide-angle X-ray scattering (SAXS & WAXS) measurements were utilized to analyze porous structures at different scales for Cu-BTC metal-organic frameworks (HKUST-1) of varied size populations prepared by different synthesis routes. Our objective is to establish a fast and low-cost method for effectively measuring specific surface area of pores, and to understand the change of HKUST-1’s structure after dehydration. Two kinds of HKUST-1, M700 and Nano-size, were provided by ITRI. An in-situ SAXS/WAXS experiment demonstrates the effect of temperature on the concurrent evolutions of pore structure and crystal phase during the removal of water upon heating. The results were also compared to the commercial sample (C300). By simulation modeling of SAXS profiles, the pore size distribution and specific surface area could be quantitatively determined. Quantitative curve analysis of SAXS indicates that the hierarchical pore structures of MOFs have the size-dependent specific surface areas. This gives us more insights in understanding which scale of pore size within MOFs is dominant for controlling the ability of CO2 adsorption. On the other hand, HKUST-1 shows special peak intensity enhancement in WAXS result. Dehydration and grain growth are the two main reasons. GSAS refinement also reveals that the lattice constants and the Cu-Cu distance decreased after dehydration.