Applications Of Metal-Organic Frameworks To Adsorption And Catalysis

Metal-organic frameworks (MOFs), as a new class of porous materials, have been rapidly developed in the last20years in terms of either their initial synthesis or their later application. Research on MOFs has become a hot topic, mainly due to MOFs possessing some excellent properties, such as large specific surface area, high porosity, adjustable pore size, and chemical modification. The synthesized MOFs have been not only applied to gas adsorption, storage, and separation but also to optics, magnetics, pharmacy, catalysis, fluorescence etc. Based on the known structural characteristics and applicability of MOFs, studies on the new features of MOFs functional ized by chemical modification will have important theory research significances and actual application values. The main results are summarized as follows:1. Synthesis of Fe-MIL-101and NH2-Fe-MIL-101. By tuning the ratio of H2BDC to NH2-BDC, NH2-Fe-MIL-101with high thermo-stability, high amino loading, large specific surface area, and high porosity was successfully synthesized. The results from N2-adsorption at-196℃and TG-DSC characterization show that the specific surface area, pore volume, and thermal stability of the synthesized samples decrease with increasing amino loading in NH2-Fe-MIL-101. This is due to the fact that the loaded amine ligand can increase the steric effects between the cavities and consequently reduce the thermal stability of the framework. The adsorption isotherms of CO2on NH2-Fe-MIL-101were determined by means of a volumetric method, and the results indicate that the optimal NH2-Fe-MIL-101has a high affinity and a high saturation capacity for CO2adsorption.2. Synthesis of CPO-27(Ni) and its adsorption properties. CPO-27(Ni) was synthesized and applied to the adsorption-based separation of CO2/CH4and C2H4/C2H6. The results show that due to CPO-27(Ni) contains the coordinatively unsaturated Ni(Ⅱ) sites that can strongly interact with C=C (C2H4) and C=O (CO2) to form π-complexion, resulting in a higher adsorption affinity to CO2and C2H4. Additionally, the Ideal Adsorbed Solution theory was used to predict the separation performance of CO2/CH4and C2H4/C2H6mixtures by CPO-27(Ni).3. Synthesis and purification of MIL-101(Cr) and application of amino-functionalized MIL-101in base catalysized reactions. Alcohols (glycol, methanol, ethanol, propanol, butanol, and pentanol) with different polarities and hot NH4F solution were used to purify the synthesized MIL-101. Under the optimized conditions, the synthesized MIL-101has a specific surface area of5777cm3g-1(Langmuir specific surface area). Then the synthesized MIL-101was grafted by ethylenediamine (EDA) as amine source to obtain amino-functionalized MIL-101(NH2-MIL-101) catalysts with different amino loadings. The amino-functionalized samples were characterized by the elemental analysis and the FT-IR technique, verifying the successful incorporation of EDA onto MIL-101. These amino-functionalized MIL-101catalysts were applied in the Knoevenagel condensation and the Henry reaction. By screening a type of solvents, reaction time, and the catalysts with different amino loadings, the reaction conditions were optimized. For the first time, the amino-functionalized MIL-101catalyst was applied to the one-pot synthesis of nitroalkenes, which are important intermediates in organic synthesis, via the Henry reaction.