Synthesis Of Modified Metal-organic Frameworks For Selective Oxidation Catalysis And CO₂ Sorption

Metal-organic frameworks?MOFs?are a new class of porous materials composed of organic struts joined with inorganic nodes,which having high specific surface area,high porosity,tunable structure and qualitatively modified functionality.Up till now,various MOFs have been developed and attracted extensive attention due to their potential applications in gas separation/storage,catalysis,drug delivery,and magnetic materials.Introducing other active sites to MOFs through pre-/post-synthetic modification is an effective way to explore their performances for more applications.Cyclohexanol?A?and cyclohexanone?K?,the so called KA oil,are the products of the oxidation of cyclohexane?CH?and also the intermediates in the production of Nylon-6 and Nylon-66.And the efficient capture of carbon dioxide is a way to reduce its emissions and the premise of its further conversion.In this thesis,a series of modified MOFs have been synthesized by the coordination of2^nd Metal with the free bipyridine sites of the organic ligands,including UiO-67-MoO?O₂?₂,UiO-67-WO?O₂?₂,UiO-67-[KVO?O₂?₂],UiO-67-FeCl₂,UiO-67-[KVO?O₂?₂]-FeCl₂,UiO-67-MoO?S₂?₂,UiO-67-MoS_x and MOF-253-MoS_x.The obtained materials are characterized by X-ray diffraction?XRD?,fourier transform infrared and far-infrared spectrum?FT-IR and FT-FIR?,low temperature nitrogen adsorption,inductively coupled plasma atomic emission spectroscopy?ICP-AES?,X-ray photoelectron spectroscopy?XPS?as well as scanning electron microscope?SEM?.The performance of cyclohexane oxidation on metal peroxide modified MOFs and the performance of CO₂ adsorption on molybdenum sulfide modified MOFs have been evaluated.In these metal peroxide modified UiO-67s,UiO-67-[KVO?O₂?₂]showed the best performance for cyclohexane oxidation with 78%selectivity to KA oil and 3.2 ratio of K/A at 9.4% conversion.What is more,the performance can be improved with the addition of Fe²⁺.For CO₂ adsorption,with the modification of MoS_x,the isosteric heats(Q_st)of UiO-67 and MOF-253 both increased,in which Q_st of MOF-253-MoS₄ reached 43 kJ/mol at the limite of zero coverage indicating stronger interaction between CO₂ and MOF surfaces.