Synthesis,Characterization And Application Of Amphiphilic Core-Shell Zeolite Hierarchical Porous Composites

Core-shell nanocomposites have been extensively studied by chemists and used in adsorption separation,drug delivery,and industrial catalysis.Zeolite molecular sieves,as one of the earliest studied pore materials,have certain practical applications in adsorption separation,selective catalysis,acid catalysis and petroleum catalytic cracking due to their unique pore structure and special atomic bonding.However,the single hydrophilicity of most zeolite limits the catalytic efficiency in some organic catalytic reactions or adsorption property on organics.Periodic mesoporous organosilicon shells?PMOs?have been widely used in drug release,phase catalysis,sensing,etc.These are attributed to their mesoporous pores with adjustable pore size,simple synthesis methods,amphipathicity and modified organic functional groups.The amphiphilic core-shell zeolite material can not only be used as an excellent adsorptive separation agent,but colud served as a solid surfactant to emulsify different two-phase systems.It has great potential in Pickering multi-phase interface catalysis.In this thesis,two different zeolite nanoparticles prepared were used as cores.Two kinds of zeolite-mesoporous organosilicon core-shell composite with different functions were prepared via Stober method and growth-induced corrosion method,which is expected to strength mass transfer effect and improve catalysis efficiency.Main tasks are listed as follows:Chapter One,Nano-zeolite ZSM-5 was prepared by the template-free method reported in the literature,and then mesoporous silica-coated zeolite with different thicknesses was prepared by controlling tetraethyl orthosilicate.The silica on the surface of zeolite is then etched by growth-induced etching to form a core-shell composite ZSM-5@Et-PMO?Z/Six@Et-PMO?with different cavity sizes.The core-shell structure ZSM-5@Et-PMO?Z@Et-PMO-X?with different shell thicknesses is obtained by adding different proportions of ethylsilane.The morphology and structure of material are subjected to a series of characterization methods by Scanning Electron Microscopy?SEM?,Transmission Electron Microscopy?TEM?,Powder X-ray diffraction?XRD?,Fourier Transform infrared spectroscopy?FT-IR?,N₂ adsorption desorption isotherm,thermogravimetric analysis?TGA?,NH₃-TPD?Temperature Programmed Desorption?.The core-shell material has a high specific surface area and pore volume and the mesopore of PMOs is regularly ordered.A gradient acid distribution was formed between different materials.The material is used for the glycerol-catalyzed reaction of acetone and glycerol and the conversion rate of acetone can reach 37%,which is higher than the traditional zeolite catalyst.Chapter Two,Using adsorptive zeolite A as a model,yolk-shell structure YS-A@Et-PMO with fixed cavity and fixed shell thickness was synthesized by a one-stepmethodcombiningStoberandgrowthinductionstrategy.Cu/YS-A@Et-PMO is then obtained by loading copper metal nanoparticles by impregnation and reduction.The morphology and chemical microenvironment of sample and valence state of metal nanoparticles were fully characterized through a series of characterization methods.The performance of materials for removal of MB in Fenton reaction was tested using an ultraviolet spectrophotometer?UV-vis?.At room temperature,the material can quickly and completely remove 60 mg/L MB in10 min and even higher concentrations of MB.At the same time,the functionalized material also has better recyclability.