Fabrication And Application Of Porous Microspherical Layered Inorganic Function Materials

Layered inorganic functional materials are an classic advanced materials which are composed by highly ordered host and guest. Layered inorganic functional materials are a large family due to the diversity of their structure and composition. As a result, a large calss of functional isostructural materials with widely varied physicochemical properties can be obtained by changing the nature and molar ratios of the metal elements as well as the type of intercalated anions. Thus, layered inorganic functional materials are promising functional materials for a large number of applications in catalysis, adsorption, separation, functional additives, pharmaceutics and biomaterials. So far the layered inorganic functional materials were extensively used in powder form. If assembled the functional materials into microspheres, there has great chance to expand the application and furthermore speed up the industrial process.In thesis we described the synthesis and studied the performance of the micropherical layered inorganic functional materials.α-zirconium phosphate (α-ZrP) and layered double hydroxides (LDHs) which were typical representative of cationic and anionic inorganic materials, were shaped into microspheres with porous architecture and macrospherical composites through spray drying technology. We controlled the process parameters to synthesize micorspheres with needed morphology and porous architecture which were used as catalytic and magnetic materials. This work lays the foundation for design the morphology, controll the process parameters and intensive applied research.The main results are as follows:1. We investigated the preparation of nanoparticles ofα-ZrP involving separate nucleation and aging steps (SNAS) and coprecipitation by HF. The size of nanoparticles synthsized by former was about 40 nm, which was more uniform than latter. We prepared microsphericalα-ZrP by uniform nanoparticles using spray drying technique without the help of templates. Scanning electron microscopy (SEM), low-angle laser light scattering and microscopic particle size analysis system (MPSAS) techniques were adopted to characterize the products. The resulting products are composed of nanosizedα-ZrP particles aggregated into solid microspheres with an average diameter of 20μm, a sphericity of 0.84. After calcined at 300℃, the morphology of theα-ZrP had no obvious changed. Mercury porosimetry was further consolidated that the surface area of 36.2 m2/g and total pore volume of 1.27 cm3/g. When calcined for 8 h at 300℃the surface area turned into 43.8 m2/g and total pore volume of 1.37 cm3/g. Pore size distribution was from micropore to macropore. The microsphere was well restained, which demonstrated that these microspheres have a good structural stability. Compared with their powder sample, the surface area of 29.9 m2/g and total pore volume of 0.07 cm3/g. When calcined for 8 h at 300℃the surface area turned into 35.6 m2/g and total pore volume of 0.35 cm3/g. Catalytic reactivity was investigated by the calcined microspherical a-ZrP using acylation of methyl stearate as probe reaction. The a-ZrP catalyst showed an amide yield 92.9% and selectivity 93.3% at 120℃for 12 h, which was increased by 20% compared to a-ZrP powders at the same reaction conditions. The enhanced performance in the reaction is determined by large surface area and the increased number of acidic sites in the multiple-scales porosity ofα-ZrP microspheres.2. Spray drying technology were adopted to prepare MgAl-LDHs by combining hard template method. We take the morphology control of synthetic LDHs as target and put emphasis onto the preparation of microspherical LDHs with porous architecture and macrospherical composites. The nanoparticles by SNAS mixed with the sulfonated polystyrene completely. The mixture was shaped into PS/MgAl-LDH microspheres. The average diameter of PS/MgAl-LDH microspheres was 20μm, a sphericity of 0.84. When calcined for 8 h at 500℃and rehydrated in decarbonized dioxide water at N2 atmosphere, the spherical morphology was well restained, which demonstrated that these microspheres have a good structural stability. Mercury porosimetry was further consolidated that the surface area of 65 m2/g and total pore volume of 1.36 cm3/g. When calcined for 8 h at 300℃the surface area turned into 82.6 m2/g and total pore volume of 1.68 cm3/g. Pore size distribution was from micropore to macropore. Catalytic reactivity was investigated by the rehydrated MgAl-LDHs using acylation of methyl stearate as probe reaction. The MgAl-LDHs catalyst showed a amide yield 50.8% at 120℃for 4 h, which was high efficiency. The short conversion time can also be ascribed to its more porous distribution and increased Lewis acid sites. This reaction was mainly domained by Lewis acid. So the distrbution of Lewis acid site led to the different efficiency of the catalyst of the MgAl-LDHs and the a-ZrP.3. In order to demonstrate the common utility of the spray drying combined template method, PS/CoⅡFeⅡFeⅢ-LDHs were successfully prepared and fabricated into microspheres using the same procedure as for PS/MgAl-LDHs microspheres. After calcined porous CoFe2O4 microspheres was obtained. This confirms that the method is a very simple yet effective common process for the preparation of solid LDHs microspheres with macroporous. Mercury porosimetry was further consolidated that the surface area of 7.4 m2/g and total pore volume of cm3/g. When calcined for 4 h at 700℃the surface area turned into 12 m2/g and total pore volume of 2.49 cm3/g. The tap density is 1.72 g/cm3 and saturation magnetization is 51.2 emu/g. It has great potential application in microwave absorption, adsorbent and catalysis.