Functionalization, Assembly And Applications Of Inorganic Porous Materials

Inorganic porous materials have attracted considerable interests due to their unique properties such as ordered channels arrays, high surface area, and various compositions. They were widely used in the fields of catalysis, ion-exchange, adsorption and separation. In these years, inorganic porous materials were highly desired to meet the long-term need of applications, and there are two objects that aim at promoting their efficiency and exploring their new potentials. Two ideas can lead us to these aims: (1) developing new approaches, synthesizing new materials with novel properties and applications; (2) modifying or assembling the well-known porous materials (e.g. NaY, Silicalite-1, MCM-41, and SBA-15). In this dissertation, based on these ideas, we describe the design of functionalization and assembly of inorganic porous materials, and their significant applications. Three works concerning the functionalization of mesoporous and preparation of zeolite coating were presented here: (a) syntheses, characterizations, and applications of titanium organophosphonates with chiral organic groups; (b) layer-by-layer surface modification of SBA-15 with metal phosphate; (c) preparation of superhydrophobic antireflective zeolite coating with layer-by-layer deposition technique.Based on"acid-base pairs"method, we synthesized two mesoporous titanium organophosphonates with chiral organic groups (L-hydroxyproline and L-proline groups) in the mesopores. A two-step template-removal process involving low temperature heating followed by ethanol extraction was developed to form ordered mesopores and maintain the structures and chiralities of the organic groups. By changing the incorporated amount of organophosphonate acids, the pore diameters of the mesopores could be continuously tuned. We chose enantiomers and racemic solutions of valine (as a testing system) to demonstrate the enantioselective property of the prepared materials. Furthermore, their performance in bio-adsorption of proteins was investigated on cytochrome c, and the organic groups played a significant role in promoting the adsorption ability of mesoporous titanium phosphonate.Metal phosphates have many applications in catalysis, separation, and proton conduction, however, their small surface areas limit their effective utilization. In our work, we controlled liquid-phase grafted titanium phosphate (or zirconium phosphate) onto mesoporous silica (SBA-15) surfaces. Ti(OPri)4 (or Zr(OPr)4) (a base) and POCl3 (an acid) were employed as an appropriate"acid-base pair" precursors for the formation of grafted titanium phosphate. Both the size of mesopores and the content of titanium phosphate can be adjusted by increasing the number of modification cycles in a stepwise (or layer-by-layer) fashion. Two approaches in this work involve (1) the alternate liquid-phase grafting with Ti(OPri)4 (or Zr(OPr)4) and POCl3 on SBA-15 and (2) the one-pot surface-mediated grafting of titanium phosphate (or zirconium phosphate) formed in situ. Their performances in acid catalysis and metal-ion adsorption were investigated. This work furnishes new methodologies for the general synthesis of metal phosphate-based materials with large surface areas, ordered nano-porous structures, and acidic properties.In the last part, we synthesized antireflective MFI coating by layer-by-layer deposition of Silicatlite-1 nano-crystals. It is known that many commercial antireflective coatings (e.g. MgF2) are of high light transmittance, but hold the disadvantages of toxicity and complicated synthetic processes. SiO2 has been used in the preparation of antireflective coatings due to its low refractive index. In this work, Silicalite-1 nanocrystals (60-80 nm, negative charged surface) and poly(allylamine hydrochloride) (PAH, positive charged polyelectrolytes) were layer-by-layer alternately deposited on a quartz substrate. The light transmittance of the Silicatlite-1 coating on a quartz substrate with 10 cycles after calcination achieves as high as 99.3% at 630 nm. After chemical vapor deposition (CVD) of a layer of silylation rageant on the surface of zeolite coating, a surperhydrophobic antireflective zeolite coating was obtained.