Synthesis Of Functional Mesoporous Materials In Catalysis

In the past two decades, mesoporous materials have found their applications in many areas such as catalysis of large molecules, absorption and separation of biomolecules, chemical sensors, biomedicines, environmental remediation and synthesis of nanomaterials. Mesoporous materials own many unique properties, such as uniform and adjustable pore size, high surface area, large pore volume, diversified composition and mesostructure, well-controlled morphology, and easily functionalized surface. To date, numerous mesoporous materials with various composition, structure, pore size and function have been obtained, and many synthetic pathways and application fields have been explored and demonstrated. However, there are still a lot of opportunities and challenges in the further study of mesoporous materials.This thesis mainly focuses on two aspects:1) develop new synthetic methods for functionalized mesoporous materials, and 2) explore their applications in catalysis.Chapter 1 mainly reviewed the state of art of mesoporous materials, including synthetic methods, growth mechanisms, structure control and their applications in catalysis, biology, energy storage and water treatment.In chapter 2, mesoporous silica was used as catalyst supports to immobilize molecular catalysts. It contains two works. In the first work, we immobilized the cyclometalated platinum(II) complex into the pore channels of the ordered mesoporous silica SBA-15 by virtue of coordinative interaction, and used the immobilized catalyst for photooxidation of olefins. The activity of the photooxidation is high due to the enrichment effect by the channels. And the immobilized catalyst can be reused for 10 cycles without obviously degradation and leaching of the photosensitizers. In the second work, the tungstate was immobilized into the pore channels of the SBA-15 for the alcohol oxidation reaction. The reaction of benzylic alcohols oxidized by hydrogen peroxide is a typical liquid-liquid biphase reaction. By using the SBA-15 immobilized tungstate catalyst, a "triphase catalysis" reaction efficiently occurred in the absence of phase transfer reagents and co-solvents as well. The catalysis activity is high and the immobilized catalyst can be reused by 8 cycles.Chapter 3 describes a simple in-situ carbonization process of surfactants with sulfuric acid to synthesize ultra-stable ordered mesoporous metal oxides with highly crystalline frameworks. Commercially available amphiphilic triblock copolymers (Pluronic P123, F127 and F108) were used as surfactants. This chapter also contains two works. In the first work, we synthesized mesoporous titania with anatase frameworks. The obtained mesoporous TiO2 has high surface area (up to 193 m2/g) and uniform pore size. We used the mesoporous TiO2 in the photocatalytic degradation of rhodamine B (RhB) in aqueous suspension, and found its activity is higher than that of P25. In second work, mesoporous zirconium oxides with crystalline frameworks were synthesized with a relatively high surface area (98 m2/g) and uniform pore size. The mesoporous ZrO2 has a wide acidity distribution, which may have potential applications in acid catalysis.In chapter 4, we synthesized mesoporous carbon and silica with crystalline frameworks. In the first work, we introduced a secondary hard template method to synthesize mesoporous carbon frameworks. Mesoporous carbon with hexagonal structure and well graphitized frameworks was obtained. Since the growth direction of the mesopore walls of graphitc mesoporous carbon was parallelized to the (001) direction of the mesostructure, the conductivity of the MCF may be much higher than the pre-reported mesoporous carbons, which can extend the applications of this materials in electronic fields. In second work, we combined Li+ catalyzed crystallization of SiO2 with the inside-outside carbon confinement method to synthesize mesoporous silica with crystalline porewalls. The obtained materials show a-quartz crystalline phase, with a high surface area (193 m2/g) and uniform pore sized distribution.