Preparation Of Hydrophobic Metal Nanoparticles And Research Of Catalytic Activity

The noble metal nanoparticles with some characteristics such as surface effect, small size effect, quantum size effect and quantum tunneling effect are widely used in the fields of biotechnology, electronics, non-linear optics, in particular the areas of industrial catalysis. Therefore, the preparation and application of gold nanoparticles has been a hot research field in the nano-materials field.This thesis introduces a novel surfactant3,4-dicetyloxybenzylamine, which can be mixed with n-butanol, n-heptane and HAuCl4·4H2O to form W/O microemulsion. Using this reverse microemulsion as template and microwave radiation as heating means, by formic acid reduction of HAUCl4·4H2O, we obtained super highly dispersed, uniform, small particle size of gold nanoparticles. When the prepared hydrophobic gold nanoparticles are surpported on Al2O3or activity C, the catalyst plays a good catalytic activity in reduction of nitrophenol and Suzuki coupling reaction. All the products have been characterized by1H NMR, FT-IR, UV-vis, TEM, HR-TEM, XRD, CA, GC and so on. The main work completed in this thesis are summarized as follows:1.3,4-dicetyloxybenzylamine (DDOBA) are synthesized by zinc dust reduction of3,4-dicetyloxybenzyloxime, which was obtained from3,4-dicetyloxybenzyldehyde (obtained from3,4-dihydroxybenzaldehyde by alkylation) by reacting with hydroxylamine hydrochloride. Then under the promotion of microwave irradiation, by the reduction of formic acid, gold nanoparticles stabilized by DDOBA are prepared in DDOBA/n-butanol/n-heptane/formic acid/HAuCl4(aq.) W/O microemulsion. The results showed that the size of gold nanoparticles gradually decreasing with the molar ratio of aime/gold increasing, and the monodisperse getting better and better, the gold particles was super uniform and dispersed, which could spontaneously form two-dimensional self-assembly gold film at the interface of air-water.2. A supported catalyst All/Al2O3was prepared successfully by loading C12OBA-coated gold nanoparticles onto the surface of Al2O3particles. Then the supported catalyst was characterized by TEM, SEM photograph and EDS, respectively. It was found that Au/Al2O3supported catalyst had high catalytic activity and low loss of gold nanoparticles due to the hydrophobic property of gold nanoparticles and strong adhesive force on carrier in the reaction through borohydride reducing nitrophenol. Such catalyst could be separated and washed conveniently and still hold high catalytic activity after many times of cycle-utilization. Then, the catalytic activity in the reduction reaction of p-nitrophenol、o-nitrophenol and m-nitrophenol are tested. Meanwhile, we study the influence of the size of the gold naoparticles, the amount of the supports and the temperature of the reaction. The optimum reaction conditions are described as follows:the size of the gold naoparticles is4.94±1.05nm, the load ratio of gold nanoparticles is0.1ωt%and the reaction temperature is50±. The All/Al2O3catalysts can be recycled.3. C12OBA-coated bimetallic Au/Pt nanoparticles are obtained in C12OBA/n-butanol/n-heptane/NaBH4/HAuCl4·H2PtCl6reverse microemulsion system with NaBH4as a reductant. Catalysts are prepared by loading the bimetallic Au/Pt nanoparticles onto the surface of vectors. Then, the catalytic activity in the Suzuki coupling reaction are tested. Meanwhile, we studied the influence of the temperature to the reaction, the type of catalyst, substrate, reaction time and so on.