Preparation Of Nano-Ag-zeolite Membrane And Its Application In Electrocatalysis Of Bromobenzene

Organic halides, as a kind of important and versatile compounds, are widely applied in synthetic organic chemistry. However, most of halogenated organics are toxicity owing to the existence of halogen atoms in the molecules, and they often have stable chemical properties so they often degrade slowly and cause long-term harm to nature. Thus, the research on quick and efficient dehalogenation becomes important and urgent.As far as the current research is concerned, reduction technology of dehalogenation includes catalytic hydrogenation, biological technique and electrochemical reduction and so on. Among these, electrocatalytic dehalogenation, which reacts under a nild condition, highlights obvious advantages such as excellent efficiency of dehalogenation to halogenated organics and environmentally safe. Hence, electrocatalytic reduction of organic halides has been a central topic from both theoretical and industrial points of view over the last few decades. Carbon dioxide is a cheap, nontoxic and abundant C1 source. Methods to catalytically activate CO2 for C-C bond forming in reactions have been extensively investigated. Among the possible products that may be prepared by C-fixation of CO2, arylcarboxylic acids represent an important class of compounds in organic synthesis. From the view of’Green Chemistry’, combining the cleavage of C-X with the forming of C-C, electrocatalytic reduction of organic halides not only takes advantage of the green electrochemical method but also can make use of CO2 waste to treasure, to alleviate the greenhouse effect.Many studies show that, transition metals especially Ag have peculiar affinity to halogen, so that Ag shows remarkable electrocatalytic properties toward the elctroreduction of organic halides. As is well known, nano-metal materials display unique optical, electrical, and chemical properties, which can exhibit extraordinary catalytic properties compared to ordinary bulk metals. However, it has been observed in most cases, that due to the existence of a highly exposed surface, the nanoparticles tend to aggregate and form large clusters even during the preparative process. Therefore, there is a need to disperse nano-particles onto a carrier so as to obtain a stable, well monodispersed nano-particles. In this thesis, we chose one kind of stable materials-zeolite, which has ordered inorganic nanostructures and higher surface area. We dispersed Ag nanoparticles onto the zeolite, and prepared nano-Ag-zeolite membrane modified electrode under certain conditions. In this thesis, we made two different zeolite membrane modified electrode:Ag-SBA-15/GC and Ag-Y/SS depending on the method. Meanwhile, we studied their electrocatalytic reduction of the main example of bromobenzene. The specific experiments as follows:(1) Preparation of Ag-SBA-15/GC by artificial coating and study of its electrocatalytic reduction for bromobenzene. Firstly, we prepare Ag-SBA-15 complexes by chemical reduction. Then, we prepare Ag-SBA-15/GC modified electrode by artificial coating and applied it as working electrode into the cycle voltammagrames (CV) study about electrocatalytic reduction of bromobenzen. The study of CV shows that the Ag-SBA-15/GC modified electrode has remarkable electrocatalytic activity compared to bare Ag electrode and bare GC electrode. Next, the other factors such as different Ag+ concentration in chemical reduction process and different preparation method were investigated:the different Ag-SBA-15/GC modified electrodes, which made by above different conditions, were characterized and analyzed by XRD, TEM, and FT-IR, BET and so on. Afterwards, the electrocatalytic activities of different Ag-SBA-15/GC modified electrodes were detected by CV. Finally, the best modified electrode was chose to apply into the electrocatalytic reduction of bromobenzene by galvanostatic.(2) Preparation of Ag-Y/SS by surface growth and study of its eletrocatalytic reduction for bromobenzene. Firstly, we prepare a layer of Y-type membrane on the surface of Stainless steel. Then, the Ag-Y/SS modified electrode was made by double- pulse electrodeposition. After its electrocatalytic activity was confirmed by CV, the factors such as nucleation pulse potential, nucleation growth time were investigated. Combined with the characterization technology of XRD and Semite different electrocatalytic activities of different modified electrodes were analyzed. Finally, the best modified electrode was chose to apply into the electrocarboxylatic reaction of bromobenzene, and different current density was also investigated.