Preparation Of Ag Nanoparticle Suported On Mesoporous Carbonts And Its Applications In Electrosynthesis Of Methyl Benzoate

The interest toward the ordered mesoporous materials has continuously increased as their potential applications in many fields.Mesoporous carbon materials have unique optical,electrochemical and electromagnetism properties.Therefore,it has a great prospect in catalysis,adsorption,separation and sensors.However,the mesoporous carbon material also has many unsatisfactory features,such as strong hydrophobicity,less reactive sites,etc.,making its application in the field of catalysis and sensors limited.In order to obtain a number of unique properties to produce more mesoporous carbon composites and catalyst carriers,more and more functional mesoporous carbon materials have been reported.When some electron-withdrawing or electron-donating heteroatoms,such as B,P,N and O,are doped into the mesoporous carbon skeleton,it is not only possible to increase the functional groups on the surface of the mesoporous carbon material,but also to completely change the internal electronic properties and greatly enhance its electrochemical properties,so that the materials could be applied in other new areas,such as semiconductor,optical and electronic devices,fuel cells and lithium batteries.Organic halides have a wide range of applications in synthetic organic chemistry,and the study of C-X bonds has attracted the attention of many researchers.The electrochemical synthesis route has excellent selectivity and environment-friendly characteristics and is an effective method for the reduction and carboxylation of organic halides.This method on the one hand can synthesize organic carboxylic acid compounds,on the other hand it uses greenhouse gas CO₂,which is a clean,cheap,rich in content,non-toxic and renewable carbon resources,as raw materials.Many catalysts can catalyze the reduction of organic halides.It has been reported that Ag shows excellent electrocatalytic activity for organic halides.However,the amount of Ag used in the pure metal electrode is too much,and the reaction is carried out only on the surface of the Ag electrode,providing less reaction sites and less catalytic activity.More recently,more and more researchers have focused on the preparation and application of metal nanoparticle/carbon composites.Conventional methods for preparing metal-supported carbon materials are liquid impregnation,colloidal deposition,coprecipitation,and the like.In this thesis,a method of vapor oxidation and in situ self-reduction was selected to prepare mesoporous carbon materials loaded with Ag nanoparticle catalyst.The distribution of Ag nanoparticles in the prepared materials is highly uniform and the particles are smaller.And in the further improvement of the experiment through the soft template one-step preparation of P-doped mesoporous carbon material,effectively expanding the material pore size.The experiment of supporting the Ag nanoparticles by the method of vapor oxidation-in situ self-reduction was carried out.It was proved that the large pore size favored the loading of Ag.Finally,the functionalized mesoporous materials of Ag were prepared into modified electrode,which was used in the electrocarboxylation of bromobenzene.The specific work was carried out as follows:.?1?Preparation of Ag-supported mesoporous carbon materials by steam oxidation-in situ self-reduction method and their electrochemical applications.The Ag nanoparticles catalyst supported on the ordered mesoporous carbon was prepared by combining the method of steam oxidation and in situ self-reduction.The feasibility of this loading method was proved by XRD and FT-IR.Subsequently,three kinds of mesoporous carbon composites with different Ag contents were prepared,and various materials were characterized by BET,TEM and so on.Finally,the mesoporous carbon composites prepared by Ag loading were applied to the electrocarboxylation of bromobenzene.The effects of different electrolysis potentials and different Ag loading on the reaction were investigated.It is proved that this composite has better catalytic performance than pure silver.When the content of Ag in composites is 10%,the catalytic performance is the best.?2?Preparation of large-porous P-doped mesoporous carbon materials and its application in bromocarbon carboxylation.In the third chapter,in order to increase the pore size of the mesoporous carbon material,a P-doped large-porous mesoporous carbon material was prepared by one step method and the Ag nanoparticles were loaded by steam oxidation-in situ self-reduction.The material is characterized by various characterizations.Finally,they were applied to the electrocarboxylation of bromobenzene.At the same time,the effect of phosphorus on the mesostructure was also investigated,and the effect of phosphorus on the structure of the material was further explained.Three kinds of P-doped macroporous carbon composites with different Ag contents were prepared and applied in the electrocarboxylation of bromobenzene.