Green Synthesis Of Functionalized TS-1 Zeolite

Titanosilicate zeolite TS-1,as a green and efficient heterogeneous catalyst,is widely used in the fine chemical industry.Hydrothermal method is a common method for preparing TS-1 zeolite,but the method has some problems such as long reaction period,high energy and resource consumption,low production efficiency,large amount of sewage and complicated process,which seriously hinder the development of TS-1 zeolite.Recently,a strategy of preparing zeolite by grinding solid-phase raw materials has attracted extensive attention of researchers.It does not require any solvent to be added during the synthesis process,and has advantages of high yield,safe and simple synthesis process,and no sewage.It has become the research focus of green synthesis of zeolite.Therefore,based on a solvent-free synthesis strategy,this paper explores the particle size,pore channels and supported metals of TS-1 zeolite.The main research contents and achievements are as follows:Using a solvent-free method,nanosized TS-1 zeolite（～114 nm）was synthesized by directly introducing pure silica zeolite seed solution without additional organic template and solvent.The result shows that the nanosized TS-1 sample has a large specific surface area,high pore volume,and contains highly active Ti sites（“mono-core Ti O₆”）and no additional framework anatase（Ti O₂）.At the same time,no additional templating agent is required,which brings higher economic benefits and reduces pollution.In addition,it was found that the size and number of pure silica seeds had a certain influence on the particle size of TS-1 zeolite.In the epoxidation reaction of allyl chloride,the TS-1 sample prepared by solvent-free method shows excellent catalytic ability,especially the nanosized TS-1 zeolite.Hierarchical TS-1 zeolite was successfully synthesized by a solvent-free strategy using carbon black as a mesoporous template.By examining the amount of carbon black added,it was found that when the amount of carbon black was 0.2 g,the prepared hierarchically porous TS-1 sample had good crystallinity and a large pore structure appeared on the surface.In addition,by changing the order of carbon black introduction,it was concluded that a mesoporous structure of about 3.8 nm was produced in the hierarchically porous TS-1 zeolite prepared under different orders.Among them,when carbon black and seed crystals were introduced together,a mesoporous structure with a larger size of 10-20 nm was also produced in the sample.Due to the introduction of mesopores in the TS-1 zeolite,which plays a huge role in increasing the mass transfer efficiency of the reactants,exposing the internal Ti sites.Through the epoxidation test of 1-hexene,the conversion rate of the hierarchically porous TS-1 zeolite is significantly higher than that of the traditional microporous TS-1 zeolite.In addition,an iron-supported TS-1 zeolite was in situ synthesized by a solvent-free method using the complex formed by the organic ligand ethylenediamine with Fe ions as the metal precursor,in which the Fe loading was 4.9 wt%.During the preliminary exploration of the location and morphology of Fe in zeolite,it was found that iron mainly existed in the form of divalent and trivalent oxides,and no iron oxide particles were found on the zeolite,which indicated that the metallic iron was uniformly encapsulated in the zeolite.During the process,ethylenediamine effectively reduces the surface energy of the metal,avoids the precipitation of metal ions in an alkaline synthesis environment,and effectively limits the size of the metal.This iron-loaded TS-1 zeolite exhibits excellent catalytic performance in the degradation of phenol.Furthermore,under this synthetic strategy,the success can be extended to other metal species,including Co,Ni,Zn,and bimetallic Co-Ni.