Synthesis And Modification Of Titanium Silicate TS-1 And Its Catalytic Performance For Epoxidation Of Allyl Chloride

Epichlorohydrin,ECH,is widely used in organic synthesis including glycerol,epoxy resin,chlorohydrins rubber,etc,due to its epoxy group and a chlorine.At present,the main process for the production of ECH are the method of allyl chloride and the method of allyl acetate method in the world.However,both process have shortcoming of environment pollution and do not conform to the sustainable development.But the process of the epoxidation of allyl chloride reacting with H2O2 using titanium silicalite TS-1 as catalyst makes possible to obviate these adverse affect.The process is carried out at the moderate conditions with fast reaction rate and no pollution.However,the best way of TS-1 synthesis is the improved hydrothermal synthetic method which demands hash conditions,high cost and has poor reproducibility.In order to obtain excellent and stable TS-1,the major research content is as follows.In the first part of this thesis,TS-1 is adopted which has been industrialized in the ammoxidation of cyclohexanone.Different factors affecting the epoxidation of allyl chloride in the TS-1/H2O2 system are investigated,including the amount of catalyst,molar ratio of allyl chloride to H2O2,feed time of H2O2,reaction temperature and the amount of methanol.The results show that the optimal process conditions of the epoxidation of allyl chloride to ECH are as follows:the amount of TS-1 7.5 g/L,allyl chloride:H2O2?1.5:1(molar ratio),feed time of H2O2 20 minute,reaction temperature 35?,methanol:allyl chloride=8.5:1(volume ratio).Secondly,aimed at the optimal hydrothermal synthetic conditions,the influence of the n(TPAOH)/n(TEOS),n(H20)/n(TEOS),n(TBOT)/n(TEOS),crystallization time and temperature,calcinations time and temperature are studied.The samples are characterized by XRD,UV-Vis,SEM,FT-IR,N2 adsorption-desorption and other methods.The results show that the optimal conditions for TS-1 synthesis:the best molar ratio among TEOS and TBOT and TPAOH and H2O is 1:0.04:0.25:35;the temperature and time of crystallization are 200?and 72h respectively;calcinations time is 4h and calcinations temperature is 550?.TS-1 samples obtained under these conditions possess good repetition and high catalytic activity while the amount of TPAOH reduce markedly.The yield of epichlorohydrine reaches 92%.What's more,these samples have the same micropore structure consisting of particles of less than 0.4 ?m in size.In the process,under the conditions of low pH value in the solgel solution,longer crystallization time and higher crystallization temperature,larger particles are formed.Finally,under the optimal synthetic conditions,TS-1 samples are modified by HCl/H2O2 as acid modifier and by hexamethyldisilazane(HMDS)as silane agent respectively.By means of FT-IR,UV-Vis,N2 physical absorption techniques,the results show that the selectivity of ECH is improved after acid modification and silanization.But when modifying by HCl/H2O2 after the calcination,the framework Ti and pore volume of TS-1 are decreased.After silanization,not only the pore volume and the Ti in framework but also the surface area of TS-1 is decreased.