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Synthesis Of TS-1 Microspheres And Their Catalytic Properties In Epoxidation Of Methylallyl Chloride

Posted on:2018-04-23Degree:MasterType:Thesis
Country:ChinaCandidate:Z X DengFull Text:PDF
GTID:2321330512994189Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
Using titanosilicate as catalyst and hydrogen peroxide as oxidant,direct synthesis of 2-methyl epichlorohydrin(MECH)via liquid-phase epoxidation of methallyl chloride(MAC)is an environmentally benign technique featured by short reaction pathway and zero-emission.This dissertation is aiming at synthesizing highly active TS-1 microsphere zeolite that is of easy liquid-solid separation and suitable for slurry bed reactor.Detailed study has been carried out to investigate the formation process and oxidation activity of TS-1 microspheres,their optimal reaction conditions for the epoxidation of MAC to MECH and the regeneration methods for the deactivated catalyst.We introduced triblock copolymer F127 into the synthetic system for crystallizing conventional TS-1 and carried out stepwise crystallization,which assembled the TS-1 nanoparticles into microspheres.The controled The microsphere size was controlled by adjusting the amount of F127,whereas the uniformity of the microspheres could be improved by co-adding a small amount of surfactant CTAB.When the mole ratio of the synthetic gel was set as TEOS:TPAOH:TBOT:H2O:F127:CTAB= 1:0.18:0.033:13.2:0.0027:0.0032,the diameter of TS-1 microspheres was about 15 ?m.Comparing with the conventional TS-1 powder,TS-1 microspheres possessed a high specific surface area and also contained regular intercrystal mesopores.The epoxidation of MAC to MECH with H2O2 using TS-1 microsphere catalyst in a continuous slurry reactor was investigated.The reaction parameters,which governed the efficiency of hydrogen peroxide,selectivity of MECH epoxide and catalyst deactivation,were studied.in detail by simulating the operating conditions of industrial process.Under the optimized reaction conditions,the process was successfully run for 257 h at a high MECH selectivity(>95%)as well as a high utilization efficiency of hydrogen peroxide(>97%).In the process of the reaction,TS-1 microspheres showed high catalytic activity and solid-liquid separation ability.The deactivation of catalyst could be attributed to the blocking of micropores by organic byproducts,which hindered the substrate molecules from reacting with H2O2 on Ti active sites.And some framework Ti ions were leached out of zeolite framework and changed to extra-framework Ti species during reaction,which is also the reason of catalyst deactivation.The microsphere morphology and particle size were well maintained for the deactivated TS-1 microsphere catalyst,which was regenerated readily by a combination of hydrogen peroxide washing and calcination.With the number of regeneration increased,the catalyst activity of TS-1 microspheres was gradually reduced.
Keywords/Search Tags:TS-1 microsphere, epoxidation of methallyl chloride, 2-methyl epichlorohydrin, deactivation, regeneration
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