Fabrication And Application Of Titanium Silicalite-1Membranes In Direct Hydroxylation Of Benzene

Phenol is an important chemical raw material. It is mainly produced by cumeneprocess, which occupies more than95%of the market. Together with this process, thetraditional methods have the problems such as complex reaction, highenergy-consuming, unwanted byproducts and environmental pollution. Thus, todevelop the direct oxidation of benzene to phenol is desired.Titanium silicalite (TS-1) membrane can be used to constitute the process ofmembrane catalysis by combining the separation performance of inorganic membraneand catalytic process. The integration of catalytic reaction and separation of productexhibit both thermochemical stability and mechanical strength of inorganicmembranes, and the well performance in part oxidation of alkanes, epoxidation ofolefins, oxidation of alcohols, hydroxylation of aromatic hydrocarbon and ammoniaoxidation of cyclohexanone, etc. In the TS-1/H2O2catalytic system, the reactionyields the only byproduct, H2O, and has the advantages of high atom economy andlow environmental pollution. Therefore, the research of the fabrication andapplication of TS-1zeolite membrane is very significant.In this study, the TS-1zeolite membranes were synthesized by the secondarygrowth method. The TS-1membranes were characterized by SEM, XRD, FT-IR, andUV-Vis. Results showed that the morphology of TS-1zeolite crystal particles wereuniform and the TS-1zeolite membranes were dense, with smooth surface andc-orientation. No cracks or pinholes defect were detected, and the thickness of themembranes was uniform; titanium atoms were well introduced into the zeoliteframework, and the extra-framework titanium content was low. The goodreproducibility of the preparation method made it possible being used in the catalyticexperiments.The membrane reactor assembled with TS-1membrane was used to study thecatalytic properties of TS-1/H2O2catalytic system in the hydroxylation of benzene tophenol. Template removal methods, reaction temperature and reaction time were alsoinvestigated here. The results showed that low-temperature method (method I) couldreduce defects, which effectively improved the rate of conversion of benzene (about2-3times compared with traditional methods), and it had no significant influence on the selectivity for phenol. The impact of reaction temperature and reaction time tobenzene conversion and phenol selectivity was also illustrated in this thesis.