Synthesis Of TS-1Molecular Sieve And Its Membrane Using Inorganic Ti Sources

Titanium silicalite-1is a high activity, high selectivity and green catalyst for a seriesof organic oxidation reactions using hydrogen peroxide as oxidant, its discovery isconsidered a milestone in the field of zeolite and heterogeneous catalysis, it opens up a newway for petrochemical production.In traditional hydrothermal route, TS-1has been synthesized by using alkalifreetetrapropyl ammonium hydroxide (TPAOH) as template, tetraethyl orthosilicalite (TEOS)and tetrabutyl orthosilicate (TBOT) as Si and Ti sources respectively. This route is complexand requires protective atmosphere because tetrabutyl titanate is easy to hydrolysis in air,besides the products usually contain large amounts of anatase, which affect its catalyticperformances and industrial production to some extent.In this paper, TS-1zeolite has been synthesized successfully using inorganic titaniumas titanium source, this method is simple and hard to produce anatase. However the resultsshow that TS-1membranes prepared by this method under normal conditions arediscontinuous, so secondary growth method is adopted to synthesized TS-1membrane.To obtain zeolite seeds with suitable particle size, synthesis of smaller zeolites has alsobeen studied in this paper. Finally, the molecular sieve seeds are successfully synthesizedat a low temperature(393K) for2days.To improve reproducibility of the experiments, TS-1membranes are fabricated on thecarriers which have been coated smaller seeds by spreading-wetting method by thricehydrothermal crystallization. By means of XRD patterns and SEM images, the resultingTS-1membranes are continuous and highly intergrown with a double membrane structure. By further testing of EDS and water contact angle, TS-1membranes have excellenthydrophobicity, that’s because the middle layer prevents the precipitation of aluminumelement. Another innovation of this experiment is employing Pd/SiO2catalytichydrocracking method to activate TS-1membranes at593K. Such mild method helps tomaintain the completeness and hydrophobicity of TS-1membrane. Air permeationexperiment further validates that the resulting TS-1membranes are continuous and highlyintergrown.