Synthesis, Characterization And Application Of Magnetic Molecular-sieve Material γ-Fe₂O₃＠TS-1

Nanosized titanium silicalite TS-1 shows the unique catalytic oxidation performance in oxidation reaction with H2O2 as the oxidant, such as olefin epoxidation, aromatic hydroxylation, cyclohexanone ammonia oxidation, sulfide oxidation and so on. However, because of its small crystal size, it's difficult to separate from liquid after synthesizing, washing and catalytic reaction through the ordinary filter, which is the key problem of restricting the application of nanosized catalyst. Therefore, to synthesize magnetic materials by introducing the magnetic core into TS-1 synthesis system and separate, recover it after synthesizing, washing and catalytic reaction can resolve the separation and recovery problem of nanosized TS-1.In this paper, the magnetic nanosized materialsγ-Fe2O3@TS-1 were prepared by using tetrapropylammonium hydroxide (TPAOH) as the template, tetraethyl orthosilicate (TEOS) as the silica source, tetrabutyl titanate (TBOT) as the titanium source and the magnetic source Fe3O4. The effects of addition method and the amount of magnetic core onγ-Fe2O3@TS-1 were studied. The obtained materials were characterized by XRD, FT-IR, UV-Vis, SEM, TEM and so on. The results show that the introduction of a small amount of magnetic core does not affect the crystallization of TS-1 and the titanium into zeolite framework. Their catalytic performances were also evaluated by reactions of phenol hydroxylation,2-methyl thiophene and thiophene oxidation and photo-Fenton. The results reveal that the active site is framework titanium in the reactions of phenol hydroxylation,2-methyl thiophene and thiophene oxidation. It has a competitive effect between the decomposition of hydrogen peroxide by magnetic core and the substrate oxidative reaction by hydrogen peroxide. The reaction of phenol hydroxylation which has a high reaction temperature and long reaction time is affected much, while it has a little effect in thiophene oxidation. The removal rate of thiophene can up to 96%, and the catalyst also can be reused. The active site is magnetic core in the reaction of photo-Fenton. The existence of TS-1 doesn't affect the phenol degradation, and has a synergistic effect with magnetic core on phenol degradation.