二次晶化法合成高钛含量TS-1分子筛及其催化性能评价

Synthesis of Titanium Silicalite-1(TS-1)Molecular Sieves with High Ti Content by Re-Crystallization Method and Their Catalytic Performance

以正硅酸乙酯为硅源、钛酸丁酯为钛源、四丙基氢氧化铵（TPAOH）为模板剂,采用二次晶化法在TPAOH/SiO2=0.1时合成不同硅钛比的TS-1分子筛,通过XRD、FTIR、UV-Vis、SEM等对TS-1分子筛的结构和形貌进行表征,并以苯酚羟基化反应为探针反应考察其催化性能。结果表明,胶液中硅钛比相同时,二次晶化法合成的TS-1分子筛骨架钛含量高于传统方法,且随着胶液中钛含量的增加,骨架钛含量呈增加趋势;当硅钛比为20时,骨架钛含量达到饱和,多余钛原子以锐钛矿形式聚集;TS-1分子筛粒径较小,为200-300nm。由于骨架钛含量高、粒径小,TS-1分子筛在苯酚羟基化反应中表现出较好的催化性能,当硅钛比为20时,苯酚转化率达到最高,为27.30%。

Using ethyl silicate as a silicon source,butyl titanate as a titanium source,and tetrapropylammonium（TPAOH）as a template,titanium silicalite-1（TS-1）molecular sieves with different Si/Ti ratios were synthesized by a re-crystallization method at TPAOH/SiO2 value of 0.1.The structure and morphology of TS-1molecular sieves were characterized by XRD,FTIR,UV-Vis and SEM.The catalytic performance of TS-1molecular sieves was evaluated by hydroxylation of phenol.Results showed that,when Si/Ti ratio in gels was the same,Ti content in framework of TS-1 molecular sieves synthesized by re-crystallization method was higher than that by traditional method,and Ti content in framework increased with the increasing of Ti content in gels.When Si/Ti ratio in gels was 20,Ti content in framework reached saturation,so residual Ti atoms togethered in anatase form.The particle size of TS-1molecular sieves was still 200-300nm in this way.TS-1molecular sieves synthesized by re-crystallization method exhibited the better catalytic performance in hydroxylation of phenol due to their high Ti content in framework and small particle size.The phenol conversion was as high as27.30% when Si/Ti ratio was 20.