液相酸溶液后补钛合成Ti-MWW分子筛

首先在含钠体系硼酸与哌啶用量较少的条件下水热合成B-MWW分子筛前驱体, 然后对其进行液相酸溶液后补钛, 合成了高结晶度的Ti-MWW分子筛. 利用粉末X射线衍射、 氮气吸附-脱附分析、 紫外-可见漫反射光谱和紫外拉曼光谱等技术考察了硅钛比、 温度等后补钛参数对所合成Ti-MWW分子筛的织构性质、 钛物种周围配位环境及催化1-己烯环氧化性能的影响, 确定适宜液相后补钛的硅钛比为30, 温度为373 K. 并且发现, 在后补钛体系中添加少量氟化铵可显著提高所合成Ti-MWW分子筛对1-己烯环氧化的催化活性. 本研究不仅证实了酸处理Ti-MWW分子筛前驱体的脱硼补钛机制, 也为Ti-MWW分子筛的合成提供了一种新的方法与思路.

Post-synthesis of Ti-MWW Zeolite via Titanium Incorporation in Liquid Acid Solution

B-MWW zeolite precursor was first hydrothermally synthesized with less amount of boric acid and piperidine under the condition of sodium hydroxide introduced， and then the incorporation of titanium was performed in liquid acid solution to obtain Ti-MWW zeolite with high crystallinity. With the help of powder X-ray diffraction， N₂ adsorption-desorption characterization， UV-Vis and UV Raman spectroscopies， the effects of parameters including Si/Ti ratio and temperature on the texture properties， the state of titanium species and the catalytic performance in 1-hexene epoxidation of obtained Ti-MWW zeolite were investigated. The Si/Ti ratio and temperature beneficial for titanium incorporation are 30 and 373 K， respectively. Moreover， the catalytic performance of the obtained Ti-MWW zeolite in 1-hexene epoxidation can be significantly improved with a small amount of ammonium fluoride added during post-synthesis. This study not only demonstrates the deboration-based titanium incorporation mechanism during acid treatment of Ti-MWW zeolite precursor， but also provides a new method for the synthesis of Ti-MWW zeolite.