钛硅分子筛的制备、表征及其催化丙烯环氧化工艺的研究

PREPARATION OF TITANIUM SILICALITE,CHARACTERIZATION AND ITS APPLICATION IN PROPYLENE EPOXIDATION WITH HYDROGEN PEROXIDE

以正硅酸乙酯为硅源、钛酸四丁酯为钛源、四丙基氢氧化铵为模板剂,采用水热合成法制备钛硅分子筛。利用X射线粉末衍射(XRD)、紫外-可见吸收光谱(UV-Vis)和扫描电镜(SEM)方法对该分子筛进行了表征。以H2O2为氧化剂、甲醇为溶剂,在淤浆床反应器中研究了钛硅分子筛催化丙烯环氧化反应的性能。结果表明:所制备的钛硅分子筛样品具有典型的MFI结构和良好的结晶度,基本上没有非骨架形式的锐钛矿型TiO2存在;在钛硅分子筛用量1.5g、甲醇用量150mL、30%H2O2用量25mL、2.5%NaHCO3用量0.2mL、反应温度55℃、反应压力0.2MPa、反应时间1h、丙烯流量1L/min的条件下,环氧丙烷选择性和收率分别为98.7%和87.6%。

Titanium silicalite was hydrothermally synthesized with tetraethyl orthosilicate, tetrabutyl titanate and tetrapropyl ammonium hydroxide template. The structures of titanium silicalite were characterized by XRD, UV-Vis and TEM. The characterization results indicate that the samples prepared possess MFI structure and good crystallinity, and no non-frame anatase type TiO2 is found. The performance of catalytic epoxidation of propylene by titanium silicalite was studied in a slurry bed reactor using hydrogen peroxide as oxidant and methanol as solvent. Under the optimized conditions （1.5 g titanium silicalite, 150 mL methanol, 25 mL 30% H2O2, 0.2 mL 2.5% NaHCO3, propylene flow 1 L/min, at 0.2 MPa and 55 °C,reaction time of 1 h）, the selectivity and yield of propylene oxide are 98.7%, 87.6%, respectively.