气固相法制备的高效Ti-ZSM-5沸石的表征和催化性能

Characterization and catalytic properties of highly effective Ti-ZSM-5 zeolite prepared by gas-solid reaction

采取变温晶化的方式,以水热法合成了具有较小晶粒尺寸和合适骨架硼含量的BZSM5沸石;以BZSM5沸石为母体,经过预处理脱硼以后,与TiCl4进行气固相反应制备了TiZSM5沸石.利用SEM、XRD、FTIR、UVRaman、UVVis等手段对其进行了表征,并考察了TiZSM5沸石的苯酚羟基化性能.结果表明:该路线制备的TiZSM5沸石晶体粒度较小,具有完整的MFI拓扑结构和较高的结晶度,骨架钛含量较高,不含非骨架钛.该含钛沸石用于催化苯酚羟基化反应,合适的反应条件为:丙酮为溶剂,反应温度343K<T<363K,催化剂用量占苯酚质量的5.0%～10.0%,苯酚与过氧化氢的摩尔比3～6,反应时间3～6h,苯酚的转化率可以达到23%以上.

B-ZSM-5 zeolite with a smaller crystal size and a suitable amount of framework boron was synthesized by modifying hydrothermal synthesis temperature. Ti-ZSM-5 zeolite was prepared by the gas-solid reaction of acid-treated B-ZSM-5 with gaseous TiCl4. The samples were characterized by SEM, XRD, FT-IR, UV-Raman and UV-Vis. The performance of Ti-ZSM-5 in phenol hydroxylation was investigated. The results showed that the smaller sized Ti-ZSM-5 samples had MFI topology structure and high crystallinity, higher content of framework titanium and no extra-framework titanium. The optimal reaction conditions of phenol hydroxylation over Ti-ZSM-5 were as follows： acetone as solvent, reaction temperature 343-363 K, the mass ratio of catalyst to phenol 5.0%-10.0%, the molar ratio of phenol to hydrogen peroxide 3-6, reaction time 3-6 h. Phenol conversion could be more than 23%.