气-固相法制备Ti-ZSM-5及其苯乙烯氧化性能

CHARACTERIZATION AND CATALYTIC PROPERTIES IN STYRENE OXIDATION OF Ti-ZSM-5 ZEOLITE SYNTHESIZED BY GAS-SOLID REACTION

采用变温晶化的方法,水热合成了具有较小颗粒尺寸的B-ZSM-5沸石。以B-ZSM-5沸石为母体,经酸洗脱硼后,与TiCl4进行气-固相取代反应制得Ti-ZSM-5样品。采用SEM、XRD、FT-IR、UV-Vis等手段对其进行了表征,并考察了其在苯乙烯氧化反应中的催化性能。结果表明,采用变温晶化水热合成法得到的Ti-ZSM-5颗粒较小,且具有完整的MFI拓扑结构和较高的结晶度。在苯乙烯氧化反应中,Ti-ZSM-5的骨架钛易于将苯乙烯氧化并转化为苯乙醛,孔道的限制作用将导致生成苯甲醛。适宜的反应条件:丙酮作为溶剂,反应温度333K,催化剂用量占苯乙烯质量的20%,苯乙烯与过氧化氢的摩尔比为3,反应时间4h。在此条件下,苯乙烯最高转化率为26.0%,苯乙醛的选择性达到94%。

B-ZSM-5 with small crystal size was synthesized by adjusting hydrothermal synthesis temperature. Ti-ZSM-5 was then prepared from acid-treated B-ZSM-5 by gas-solid reaction with gaseous TIC14. The Ti-ZSM-5 samples were characterized by means of SEM, XRD, FT-IR and UV-Vis. The performance of Ti ZSM-5 in styrene oxidation was investigated. The results showed that the smaller sized sample prepared by the method above mentioned had MFI topology structure and high crystalline. In the styrene oxidation, the framework Ti in Ti ZSM-5 catalyzed styrene easily into phenylacetaldehyde, and the formation of benzaldehyde could be contributed to the resistance of pore texture in Ti ZSM-5. The best result, styrene conversion of 26.0% and phenylacetaldehyde selectivity of 94 %, was obtained by using acetone as the solvent and under the optimal reaction conditions, that were the reaction temperature 333 K, mass ratio of catalyst to styrene 20 %, molar ratio of styrene to hydrogen peroxide 3, reaction time 4 h.