晶种法合成ZSM-5分子筛规律的研究

以水玻璃为硅源，采用晶种替代有机模板剂在水热条件下合成ZSM-5分子筛。考察晶化温度、晶化时间、水硅比及合成凝胶pH值对ZSM-5分子筛相对结晶度的影响，结果表明，在无机体系中，当水硅摩尔比n(H2O)/n(SiO2)]为18时，合成ZSM-5分子筛的最佳条件为：晶化时间10～13 h，晶化温度180 ℃，凝胶pH值控制在9左右。采用XRD、SEM等方法对采用晶种和引入有机模板剂正丁胺两种方法合成的ZSM-5分子筛样品进行表征，并以大庆VGO为原料，在重油微反装置上对分子筛进行催化性能评价，结果表明：在原料配比相同的情况下，两种方法合成的ZSM-5分子筛样品的结晶度、晶体形貌都相差不大，且具有较高的结晶度；两种方法合成的ZSM-5分子筛的催化性能差别不大。

STUDY ON ZSM-5 SYNTHESIS BY SEEDED METHOD

ZSM-5 was synthesized by seeded method and compared with that by using template. The sodium silicate was used as a silica source and the products were characterized by XRD, SEM and N2 adsorption. To obtain detailed information on the rules of synthesis process, the effect of crystallization time, crystallization temperature, n（H2O/SiO2）and the initial gel pH on ZSM-5 crystallinity were systematically studied. The results show that the prepared ZSM-5 with relative high crystallinity can be obtained successfully by seeded method at the conditions of crystallization time of 10～13 h，crystallization temperature of 180 ℃，gel pH of 9 under the fixed n(H2O)/n(SiO2)] of 18. No differences are found in physical and chemical properties of ZSM-5 prepared by seeded method and template n-butylamine. The zeolites were tested in a micro fixed-bed reactor using Daqing vacuum gasoline oil (VGO) as a feed. The similar results are observed for the two zeolites.