晶种法合成ZSM-5分子筛规律的研究

STUDY ON ZSM-5 SYNTHESIS BY SEEDED METHOD

摘要：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En（H2O）／n（SiO2）]为18时，合成ZSM-5分子筛的最佳条件为：晶化时间10～13h，晶化温度180℃，凝胶pH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VG0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。

Abstract： 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 ad- sorption. To obtain detailed information on the rules of synthesis process, the effect of crystallization time, crystallization temperature, n（H20）/n（Si02） 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,crystalliza- tion temperature of 180℃ ,gel pH of 9 under the fixed n（H20）/n（SiOz） 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 gas oil as a feed. The similar results are observed for the two zeolites.