超细ZSM-5分子筛的制备及其形貌表征

摘要

The influence of different types of structure-directing agents（SDA）,crystallization temperature and content of alumina source on the crystallization of ultra-fine ZSM-5 zeolite was studied.Scanning electron microscope（SEM）,transmitting electronic microscopy（TEM） and X-rays diffraction（XRD） techniques were used to characterize the morphology of the ultra-fine zeolite.The results indicated that the type of SDA had great influence on the crystallization of zeolite.Tetrapropylammonium hydroxide（TPAOH） acted as an excellent SDA for the preparation of ultra-fine ZSM-5 zeolite.Comparatively,the proper temperature for the static crystallization of ultra-fine crystals was in the range from 70 ℃ to 120 ℃ with TPAOH as the SDA.The existence of alumina in the sol-gel inhibited the formation of the crystal nuclei of ZSM-5 zeolite.As a result,without the addition of alumina source,crystallization of zeolite was much faster than that with the existence of alumina source,while an increase in the content of alumina source led to slower crystallization and a much smaller crystal size of zeolite crystallized at the same time of crystallization.%对比考察了模板剂的种类、晶化温度以及铝含量等影响因素对超细ZSM-5分子筛晶化行为的影响,采用扫描电镜（SEM）、透射电镜（TEM）和X射线衍射光谱（XRD）技术对所制备的超细产物的结构及形貌进行了表征。结果表明,模板剂的种类对分子筛的晶化过程有重要影响,四丙基氢氧化铵是优良的制备超细ZSM-5分子筛的模板剂;以四丙基氢氧化铵为模板剂,适宜采用静态法制备超细ZSM-5分子筛的晶化温度为70～120℃;凝胶体系中铝的存在抑制ZSM-5分子筛晶核的生长,无铝条件下,分子筛的晶化速度最快;随着铝含量的增加,分子筛的晶化速度变慢,在相同的晶化时间内,生成的分子筛的粒径更小。